@@ogasama6028 Those are the charger's line/input numbers. Usually lots of flexibility there. What matters most is the output that's going in to the device you're charging. Those numbers are important.
I am a college music professor looking to teach this subject in class and you explained it perfectly. I’ve been searching for an explanation like this for a long time. Thank you!
6:17 That "center negative" or "center positive" polarity diagram for barrel connectors was so helpful! I looked at the brick part of the adapter and it was right there! In plain sight!! Many thanks!
Well done. My Elmer who coached me for my general license presented voltage and amperage in virtually the same fashion. He has been a silent key for nearly 30 years but listening to you brought back my memories of him. It is odd that something so simple confuses so many people. I now find myself eager to watch more of your videos. 73's
At the risk of confusing things further, it might help some people with an analogy to demystify what voltage and current (amps) are. The analogy isn't perfect, but helpful in some situations. The analogy is with water in pipes and hoses. Voltage is analogous to water pressure (PSI or Pascals). Current is analogous to flow of water (gallons per minute or liters per minute). The computer is analogous to an "appliance," such as a lawn sprinkler, that you attach to a faucet with a garden hose. And, the power supply is analogous to the faucet connected to the garden hose, limiting the flow of water (current) that goes to the sprinkler. That's why the water pressure (voltage) has to match what the lawn sprinkler can handle. If the water pressure is extremely high, then it might blow out the sprinkler, damaging it. If the water pressure is lower than the sprinkler is designed for, then the sprinkler doesn't operate correctly, dribbling water out and probably not rotating as designed. The results are similar if the flow of water supplied is less than what the sprinkler needs and is designed for.
My wife brought home a Samsung Freestyle Projector… from her clients trash! (Worth about $300). It didn’t work but I noticed it had an 9v Apple charger with it. I bought the correct Samsung 20v charger and it works like a champ. Knowledge is power… or in this case.. money!
I just watched this video and would like to add that if you are reading the specs directly off the charger, make sure to take notice of whether it is rated AC or DC output. Make sure the charger and the device are the same type.
Excellent. Only just seen this video. Very clearly explained, and best explanation I've seen. Can't understand why other videos have to complicate things.
Thank you do much for the refresher. It's been a while since my tinkering days of yore, and I needed to confirm a variable output on a buck box. Since W (P) is drawn, the equations imply that A (I) are drawn as well. But as my grandfather said, measure twice, cut once.
Also important is to plug the power supply into the device first and then into the wall outlet to avoid a surge that could damage your device. When your done unplug the power supply from the wall outlet and then unplug from the device being used.
I have to disagree with that. Power supplies, whether linear or switching contain reactive elements (coils and capacitors). When the power supply first turns on, those devices go through a transient period while they reach a steady state. It is during that transient period that anything bad could happen such as inductive voltage spikes that could potentially damage a device. Likewise, when the device loses power, it again goes from a steady state to a transient state while the reactive devices discharge. Once it has reached a steady state, it will regulate the voltage normally. The WORST that could happen while it is running steady state is that the device attempts to draw to much instantaneous power as might happen during the transient while the device is first plugged in. When that happens, the output capacitor buffering the voltage (present on any kind of related power supply) will be drained too quickly causing drop in voltage -- if the power supply isn't designed to be able to handle the power. A drop in voltage might disrupt the device for a moment; but, it will not damage the device the way that a voltage spike could. So in theory, to be as safe as possible, you should always plug the power supply in first and then plug the device into the power supply once it has reached steady state. Likewise, disconnect the device and then unplug the power supply so that it is not subject to any during shutdown transients. In reality, none of this should be important. A well engineered power supply should be designed to effectively filter the transients or to inhibit voltage output until the transients have subsided. That is why some higher power supplies with large active components may take take a few seconds to power on. When they do, you will hear the click of a relay enabling the power output. That relay is timed based on the length of time that the circuit transient needs to subside. So as long as you purchase power supplies from reputable brands, you shouldn't have any trouble. After all, what would happen during a power glitch? Your power supply and device would have to through power down and then power up transients. If you buy a cheap chinesium power supply from EBay, the engineers might not have spent enough time designing around the transients.
Jumble of B.S. I have been working in electronics for over 50 years. Worked on everything from radar, ICP, GCMS,ICPMS and have seen many devices powered by the beloved WALL WART destroyed by not proper plug in sequence. But this is what you can expect form a theory guy who has never worked in the real world. I guess I was not specific enough ! Have you ever seen a circuit board loaded with CMOS chips get destroyed by static electricity. Switching power supplies cannot handle transient spikes. It may be better now but in the 80s and 90s. We had to replace 5 power supplies in GCMS units because of power surge. Go online and see all of the power line conditioners on the market as well as C.V.T. units for 120, 220 and 440 volt three phase ! Equipment costing 100k or more with power supplies from CHINA that are amazing if the last 5 years !@@timharig
2:11 I was coerced into subscribing. He was answering questions I didn’t know I wanted to know the answers to. Now I know them both. I think he put knowledge in my brain before I could decide if I wanted it in there 😂
Good tip on the polarity. Thanks for all this info. I admit that I only skimmed this video looking to answer my primary question, but am wondering if AC vs DC is discussed, sometimes I see "switching."
Thank you for your video. I am currently looking for a longer barrel cable to connect between my Sony NPF battery plate and an LED light. The light requires 20v 6amps (which the batteries can provide), but so far the only cables I've seen can handle the voltage, but state that the amps should be no more than 3. I take it this will cause problems/damage the cable the cable - or not even work?
Thanks, great explanation! clear & comprehensive. Question though, about 6:15 into your video you delve into polarity. What is the standard? center positive or negative & why would a vendor not use the standard, other than sheer hubris?
Sure you can use a charger with the same voltage and different amperage rating, it will charge at a different rate, but it will still charge. What is voltage, what is current? They actually go together, it might be what’s stamped on the device, but it’s the thing that is being charged that determines the current voltage relationship. You put a load on the battery and current will flow based upon the resistance within the device you are charging, but it’s the voltage that matters and determines how much current will flow. So as long as you don’t exceed the voltage rating for the device, only the current based upon the internal resistance will flow.
I was on my computer and looking for an answer for this subject, you explained it simple and easy to understand that i had togot my phone to like, subscribe and comment on the video. Thank you soo much. 🙏
If it’s lithium ion that you are charging I thought it shortens the life of a battery the higher the amperage charger you use. I’ve had the notion that when charging a lithium battery the slower the charge the longer the overall life of the battery. Is any of this true. Thanks! I appreciate this video!
I have a quick question if you could answer. What if a charging block is rated at an amperage amount that is higher than the power providing source? For example, rating of power supply is 32amps but the power being supplied is rated 24amps both have 240V. This is specific to my level 2 EV charging situation.
Great information. Thank you. This is why TH-cam can be such a powerful learning aid, but it does not work without the support of professional like you.
I have an everstart jumpstarter. The charger that came with it is 19vdc 500mA. I have a laptop charger that is 19v and just shy of 5A. Why do I smell smoke when I plug it in? The voltage is the same. The amps are more. The wattage is high, but I don't understand the problem after watching this video
If you are referring to a USB-x 5V powered device then the actual voltage from the power supply should be 5.1V-5.25V. That is to account for the voltage drop by the cord between the power supply and the device.
This was so helpful! I went through a bunch of videos but couldn't make it past rhe 5 minute mark. I just wanted ti know if i can use my laptop charger to charge my phone. Thank you 🙏🙏
Hello , i have a question regarding one of your videos. The question is : If i connect the drill Charger directly to the drill without charger (The charger 12 and the drill 12v) The drill will work normal, as if it had a battery? Thank you!
I agree that your explanation is absolutely correct. However, product descriptions of my mouse device, which is rechargeable, said that the output current of the charging adapter cannot be higher than 500mA. What do you think about this?
I could see a device designed that way for some reason. Seems like a bad design, but that's why I harp so hard on it being dependent on the quality of the devices involved.
@@hanif6313 If it's labelled that it can't be connected to something over 500mA (which I've never heard of, by the way), then that's what I'd do. USB 2 ports on laptops are supposed to be 500ma, but I believe that changed with USB 3. I would really double check that the mouse really has that restriction.
@@askleonotenboom It's strange to me too. Maybe because it's a Chinese product, the translation wasn't done correctly or there's some ambiguity in the text. The text is 'The output current of the charging power adapter cannot be higher than 500mA.' Anyway, thank you for the guidance you provided
Thanks for clearing it up a bit. But I still am a bit confused. I am looking for a 9V and 2A charger. I found some that support 9V and 3A so by your explanation it's fine. But this exact same charger also supports 6V and 12V. So 3 different voltages. You can't tell the charger which one to use. Can I assume it just knows what to do?
No. It sounds like it might be a special purpose charger intended for specific devices. If you can't tell it what to use, I'd not trust it to use the right one.
Same problem here. I have a device that requires 5v/2a i have a Samsung super fast charger that reads 5v/3a; 9v/3a; etc... I don't know if it'll work or not for the device. You can't select voltage on it. Just a basic Samsung phone charger. I don't get it.
You are definitely the best at explaining it all 100%. Now I have a e scooter needs 54.6v but I only can get a 54.5v. I thinking have the answer but can you tell me yes or no if I should be ok to use this, the parameters are the same.
How can I tell what the polarity is on a device? neither the old power supply or the device (In this case a Elliptical) has no markings. And since power supply is dead no way to check polarity. If I was to put batteries in device could I check polarity of device by measuring the barrel of the device? It seems logical but I don't want to screw it up LOL. Thank you for a great clear informative video :)
Thanks very informative. but how about watts in my charger with different wattage. I mean can i used 33 watts charger for my phone but my old charger is only 20 watts? thanks in advance
If Amps are 'drawn', should I assume Volts are 'pushed'? And if so, why the difference please? (The device draws what it needs, but the power supply is pushing its designated 'load'? Why does the device not draw the volts it also needs?
A voltage supply attempts to maintain a constant voltage. It does this by varying the current to maintain the voltage within its limits. A current supply attempts to maintain a constant current. It does this by varying the voltage within its limits. The vast majority of supplies that you are familiar with are voltage supplies.
May i know about the watt? This is for my monitor adapter. I found something almost similar to original adapter but the original only 65w. And from the shop is 90w. Can you help me here? Thanks
Watt = volts x amps. The 90w adapter should work fine (so long as it provides the same voltage). The adapter provides power, the monitor consumes power. In order for the monitor to work correctly, the adapter must provide at least as much power as the monitor requires. A 90 w adaptor provides 90 watts. That is 25 watts more than the original adapter. It is important that the VOLTAGE of the replacement adapter be the same as the voltage of the original. If the original 65 watt adapter provided 24 volts, then it was rated at 2.7 amps (65/24 = 2.7). The replacement adapter should offer the same voltage as the original, 24 v in this example. A 90w adapter at 24v can therefore provide 3.75 a (90/24 = 3.75). As the video explains, this should be fine.
I have a home address lite which has two 3 W bulbs inside. I have seen two different voltages for the same brand lite some 12 V and some 14 I am trying to convert it to a constant power supply using an adapter Instead of batteries can you please talk about about what is watt and what is amp? How do I choose adapter for this address lite having two 3 W bulbs
@askleonotenboom thank you so much for answering It's hp pavilion dv5 I tried it but the laptop didn't read it (led didn't turn on) because my employer demand proof no matter what
If the power supply has higher amperage than required by the device, would the power supply heat up? Eg that example you have with 100A power supply and 0.5A device, it won't damage the device but would it heat up and become e a fire hazard for the power supply (eg an adaptor)?
I have a question, please answer it - My mobile's charger output says 3 different values are: 5V 3A/9V 2A/12V 1.4A (it's a fast charger) and I have a smartwatch and earbuds both needs to be input of 5V 2A. Now the question is that can I use that charger to charge these devices or should I use 5V 2A charger only?
Hi Sir, kindly answer it My phone support 100W charging....i want to charge with slow charger..... in the original charger least 20W are mentioned and I'm using Apple original 20W charger. but the phone only Get 4W why? kindly explain
Depends on the situation, but yes, generally. That's why the cables to your car battery are so thick. Still 12 volts, but when starting the car the draw is many, many amps.
Can I use an AC power supply/converter to charge a 1000w LiFePO4 solar power station into it's (5521) DC INPUT? (the AC invertor is dead, but all else works fine) The spec on the DC input is: 12-30V 7A 200W Max. The port is actually provided to enable you to charge the power station while your driving you car. It has a cable with a 5521 male plug on one end, and a male cigarette plug on the other. If this can work, what configuration should I get for a power supply? Any help on this is greatly appreciated.
@@askleonotenboom how would it damage the same considering that it would only give the same amount of ampere? Is it not the electrons that generate heat? So if the same 2 amperes circulate in a circuit, what is the difference? Is not voltage a mere potential difference and resistance determines the amount of current?
It. Does. Not. Work. That. Way. If this were true you could plug a 110v U.S. lightbulb into a 220v European power source - if you do that the bulb will explode. Devices are designed for a specific voltage. Period.
In your example you said if u have a device that needs 5v and 1A and your charger is 5v and 1.5A so it can be slow or unlikely damage the device but nearly you said that it's ok if your charger A more than device takes, I'm confused , or their something I missed
Can I power multiple with devices with one supply? Let's say I cut and split the wire. If the voltage is equal and the sum input amperage is covered that sounds useable. But what would you do if there are different devices with different voltages. Can a resistor be put to drop the voltage? What is this kind of setup called? I'm planning on an iot project and got about 6 of these bricks in a very confined space.
It is possible, but I don't recommend it. I've done something similar: I have a bunch of radios that charge on 12v, and one silly pair that requires 9v. I purchased a 12v->9v converter. It's not as simple as just adding a resistor.
With the use of an appropriate adaptor, can i interchange a 5v1A micro USB switching adaptor power supply (which has no polarity symbol) with a 5v 1A positive polarity Barrel power supply
I believe you are making some confusion with the terms here. Tha voltage refers to eletrical tension and is either 110V or 220V that comes out of the outlet. In this explanation, matches a 19 watts power supply with a 19 watts, watts not volts. Am I mistaken?
You are mistaken. ALL electricity has a measurement for both voltage and current. Power, measured in watts, equals voltage times current. Both sides of the power supply have a voltage across them and a current running through them. The input takes 110V or 220V. The input current will vary based on the load of the output. The output is 19V up to 1.58A of current. Assuming that the device uses the full 1.58A at the full 19V, it will be using 19V×1.58A = 30 watts. If we further assume that the input is 110V, then the input current being drawn would theoretically be 30W/110V = 0.27A. Realistically, the current will be a little higher do to conversion loss.
In my experience my devices always broke when I use more amperage . My bar keypad phone required 5v 0.5A, but whenever I used 5v 2A or 3A it always damaged my phone, then I bought 5v and 0.75A, which is working just fine. I charged my Redmi Buds 4 lite with 5v 3A charger, it cooked them and not working anymore.
hello sir. I have a question....I have a plug in phone that requires 5v 2amps....from the wall...can I power it over a battery charger thats portable, for cell phone....it has the same power requirements....5v 2amps, thanks
I have an external HD that only specifies volts (12) and the DC symbol (dashed lines). No indication of amps or polarity on the device, in the manual, or on manufacturer's website. Fortunately, I found an image of the charger for the model on line. But what does it mean if a device doesn't give you all the necessary information? Are there default values?
I have a charger that also says it's 14.4VA. What is this and can it be disregarded if following the other advice you gave regarding volts & amps.? Thank you.
@@benvaughan9525 Then I would pay attention to the 24V and 0.6A. As it turns out 0.6 * 24 = 14.4, so I would assume "VA" probably means Volt-Amps, which is another possible name for Watts.
@@askleonotenboom Thanks, but it says 24V 0.6A 14.4VA. Wikipedia says VA is Volt-Ampere but I don't understand the explanation it gives. Any chance you can take a look and make some sense of it. It would be good to know if it can be safely ignored and just go on the volts and amps? Thank you.
Oops....... the specified voltage on a transformer is the correct voltage when the current being drawn is at the specified maximum of the transformer. If you are using a device which requires 5V 1amp and you use a transformer which can supply 5V 2amp, then the actual output voltage applied to the device will be greater (significantly) than the specified 5V. Case in point: My laptop requires 5V 1amp. When using any 5V 2amp transformer, my laptop charging goes completely haywire! After changing to a 5V 1amp charger the laptop charging is exactly as it should be. I've been using the 5V 1amp charger for two years now and my laptop with the 5V 1amp charger has not missed a beat!
"a transformer which can supply 5V 2amp, then the actual output voltage applied to the device will be greater (significantly) than the specified 5V." This is absolutely false. It should produce 5V regardless. Something else is going on.
How about adapters/chargers that output multiple voltage? For example my Macbook air adapter gives 5V-9V-15V-20V at different amp, is it OK to use it for devices with small battery of say 200-300mah max (with the producer stating on the device Input: 5V-400mah max, my Xiaomi Mi band 8 for example)?
USB-C has a data protocol that gives it the ability to negotiate the voltage for faster charging. If you plug a dumb device into it, it will default to 5V. In order to get the higher voltages, you will need a smart device to request them. Smart devices will not request higher voltages than they can handle. So you can plug the fast charger into a 5V only device so long as the power supply has a 5V amp rating higher than the device plugged into it.
so I have a AC to DC charger for a hairclip buzzer (Wahl brand). it runs at 4v and 2a. the charger block isn't a USB, it's a clumsily and heavy corded charger. I wanted to switch to something small and portable, preferably a USB charger, that I can take for travel and connect it to any of the charger outlets I have that have usb slots. I found a USB charging cable online that I have purchased that runs on 5 volts( of course all USB is 5v standard) that can fit on my Wahl hair buzzer. so I'm basically now using this USB charging cable on a charging block that is rated 5v 2a on a 4v 2a device (Wahl) and it works fine.
what if i have a battery charger that says 2A and i want to charge batteries that the company suggests the 4.5A charger. Will the batteries be charged slower and that's all or it may be a problem later with the batteries?
@@askleonotenboom it's a laptop i searched a lot for the same charger ..but nothing ...I'm already using that charger "6.3A" it seems fine .. thanks leo ,have a good day
Dear Leo i hope you can help me. I am in the UK. I have an Alfred Cam Plus outdoor security camera, it is powered by a C charger cable that goes in to a power charger/ adapter. Written on the adapter is the following: input 100-240V ~ 50/60Hz 0.25A max Output 5v --- 1000mA What I want to know is what is the 0.25A max? And is that an important factor when looking for a new charger/adapter as my adaper is broken and I cant seem to find one with exactly the same figures as the ones above. The camera itself has a label underneath that says 5V --- 1A Ive been told that any phone charger such as samsung or iphone would work but i dont want to fry it lol... could you please advise me? Thank you
5V-1A is what you care about. That's the power being provided to your device. The 0.25A is a measure of the max power that would be drawn from your line/wall socket power.
@askleonotenboom Hi Leo, thank you for the fast reply... so as long as the new adapter I buy has the output of 5v --- 1000mA it will be ok? I have Samsung phone chargers with that output, so I can use one of them without fear of over heating the security cam?
Hello Leo! i have a situation that i am not sure if these comply! i have created a power supply to charge a 5S Lithium battery that needs 21 volts to fully charge, i have manage to fix the voltage exactly 21 volts, knowing that it will never meet exactly the full charge but its ok, But my problem is that the amperage is a little more than 5 amps...and as we know , lithium batteries must not exceed 1,16 amps while charging , but i have 5 in series, will it distribute nicely or having them in series make it one battery? Will it be sustainable to charge 5 amps at 21 volts a 5S 1P battery? Thank you in advance for your answer! Geozibra!
WRT amperage, I could well be wrong, but I suspect that if the device being charged requires a higher amperage than the charger can supply, it's possible that the charger could overheat because too much load is being applied to it. If that happens, the charger could be damaged, possibly even catch fire, and the device being charged could also be damaged. Please correct me if I'm wrong about this.
In generall that's NOT the case. You don't "pull" more amperage out of a charger - it provides what it provides. Now, with that being said, chargers have many different designs, characteristics, and more. Some could in fact overheat. But the kinds of chargers we're generally talking about here (USB 0.5 amp chargers perhaps the most common), will just provide what they can provide and charge slowly, if at all, if more than what they provide is really required.
Afternoon, Sir. Was recently gifted a portable record player from Japan. The *Anabas GP-N3R.* And being a ‘beginner’ (at best) when it comes to all things all things electronics, I had no clue that I could not use the same 8V adaptor it came with here in Canada. So without taking up to much of your time & if you don’t mind me asking, might you know what I could purchase as a replacement for it that will suffice? Thanks kindly for your time. A lovely day to you & yours. *Now subscribed.* Cheers!!!*
Hello please i want an answer my new adapter laptop OUTPUT is exactly as same as the original which is 20V and 14a but its hugely different in the input amperage which my original has 4a and the new one is 1.5a will that damage my laptop?
Volts and amps combine to confuse. Understanding how they work can help clear it up.
Thanks Leo!!
Thank you, Sir.
Respect from India
About wiggle room, Can I use a 250V 10A charger as a replacement for 220V 5A charger?
@@ogasama6028 Those are the charger's line/input numbers. Usually lots of flexibility there. What matters most is the output that's going in to the device you're charging. Those numbers are important.
One of the confusion questions we asked regarding choosing power connector
"Amperage is drawn, not pushed." That's the clearest explanation I have ever heard. Thank you!
Yes.. I never understood this… until now. Thanks Leo!
Same here 😀
"voltages must match and amperage must either match or exceed that required by the device" -- concise and practical, thank you!
I am a college music professor looking to teach this subject in class and you explained it perfectly. I’ve been searching for an explanation like this for a long time. Thank you!
6:17 That "center negative" or "center positive" polarity diagram for barrel connectors was so helpful! I looked at the brick part of the adapter and it was right there! In plain sight!! Many thanks!
Well done. My Elmer who coached me for my general license presented voltage and amperage in virtually the same fashion. He has been a silent key for nearly 30 years but listening to you brought back my memories of him. It is odd that something so simple confuses so many people. I now find myself eager to watch more of your videos. 73's
He’s a joy to watch and listen to. Not bad looking either 😊. Thank you for sharing this video in such an easy to understand way ❤
Thank you!
This is the best video I have ever seen explaining this is super simple terms. Thank you so much
A lucid and to the point explanation. Loved it. Keep up the good work.
At the risk of confusing things further, it might help some people with an analogy to demystify what voltage and current (amps) are. The analogy isn't perfect, but helpful in some situations. The analogy is with water in pipes and hoses. Voltage is analogous to water pressure (PSI or Pascals). Current is analogous to flow of water (gallons per minute or liters per minute). The computer is analogous to an "appliance," such as a lawn sprinkler, that you attach to a faucet with a garden hose. And, the power supply is analogous to the faucet connected to the garden hose, limiting the flow of water (current) that goes to the sprinkler. That's why the water pressure (voltage) has to match what the lawn sprinkler can handle. If the water pressure is extremely high, then it might blow out the sprinkler, damaging it. If the water pressure is lower than the sprinkler is designed for, then the sprinkler doesn't operate correctly, dribbling water out and probably not rotating as designed. The results are similar if the flow of water supplied is less than what the sprinkler needs and is designed for.
this analogy just explain the voltage part of the thing not amperage. And actually I believe you are referring to wats and not volts in this analogy.
This is by far the best explanation of this topic that I have found. Well done, and thanks.
Thank you for making this! This is exactly what I was looking for. Super helpful and well done.
My wife brought home a Samsung Freestyle Projector… from her clients trash! (Worth about $300). It didn’t work but I noticed it had an 9v Apple charger with it. I bought the correct Samsung 20v charger and it works like a champ. Knowledge is power… or in this case.. money!
Thank you, sir. Simplicity is the ultimate sophistication...!
I just watched this video and would like to add that if you are reading the specs directly off the charger, make sure to take notice of whether it is rated AC or DC output. Make sure the charger and the device are the same type.
Excellent. Only just seen this video. Very clearly explained, and best explanation I've seen. Can't understand why other videos have to complicate things.
This is so helpful and easy to remember! Maybe now I can trim down the pile of various old usb chargers I have lying around too.
Thanks for your time I've been working in electronics for a long time. And this is the first clarification I've really heard
Thank you do much for the refresher. It's been a while since my tinkering days of yore, and I needed to confirm a variable output on a buck box. Since W (P) is drawn, the equations imply that A (I) are drawn as well. But as my grandfather said, measure twice, cut once.
Also important is to plug the power supply into the device first and then into the wall outlet to avoid a surge that could damage your device. When your done unplug the power supply from the wall outlet and then unplug from the device being used.
I have to disagree with that. Power supplies, whether linear or switching contain reactive elements (coils and capacitors). When the power supply first turns on, those devices go through a transient period while they reach a steady state. It is during that transient period that anything bad could happen such as inductive voltage spikes that could potentially damage a device. Likewise, when the device loses power, it again goes from a steady state to a transient state while the reactive devices discharge.
Once it has reached a steady state, it will regulate the voltage normally. The WORST that could happen while it is running steady state is that the device attempts to draw to much instantaneous power as might happen during the transient while the device is first plugged in. When that happens, the output capacitor buffering the voltage (present on any kind of related power supply) will be drained too quickly causing drop in voltage -- if the power supply isn't designed to be able to handle the power. A drop in voltage might disrupt the device for a moment; but, it will not damage the device the way that a voltage spike could.
So in theory, to be as safe as possible, you should always plug the power supply in first and then plug the device into the power supply once it has reached steady state. Likewise, disconnect the device and then unplug the power supply so that it is not subject to any during shutdown transients. In reality, none of this should be important. A well engineered power supply should be designed to effectively filter the transients or to inhibit voltage output until the transients have subsided.
That is why some higher power supplies with large active components may take take a few seconds to power on. When they do, you will hear the click of a relay enabling the power output. That relay is timed based on the length of time that the circuit transient needs to subside.
So as long as you purchase power supplies from reputable brands, you shouldn't have any trouble. After all, what would happen during a power glitch? Your power supply and device would have to through power down and then power up transients. If you buy a cheap chinesium power supply from EBay, the engineers might not have spent enough time designing around the transients.
Jumble of B.S. I have been working in electronics for over 50 years. Worked on everything from radar, ICP, GCMS,ICPMS and have seen many devices powered by the beloved WALL WART destroyed by not proper plug in sequence. But this is what you can expect form a theory guy who has never worked in the real world. I guess I was not specific enough ! Have you ever seen a circuit board loaded with CMOS chips get destroyed by static electricity. Switching power supplies cannot handle transient spikes. It may be better now but in the 80s and 90s. We had to replace 5 power supplies in GCMS units because of power surge. Go online and see all of the power line conditioners on the market as well as C.V.T. units for 120, 220 and 440 volt three phase ! Equipment costing 100k or more with power supplies from CHINA that are amazing if the last 5 years !@@timharig
2:11 I was coerced into subscribing. He was answering questions I didn’t know I wanted to know the answers to. Now I know them both. I think he put knowledge in my brain before I could decide if I wanted it in there 😂
Thank you! This is exactly what I was looking for. Very helpful
Thank you for educating me to this question that I've had forever.
Damn man, this is the clearest explanation I've ever heard in my life
Good tip on the polarity. Thanks for all this info. I admit that I only skimmed this video looking to answer my primary question, but am wondering if AC vs DC is discussed, sometimes I see "switching."
Thank you for your video. I am currently looking for a longer barrel cable to connect between my Sony NPF battery plate and an LED light. The light requires 20v 6amps (which the batteries can provide), but so far the only cables I've seen can handle the voltage, but state that the amps should be no more than 3. I take it this will cause problems/damage the cable the cable - or not even work?
hey thanks leo, i always had this doubt about the amperage, thank you
Thanks, great explanation! clear & comprehensive. Question though, about 6:15 into your video you delve into polarity. What is the standard? center positive or negative & why would a vendor not use the standard, other than sheer hubris?
In my experience there's no real standard. Center positive seems the most common, BUT it's not something you can count on.
Sure you can use a charger with the same voltage and different amperage rating, it will charge at a different rate, but it will still charge.
What is voltage, what is current? They actually go together, it might be what’s stamped on the device, but it’s the thing that is being charged that determines the current voltage relationship. You put a load on the battery and current will flow based upon the resistance within the device you are charging, but it’s the voltage that matters and determines how much current will flow. So as long as you don’t exceed the voltage rating for the device, only the current based upon the internal resistance will flow.
I was on my computer and looking for an answer for this subject, you explained it simple and easy to understand that i had togot my phone to like, subscribe and comment on the video. Thank you soo much. 🙏
If it’s lithium ion that you are charging I thought it shortens the life of a battery the higher the amperage charger you use. I’ve had the notion that when charging a lithium battery the slower the charge the longer the overall life of the battery. Is any of this true. Thanks! I appreciate this video!
Thanks Leo! I learned something again. Always was confused about the amperage thing. JimE
I have a quick question if you could answer. What if a charging block is rated at an amperage amount that is higher than the power providing source? For example, rating of power supply is 32amps but the power being supplied is rated 24amps both have 240V. This is specific to my level 2 EV charging situation.
Addressed in the video. As long as the power supply is rated higher than that needed by the device being charged, all is well.
I watch a few different IT guys. Each of them are different. But you Leo.......... You really take us to class..
Great information. Thank you. This is why TH-cam can be such a powerful learning aid, but it does not work without the support of professional like you.
FINALLY I UNDERSTOOD,THANK YOU! IT CANNOT BE CLEARER.
I have an everstart jumpstarter. The charger that came with it is 19vdc 500mA. I have a laptop charger that is 19v and just shy of 5A. Why do I smell smoke when I plug it in?
The voltage is the same. The amps are more. The wattage is high, but I don't understand the problem after watching this video
sir...the way you explain is so great...you keep repeating the importance point..which it had deep eatching deep in my memory..thank
Thanks 🙏
Is 5.2 V output instead of 5V too much? Or does it fall within the "small" difference? Thanks
No way to know. It depends on the specific device.
@@askleonotenboom I see. Thank you 🙏
If you are referring to a USB-x 5V powered device then the actual voltage from the power supply should be 5.1V-5.25V. That is to account for the voltage drop by the cord between the power supply and the device.
A question that was lingering a long time became a useful piece of knowledge that I will pass on alot I presume.
Thanks
This was so helpful! I went through a bunch of videos but couldn't make it past rhe 5 minute mark. I just wanted ti know if i can use my laptop charger to charge my phone. Thank you 🙏🙏
short and simple and elegant explanation , thank you
Hello , i have a question regarding one of your videos. The question is : If i connect the drill Charger directly to the drill without charger (The charger 12 and the drill 12v) The drill will work normal, as if it had a battery? Thank you!
No idea. Maybe? Probably? There's no way for me to know for sure, since it depends on the specific devices involved.
Thanks, man. I learned a lot with this video. You are the best!
I agree that your explanation is absolutely correct. However, product descriptions of my mouse device, which is rechargeable, said that the output current of the charging adapter cannot be higher than 500mA.
What do you think about this?
I could see a device designed that way for some reason. Seems like a bad design, but that's why I harp so hard on it being dependent on the quality of the devices involved.
@@askleonotenboom So, I have to find an adapter with 5V and 500mA, right? Does a USB connector of my laptop provide exactly 500mA?
@@hanif6313 If it's labelled that it can't be connected to something over 500mA (which I've never heard of, by the way), then that's what I'd do. USB 2 ports on laptops are supposed to be 500ma, but I believe that changed with USB 3. I would really double check that the mouse really has that restriction.
@@askleonotenboom It's strange to me too. Maybe because it's a Chinese product, the translation wasn't done correctly or there's some ambiguity in the text. The text is 'The output current of the charging power adapter cannot be higher than 500mA.' Anyway, thank you for the guidance you provided
Thanks for clearing it up a bit. But I still am a bit confused. I am looking for a 9V and 2A charger. I found some that support 9V and 3A so by your explanation it's fine. But this exact same charger also supports 6V and 12V. So 3 different voltages. You can't tell the charger which one to use. Can I assume it just knows what to do?
No. It sounds like it might be a special purpose charger intended for specific devices. If you can't tell it what to use, I'd not trust it to use the right one.
Many have a switch to select the voltage.
Same problem here. I have a device that requires 5v/2a i have a Samsung super fast charger that reads 5v/3a; 9v/3a; etc... I don't know if it'll work or not for the device. You can't select voltage on it. Just a basic Samsung phone charger. I don't get it.
needed to refresh my memory, thanks Leo :) quick and easy
You are definitely the best at explaining it all 100%.
Now I have a e scooter needs 54.6v but I only can get a 54.5v. I thinking have the answer but can you tell me yes or no if I should be ok to use this, the parameters are the same.
As outlined in the video there's no way for me to know. Maybe? Depends on the quality of the devices involved.
I needed to know this, as im getting some Vtech consoles and Vtech power adapters are INSANELY hard to find or expensive.
How can I tell what the polarity is on a device? neither the old power supply or the device (In this case a Elliptical) has no markings. And since power supply is dead no way to check polarity. If I was to put batteries in device could I check polarity of device by measuring the barrel of the device? It seems logical but I don't want to screw it up LOL. Thank you for a great clear informative video :)
Thank you for sharing your knowledge and time 😊
Thanks very informative. but how about watts in my charger with different wattage. I mean can i used 33 watts charger for my phone but my old charger is only 20 watts? thanks in advance
If im having source of 20A 250V, should i able to charge my devices on this source like AC power plug and etc
If Amps are 'drawn', should I assume Volts are 'pushed'? And if so, why the difference please? (The device draws what it needs, but the power supply is pushing its designated 'load'? Why does the device not draw the volts it also needs?
A voltage supply attempts to maintain a constant voltage. It does this by varying the current to maintain the voltage within its limits. A current supply attempts to maintain a constant current. It does this by varying the voltage within its limits. The vast majority of supplies that you are familiar with are voltage supplies.
Question i have a hauppauge 9100. It says 5volts no amps specific . Can i use a generic 5 volt output with 1 amp adapter.
May i know about the watt? This is for my monitor adapter. I found something almost similar to original adapter but the original only 65w. And from the shop is 90w. Can you help me here? Thanks
Watt = volts x amps. The 90w adapter should work fine (so long as it provides the same voltage). The adapter provides power, the monitor consumes power. In order for the monitor to work correctly, the adapter must provide at least as much power as the monitor requires. A 90 w adaptor provides 90 watts. That is 25 watts more than the original adapter. It is important that the VOLTAGE of the replacement adapter be the same as the voltage of the original.
If the original 65 watt adapter provided 24 volts, then it was rated at 2.7 amps (65/24 = 2.7). The replacement adapter should offer the same voltage as the original, 24 v in this example. A 90w adapter at 24v can therefore provide 3.75 a (90/24 = 3.75). As the video explains, this should be fine.
I have a home address lite which has two 3 W bulbs inside. I have seen two different voltages for the same brand lite
some 12 V and some 14
I am trying to convert it to a constant power supply using an adapter Instead of batteries
can you please talk about about what is watt and what is amp?
How do I choose adapter for this address lite having two 3 W bulbs
03:24
Hp input
18.5 V dc / 3.5 A
65 W
or
19 V dc / 4.74 A
90.06 W
And the new charger input
19.5 V dc / 4.62 A
90.09 W
Is it safe to use?
There's no way to know. Could be. But it also could not be. It depends ENTIRELY on the specific devices in play.
@askleonotenboom
thank you so much for answering
It's hp pavilion dv5
I tried it but the laptop didn't read it (led didn't turn on)
because my employer demand proof no matter what
How do I reduce the amperage cos I'm not investing in a charger this time. I could put some bulbs in between or something?
i can charge li-ion batteries in a 2A charger but with 0,5 or 1 A adapter?
Excellent clarification. I have a question. Can I use a power bank to power on the laptop without internal battery? Thank you.
Usually, yes.
If the power supply has higher amperage than required by the device, would the power supply heat up? Eg that example you have with 100A power supply and 0.5A device, it won't damage the device but would it heat up and become e a fire hazard for the power supply (eg an adaptor)?
Nope.
I have a question, please answer it - My mobile's charger output says 3 different values are: 5V 3A/9V 2A/12V 1.4A (it's a fast charger) and I have a smartwatch and earbuds both needs to be input of 5V 2A. Now the question is that can I use that charger to charge these devices or should I use 5V 2A charger only?
Should be fine. It's a USC-C smart charger.
Thank you sir, your explanation is very clear and easy to understand. It really helps.
Hi Sir,
kindly answer it
My phone support 100W charging....i want to charge with slow charger..... in the original charger least 20W are mentioned and I'm using Apple original 20W charger.
but the phone only Get 4W
why?
kindly explain
Thanks, Leo! How do I find out the voltage and amps that my device require? Is there somewhere on my phone or laptop that indicates that?
The users manual should have it.
@@askleonotenboom My manual just says battery capacity is 4500mAh. No mention of voltage. I have a Samsung Galaxy S20FE. Thanks!
Would higher amperage or current not affect cable size? Because higher current have thicker wires
Depends on the situation, but yes, generally. That's why the cables to your car battery are so thick. Still 12 volts, but when starting the car the draw is many, many amps.
Can I use an AC power supply/converter to charge a 1000w LiFePO4 solar power station into it's (5521) DC INPUT? (the AC invertor is dead, but all else works fine)
The spec on the DC input is: 12-30V 7A 200W Max.
The port is actually provided to enable you to charge the power station while your driving you car. It has a cable with a 5521 male plug on one end, and a male cigarette plug on the other.
If this can work, what configuration should I get for a power supply?
Any help on this is greatly appreciated.
Thank you so much sir, I am grateful to you, with this I can finally finish a project, and solve a doubt I had for years.
Thank Sir Leo, You explain everything i want want to hear.
Voltage is the product of resistance and current, so what is the difference between a 9 volts 2A and 12 volts 2A? Would that damage a device?
12v could damage a 9v device. The math has little to do with it.
@@askleonotenboom how would it damage the same considering that it would only give the same amount of ampere? Is it not the electrons that generate heat? So if the same 2 amperes circulate in a circuit, what is the difference? Is not voltage a mere potential difference and resistance determines the amount of current?
It. Does. Not. Work. That. Way. If this were true you could plug a 110v U.S. lightbulb into a 220v European power source - if you do that the bulb will explode. Devices are designed for a specific voltage. Period.
In your example you said if u have a device that needs 5v and 1A and your charger is 5v and 1.5A so it can be slow or unlikely damage the device
but nearly you said that it's ok if your charger A more than device takes, I'm confused , or their something I missed
Got it backwards. If the charger has more Amps (1.5) than the device needs (1A), all will work normally.
@@askleonotenboom thanks , now I understand, you are a life saver )
Can I power multiple with devices with one supply? Let's say I cut and split the wire. If the voltage is equal and the sum input amperage is covered that sounds useable. But what would you do if there are different devices with different voltages. Can a resistor be put to drop the voltage? What is this kind of setup called?
I'm planning on an iot project and got about 6 of these bricks in a very confined space.
It is possible, but I don't recommend it. I've done something similar: I have a bunch of radios that charge on 12v, and one silly pair that requires 9v. I purchased a 12v->9v converter. It's not as simple as just adding a resistor.
Thank you my case is 12. Volts 3.33 Amp the old one.. and the replacement is 12 volts but 5 Amp. God bless and kudos
With the use of an appropriate adaptor, can i interchange a 5v1A micro USB switching adaptor power supply (which has no polarity symbol) with a 5v 1A positive polarity Barrel power supply
Use your voltmeter to verify the polarity.
I believe you are making some confusion with the terms here. Tha voltage refers to eletrical tension and is either 110V or 220V that comes out of the outlet. In this explanation, matches a 19 watts power supply with a 19 watts, watts not volts. Am I mistaken?
You are mistaken.
ALL electricity has a measurement for both voltage and current. Power, measured in watts, equals voltage times current.
Both sides of the power supply have a voltage across them and a current running through them. The input takes 110V or 220V. The input current will vary based on the load of the output.
The output is 19V up to 1.58A of current. Assuming that the device uses the full 1.58A at the full 19V, it will be using 19V×1.58A = 30 watts. If we further assume that the input is 110V, then the input current being drawn would theoretically be 30W/110V = 0.27A. Realistically, the current will be a little higher do to conversion loss.
In my experience my devices always broke when I use more amperage . My bar keypad phone required 5v 0.5A, but whenever I used 5v 2A or 3A it always damaged my phone, then I bought 5v and 0.75A, which is working just fine. I charged my Redmi Buds 4 lite with 5v 3A charger, it cooked them and not working anymore.
Thank you sir, you have explained this so well. I have taken this in, very helpful.
hello sir. I have a question....I have a plug in phone that requires 5v 2amps....from the wall...can I power it over a battery charger thats portable, for cell phone....it has the same power requirements....5v 2amps, thanks
Make sure that it's DC not AC. If DC then yes, seems like it should work (along with all the other cautions from the video)
yes sir it says 5vdc output 2 amps
I have an external HD that only specifies volts (12) and the DC symbol (dashed lines). No indication of amps or polarity on the device, in the manual, or on manufacturer's website. Fortunately, I found an image of the charger for the model on line. But what does it mean if a device doesn't give you all the necessary information? Are there default values?
There aren't really default values that I know of.
I have a charger that also says it's 14.4VA. What is this and can it be disregarded if following the other advice you gave regarding volts & amps.? Thank you.
Not sure, but I would read that as 14.4V.
@@askleonotenboom Thanks, but it says 24V 0.6A 14.4VA. Can you solve this mystery? :)
@@benvaughan9525 Then I would pay attention to the 24V and 0.6A. As it turns out 0.6 * 24 = 14.4, so I would assume "VA" probably means Volt-Amps, which is another possible name for Watts.
@@askleonotenboom Thanks, but it says 24V 0.6A 14.4VA. Wikipedia says VA is Volt-Ampere but I don't understand the explanation it gives. Any chance you can take a look and make some sense of it. It would be good to know if it can be safely ignored and just go on the volts and amps? Thank you.
@@benvaughan9525 That's exactly what I said in my prior reply: "Then I would pay attention to the 24V and 0.6A."
Oops....... the specified voltage on a transformer is the correct voltage when the current being drawn is at the specified maximum of the transformer. If you are using a device which requires 5V 1amp and you use a transformer which can supply 5V 2amp, then the actual output voltage applied to the device will be greater (significantly) than the specified 5V.
Case in point: My laptop requires 5V 1amp. When using any 5V 2amp transformer, my laptop charging goes completely haywire! After changing to a 5V 1amp charger the laptop charging is exactly as it should be. I've been using the 5V 1amp charger for two years now and my laptop with the 5V 1amp charger has not missed a beat!
"a transformer which can supply 5V 2amp, then the actual output voltage applied to the device will be greater (significantly) than the specified 5V." This is absolutely false. It should produce 5V regardless. Something else is going on.
I almost bought a new charging brick with a lower amp rating for one of my devices. Thanks for the clear explanation.
I could like the video 10000000 times if possible... you are the best!
How about adapters/chargers that output multiple voltage? For example my Macbook air adapter gives 5V-9V-15V-20V at different amp, is it OK to use it for devices with small battery of say 200-300mah max (with the producer stating on the device Input: 5V-400mah max, my Xiaomi Mi band 8 for example)?
USB-C has a data protocol that gives it the ability to negotiate the voltage for faster charging. If you plug a dumb device into it, it will default to 5V. In order to get the higher voltages, you will need a smart device to request them. Smart devices will not request higher voltages than they can handle.
So you can plug the fast charger into a 5V only device so long as the power supply has a 5V amp rating higher than the device plugged into it.
so I have a AC to DC charger for a hairclip buzzer (Wahl brand). it runs at 4v and 2a. the charger block isn't a USB, it's a clumsily and heavy corded charger. I wanted to switch to something small and portable, preferably a USB charger, that I can take for travel and connect it to any of the charger outlets I have that have usb slots. I found a USB charging cable online that I have purchased that runs on 5 volts( of course all USB is 5v standard) that can fit on my Wahl hair buzzer. so I'm basically now using this USB charging cable on a charging block that is rated 5v 2a on a 4v 2a device (Wahl) and it works fine.
what if i have a battery charger that says 2A and i want to charge batteries that the company suggests the 4.5A charger. Will the batteries be charged slower and that's all or it may be a problem later with the batteries?
As I say in the video there's no way to know. Typically they charge slower, but poor quality equipment could have other ideas.
Thank you...this has made what I have learned even clearer. Very nice video.
My device needs 19v ..6.5A ... What do you think about using 19v ..6.3A ? Thanks
Addressed in the video. Depends on the device.
@@askleonotenboom it's a laptop i searched a lot for the same charger ..but nothing ...I'm already using that charger "6.3A" it seems fine .. thanks leo ,have a good day
thank u! man this can get confusing. than you soo much! even here in 2022, this still helped me greatly
Dear Leo i hope you can help me. I am in the UK. I have an Alfred Cam Plus outdoor security camera, it is powered by a C charger cable that goes in to a power charger/ adapter. Written on the adapter is the following:
input 100-240V ~
50/60Hz 0.25A max
Output 5v --- 1000mA
What I want to know is what is the 0.25A max? And is that an important factor when looking for a new charger/adapter as my adaper is broken and I cant seem to find one with exactly the same figures as the ones above.
The camera itself has a label underneath that says 5V --- 1A
Ive been told that any phone charger such as samsung or iphone would work but i dont want to fry it lol... could you please advise me? Thank you
5V-1A is what you care about. That's the power being provided to your device. The 0.25A is a measure of the max power that would be drawn from your line/wall socket power.
@askleonotenboom Hi Leo, thank you for the fast reply... so as long as the new adapter I buy has the output of 5v --- 1000mA it will be ok? I have Samsung phone chargers with that output, so I can use one of them without fear of over heating the security cam?
is power supply 5v 2a same as a phone charger 5v 2a..? thinking to use my spare phone charger to my led strip as always plug in power supply.
Yes. If your LEDs specify 5V 2A then a 5V 2A phone charger will work.
Hello Leo! i have a situation that i am not sure if these comply!
i have created a power supply to charge a 5S Lithium battery that needs 21 volts to fully charge, i have manage to fix the voltage exactly 21 volts,
knowing that it will never meet exactly the full charge but its ok,
But my problem is that the amperage is a little more than 5 amps...and as we know , lithium batteries must not exceed 1,16 amps while charging , but i have 5 in series, will it distribute nicely or having them in series make it one battery? Will it be sustainable to charge 5 amps at 21 volts a 5S 1P battery?
Thank you in advance for your answer!
Geozibra!
WRT amperage, I could well be wrong, but I suspect that if the device being charged requires a higher amperage than the charger can supply, it's possible that the charger could overheat because too much load is being applied to it. If that happens, the charger could be damaged, possibly even catch fire, and the device being charged could also be damaged.
Please correct me if I'm wrong about this.
In generall that's NOT the case. You don't "pull" more amperage out of a charger - it provides what it provides. Now, with that being said, chargers have many different designs, characteristics, and more. Some could in fact overheat. But the kinds of chargers we're generally talking about here (USB 0.5 amp chargers perhaps the most common), will just provide what they can provide and charge slowly, if at all, if more than what they provide is really required.
Afternoon, Sir. Was recently gifted a portable record player from Japan. The *Anabas GP-N3R.* And being a ‘beginner’ (at best) when it comes to all things all things electronics, I had no clue that I could not use the same 8V adaptor it came with here in Canada. So without taking up to much of your time & if you don’t mind me asking, might you know what I could purchase as a replacement for it that will suffice? Thanks kindly for your time. A lovely day to you & yours. *Now subscribed.* Cheers!!!*
I have pc with 19V input. And have charger 19.5V . Same Ampere
Just Difference 0.5v.
Can I use that 19.5V Charger for my PC 19V?
No way to know. Could be OK. Could do damage. Depends on the PC and the charger.
Hi, how about watt? if voltage matches. but higher watt. will it burn?
The video covers this, I believe. No it won't "burn".
Thank you! Just bought digital clock that needed adaptor. It does not work on batteries. God Bless You!
Hello please i want an answer my new adapter laptop OUTPUT is exactly as same as the original which is 20V and 14a but its hugely different in the input amperage which my original has 4a and the new one is 1.5a will that damage my laptop?
We care only about the output.
@@askleonotenboom why?
@@hashscannerofficial Because that's all that matters to the device your connecting it to.
I fucking love this video. It answers the question so clearly I'm unlikely to ever need to watch it again. But I will be subscribing. Thank you!