Battery Discharge Characteristics
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- เผยแพร่เมื่อ 4 พ.ค. 2015
- In this lesson we'll discuss battery discharge characteristics. We’ll examine voltage regulation, discharge curves, and discuss factors that influence battery capacity like age of the battery, temperature, and discharge rate.
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At 35:40 the vertical axis is mislabeled. It should say "Power (W)". Additionally, the horizontal axis at 41:21 should be labeled "time (minutes)"
I hope this video rises again to the public and gains much more views
Oh dear
I think I just fell down a rabbit hole of electric knowledge
Sink or swim time
Dude, that's serious in-depth discussion... TY
Here's a map to the first set of tunnels! th-cam.com/play/PLdnqjKaksr8qQ9w3XY5zFXQ2H-zXQFMlI.html
Very Helpful indeed. I am doing a physics investigation on the discharge rate of batteries as a function of temperature so this was helpful.
Das hätte ich ohne Dich nie verstanden !!!! Danke !!🙏🤓 wirklich super aufgebaut 🥇
Very good ... i wish everybody on youtube would talk sense like this
Really Nice Explanation. Thank you..!!
Really well explained Sir. I appreciate how simply you explained the complicated things.
Word!
Very informative! I'm looking forward to any future battery-related videos on your channel. Well done and thank you!
Very helpful! Thank you!
Great lecture!
This is gold!!!!!
Thanks it was really helpful. 🙏
Good explanation !
@12:29 "approximately 8.41 volts" lol. Pretty specific. This is an amazingly excellent video. Thank you!!
Excellent.
Good lesson, of course...
thanks
Jim, I still remember the advice the old timer, pre OSHA mechanic gave me... "Kid, always keep one eye closed when you're working on them batteries"
Thumbs Up!
Thank you for the video. I have a question though, how can I get the exact discharge characteristics of my car battery. I was not able to find any manuals or data sheet for the same on the manufacturer's site.
Tough question. The critical piece of data is cut off voltage. Discharge beyond the cutoff voltage and you damage the battery. Check out Battery University at: batteryuniversity.com/learn/
*This. Right here.* Is a perfect example of some Aureated-American losing a race, then changing the game in mid-flight. Thomas Edison Intel & Microsoft are fine examples of such the conundrum. Jim placed it on paper for all to see; thank you.
Really Excellent lecture Jim, how we got the 123 m-ohms in voltage regulation at 11:02. is it should be 92.07 m-ohms? I lost there.
Linear approximation of data points from Excel.
I need to play ang replay this video in order for me to understand it. thank you!
Hi Jim, Thanks a lot for the great video. I have one question at 24:28. For the 24Ah, I thought the 1 C20, the discharge current should be 1.2A, so for the 0.02 C20, the the discharge current should be 24mA. Is there any thing I missed in the video? =)
Yes C rates can be confusing. While it's true over the course of a 20 hour test a 24Ah battery would be discharged at 1.2A (ie: the .05C rating) to keep things simple customarily the discharge rate is expressed as a multiplier times the capacity. (ie: 1 times 24Ah).
@@bigbadtech O.K. Got it. Thanks for the explanation. =>
@@bigbadtech it's only became clear to me after watch video explanation about 1-2(C20) times;)
Thanks
Are there models online that you can input battery characteristics and get these curves?
I've never seen any. My go to for all things battery is Battery University at: batteryuniversity.com/
this explains my sucky battery, great info, cant wait for superconductors to be added into the equation, would make the math very easy no? Or does 0 resistance break ohms law when you try to divide by 0?
Sir hope you are fine
In manufacturing of battery there is no capacitor involved in lead acid battery
I want to confirm that you are talking about the resistor and capacitor which are built in rectifier
Plz clear my point
Waiting for your response
Thank you❤
Wow, you nailed my question about internal resistance. I am considering using an Arduino to determine the ESR of the used Li-Ion cells I am harvesting. It will save me time and energy to get an idea quickly if the cell is at the end of its life cycle or if it has a chance to be resurrected again. I wouldn't need it to be as accurate as of the results from a calibration lab. It would be a reference to grade the general health of the cell.
Since the voltage drop curve is exaggerated at the start going from 0.0A to 0.1A and perhaps even higher, what current points would you choose if you were to build a tester? Would you pick something like 100mA and 1.0A for two points or would you go even higher? I will be wanting this to also test other types of rechargeable batteries and I fear I may damage some cells if the test current exceeds the max safe level.
Speaking of maximum current ratings, I have questions about discharge C-Ratings. If I understand what you said, the manufacturer has determined the battery's optimal capacity using the discharge C-Rating as a function of time. Then you mentioned it also has a different number associated with this C rating to express the maximum safe discharge draw. You used several multipliers including 0.02, 0.05,, 0.1, 0.2, 0.5, 1.0, 2.0, etc. as examples. Where do I find this additional information? Finding the spec-sheets is difficult for many of the cells I come in contact with. Just finding the C-Rating is difficult enough let alone this multiplier you spoke of.
In your experience, can you say that an unmarked cell might have a general C-Rating and multiplier rating? For instance, when dealing with a Nimh cell are there typical C-Ratings that apply if they didn't make it obvious?
You mentioned that the subject covering the C-Rating is very slippery. I see a lot of information about how others determine the safe maximum discharge current by simply multiplying the C-Rating with the mAh rating. Are these cells not only advertising the capacity in mAh but the multiplier too? This would mean a 1000mAh battery with a 20C rating (designed to deliver optimal energy with a 50mA load) could safely handle a 20A discharge rate. Given the same conditions for a 100C rated battery, it implies it could be discharged with a staggering 100A ( compare that to the optimal 10mA recommended by the manufacturer). I did notice that the sites were talking about racing LiPo batteries and they were happy with a battery only delivering its power for a couple minutes before it was drained. They were using large capacity batteries such as one battery was rated 1600mAh with a discharge rating of 150C. He claimed he used it for his drag-strip racing and it could safely deliver 240A with burst current of 480A for a short duration just to finish a race.
I feel if a manufacturer put a higher C-Rating then the battery was designed to deliver a lower current not, a higher current these guys are talking about.
Battery University, the answer to all your questions and more! batteryuniversity.com/
As to the voltage regulation curve 12V 7 Ah, a bit uncertain about the formula.If current is 0 E = 12.68 as per the formula. Whereas You said when 0.14 A is drawn the battery provides 12.89 V to the load. When current is 0.14A then internal voltage loss is 0.123 Om x 0.14A = 0.017 V and the output voltage to be 12.66V and not 12.89 V.
Sir can you help in finding an equation for the voltage vs time curve shown for different load currents.
I'd hit up a mathematician for curve fitting advice. Really the only 2 points of interest are the sled hill at the start and the roll off into the cliff at the end. In between these 2 action zones you can probably use a simple y=mx+b linear approximation.
Dear sir,
Great vid, thanks. I have a
2 Pack - 12V 55Ah agm Scooter Battery UB12550 Group 22NF for Pride Jazzy 1115.
I used these 2 batteries in series for a 24 volt system to power my riding lawn mower.
I use a me-1004 DC 11 hp motor. When the mower is on its pulls 22 amps.
I never use it for more than 25 minutes. I have two digital displays that shows me the charge state of each battery. When the mower is on, the charge state meter drops. When the mower is off, the charge state meter is about 12.6 for each battery. Would you please let me know volt limit amount I should never go below when the mower is running as indicated by the state of charge digital meter? I don't know the C rating. It seems like these two batteries are degrading very quickly the more I use them. I got these batteries at Amazon and was promise a 3 year warranty about two months ago.
Thanks
robviolin1 Rob, unfortunately I'm going to have to give you my official "I cannot give professional engineering advice without being actively involved" response. This being said, check out the datasheet for the UB1550 at:
upgi.com/Themes/leanandgreen/images/UPG/ProductDownloads/40740.pdf
This will make a great homework assignment to practice the skills in this video! Check out the second page top right.
Thanks Jim for the data sheet. Thanks also for your reply. Most people don't even reply. I have a degree in music, so this battery stuff is very strange to me. Could you tell me what you think would be a choice of a battery ( I need two 12 v batteries in series for 24v system), that would give suitable power to handle a draw of 22 amps for 30 minutes? For example:
1. Two 12v batteries with 100 ah with a C rating of 20 that is an AGM will be a good choice , but only for 30 minutes at a time.
2. Only buy 12v 200 ah batteries .
I guess I need an "easy to understand" general formula that tells me how much residence (like a DC motor) a battery can handle and for how long.
Your vids are great but are light years ahead of my current level of understanding.
Thanks again for sharing.
robviolin1 All things being equal cost would be the primary concern for the two different configurations. Unfortunately, nothing in electronics is "easy to understand" ... that's why technicians make the big bucks! Take heart though ... I designed the "Batteries" playlist to plug into the "Basic Electronics 1: DC Circuit Analysis" playlist early on after a student has finished "Unit 4: DC Series Circuit Analysis". Pretty much everything you need is right there for the taking. Check out the welcome and orientation at:
th-cam.com/video/Do7VzDuB_Rc/w-d-xo.htmlm41s
Thanks for the interest!
Thanks
"that's why technicians make the big bucks!" I wish.
so, what is the safe discharge current in ampere for a 12v batter?. because we need to always take count how many battery for a system. this didnt gave me any answer. im aware of all this but all the video only tell us the problem but didnt realy answer any question. as 12v battery can gave us 10A max off early discharge, taking the factor of time and 50% discharge max rate, im assuming the best rate to take is around 4to5Amp max to drain as when it reach the 50% discharge mark.it will reach around 5 to 7 amp max. so to have about a 1000 watt usage on a 24v system. you will need a 24v parallels of 6 in minimum to safely discharge for a 1kw system. if you are using 12v battery, that would be around 12batteries in 24vseries. 6couple in parallel
Need help here.. what is the Vf rating in battery..usually china drill battery using that rating which unusually higher that standart Volt rating.
I can only guess what "Vf" means however float voltage (ie: slightly higher than nominal voltage) is an excellent supposition.
discharge time for discharge current of 3.5A should be 7/3.5=2 hrs. So, how did you decide for 63 mins here at 35:24.
How are you calculating the time? I would appreciate your reply
It's not a calculation. It's experimentally obtained data. The battery reaches the manufacturer's recommended cutoff at 63 minutes, much sooner than you'd think because it's being discharged at a much higher rate than that used to determine the nominal energy content of the battery.
Good and helpful information, but it is not easy to keep the focus. Please, do not read a long list and try to go step by step.
11:55 - 12:15 I m laughing so hard
I just wonder why 70 % of this lecture is the same as the Introduction to Batteries lecture?
Isn't it C20 = 0.05C, C10 = 0.1C, C5 = 0.2C ? I am a bit confuse why it is always C20 when you add number in front of C, like 0.05C20 which as I understand you mean 0.05C?
Common confusion because C rating is a capacity measurement AND discharge current may also be expressed as a function of capacity. You are correct that the discharge current at C20 would be 1/20th (or .05 of capacity measurement).
My brain hurts. What did I do to deserve this?
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