your analysis is based on basic DC theory, which is insufficient, you need to look at it with AC and transient analysis. There are transient currents and voltages produced during a jump start and due to the nature of the inductive components in the charging system there can be large transient voltages induced, which is what can result in damage to electronics. Scotty is not wrong, his explanation may be wanting, but he is correct; safest way is to have the donor off.
The last connection should always be a negative on the body / frame unless you have dedicated jumper terminals. That way the spark has no chance to ignite the flammable off gasses of a batter. Positive to positive. then neg battery on the dead car, and then frame or non-battery connection on the good car. In the specific case you show, I would do pos to pos, then Neg Battery on the good car then the neg terminal on the BMW because it is away from the battery. If jumping with the BMW being the good car, then pos to pos, neg on the dead car, then neg bat terminal on the BMW (again only because it is away from the battery.) Agree the donner / good car running.
I had to listen to this video several times because everything uou said wa subtly wrong. First of all, you should definitely connect the jumper cables when both cars are shut off. Doing it while the car is on not only increases your own risk of electrical shocks, but increases the risk of you shorting out some sensitive electrical components. Second, you never connect the black jumper cable to the negative post of the Dead car, you connect it to metal on that vehicle that provides grounding. Third, you should always connect in the order of dead positive to donor positive then donor negative to dead ground. That's the way least likely to cause shorts. You talk about voltage requirements for starting vehicles, but that is only half of the equation. You also need enough amperage. In general, when you hook two batteries together in parallel, you're adding the amperage and getting an average for the voltage. Physical size of the battery is not necessarily the important factor, the amperage of the battery is. That's why you can't take 2 9 volt batteries in series and use them to jump start your car. The internal resistance in those batteries means they can't deliver the amperage. You can, however, potentially use them to recharge the battery and then you might be able to start your car. Minimum voltage to start a car is generally around 11.8 volts. That number is for the resting with no load. voltage actually drops significantly below that when you crank the vehicle. The number of amps that are required is based on two things. The first is the displacement of the engine and it's compression ratios. Larger engines with higher levels of compression or more difficult to start because of increased resistance and therefore require greater amperage. The other thing is temperature. The colder it is, the more amps you're going to need. Again, greater resistance in the engine.
We utilized the body grounding point on the BMW. Not every car has a body grounding point (like the Infiniti or Miata) And no 11.8 volts will not be sufficient to start an engine, esp if there is a drain somewhere in the car that caused the battery to die. Last thing you want it to drain the donor battery and cause that car to not start, then you’re left stranded. But yes amperage is important and that’s where the battery size matters as a larger batter with have higher CA ( cranking amps) and CCA (cold cranking amps ) which the bigger number the better, esp in cold.
Good Video!!! But ,I agree with Scotty! 💯 Percent. Now, I I e jumped cars off both ways.But, the safest way is to let the donar car charge the dead battery 4- 5 minutes. Then unhook cables, then start up Dead battery car . Ive had ppl act like I'm crazy for doing it this way , and it takes more time, But it's the only way to be sure you don't fry your electric system.
That is also a great method! But does not work for everyone that’s in a rush! Best method and safest is still using a jump juice or jump pack, you run the least risk that way!
@@partsavatar "Shut the front door" Lol, I borrowed a jump pack from my buddy about 1.5 years ago, my battery was old and dead, the jump pack started my car in LITERALLY 2 SECONDS! 🤯🤯🤯
I wish you had elaborated a little more on giving/receiving a jump with at least one vehicle in which the battery is not located under the hood. What do you do when one or both vehicles have jump points that are not clearly marked? I once tried to get a jump from a Nissan Rogue, the battery of which is somewhere other than under the hood. I was aware that some manufacturers do this, and I looked for several seconds, but didn't find any clearly marked jump points under the hood. I was expecting bare metal bolts with clearly marked red and black labels showing positive and negative. In the end, I thanked the other driver for her willingness to help me, but told her that I wasn't sure where to make the connections and decided not to try risking her engine.
Hey Chris! I will have to find two cars that have jump points like that. I never realized that the Nissan Rouge has points like that, I will have to look into it! - Alex
@@partsavatarmaybe you can connect into a always active accessory plug with your booster pack. Old cars had cigarette lighter plugs. They connected to battery!
@@PeterCrane-y1g the cigarette lighter/power port only has access to 2 or 3 amps at 12 v, and it's protected by a fuse to limit its power draw. Nowhere near the hundreds of amps needed to jumpstart a car.
Thanks Chris, but I believe the booster technology just supplies more voltage. The CURRENT to start the car would come from the battery. As I stated : if in doubt. Do not guess. I meant old cars.
I've always just hooked up the cables you the dead car to the good car connected the right way. Start the good car then start the dead car Never Had A Problem??
I think the safest way of connecting the cables is connect the positive first to the donor and the flat battery (so even if the negative cables touch the positive, nothing happens) and then connect the negative to the donor and the flat battery. Never connect the two cables to the donor and then to the flat battery since even if you try to keep the leads apart, the can touch accidentally and damage the donor.
This is a good way too, but since you don’t see where the other negative is, you don’t want it touching unknowingly! So eyes and hands on both ends is usually the best method imo!
The "dead" battery will have less charge, or can be even dead, which is safer to connect the lower voltage or dead battery first, then plug into the higher voltage charging. Realistically either way will give the same result but less risk this way!
Batteries doesn't need to be of same 'size' all you need is to be able to pass on the required power (amperage) that the dead battery is gonna draw just to crank the starter. I've never seen a car jumper packs of a real battery-size.
Correct that it is the amperage that matters BUT Car Jumper Packs have higher amperage since they are Lithium Ion battery's, Very different then Lead Acid, or AGM as typical car batteries are!
What we did here is negative to body (ground). That will avoid anything shorting out. The best way obv to do it is if you have two people though so you fully avoid any unwanted contact, or as mentioned, a booster pack!
@@partsavatar The point is you are not ensuring the basic rule and that can cause problems, I am not a fan of Scotty and I understand and agree with what you say, BUT you must NEVER ignore the basic rule first off last on.
This Kid has no idea concerning vehicles. He needs to open a owners manual for a new vehicle and read it carefully. If connectly incorrectly you can send a voltage surge back to the new vehicle and completly fry the computer. I worked at a GM dealership and would get 2-3 new vehicles towed in and all required a new ECM and sometimes worse. We began selling Jump Starters in parts. All are fairly discounted!! I carry one in each of our own vehicles and they work great!
You are dead wrong! Do not start the donor car for the first 5 minutes in order to allow the dead battery to recover at least partly up to 12V because it is drawing a lot more Amps than the donor alternator can provide!!! (Been there done that!). Allow the dead battery to recover to 12V. Check if you have a shorted cell also (battery not recovering). Then start the car with the dead battery and see if it's alternator can supply up to 13,5 or 14V. This way you do not endanger the donor car at all!
And then you try to assist a cute girl driving that fancy Rubicon Jeep and you forget about the hidden second battery that many Jeeps have and it ruins your day in more ways than one.
Never trust a kid. Especially a kid who can't draw a car when talking about car's. I'd trust Killgore before a kid who looks likes he has been driving for maybe a year. Example:@2:29 he says a battery that has LESS then 10 volts and proceeds to draw a battery with 10.1 volts. Someone needs to not only relearn math, but they need to start reviewing their videos before posting,
@@partsavatar Yes you look young. But I'm 67 and everybody looks young. And speaking of young, I'd like to get my daughter a set of jumper cables but I'd like to know your opinion on the portable jump starters versus jumper cables. And if you have a recommendation for each in terms of a good brand if you like jump starters, and or a gauge and length for jumper cables. Thanks.
Wow! Correcting one wrong video with another wrong video. Shut off everything in both cars. Removing the keys is a good idea, I will give you that one. You can absolutely jump start a larger battery with a smaller one if the alternator is running - I have done this myself. Start with the DEAD battery, then connect positive of the dead battery to positive of the good battery, negative of the good battery, then an engine block ground on the dead battery side. ALWAYS IN THAT ORDER! NEVER connect to the negative terminal of a dead battery! Start the car with the good battery and wait. In warm weather, wait a few minutes. I REALLY cold weather like -10°F / -23°C or below you may need to wait 5, 10 or 15 minutes before attempting to start the car with the dead battery. Once the car is started, disconnect in the opposite order of connection. It helps to have really thick (low gauge) jumper cables when in cold weather or with larger engines.
Hey @ICEcarOwnerDIY, for the small battery example we were using that example in the terms of how Scotty was saying to start the car, with neither of them running. I’m that case the smaller battery (not running or charging) would not be able to start the bigger battery and die!
About 25 years ago, a mechanic and I once helped a lady jump-start her large SUV's dead battery with the very small four-cylinder car I was driving. The lady expressed concern about the size difference between donor and recipient, but the mechanic assured her that it was okay. It worked fine, of course, because both cars had an old fashioned 12v non-hybrid electrical system and the donor car's engine was running before cabling them up. I wonder if a modern hybrid battery system gone dead would complicate the issue, though, due to the large battery pack drawing more amps than a standard donor car's alternator could provide.
your analysis is based on basic DC theory, which is insufficient, you need to look at it with AC and transient analysis. There are transient currents and voltages produced during a jump start and due to the nature of the inductive components in the charging system there can be large transient voltages induced, which is what can result in damage to electronics. Scotty is not wrong, his explanation may be wanting, but he is correct; safest way is to have the donor off.
The last connection should always be a negative on the body / frame unless you have dedicated jumper terminals. That way the spark has no chance to ignite the flammable off gasses of a batter.
Positive to positive. then neg battery on the dead car, and then frame or non-battery connection on the good car.
In the specific case you show, I would do pos to pos, then Neg Battery on the good car then the neg terminal on the BMW because it is away from the battery. If jumping with the BMW being the good car, then pos to pos, neg on the dead car, then neg bat terminal on the BMW (again only because it is away from the battery.)
Agree the donner / good car running.
I had to listen to this video several times because everything uou said wa subtly wrong. First of all, you should definitely connect the jumper cables when both cars are shut off. Doing it while the car is on not only increases your own risk of electrical shocks, but increases the risk of you shorting out some sensitive electrical components.
Second, you never connect the black jumper cable to the negative post of the Dead car, you connect it to metal on that vehicle that provides grounding.
Third, you should always connect in the order of dead positive to donor positive then donor negative to dead ground. That's the way least likely to cause shorts.
You talk about voltage requirements for starting vehicles, but that is only half of the equation. You also need enough amperage. In general, when you hook two batteries together in parallel, you're adding the amperage and getting an average for the voltage. Physical size of the battery is not necessarily the important factor, the amperage of the battery is. That's why you can't take 2 9 volt batteries in series and use them to jump start your car. The internal resistance in those batteries means they can't deliver the amperage. You can, however, potentially use them to recharge the battery and then you might be able to start your car.
Minimum voltage to start a car is generally around 11.8 volts. That number is for the resting with no load. voltage actually drops significantly below that when you crank the vehicle.
The number of amps that are required is based on two things. The first is the displacement of the engine and it's compression ratios. Larger engines with higher levels of compression or more difficult to start because of increased resistance and therefore require greater amperage. The other thing is temperature. The colder it is, the more amps you're going to need. Again, greater resistance in the engine.
We utilized the body grounding point on the BMW. Not every car has a body grounding point (like the Infiniti or Miata)
And no 11.8 volts will not be sufficient to start an engine, esp if there is a drain somewhere in the car that caused the battery to die. Last thing you want it to drain the donor battery and cause that car to not start, then you’re left stranded.
But yes amperage is important and that’s where the battery size matters as a larger batter with have higher CA ( cranking amps) and CCA (cold cranking amps ) which the bigger number the better, esp in cold.
Good Video!!! But ,I agree with Scotty! 💯 Percent. Now, I I e jumped cars off both ways.But, the safest way is to let the donar car charge the dead battery 4- 5 minutes. Then unhook cables, then start up Dead battery car . Ive had ppl act like I'm crazy for doing it this way , and it takes more time, But it's the only way to be sure you don't fry your electric system.
That is also a great method! But does not work for everyone that’s in a rush!
Best method and safest is still using a jump juice or jump pack, you run the least risk that way!
@@partsavatar "Shut the front door" Lol, I borrowed a jump pack from my buddy about 1.5 years ago, my battery was old and dead, the jump pack started my car in LITERALLY 2 SECONDS! 🤯🤯🤯
See there ya go! :D
Yes, more voltage when running but if you're car is boosting another; the crud that happens on the electrical systems could fry things!!😮
Thats why you have to have the other cars ignition off to no power is running to any systems to avoid that...
@@partsavatar right ,both saying the same thing. I am just stating why.
I wish you had elaborated a little more on giving/receiving a jump with at least one vehicle in which the battery is not located under the hood. What do you do when one or both vehicles have jump points that are not clearly marked?
I once tried to get a jump from a Nissan Rogue, the battery of which is somewhere other than under the hood. I was aware that some manufacturers do this, and I looked for several seconds, but didn't find any clearly marked jump points under the hood. I was expecting bare metal bolts with clearly marked red and black labels showing positive and negative. In the end, I thanked the other driver for her willingness to help me, but told her that I wasn't sure where to make the connections and decided not to try risking her engine.
Hey Chris!
I will have to find two cars that have jump points like that. I never realized that the Nissan Rouge has points like that, I will have to look into it! - Alex
@@partsavatarmaybe you can connect into a always active accessory plug with your booster pack. Old cars had cigarette lighter plugs. They connected to battery!
Good idea. Don't take chances. A lot of current even from a " dead " battery!
@@PeterCrane-y1g the cigarette lighter/power port only has access to 2 or 3 amps at 12 v, and it's protected by a fuse to limit its power draw. Nowhere near the hundreds of amps needed to jumpstart a car.
Thanks Chris, but I believe the booster technology just supplies more voltage. The CURRENT to start the car would come from the battery. As I stated : if in doubt. Do not guess. I meant old cars.
I've always just hooked up the cables you the dead car to the good car connected the right way. Start the good car then start the dead car Never Had A Problem??
Glad it’s worked good for you!
Luckily if you have a newer vehicle
great video and entertaining! I thought Scotty was a little off to.
Glad you enjoyed it
I think the safest way of connecting the cables is connect the positive first to the donor and the flat battery (so even if the negative cables touch the positive, nothing happens) and then connect the negative to the donor and the flat battery. Never connect the two cables to the donor and then to the flat battery since even if you try to keep the leads apart, the can touch accidentally and damage the donor.
This is a good way too, but since you don’t see where the other negative is, you don’t want it touching unknowingly!
So eyes and hands on both ends is usually the best method imo!
Boomba! Even a "dead" battery. Never safe to short any battery!!😮
Correct
Thank you!
You always hook the cables to the donor car first.
The "dead" battery will have less charge, or can be even dead, which is safer to connect the lower voltage or dead battery first, then plug into the higher voltage charging. Realistically either way will give the same result but less risk this way!
Batteries doesn't need to be of same 'size' all you need is to be able to pass on the required power (amperage) that the dead battery is gonna draw just to crank the starter. I've never seen a car jumper packs of a real battery-size.
Correct that it is the amperage that matters BUT Car Jumper Packs have higher amperage since they are Lithium Ion battery's, Very different then Lead Acid, or AGM as typical car batteries are!
Disagree you always connect Neg Last to avoid shorting out, Basic mechanics 101. Rule is (neg) first off last on.
What we did here is negative to body (ground). That will avoid anything shorting out.
The best way obv to do it is if you have two people though so you fully avoid any unwanted contact, or as mentioned, a booster pack!
@@partsavatar The point is you are not ensuring the basic rule and that can cause problems, I am not a fan of Scotty and I understand and agree with what you say, BUT you must NEVER ignore the basic rule first off last on.
Always also remember. The sparks you get from connecting can ignite fumes from battery gases or under hood.
This Kid has no idea concerning vehicles. He needs to open a owners manual for a new vehicle and read it carefully. If connectly incorrectly you can send a voltage surge back to the new vehicle and completly fry the computer. I worked at a GM dealership and would get 2-3 new vehicles towed in and all required a new ECM and sometimes worse. We began selling Jump Starters in parts. All are fairly discounted!! I carry one in each of our own vehicles and they work great!
The whole point of the video is how to connect them correctly. Like I said a jump starter is the safest method of them all…
You are dead wrong! Do not start the donor car for the first 5 minutes in order to allow the dead battery to recover at least partly up to 12V because it is drawing a lot more Amps than the donor alternator can provide!!! (Been there done that!). Allow the dead battery to recover to 12V. Check if you have a shorted cell also (battery not recovering). Then start the car with the dead battery and see if it's alternator can supply up to 13,5 or 14V.
This way you do not endanger the donor car at all!
If there is a draw causing the "Dead" cars battery to drain, you would cause the battery to die in the donor leaving both cars stranded.
And then you try to assist a cute girl driving that fancy Rubicon Jeep and you forget about the hidden second battery that many Jeeps have and it ruins your day in more ways than one.
But you have to remember that electricity actually flows negative to positive.
Current flows from positive to negative and electron flow is from negative to positive.
Never trust a kid. Especially a kid who can't draw a car when talking about car's. I'd trust Killgore before a kid who looks likes he has been driving for maybe a year. Example:@2:29 he says a battery that has LESS then 10 volts and proceeds to draw a battery with 10.1 volts. Someone needs to not only relearn math, but they need to start reviewing their videos before posting,
I look young? Phew thank you! :D
And thanks my math is at a 4th grade level ;)
@@partsavatar Take the criticism. You'll be aight..
@@partsavatar
Yes you look young. But I'm 67 and everybody looks young. And speaking of young, I'd like to get my daughter a set of jumper cables but I'd like to know your opinion on the portable jump starters versus jumper cables. And if you have a recommendation for each in terms of a good brand if you like jump starters, and or a gauge and length for jumper cables. Thanks.
I love all the clowning on Scotty 😂
😂😂
Wow! Correcting one wrong video with another wrong video. Shut off everything in both cars. Removing the keys is a good idea, I will give you that one. You can absolutely jump start a larger battery with a smaller one if the alternator is running - I have done this myself. Start with the DEAD battery, then connect positive of the dead battery to positive of the good battery, negative of the good battery, then an engine block ground on the dead battery side. ALWAYS IN THAT ORDER! NEVER connect to the negative terminal of a dead battery! Start the car with the good battery and wait. In warm weather, wait a few minutes. I REALLY cold weather like -10°F / -23°C or below you may need to wait 5, 10 or 15 minutes before attempting to start the car with the dead battery. Once the car is started, disconnect in the opposite order of connection. It helps to have really thick (low gauge) jumper cables when in cold weather or with larger engines.
Hey @ICEcarOwnerDIY, for the small battery example we were using that example in the terms of how Scotty was saying to start the car, with neither of them running. I’m that case the smaller battery (not running or charging) would not be able to start the bigger battery and die!
About 25 years ago, a mechanic and I once helped a lady jump-start her large SUV's dead battery with the very small four-cylinder car I was driving. The lady expressed concern about the size difference between donor and recipient, but the mechanic assured her that it was okay. It worked fine, of course, because both cars had an old fashioned 12v non-hybrid electrical system and the donor car's engine was running before cabling them up.
I wonder if a modern hybrid battery system gone dead would complicate the issue, though, due to the large battery pack drawing more amps than a standard donor car's alternator could provide.
Why would you even listen to Scotty????
idk you tell me
Kid is FOS , why is someone else trying to change how some does something , MUST BE BORED OUT OF THEIR LITTLE MINDS , GET A HOBBY!!!!
This is a hobby and my job LOL 😂
Kid's doing all right! Better than some.....😂