Electricity and car quick question.

On a semi newer car. For a jump, and if you were to put the leads on backwards from a charge pack. Aside from the ensuing shower of sparks, would that conceivably blow the entire engine/electrical system?

Had a customer have a battery jump twice and basically concluded that it was bad alternator as it'd die after it was in gear and started to go. Now a week some later they are trying to claim the jump was bad and blew the whole thing. (Vehicle was left running, but gas not revving engine and headlights dim and them calling a tow truck.) Didn't have swapped cables, but I'm trying to shoot down that claim since otherwise it's more of a he said she said.

There should be a main fuse that protects the electrical system from the battery.
The high current will probably damage the batteries, maybe not making them unusable but internal damage could occur.
The jumper cables could be damaged as it could heat them up quick and melt the insulation/rubber.
The alternator in the charged battery vehicle if it was left running could be damaged as well.
The polarity would be reversed as well which on the dead battery vehicle could damage the sensitive electronic components like the computer or some sensors. I would think that fuse would help protect this though.

It is possible, but I would hope if you do this on a fair occasion you could say it isn't your first rodeo and made sure they were correct.

the best way to try first is disconnect the battery on the good vehicle and hook that up to the dead vehicle. then you only risk your battery and not the good vehicles systems

It's possible to have fried components or a component but it wouldn't fry the entire system.

The main fuse would be on the wrong side if the cables were connected backwards so it wouldn't come into play

There is a very good possibility it fried computers. Modern cars are very sensitive to voltage spikes and reversing the leads can lead to very bad things.

On Euro cars I tell my customers to just have it towed if the battery is dead unless it is an emergency. I have seen multiple dead computers from jumping euro cars.

Want to say like a honda or something. 4 banger. Been a week already hazy as it was run of the mill other than the car not running right.

@wulf. Was a small portable charge pack not a vehicle to vehicle.

I did this once.
Used the wife's 1999 Audi to jump my 2002 F150 - had the cables backwards.
Sparked really nicely, but it only blew two small fuses in the fuse box - accessory, and interior lights - if I remember correctly.
Truck ran fine otherwise.

Don't drink and jump!

Most of the jump pack units have circuitry to disallow current flow if they are on backwards. See if yours has this.

Roomate in college did this to his 87 celica, car caught fire

Most American vehicles have a 150-200 amp maxi fuse that will blow, doesn't sound like it in this case. I had one a while back with the same problem that popped the maxi fuse and fried the fusible link before the alternator. Once I got the maxi fuse in, no charge from the alternator, after some digging I found a burned spot on the link, you might want to check that.

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Originally Posted by J

Most of the jump pack units have circuitry to disallow current flow if they are on backwards. See if yours has this.

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this.

definitely check this. would solve any problems you have if it has that function.

It's a Westward 3LE85R. Chinese made Grainger unit. Couldnt find anything saying it did have it.

Been going around with a few others theoryizing.

Basically what I know: Battery replaced by son day before who's mechanic in Greeley (Honda dealership?). Was a Honda, not sure what other than a 2000+ model. First jump, it died when she put it in gear. Second jump, when I had her turn lights on they were very dim but the engine remained running while I was there several minutes off the charge pack. She was then saying how she was hitting the gas and not getting any rev and I couldn't hear any noises like it was trying. The claim is that I in the second jump had it on wrong and it was shooting sparks.(No) Our pack is still good and the vehicle had the engine running when I had to leave while she was talking to son about a tow.

Theories from assorted places: Main idea being out of warranty, looking for deep pockets to do her repairs.

Son putting battery in (top terminals) had it in reverse initially, fried up some stuff. Car ran enough to make it to work but otherwise got worse and now borked. (Why did we only get a call a week after the fact? What's been done to the vehicle since we had it on property? With a new battery what was wrong with it in the first place to be dead, and then die again after the first jump?)

Car just had an existing issue with charging system or other components, new battery got the car to work, but jumping it from pack not enough for it to get up and go? (But if I'd done the damage she said, wouldn't it not even start I'd think?)


My thoughts include from what you guys said and online. If I'd put it on wrong, and somehow ignored a cascade of sparks. The charging end I thought takes most of the damage (pack is fine), the dead battery could be damaged, and then yes the fused link could burn open. I don't have all the details yet from my boss other than a claim of something like the whole engine? needs replaced or just the entire computer system. (Not clear on this). This was from the dealership/shop son works at. They've told them they need at least 2 more estimates/appraisals from other shops before we'll even begin to debate with them on liability.

My employee and then me following him in turn did fuck up in not having her sign a release. Status quo for most the department had kinda become that we didn't have that book in our car and no one messed with it. (I thought idea had become the little form for check for service (jump/tirechange)and signature wouldnt hold in court?) Being an employee being jumped and knowing how to do a jump I'd always figured not really any risk. Too innocent and didn't consider doing it right, but still being targeted for taking blame. So corporate seems to be ready to leave me on my own so looking at if she wants to try it potentially a civil suit. Hopefully since it's already a he/she said combined with some of the points above that'd throw enough question into it. Was hoping there had been a definitive way of proving that her claim was impossible.

Sounds like they are trying to pull one over on your guys. I'm interested to see what they are wanting replaced.

Make up some unpaid invoices and put a mechanics lien on their vehicle. [Evil]

I do not think it would have started at all if you had the connections reversed. Obviously there were problems with the car before you got there or they wouldn't have called you.

Is it possible when the new battery was installed it was not fully charged and it killed the alternator? I have heard this can happen but have never actually seen it.

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Originally Posted by fitz19d

Basically what I know: Battery replaced by son day before who's mechanic in Greeley (Honda dealership?).

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So a Mom blames her son for damage: unlikely!!

Whole problem solved, all you need to say is when she sues you, son and dealership will be brought into lawsuit.

I know Toyota's have that 100 maxi-fuse that will pop to save the whole system from taking damage. Costs about $100 to replace that fuse, but whole car is disabled at that point.