If he did negative post to negative post and engine block to engine block, no circuit, no harm.
If he did negative post to negative post and positive post to engine block, big problem.
See posts #17 and 19 above.
Since he did not get an impromptu lesson in arc welding I’m thinking he may have been attaching to a painted part of the block And luckily didn’t complete the circuit.
To the OP seriously if you don’t know, don’t do it. You could have done serious damage or hurt yourself.
This is true. The brother of a high-school friend died due to an exploding battery during a jump start. Always read the rules (which should be on a plasticized sheet attached to the cable) or on the front of the battery starter kit.
If you have to use the vehicle:
If possible:
Invest in either a new battery, or better: one of those jumper boxes that carry like an attache case.
See how far you can go/ how many times you can stop/start the engine.
If your problem is the alternator, you are running on the battery and only the battery: it is NOT getting recharged.
If you are away from home when it dies, having a way to re-charge (or replace) the battery will save the cost of a tow truck.
p.s. - always connect the ground LAST - it will save you some arching on the positive post.
Or, belong to AAA.
This is strange. Are you guys saying that what I did should definitely have caused a disaster? Or only that it could have?
I ask because when I did it the wrong way, hooking live-positive to dead-engine block, I put the clamp in exactly the same spot on the engine block that I did later when I did it the right way. This would indicate to me that I did indeed have it touching the block the first time. So why didn’t it explode?
Could have. If the car now starts and everything electrical works correctly, you dodged a bullet. If things like the radio doesn’t work now or the alternator isn’t charging, hooking up the jumper cables backwards could have caused some damage.
It’s possible that your radio presets are gone, but just a very dead battery can do that.
Or the $20-zillion engine computers and stuff operated from the key fob, and $10-zillion dashboard display.
I stopped offering my car as a jump starter in '94.
Could have.
Many many years ago I learned my lesson when I unhooked a positive clamp first (on a forklift). The ratchet hit the something and shorted out and made a big shower of sparks, that was it.
One other time, same forklift, I put the jumper cables on backwards, melted one of the wires that comes off the battery, but that was it. Replaced the wire and everything was fine. It’s not always a disaster, but it certainly could be. I wouldn’t do it for fun.
batteries explode when a spark ignites any built up hydrogen gas in the battery. What you did wouldn’t cause an explosion because you clamped it to the engine.
But if you had made a good connection then all the current in the donor battery would have started to weld the jumper cable to the ground. For whatever reason you didn’t complete the connection.
Very strange. It was literally exactly the same place both times…
Oh well, I’ll just count my fortunes…
Indeed. I did that once, and I was very fortunate that all it did was leave an immediate spot-weld on the other person’s car in the engine bay that she fortunately didn’t make a big deal about. The sparks were pretty impressive as well.
Oh yeah. I lost about an almond size piece of battery terminal. It was just vaporized by the spark. Damn lucky the battery didn’t explodebecause I completed the connection at the battery.
I’ll second the ratchet experience. When I was a kid, about 17, I was working in my truck with more confidence than knowledge. I was removing the battery for some reason and started with the positive terminal. The ratchet slipped from my hand and fell against the quarter panel of the truck. I was rewarded with an amazing shower of sparks and my father’s Craftsman ratchet welded firmly to the panel. I had to hit it with a hammer to release it from the car.
Of course, then I had to do the Walk of Shame into the house and tell my father. That was one of the many times in my childhood he just looked at me and mumbled “dumbass”. Amazing how right my father usually was!
Back in the day…:
Don’t try this at home.
When a diesel truck wouldn’t start, the driver would sometimes run the battery flat trying. We would go out to rescue it but even with a good battery connected in parallel (pos to pos - neg to neg) it wouldn’t start. As a last resort, we would leave the batteries connected for a while with the donor engine running to put some charge into the dead battery, and then use the two batteries in series. This meant that instead of 12 volts, the starter motor would get 24 volts, and thus spin a lot faster, hopefully starting the truck before it burned out.
What kind of rig was this? Most big diesel rigs start on 24 volts and run on 12 volts.
There is a series-parallel switch in the starter circuit that hooks the two 12 volt batteries in series for starting (on 24 volt). Then, once the starting circuit is disengaged, sets them to be parallel with each other for running/charging (on 12 volts). This gives more amps and voltage (power) to the starter.
Semi trucks usually have four six volt batteries for this. Two sets of two six volt batteries in series. Each set of six volt batteries will produce twelve volts. The series-parallel switch will treat each set of two six volt batteries as one 12 volt battery. Using four six volt batteries instead of four 12 volt batteries is because the batteries last longer this way. I do not know how to explain why this is, sorry. Maybe some EE (Electrical Engineer) on this board will be able to explain this for us.
In any case, you either needed two 12 volt batteries, or, if you had just jumped the batteries for a long time, it probably would have charged both 12 volt batteries enough to start the rig. It takes at least 30 minutes of jumping to charge a semi with dead batteries with a pickup. This I know from lots of experience.
IHTH, 48.