Connecting battery jump cables the wrong way.

I am hearing different views on this...

What happens if the battery jump cables (Camry 2003) are connected the wrong way? Will it cause major damage?

Don't modern cars have built-in protection for this scenario?

Reply to
Rav
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Major damage? No, since all it could hurt is electrical stuff. Expensive to replace stuff? Maybe.

That would cost more.

Reply to
Brent P

No, they dont have protection from people connecting two batteries in series aiding circuits. The battery can blow up, etc etc.

You could do a lot of damage to the electrical system which gets expensive in a hurry.

Is your Camry damaged?

Reply to
HLS

It varies from the cables getting really hot and melting on up to the batteries exploding and spraying battery acid all over you.

The batteries don't.

--scott

Reply to
Scott Dorsey

You can't really protect against reversing your primary power storage source very easily. In particular, the alternator diodes can't be protected. The computer is *probably* reasonably safe behind its power conditioning circuits, but the alternator can't be protected in that way and still do its job.

Reply to
Steve

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And it has been known to start fires. If not properly extinquished that could cause major damage.

Reply to
Don Stauffer

What exactly do you mean by "the battery jump cables"? Cables between the battery and what else? I can imagine two different meanings for this unusal phrasing.

--Dave

Reply to
Dave Allured

I understand the term "jump leads" to refer to the pair of cables with very large crocodile clips on the end used to connect one car's battery terminals to those on another so that a car with a good battery can be used to jump-start one with a flat battery.

I woudn't think of the leads within the car, from the battery terminals to the alternator/chassis as being jump leads, though looking more closely at the OP's question I wonder if this might be what he was referring to.

Connecting the battery leads the wrong way round would probably fry the electronics and/or the alternator but probably wouldn't do anything worse than that (though that is bad enough).

Connecting jump leads the wrong way round, so the + on one car is connected to the - on other car and vice versa, would probably cause the leads to melt and may cause one or both batteries to explode. An exploding battery is not something you want to experience. One of the teachers at my school had large bald patches on his scalp and burns on his face apart from "panda eyes" because he was wearing glasses when a battery blew up because he accidentally dropped a spanner which shorted the battery terminals.

Reply to
Mortimer

You're exactly right. There's a lot of misunderstanding about what makes a battery explode. Not that its a bad thing- they CAN explode and people should be careful around them rather than assume that they know when one is more or less likely to explode.

A battery is *most* likely to explode when two conditions are met:

1) its been in a charge cycle recently enough so that there's a lot of hydrogen gas inside it, and some H2 gas is escaping through the vent mechanism and mixing with oxygen in the air. 2) there's a spark near where the H2 is meeting the atmosphere

Battery explosions when hooking up jumper cables are common because even if you do it *right*, both of those conditions are met. The "donor" car is running so its battery is being charged and there's a source of H2. The "recipient" car's battery is dead, but gets a huge surge in charging current when you connect the donor to it, so it makes a lot of H2. And you're connecting leads right at the battery terminal, so there's the spark. That's why the SAFEST thing to do is make the very last connection of jumper cables not to the battery negative post, but to the engine block of one of the cars so that the spark is far away from the battery.

Note that the above assumes both batteries are actually working right and in good condition, but one is just dead.

Things get even riskier when one of the batteries has an internal fault (broken connection or dead cell) because then there can be an internal spark, or the dead cell can act like a resistor, get hot, and boil the electrolyte enough to (possibly) spray out even without an "explosion."

When you hook jumper cables backward neither battery starts producing H2 because they're both DIScharging into each other. But the two batteries form a circular current path in series, and dump energy into the jumper cables and each other at a huge rate, so things start getting really hot really fast. Plus when you make that final connection you get a BIG spark, so any H2 that's lingering around either battery has a good chance of going "boom."

Reply to
Steve

I had a cousin-in-law who worked as a claims agent for an insurance company and Sears was a customer -- He had plenty of cases where DieHard batteries had blown up causing damage -- I don't know the outcomes.

Pete

Reply to
ratatouillerat

I fixed a Taurus that this happened to. It blew the big alternator fuse and fried the remote starter. The remote starter lit up the head lights when it died. I don't remember if the Taurus was the jumper or the jumpee.

Reply to
Steve Austin

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Reply to
man of machines

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