Arcing while jump starting battery

[greyhair]

Had to replace my battery yesterday.
Prior to replacing it I tried to jump start it.
Followed the directions in Mazda owners manual, posotive to posotive and grounding the negative lead on the boot latch rather then the MX5's battery terminal.

When I went to secure the lead clamp to the boot latch I got a lot of arcing and sparks.
When I went to start my Ford prior to starting the Mazda it would not turn over.
Dissconnected the booster leads and they were really hot and smelt of burning plastc.
the Ford kicked over no problem when the jumper leads were taken off.

Called NRMA and they jump started the Mazda with a portable jump start without problem.

Thought the purpose of connecting the negative lead to the body was to prevent arcing and potential for battery gases to ignite?
Did I do something wrong?
Have jump started cars in the past without this problem.

[hks_kansei]

was it in the correct order?

I cant remember the order to connect the leads but I know there is one.


I used to jump my 626 just with straight neg to neg, pos to pos, without and issue, and have jumped the Mondeo the same way with no problems.

[AJ]

sounds to me like you had the leads around the wrong way.....not saying you DID, but hot jumpers, sparks & no kick generally means jumpers were bass-ackwards

[Jeo]

I've used the earth on the body where the battery grounds itself many times before, just because its easier than reaching the negative terminal. As in positive to positive, negative to ground.

Have also done straight positive to positive, negative to negative a few times before I figured that.

I never understood people trying to tell me "there's an order". Correct me if I'm wrong but my understanding of car electronics says positive is positive, no matter where it is; the negative terminal connects directly to the body, so any exposed metal connected to the chassis is a ground/negative, no matter where it is. Therefore, negative is negative and positive is positive, as long as you get that right you can't really stuff it up can you? (other than the obvious shorting somewhere, but thats not that hard to avoid; don't let the two ever touch.)

[Kain]

I'd say some people recommend connecting them in a specific order (Negative, then positive) just for safety reasons. The power flows from positive to negative, but it isn't particularly choosy about which 'negative' it connects to. For example, if you connect the positive first then accidently brush the negative jumper against a speaker wire or something, you be pushing 12V into the speaker, which would most certainly kill it. Bit of a silly example, but you get the point.

So I'd say the order isn't a necessary step, but just a 'good practice' one. I'm just explaining how it makes sense to me, so feel free to correct me if I'm wrong

[greyhair]

Pretty sure i had the leads connected correct way, have jump started cars before when have connected the negative to negative and posotive to posotive on the batteries.
This was first time that I have connected the negative clamp to a metal part of the car body but that is what the manual says to do.
Ive got a trickle charger connected to the battery now so hopefully will not get a flat battery in the future.

[Benny]

Personally, I always use the battery's contacts, as you get the very best connection that way.
Using a part of the body for the earth, or negative polarity, can often lead to a decrease in power as many body parts are rubber mounted or the contact is poor, especially if the part is painted.

Mounting the leads directly will always mean there is much less chance of any drop in current or volatage.

Just my 2c worth.

[AJ]

Personally, I always use the battery's contacts, as you get the very best connection that way.
Using a part of the body for the earth, or negative polarity, can often lead to a decrease in power as many body parts are rubber mounted or the contact is poor, especially if the part is painted.

Mounting the leads directly will always mean there is much less chance of any drop in current or volatage.

Just my 2c worth.

X2

[TieNN89]

Personally, I always use the battery's contacts, as you get the very best connection that way.
Using a part of the body for the earth, or negative polarity, can often lead to a decrease in power as many body parts are rubber mounted or the contact is poor, especially if the part is painted.

Mounting the leads directly will always mean there is much less chance of any drop in current or volatage.

Just my 2c worth.

X2

x erh 3?

[Garry]

The theory is that mounting the negative lead to an earth point rather than to the battery negative terminal is that you avoid any sparking near the battery which could lead to an explosion. I'm not sure if this has ever happened though. And seeing as the MX5 uses a vented battery the chances of an explosion would be virtually zero.

Maybe the boot latch wasn't a good earth point? Though I'm not sure why you'd be getting extra sparks or why the donor car wouldn't start. I've used both methods in the past and haven't had any problems, though I've never used the boot latch as the earth.

[Juffa]

http://en.wikipedia.org/wiki/Jump_start_(vehicle)

and

http://en.wikipedia.org/wiki/Arcing

J

[corners]

If everything is off in the car then there should be minimal or no arcing.

If there is arcing there is something pulling power which is prob why the battery is draining...

[marcusus]

If everything is off in the car then there should be minimal or no arcing.

If there is arcing there is something pulling power which is prob why the battery is draining...

If you've connected a second battery to the dead one, then of course something will be on, as that second car will be running.

The arc isn't caused from the dead battery because, well, it's dead.

[corners]

If everything is off in the car then there should be minimal or no arcing.

If there is arcing there is something pulling power which is prob why the battery is draining...

If you've connected a second battery to the dead one, then of course something will be on, as that second car will be running.

The arc isn't caused from the dead battery because, well, it's dead.

That right. The arc will be caused by something in the car requiring power thus causing the dead battery in the first place.

[marcusus]

That right. The arc will be caused by something in the car requiring power thus causing the dead battery in the first place.

But you won't be able to get an arc at all if the battery is dead. And you wouldn't hook up jumper leads to a battery unless it's dead.

And I think I just got what you were trying to say... You're saying make sure that when you're going to do a jump start, make sure everything in the car to be jumped has everything off, otherwise it will arc. Wish I'd got that the first time round instead of having this round about conversation