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Spitfire Jumping a dead battery on a Spit MK1


Jedi Trainee
I had a busy schedule on my last trip home, but I made time to take the Spit for its paperwork. Unfortunately the battery was dead, and it needed a jump start. It's too late, I already tried it and burned something up. I wasn't thinking. darn the reverse grounding. I appreciate out-of-the-box thinking, but why-oh-why did they do that?

Anyway, something is toast, and my best guess and clue from my mechanic is probably the alternator. Is there consensus?

Next time I'll take the battery out of the car and charge it up. That's a $150 impatient mistake for not asking on the forum first. Sigh.

Andrew Mace

Staff member
Country flag
Dan, did something "physically" burn up as in smoke and flames, or is it just that something now appears not to be working? Yes, you could have burned up an alternator if you had one, but odds are pretty good that anyone who fitted an alternator to an older Spitfire would also have reversed the battery polarity to the now nearly universal Negative Ground, seeing as there weren't and aren't all that many Positive Ground alternators around.

Otherwise, it makes no difference how the "dead" car is grounded, nor the "live" car, so long as you make sure the cars don't touch and that Positive goes to Positive and Negative to Negative. Actually, in jumping a Positive Ground car from a modern Negative Ground car, I suppose it might make sense to connect the Negative cables to the respective battery posts and then connect the Positive cable from the jumper car to a good ground on the dead car. Frankly, I never bother with that. (Actually, I've jumped more Negative Ground cars with my Positive Ground Herald than the other way 'round!)


Country flag
Sorry to hear of your trouble Dan - but can we get a bit more specific.

Is the battery still totally dead? Is it holding any charge? What happens when you turn the ignition key?


Jedi Trainee
Thanks Andy and tdskip, no, it didn't really burn up or smoke... drama on my part. The battery had enough juice in it to cause a click, but not enough to turn over. So when I saw the battery was put in backwards, I called my mechanic and he explained it was a positive ground car. He said to reverse the jumper cables. I did, and sparks started to fly. Big sparks. I immediately removed the cables, but then I no longer had the click. I assumed that I burned something out.

Now I am back overseas and can't get at it until July, but I want to have a part waiting for me to put in. I want to work on this myself if possible. This is my learning car. So far, my score card isn't looking so good.

Andrew Mace

Staff member
Country flag
I'm still not totally clear, but now I'm wondering if you were actually ok the first time. But when you reversed the jumper cables, THEN the connection WAS backward? That could cause sparks, I suppose; worse, it could have caused problems with the vehicle from which you were jumping. Or were you just using a bare battery as a jumper source?

Again, on a generator system, I don't think you'd have done much if any harm to the Spitfire, with the possible exception of the "dead" battery.


Darth Vader
It doesnt matter jumping positive ground cars as long as the cables go positive post to positive post and negative post to negative post



Jedi Trainee
I would speculate that the sparking that occurred when the leads were reversed drained what little remained in the Spit's battery. In your position with what appears to be limited time, a new charged battery probably is in your future. Buying anything outside of that would be a bit speculative unless you really need spares. If car is generator equipped, I would suspect the voltage regulator would take a hit sooner than the generator in a quickie reversed lead situation. I guess it all really depends on the amount of time you have to fuss with the car but I can't see being in big rush to buy a new alternator particularly since this sounds like the leads were reversed for a very short time. For those with more time than money and scottish heritage, I've been able to buy some extra mileage out of marginal batteries by dropping an aspirin down each cell and charging. The aspirin seems to clean the plates a bit and buy a little extra oomph.


Jedi Trainee
Lol. I've dropped aspirin in car batteries when I was younger and had forgotten about that trick. Okay, I'll try a good charge on the battery when I get back and go from there. Thanks for all your advice.

P.S. I was jumping the Spit from another car - no damage.
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