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  #1  
Old 09-11-2012, 10:10 AM
t walgamuth's Avatar
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Reversed battery cables on my Formula Ford

I accidentally reversed the cables on my Formula ford.

To summarize the race car does not have much in it electrically. It has no alternator being a total loss system running the ignition only, which is points and condensor. There is a small battery on board and a large MB diesel battery which is used to start so that the little battery does not get worn out.

The booster battery has a large plug in which I ran over recently and replaced. In doing so I managed to reverse the pos and neg. I ran the car this way at at least one event without clear evidence of problems.

In the last few days I have been chasing starter difficulties and noticed a dead short situation under some situations. Yesterday at 4 am I woke up and while up had the flash that I had reversed the cables in the plug. I got up and went to the garage and verified it.

Yesterday evening I repaired the mistake on the cables and am now wondering what else is damaged. I don't think the coil or the guages are damaged but my little battery seems to be fried. I thought it was going to explode before I got it unhooked last night when I attached the booser battery with the correct positioning of the cables.

Anybody have experience which will verify what can be damaged by reversing the battery cables?

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  #2  
Old 09-11-2012, 10:21 AM
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I did the same thing on my VW years ago.

The only damage I discovered was that I fried the voltage regulator...it was an older setup where the regulator was a separate unit apart from the alternator. I later swapped out for the upgraded alternator with the built-in regulator.

Did the same years later and THIS time, I fried a rather expensive stereo head unit! Even after repairs, it was never the same.

Since you aren't running an alternator, and it sounds like the rest of the race car is all business with little if any electrical "convenience" frills, I suspect you haven't really destroyed much. Sounds like the starter has a "flat spot" though, and it may not be tied to the reverse polarity issue.

I am surprised that the starter didn't try to rotate the flywheel in the opposite direction though...
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  #3  
Old 09-11-2012, 10:26 AM
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Quote:
Originally Posted by t walgamuth View Post
Yesterday at 4 am I woke up and while up had the flash...
Ha ha! Welcome to my world.
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Old 09-11-2012, 10:32 AM
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Tom,

It sounds like there's nothing with semiconductors, so you're probably home free. Do you have any kind of electronic engine monitor or anything else that might have semiconductor electronics?
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  #5  
Old 09-11-2012, 11:22 AM
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No, no fancy schmancy engine monitors.

there is no chance the little battery can be saved is there?
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..I also have a 427 Cobra replica with an aluminum chassis.
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  #6  
Old 09-11-2012, 12:06 PM
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I don't know about the battery...

Many 60's Britcars ( incuding my '69 Austin America) were meant to be positive ground (earth) and it was a simple matter to change to negative ground. Seems to me there was a procedure needed to get the generator to charge, IIRC. So , there's probably little to no damage to anything unless "modern" electronics are involved.
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  #7  
Old 09-11-2012, 01:05 PM
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Originally Posted by rs899 View Post
I don't know about the battery...

Many 60's Britcars ( incuding my '69 Austin America) were meant to be positive ground (earth) and it was a simple matter to change to negative ground. Seems to me there was a procedure needed to get the generator to charge, IIRC. So , there's probably little to no damage to anything unless "modern" electronics are involved.

Yes, in the generator days, you sometimes had to polarize the generator to get it to charge in the correct direction. It was a simple matter of shorting a couple of particular pins on the regulator together.

Tom, I don't know how you would save the battery if it's fried. What happens if you put a battery charger on it? In the right direction that is.
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  #8  
Old 09-11-2012, 01:10 PM
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i dunno. Last night with the big jump battery attached with the correct wire location the little battery got very hot, put off smoke and steam and started whistling. I felt lucky to get it off before it exploded.
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..I also have a 427 Cobra replica with an aluminum chassis.
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  #9  
Old 09-11-2012, 01:14 PM
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Little battery gone. Just replace it. What type of ignition system do you run? Is there a ballast resistor? The ignition system is the only thing electrical on the vehicle?

MV
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  #10  
Old 09-11-2012, 01:15 PM
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So am I correct in assuming that if there's no recharging system on the car the only time the battery could have been damaged was when it was being jump started by big brother?

In that situation the little battery (here I'm also assuming it is a lead acid type) could have gotten a bit hot and bothered and if you left it connected to big brother for too long it could have gotten so hot that it exploded - however as there's no mention of expolsions in the story - the next thing to check is if it still holds its charge.

You could also check the electrolyte acid level.

If in doubt take the battery to either an aircraft maintenance place or a boat yard where they still clean out batteries and replace electrolyte - as I'm sure you know a motorfactors will just sell you a new one.

EDIT - I see you've added more information whilst I was typing. Smoke and steam - it's probably a gonner but if you can test the cells...
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Last edited by Stretch; 09-11-2012 at 01:16 PM. Reason: More information came whilst I was typing!
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  #11  
Old 09-11-2012, 01:15 PM
t walgamuth's Avatar
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Plus the water temp, oil temp and tach.

I figured the little battery is gone but felt it did not hurt to ask.
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..I also have a 427 Cobra replica with an aluminum chassis.
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  #12  
Old 09-11-2012, 01:52 PM
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If you really want to try and save the small battery, remove it and hook up a test light to it and let it drain completely. Then connect a small output trickle charger to it with the correct polarity. LA batteries can sometimes be "retrained" and it sounds as though yours was, and you may be able to retrain it to normal.
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  #13  
Old 09-12-2012, 12:22 AM
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Quote:
Originally Posted by Can't Know View Post
If you really want to try and save the small battery, remove it and hook up a test light to it and let it drain completely. Then connect a small output trickle charger to it with the correct polarity. LA batteries can sometimes be "retrained" and it sounds as though yours was, and you may be able to retrain it to normal.
+1 an easy way to tell for sure is to put a digital volt meter on it. If it reads -12v when red to red and black to black, you have your answer.
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  #14  
Old 09-12-2012, 06:29 AM
t walgamuth's Avatar
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Is 2 amp small enough?
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..I also have a 427 Cobra replica with an aluminum chassis.
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  #15  
Old 09-12-2012, 08:42 AM
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Quote:
Originally Posted by t walgamuth View Post
Is 2 amp small enough?

Yes, 2 Amps would be a trickle charge even on a small battery. If you can get it to draw 2 Amps, you might luck out.

I have not disagreed with the trickle charge idea/theory because I don't have enough experience to know one way or another. I DO remember, however, reading a post, I think by Steve Brotherton (Stevebfl) that in recent years it had been determined that modern batteries need something beyond a trickle charge. He gave a technical description of why that I don't remember. He was basically debunking the old "slow charge is the best charge" theory.

Good luck with it.

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