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Author Topic: Hooking up battery in reverse  (Read 1439 times)

Offline 68DevCon

  • Posts: 25
Hooking up battery in reverse
« on: September 18, 2010, 01:06:06 AM »
My "friend" hooked up "his" battery and, like and idiot, reversed the polarity.  Luckily "he" has a quick battery disconnect - the type  with a knob you tighten to connect and loosen to disconnect.  When "he" hooked up the battery, the knob was loose and the battery was disconnected.  When "he" screwed the nob to connect the battery, obviously it sparked and he immediately disconnected it and realized what "he" had done.  It was only connected for a split second.

Nothing appears to have happened to the car (68 caddy).  It starts and the alternator and all the electronics work.

The question is this:  I've heard hooking a battery up reverse polarity can cause the battery to explode.  Does that mean the battery can explode only when hooked up in reverse polarity?  Or, does it mean that even now that everything appears to be fine, and the battery is hooked up correctly, that the battery may have been damaged and could still explode? Or, did I - I mean "he" - dodge a bullet and everything is fine?

 I don't want to take any chances, so if need be I'll go out and buy a new battery (even though this one is brand new).

thanks

s. ororke

Re: Hooking up battery in reverse
« Reply #1 on: September 18, 2010, 01:16:39 AM »
The battery should be OK now.  If it didn't explode when it was briefly connected
wrong, you should be OK.  What could cause an explosion in a brief mis-connection is the
spark and heat.  Looks like you've escaped unharmed.  The polarity should be OK.

If you have a charger, put it on charge for a few hours -- I bet it will be OK.

Mike
1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

Offline william_b_noble

  • Posts: 162
  • CLC Number: 2371
  • Name: W Noble
Re: Hooking up battery in reverse
« Reply #2 on: September 18, 2010, 01:19:05 AM »
I have personally had a battery explode (covering my girl friend of the time with acid) - quick action with a hose and a trip to her shower saved her from any injury, but her clothes disintegrated in the wash (I am sure I was sad I missed that) - despite such an auspicous beginning we've been married a number of decades.

so, in my case I was jumping a 6 V system from a 12 V car (which you can get away with, usually), and we got the cables reversed.

to give you a decent answer to your question, you need to understand WHY a battery explodes - it explodes because an over-current condition causes the rapid electrolosis of the electrolyte, producing a lot of oxygen and hydrogen in very short order (tiny fraction of a second).  This leads to a rapid build up of pressure inside the battery, bursting the case and sending acid flying everywhere.  If you are also unlucky, there will be a spark to ignite the mixture, but there isn't that much gas total, so an actual combustion event is not the main concern.

to avoid this, you can remove the filler caps from teh battery, generally, that increases safety - of course some modern batteries make this well-nigh unto impossible.
Bill N - clc # 2371

Offline 68DevCon

  • Posts: 25
Re: Hooking up battery in reverse
« Reply #3 on: September 18, 2010, 01:28:36 AM »
so I guess the question is:  could I have damaged the battery in a way that makes it more likely it will explode in the future?

Offline Glen

  • Posts: 2789
  • CLC Number: 727
  • Name: Glen Houlton
Re: Hooking up battery in reverse
« Reply #4 on: September 18, 2010, 01:55:57 AM »
Quote
so I guess the question is:  could I have damaged the battery in a way that makes it more likely it will explode in the future?

It’s very, very unlikely. 

You should check your alternator.  It is possible that you may have blown a diode or two.  This would not show up on a normal voltage check.  Burned out diodes will just reduce the max amps the alternator will put out.  Shorted diodes will put an AC voltage on the battery and through the whole electrical system. 

Be sure to check all the electronic devices like radio, Twilight Sentinel and Guide Matic.  They would be much more susceptible to reverse voltage conditions. 

Glen
Glen Houlton CLC #727 
CLCMRC benefactor #104

Offline 68DevCon

  • Posts: 25
Re: Hooking up battery in reverse
« Reply #5 on: September 18, 2010, 02:05:52 AM »
Radio, guidematic and twilight sentinel all operational.  Not sure how to check the diodes, but I have the manual.  What is the effect of putting "an AC voltage on the battery and through the whole electrical system"?

Offline william_b_noble

  • Posts: 162
  • CLC Number: 2371
  • Name: W Noble
Re: Hooking up battery in reverse
« Reply #6 on: September 18, 2010, 02:12:38 AM »
putting AC voltage on the system will probably destroy the majority of the connected solid state devices.  check the diodes with an ohm meter if you want to be safe.
Bill N - clc # 2371

Offline 68DevCon

  • Posts: 25
Re: Hooking up battery in reverse
« Reply #7 on: September 19, 2010, 01:09:13 AM »
thanks guys - everything checked out - dodged a bullet

Offline TJ Hopland

  • Posts: 10193
Re: Hooking up battery in reverse
« Reply #8 on: September 19, 2010, 11:17:08 AM »
I have seen it done before but never done it myself.  Recently helped a friend with a 50 Nash and when he bought the car it was backwards.  It ran.  Not much for working electronics so no real damage done.    Someone had replaced both cables with red ones so it was hard to tell if it had been converted to neg ground.  I think one of the things that helped was the regulator was broken so the generator was not trying to come online.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

 

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