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Battery Terminal - Side vs Top Terminal Voltage Difference?


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#1 dheismann

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Posted 11 March 2012 - 02:56 PM

Arriving home after driving our 2001 Winnebago Brave, the unit would not restart using the coach battery. I checked the voltage on both the side terminals to which the battery cables were connected and the top terminals to which nothing is connected. The side terminals read less than 8 volts but the top ones read about 13.8! It appears that the side and top terminals are connected differently internally.

Since the battery's top terminals are reading a good voltage, would it be a good idea to bypass the side terminals and connect the battery cables directly to the top terminals? Or, should I just replace the battery.

Thanks for any advise.
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#2 wolfe10

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Posted 11 March 2012 - 03:56 PM

Welcome to the FMCA Forum.

Never heard of different internal connections between side and top terminals.

My suggestion is to call the battery manufacturer and ask THEM, but it sounds like a bad connection.
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#3 DickandLois

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Posted 11 March 2012 - 04:46 PM

dheismann ! You are describing is referred to as a dual terminal battery if I'm reading your post correctly.

They have a standard battery post on top that has a post clamp tightened by a bolt and nut and a threaded terminal on the side that uses a threaded connector.
The difference in voltage reading might be from just a little oxidation on the side terminals.
The buss bar that is internal on the battery just has been adapted to have two negative terminals and two positive terminals and are at the same point electrically, just that one sites above the other. Everything else is the same internally.
Remove the terminal connections and wire brush them. read the voltage,then reconnect the cleaned terminals and read the voltage again and let us know. What the reading is.

R.M.
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#4 hermanmullins

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Posted 11 March 2012 - 08:36 PM

Corroded terminals can limit starting voltage as well as charging ability. Try jumping positive top post to positive side post and the same with the ground. see if it will jump start itself. Then clean the terminals really good
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#5 dheismann

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Posted 02 April 2012 - 06:51 PM

I really hate it when everyone else is right and I am wrong. When I first touched the bolt on the positive side I noticed it was loose. I decided to remove the cable and, lo and behold, there was corrosion!... Once it was cleaned and re-installed, both sets of terminals read the same voltage.

Thanks for your responses..
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#6 DickandLois

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Posted 20 April 2012 - 09:28 PM

There is an expression that I have used for years. Could not see the woods for the trees.
I have often worked on something and been so involved,that I could not figure it out. Just needed to step back and look at it from a different view point.
Been in the same spot many a time.
Had a fellow employ say to me once, It might help to plug it in ! After I had spent the better part of an Hr. working on a problem.
Its the little things that eat you alive.

Rich.
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