Farmallhal- Re: truck battery

T in NE · Oct 26, 2014

Check your voltage when your gauge shows highest voltage and when it shows lowest. A properly functioning charging system should put out 14-14.2 volts, Ideally a 12 volt battery should show 13.2 volts fully charged. If your alternator isn't putting out more than that, it's not charging the battery. Sounds like maybe your alternator is dropping output once it's warmed up.

John T · Oct 26, 2014

"Ideally a 12 volt battery should show 13.2 volts fully charged"

Actually, after its sat a while and stabilized (And NO longer hooked to a charging system) a good fully charged 6 cell (2.1 volts each) so called "12 Volt" flooded lead acid battery would register around 12.6 to 12.7 volts. 13.2 volts is a typical FLOAT LEVEL CHARGE LEVEL which a Smart 3 or 4 stage Charger might maintain while in its Float setting/operation.

Hope this helps

John T

Owen Aaland · Oct 26, 2014

The only ones I have run across that were not 12.6 fully charged were the early Gates Optima batteries. They were 2.2 volts per cell, or 13.2 volts. They also did not work so well in some applications.

Since the voltage was higher it could take longer to recharge. I had one in a route truck that by the end of a week it would no longer start the truck dependably. If you recharge it, it would test out fine. A normal battery worked fine in the truck.

Another time I got a good deal on a marine battery that had been returned. The guy that bought it originally had it in a boat that would not put out enough voltage to recharge it properly. It worked fine in my boat for about 10 years.

Farmallhal- Re: truck battery

T in NE

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John T

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Owen Aaland

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