Another electrical question. Battery voltage. How high is too high?

HoosierBuddy · Apr 4, 2005

Hey guys,

Saturday I was in the barn for several hours putting my car back together. It sure was more pleasant now that:

1. It's about 60 degrees outside.
2. I've got my new stereo working fine.

I haven't started my car since fall, so I've been occasionally putting one of those little "Battery Minder" trickle chargers on my Optima. I haven't used it in a month or so and sure enough after working on the car for six or seven hours the stereo started clipping off and a check of battery voltage with my super-cheap-chinese-special-notherntool digital multimeter showed about 9 volts.

So, I put my big battery charger on for an hour and then put my trickle charger on overnight. Sunday morning my aforementioned multimeter showed 15 volts at the battery with it unhooked.

Is that too high?
If so what do you think the culprit is...the trickle charger or the $30 multimeter?

Phil

sharkmouth · Apr 4, 2005

Wonder what the output voltage of the trickle charger is....

If the meter is accurate (big if) 15 volts from the battery by itself is pushing it a little. As you know, the charging system is supposed to put out 13.8-14.8 and the battery is almost never quite that high by itself.

_SuperCJ · Apr 4, 2005

Was the battery case hot from the charging? 125deg?
If the battery gets overheated from excessive charging it will be damaged.

66HertzClone · Apr 4, 2005

I went here

http://www.optimabatteries.com/publish/o...ml#000100010006

they caution that the charger should have more than one amp output and not exceed 13.8 volts.

HoosierBuddy · Apr 4, 2005

I should also point out that the trickle charger still had the "charging" light on when I took it off.

I'm going to bring my cheap dmm to work and compare it to a nice fluke unit we have.

Phil

red1970mustang · Apr 4, 2005

I know a good battery has 2.2 or 2.3 volts per cell. The good trickle chargers can be left on continuously. The one I have turns on and off as needed automatically. Sound like your trickle charger is bad.

StangMan_67 · Apr 4, 2005

The multimeter's are usually pretty accurate, regardless of chinese origin. i say your charger is overcharging, plug it in and check the voltage without hooking to a battery.

Another electrical question. Battery voltage. How high is too high?

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