- Thread starter nickk
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13.1v is a typical float charge voltage.
Disconnect the charger & if the battery has any chance of being good - it'll settle after a short while at around 12.4, 12.5v.
The true test is putting it under load (a car starter motor cranking with a multimeter on the terminals is a way anyone can test). If fit, the battery shouldn't drop below about 11v when starting the engine.
(Putting a bit of deionised water in the cells would be a good idea though too)
Barking Mat
Cuddler of hedgehogs.
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12.6 - 12.8 volts is a happy newish battery, a couple of days after charging.
Voltage checks on batteries do not ensure their capability to work. It is the amperage that does the work so a load test is the only way to prove the batteries capability. Any good garage should be happy to oblige or you can buy a tester for not a lot of money. Ebay have a Sealey drop tester new at £36.99 free postage. This is the one I use and its good. Easy to read and accurate.
Got a link for the sealey one by any chance?
The cheap Sealey tester (and the various other badged versions) only tickle any reasonable sized battery. You're lucky if it can pull 50A.
We had one at work, and the cables aren't even single core, they're twin core to give the impression they're heavier copper!
Voltage is a pretty crude measurement, but on a battery that's sat for 12hrs, the generally guide is 12V is nearly flat, and 12.8+V is fully charged.
Ideally now you'd use a capacitive discharge tester (aka a modern digital tester), as they are far more accurate than a ye olde drop tester.
As for the OP, just top up the cells with some de-ionised/distilled water.
We had one at work, and the cables aren't even single core, they're twin core to give the impression they're heavier copper!
Voltage is a pretty crude measurement, but on a battery that's sat for 12hrs, the generally guide is 12V is nearly flat, and 12.8+V is fully charged.
Ideally now you'd use a capacitive discharge tester (aka a modern digital tester), as they are far more accurate than a ye olde drop tester.
As for the OP, just top up the cells with some de-ionised/distilled water.
Prajna
Fixing things for the love of it
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It will be fine if the plates are still covered. Fill em up (well, not full coz it will expand when you charge again). Once the plates are exposed you'll start losing capacity. 13.1 is fine too, a tad high if it's not surface charge but higher resting voltage is generally a good thing. Brand new batteries improve their capacity initially, it reaches a peak after some number of charge cycles and then slowly drops over its lifetime.
ajlelectronics
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A Voltage check tells you about the condition of the cells, a good indication of relative performance. A drop test is certainly a good thing to prove the starting capacity of a battery, the CURRENT (not 'amperage') across a heavy load will tell you about its CCA. In the absence of a drop tester, then a fully charged battery could run the headlights, engine off for a while and then another Voltage test carried out. The battery if any good should recover to around 12.6V fairly quickly.
To test battery capacity, connect a headlamp bulb across the battery and monitor the Voltage. Once it drops to around 12V (about 50% charged), take a note of the elapsed time. Using the current pulled by the bulb and the time elapsed, you can calculate the approximate capacity of the battery In Ampere hours.
