battery voltage question

[emlclcy]

quick question, a battery left uncharged for about a week or so measures 13.02v - good or bad?

[Phil Ambrose]

Good

Phil

[Tony Brooks]

Probably, but I suspect the voltmeter is lying. The rested voltage should be about 12.8 so after a week of just sitting there the surface charge should have long gone.

 

I think it needs looking into, it could also be a battery fault like its sealed and most of the water has been driven off as vapour so you are left with concentrated acid and little capacity (Ah).

[Alan de Enfield]

Probably, but I suspect the voltmeter is lying.

 

A very good point.

I had occasion, when I was testing the voltage going into the battery when the engine was running and it showed 19v, fearing that the alternator was on the way out I decided to do some testing - long story - short - the battery in the multimeter was virtually flat and would give random measurements. Changed multimeter battery everything back to normal.

[ditchcrawler]

 

A very good point.

I had occasion, when I was testing the voltage going into the battery when the engine was running and it showed 19v, fearing that the alternator was on the way out I decided to do some testing - long story - short - the battery in the multimeter was virtually flat and would give random measurements. Changed multimeter battery everything back to normal.

They do that

[Keeping Up]

The Varta batteries in my boat seem to act as if they run on surface charge. They will happily retain over 13 volts for a month or more; they have done so since new and nothing has changed now that they are 2 years old and have a reduced capacity.

Edited May 21, 2016 by Keeping Up