Dual 6v battery charging

[johnbryanpeters]

Originally Posted by boondocking

I have an Extech and a Uni-T. The battery reading with the Extech is 12.98 V and the Uni-T reading is 12.97.

Extech makes a lot of instruments. For the heck of it I looked at the specification for their EX410, which is ±0.5% for DC voltage. If you're measuring a source of exactly 13 VDC, you could get readings from 12.935 to 13.065 V, which would be perfectly adequate for estimating battery charge state.

[pgandw]

The problem is that NO 12V (or two 6V) lead acid batteries, even when fully charged, put out more than 12.7something volts. So something is not right when you are reading 12.9V+. There is one likely explanation besides mis-calibrated voltmeters - and that is that the battery is being charged, or has recently been charged when you take your voltage reading. If the batteries have been on a charger in the 24 hours prior to a voltage reading, it is possible to read higher than 12.8V. Otherwise, not. Or you batteries are not traditional lead-acid batteries.

Fred W

Fred W

[boondocking]

They are Napa GC-2 230ah batteries and were disconnected and equalized at 15.6 v in November.
So both of my meters must be wrong then.

[Jaydubya81]

12.98 volts is absolutely NOT 50 percent discharged, in fact it is most likely 100% charged, although the only real way of checking is with a specific gravity tester