Battery Charge Readings ?

[FlyingCloud1937]

Originally Posted by Don L

So I'm been on the hard so have run the battery charger numerous times. I also have run an equalizer charge a couple of times.

Yesterday when I plugged into shore power the battery charge ams quickly went down to less than 2 on my 460 AH bank. I also checked specific gravity and they indicated charged.

Today I go t the boat and the voltage is still 12.78. I used the inverter to use a drop light and was using about 2.5 amps. The voltage dropped down to 12.3V???? When I turned it off the voltage slowly went back up to 12.6V. Used a whopping 2.5AH.

This just seems all weird to me as I don't feel the voltage should have dropped like this under such a small load. But this is how my batteries have acted since they were new.

Am I confused?

Don,

Your symptoms suggest a sulphated battery bank. But we don't really have enough information to make that diagnosis.

How are you monitoring amp and amp hrs?
IIRC you have a shunt that is mis-wired has that been corrected?
What is the temp of the electrolyte?

SPG can only accurately estimate the state of charge, if it is temp corrected, and at a 24hr resting voltage.

I see your symptoms all the time, the new bank takes a while to produce the actual amp/hr ratings, but what happens is it become badly sulphated before it ever gets broke-in. From poor charging practice, and poor charge design.

Your bank's 20 amp hr rate is about 23 amps...so if at 23 amp load you should be able go a good 6-7 hrs before you would see 12.3. At 2.5 amp load you shouldn't see 12.3V for at least 40 plus hrs.

You need to go to Battery University.

Lloyd