#### ACruceSalus

##### Enlightened

We bought a pair of equivalent 12V 11Ah SLA AGM batteries made by UPG (UB12120). One of the batteries came at 12.9V and the other at 13.0V.

The initial charge took about 40 minutes and brought them up to 13.51v and 13.35v. The next five charges equalized them out to within .01V. The voltages over all six charges ranged from 13.51-14.10 V on one battery and 13.35-14.09 V on the other. The charger LED light went green on the first charge which indicates that it is complete after 40 minutes. Each subsequent charge we've removed the batteries before the charger turned green which was 3-4 hours. We did this because one of the times I could hear bubbling from the battery and we could smell hydrogen gas each time. One of our concerns is that the batteries that we replaced were overcharged so we don't know whether the charger and the replaced batteries are defective.

1. Is there a way to determine if the charger is working correctly (bulk, absorption, float)? I have access to a DMM but I'm unable to find anything on the internet that is helpful.

2. The datasheet for these batteries state that the "cycle use (repeating use) voltage is 14.5 - 14.9 V. Does this mean that it should charge to this voltage to be "full?"

3. The datasheet states that the "float use control voltage" is 13.6-13.8 V. What does this mean?

4. I understand that to prolong the life of these batteries they should not be discharged below 50% but I've seen various voltages for this 50%. Is there a definitive 50% voltage? If not then how would I calculate it for these batteries?

5. The datasheet has a chart that shows "open circuit voltage vs residual capacity" with the range being about 11.5-13.25 V with 11.5 V being 0% capacity and 13.25 being 100% capacity. I assume that this is the resting voltage after 8 hours or so. I have not been able to take a resting voltage so is there another way to use this chart to estimate capacity?

We thank you for any help you can provide.