RV Voltages too high while charging

Chandalen wrote:
I have a problem and have been wrapping my head around this for a few days.

I have four 100w Solar panels, and a Morningstar RJ-45 programmable charge controller wired to batteries. I have Four Interstate golf cart batteries in serial/parallel to make a 12v bank.

I have a Pure sine 2k inverter wired to batteries with two 1/0 wires per pole, and fused @150 amps per positive line.

My (major) problem is the Absorption phase of charging is at 15.3 volts.

This changes the RV wide battery powered voltage to 15.3 +- volts. This is really high for the LED lights I have, and I am afraid they are going to start burning out.

Because the absorption voltage is 15.3, the inverter turns off. Its voltage threshold is 10-15v.

For now, I dialed down the absorption voltage to 14.9 and everything is working. I am aware that my batteries will not fully charge with that voltage as its 0.50 less than needed. I was planning on equalizing once a month, when I'm not using the camper, as that voltage is 15.6

I can’t imagine I am the only one who has run across this issue, so is there an inexpensive fix, that won’t waste valuable battery power?

I have a small (1 amp) voltage stabilizer for a battery venting fan that can tolerate no more than 14v (which I found out the hard way) that works well for the fan.

I know that the DC items in campers can tolerate 11-15ish volts, I’m just wondering how well and for how long that fridge can run on 14.9v while the batteries are topping off, and the inverter is useless if I cant run it when the batteries are topping off either!!

I appreciate any feedback and insight!!

-James

If your interstates are flooded then 15.5 is the correct absorb voltage per the interstate site. That is why I don't use interstates any more. You also didn't note the temperature of if the CC is temp compensated. If it is temp compensated voltage goes up for temps below about 80 deg and goes up down above 80 deg.