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 15.6I 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

Post what batteries you have... my 6v GC-2's respond better to lower voltages, like 14.6-14.8 Temp Compensated. Are yours AGM? 15.4Vabs seems high, either way.

jrnymn7 wrote:Post what batteries you have... my 6v GC-2's respond better to lower voltages, like 14.6-14.8 Temp Compensated. Are yours AGM? 15.4Vabs seems high, either way.^^^ This.I'm charging GC-2s at 14.8V Absorb (temp compensated), and they seem to love it. Rarely have to equalize ...

If necessary, you could engineer in some line loss/voltage drop, but usually the crappy oem (under-)wiring does that for you... (that's likely why converters run at 13.6v, not 12.6v).I can see your inverter getting the full voltage, but have you checked how much voltage is actually getting to the 12v lighting, 12v panel, fridge's control board, etc.?

You did not state your outside temperatures. If you have a temperature sensor attached to your battery bank for your solar charger ( and you should ) then when it gets cold the charge voltage needs to go up. Inverse for when it gets hot. My BlueSky charge controller runs the absorb voltage up to about 15.1 on temps below 40ish... and this is normal. The controller was set for 14.8 but can exceed that when its cold. You could set your charge controller to what ever you feel comfortable with, but according to the manufacturers 14.8 setting is the best setting for good wet cell health.

As for EQ'ing once a month... I would let the batteries decide when they need to be EQ'd. I was going to do a Spring EQ'ing on mine, last weekend, but after being top charged occasionally throughout the winter, and then charged at normal Abs voltage for several hours, individual open circuit voltages were dead even across the bank, and SG's were all within 0.010 of each other... even the two 'prodigal' cells.One thing I have noticed is higher Vabs charging results in lower resting ocv. There seems to be a sweet spot where both ocv and sg's respond well.

RV Voltages too high while charging | Good Sam Community

79 Replies

Chandalen
Explorer
May 04, 2015
THANKS for the FAST replies!!

I am using Interstate GC-2. The inverter woeked when I adjusted to 14.9v, however with the replies I'll lower it a little more to 14.8

I do have the temp compensation sensor connected.
Inside voltage at the lights was almost equal to what the battery charging voltage of 15.4

I was wondering about those too.. I was sort of under the impression that the battery voltage thru the on board fuse box/ converter charger/ would drop the voltage to the 12-13v range. Alas, it does not seem so.

And LOL on the running the fridge on the 120 to drop the voltage! Yes it would work but i'd be interested in how many DC amps that would draw.
pianotuna
Nomad III
May 04, 2015
Put the fridge on 120 volts. That will "knock down" the battery voltage fairly fast.
westend
Explorer
May 04, 2015
brulaz wrote:
jrnymn7 wrote:
Post what batteries you have... my 6v GC-2's respond better to lower voltages, like 14.6-14.8 Temp Compensated. Are yours AGM? 15.4Vabs seems high, either way.

^^^ This.

I'm charging GC-2s at 14.8V Absorb (temp compensated), and they seem to love it. Rarely have to equalize ...

X3
jrnymn7
Explorer
May 04, 2015
Daily Top Charging is not required, if that is, in fact, what you're doing? If the bank is being maintained in the higher SOC range, and is getting fully charged (replenished) daily, there will be limited sulfation, and therefore no need to top charge daily. Watch for tiny bubbles during abs, as this is an indication of gentle gassing and de-sulfating. Personally, I only top charge if the bank has been allowed to sit at less than 100% for any real length of time, like when self-discharging while not in service.

You must check SG levels, as this is the ONLY accurate way of determining SOC, and/or whether or not top charging an/or eq'ing is required. Familiarizing oneself with their bank is best done when the bank is out of service... and then one can compare that to the effects of daily usage.
jrnymn7
Explorer
May 04, 2015
As for EQ'ing once a month... I would let the batteries decide when they need to be EQ'd. I was going to do a Spring EQ'ing on mine, last weekend, but after being top charged occasionally throughout the winter, and then charged at normal Abs voltage for several hours, individual open circuit voltages were dead even across the bank, and SG's were all within 0.010 of each other... even the two 'prodigal' cells.

One thing I have noticed is higher Vabs charging results in lower resting ocv. There seems to be a sweet spot where both ocv and sg's respond well.
Ed_Gee
Explorer II
May 04, 2015
You did not state your outside temperatures. If you have a temperature sensor attached to your battery bank for your solar charger ( and you should ) then when it gets cold the charge voltage needs to go up. Inverse for when it gets hot. My BlueSky charge controller runs the absorb voltage up to about 15.1 on temps below 40ish... and this is normal. The controller was set for 14.8 but can exceed that when its cold. You could set your charge controller to what ever you feel comfortable with, but according to the manufacturers 14.8 setting is the best setting for good wet cell health.
jrnymn7
Explorer
May 04, 2015
If necessary, you could engineer in some line loss/voltage drop, but usually the crappy oem (under-)wiring does that for you... (that's likely why converters run at 13.6v, not 12.6v).

I can see your inverter getting the full voltage, but have you checked how much voltage is actually getting to the 12v lighting, 12v panel, fridge's control board, etc.?
brulaz
Explorer
May 04, 2015
jrnymn7 wrote:
Post what batteries you have... my 6v GC-2's respond better to lower voltages, like 14.6-14.8 Temp Compensated. Are yours AGM? 15.4Vabs seems high, either way.

^^^ This.

I'm charging GC-2s at 14.8V Absorb (temp compensated), and they seem to love it. Rarely have to equalize ...
jrnymn7
Explorer
May 04, 2015
Post what batteries you have... my 6v GC-2's respond better to lower voltages, like 14.6-14.8 Temp Compensated. Are yours AGM? 15.4Vabs seems high, either way.

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RV Voltages too high while charging

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