Help with charge profile GC2 on Victron

[STW]

I have 2 6v Interstate GC2 batteries in series in my Rv. Interstate shows the following charge profile.
Interstate GC2
Bulk = 14.8
Absorb = 14.8
Float = 13.5
Equalize = 16.2

They state that for every 1 degree below 77 degree F to add .0028v per cell for temperature compensation.

I just got my solar installed (4x100w in 2S2P) with a Victron 100/30 with Smart Sense controller.
I did the math and the came up with this. Today it was 47 degrees F.

.0028v * 6 cells (there are 3 cells per 6v battery) = .0168v
.0168v * 30 (this is degrees below 77F) = .504

So the Absorb will be 14.8v + .504v = 15.304v

This seems WAY to high. When it was charging I was smelling a lot of gassing. That can’t be good.

For now I changed it to 14.5v Absorb with .0028 temp compensation for the whole battery (Instead of .0168v).
That gave me 14.584v total.

What are your thoughts on Interstate recommendations? What are better settings?

Thanks.

 

[sunshine_eggo]

Your initial numbers sound about right. It's the same for my Trojans.

Your GC2 have a very high SG - 1.300. You're going to get a lot of gassing. Golf Cart batteries tend to be charged aggressively and need frequent watering.

Since you've changed your temp comp, you are now no longer fully charging your batteries. Recommend you revert to the correct settings.

Here was my morning:



41°F, 61.18V or 15.30V per 12V.

I have mine set to 14.7V absorption vs. the 14.82V spec to address water loss issues. I'm only there 1-2 times per month and sometimes less. The last time I was there, I added 1.5 gallons across 48 cells with several of them being very very thirsty with barely exposed plates.