Duracell GC2 FLA charge rate?

[ericfx1984]

I'm curious about the maximum charge rate of a Duracell gc2 FLA battery

I have four of these batteries two strings and series then paralleled together for a grand total of 12 volts each of these batteries is a 6 volt battery and rated for about 215 amp hour

if I'm charging on generator I oftentimes will be charging as high as 100 amps as my plug-in charger does 100 amps out Max

And when I'm charging off of solar because I have two charge controllers I can sometimes see charge rates as high as 90 amps

Now I know a lot of folks are going to give me the answer of well it depends.. I haven't had any issues with cooking off electrolyte, nor have I had any issues with electrolyte coming out and spilling everywhere nor have I had any crazy heating on the batteries so I feel like I'm probably just fine

 

[sunshine_eggo]

https://www.driveduracell.com/pub/media/wysiwyg/Duracell_Spec_Sheet.pdf

page 2

Since they give no charge data, even generically, you need to follow typical charge guidelines.

0.1-0.15C is the general rule. That's 43-65A in your case. Generally speaking, when charging below 13.8V, you can double that, so 130A, and not experience significant boil-off, but you will reduce the life of the battery by a measurable amount.

With solar, because you "sometimes see charge rates as high as 90A", there's some wiggle room. 0.2C as your maximum possible from solar is not an unwise target because you won't often be significantly over the 65A limit, and there's the 0.3C limit under 13.8V.

Have you actually observed your charger do 100A? The voltage drop between the charger and the battery often serves to limit the current below the max, so the peak charge voltage is seen by the charger while the battery is below it, thus the chargers starts tapering current. Even so, as long as you're under 130A below true 13.8V on the battery, very little damage is happening.

As another data point, Trojan, who makes exceptional GC batteries, limits charge to 0.13C. Period.

 

[ericfx1984]

https://www.driveduracell.com/pub/media/wysiwyg/Duracell_Spec_Sheet.pdf

page 2

Since they give no charge data, even generically, you need to follow typical charge guidelines.

0.1-0.15C is the general rule. That's 43-65A in your case. Generally speaking, when charging below 13.8V, you can double that, so 130A, and not experience significant boil-off, but you will reduce the life of the battery by a measurable amount.

With solar, because you "sometimes see charge rates as high as 90A", there's some wiggle room. 0.2C as your maximum possible from solar is not an unwise target because you won't often be significantly over the 65A limit, and there's the 0.3C limit under 13.8V.

Have you actually observed your charger do 100A? The voltage drop between the charger and the battery often serves to limit the current below the max, so the peak charge voltage is seen by the charger while the battery is below it, thus the chargers starts tapering current. Even so, as long as you're under 130A below true 13.8V on the battery, very little damage is happening.

As another data point, Trojan, who makes exceptional GC batteries, limits charge to 0.13C. Period.

Okay I think I understand.. realistically I know that the charger tends to slow down once it hits that 13.8 range I can especially tell this when I'm hooked up to the generator because you hear the generator idle down quite a bit.. so it sounds like 65 amps anything above 13.8 and we're fine.. of course since I have been talking about doubling my battery Bank then this charge rate would probably be ideal all the way up to full charge