Costco GC2 Batts

hammick wrote:
A few clarifications on the Costco batteries. Absorb spec is 7.65v so 15.3v for a 12v system. Float is 13.4v. My specific gravity is also 1.300 with both of my hydrometers.

I'm not going to try an convince anyone or myself that the Interstate GC2 batteries are as good as the Trojans. But for recreational boondocking they work great for me. They are cheap and readily available. Plus the filler cap design makes it super convenient for a quick check of fluid level or a dip with the hydrometer.

Trojan also requires a high equalization voltage so if you have Trojans you also have to give some thought to keeping them maintained.

I have my solar charge controller set to absorb at 15.3v for one hour and then float at 13.4 If camping during a nice long summer sun sometimes I will up the absorption time and the float voltage to make sure they get a nice long charge.

And let's fact it. If you have the Interstate batteries you either self educate yourself about proper battery charging or they will have a short life. The dealers and people selling the stuff will all tell you that 15.3v is crazy and not necessary.

So if it wasn't for my Interstates I wouldn't know anything about Megawatts and Meanwells and would have missed the brain exercises trying to decipher Mex's babble.

A good way to learn this stuff is with a couple of cheap Costco batteries and a Solar charge controller. It gave me the confidence to design, purchase and self install a 48v off grid solar system using a very expensive bank of Trojan batteries. My setup is working better than I could have ever hoped and I am confident I'm not killing my batteries.

Thanks for correcting my errors.
I also do not charge as they instruct. Absorb is set at 14.8. I allow the solar controller to put in 112 percent of what was used the night before. At this point the controller fires up a "finish absorb" at 15.3 (at a regulated low current value) 4 percent in my case. At this point the controller resets the amp counter to 100 percent. Then it drops to float.
I agree with BFL13 that with enough time 14.8 (or even less) will work.
But for me it is more important to hit "charged" daily as a goal.

I agree the costo's are a great value. In my case it was more batteries
or more solar....... Solar won. Next years project will likely be LFP talk about a spendy battery. A 100AH pack with hi/lo safety's will be what I spent on solar panels.
"Mex's babble." Don't get me wrong, MEX is a great guy with a lot to give. But that describes his writing style aptly :R