September of 2010 I bought 6 GC2’s from Costco for our cabin and I promptly began abusing them. A year later having killed the bank twice (oops left the heat tape on in the winter with no sun!) I added two more. This was a 12v string so I was running 4 parallel strings.
Next in 2013 three years after the initial install I upgraded my system to 24 volts and found 4 more GC2’s that were roughly the same age and usage (one can only guess) and converted to three strings of 24v ea. I lived in the cabin most of the year following and while I abused the system still I at least had a generator back up come on when things got out of hand most of the time (sometimes I set the auto start too low or I left the inverter in ‘sleep’ mode which didn’t charge the gen battery which in turn made it not fire when needed and I was gone).
Despite constant abuse and only 20amp (max) of solar charging for a 660AH bank (at 24vdc) the batteries held reasonably well and even now the system is working though I have some low cells (sg readings after an 8hr rest) that no amount of charging and equalizing seems to resolve.
I’m replacing all 12 with brand new GC2′ from Costo as I concluded that I could keep them alive with what I’ve learned these past 5 years, for at least 7 years. Knowing this and comparing to the cost of Trojan L16’s I realized it was cheaper to go with the GC2’s and if I once again abused them too much I’d save money in the long run.
My 660ah 24v bank powers a fridge (no freezer), lights, internet, chargers etc and while I do run the genny too much in the winter when I’m there (120min max solar charging in December means the genny runs sometimes daily for a couple hours) which a typical amp draw of about 60AH over night unless I’m watching TV then it climbs to 140AH (in which case I keep the genny set to come on at 24vdc).
All in all after 5 years of serious abuse I’m impressed with the GC2’s
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