Forum Discussion

Salvo's avatar
Salvo
Explorer
Sep 11, 2014

Costco GC2 spec

I decided to replace the old GC2 batteries (4 years old). Costco's GC2's are now labeled Interstate Batteries. There isn't much data on the battery, just RC = 107. A "real" Interstate battery that btw almost costs twice as much, has a RC of 474 min @ 25A. Customer service clarified this huge discrepancy.

Costco RC 107 min is measured at 75A. The 25A spec is RC = 415 min. The Cosco GC2 has a capacity of 208 AH vs 232 AH for Interstate. Cosco's weighs 62 lbs vs. 65 lbs for Interstate GC2-XHD.

Interstate provides great charging instructions:

Bulk: 14.4V
Absorption (to 95%): 15.3V
Float: 13.4V
Equalization: 15.6V

Surprising that absorption is at 15.3V.

GC2 charging
  • pianotuna's avatar
    pianotuna
    Nomad III
    Sep 11, 2014
    Hi Salvo,

    So will you "tweak" your solar charger to those numbers?

    It is amazing that 26 extra amp-hours doubles the price.
  • time2roll's avatar
    time2roll
    Nomad
    Sep 11, 2014
    Odd to charge the last 5% on float. What does that take... another week?

    Interstate does have a 62 pound GC2. GC2-RD-UTL 208 amp/hr.
  • downtheroad's avatar
    downtheroad
    Explorer
    Sep 11, 2014
    Good info...but I'm challenged.
    So....make it simple for me. Are these Costco batteries any good?
  • landyacht318's avatar
    landyacht318
    Explorer
    Sep 11, 2014
    Interstate Deep Cycles are made by USbattery, which has had a finishing 15.3v in their specs for a while.

    I found my USbattery grp 31 needs the 15.3v, without it SG tanks, no matter how long it spends at 14.9v per day.

    anything less than 14.9absv and 15.3v float/finish on my 31 kills performance, and voltage sag under minor loads becomes pathetic.

    A few hours of 15.3v per day and this thing does tarzan yells while thumping its chest like a gorilla on meth.

    Still needs 16v for 30 to 45 minutes after about 15 cycles to max out SG and reset performance
  • Salvo's avatar
    Salvo
    Explorer
    Sep 11, 2014
    Looks like same battery for $162 list. I paid $84.



    smkettner wrote:

    Interstate does have a 62 pound GC2. GC2-RD-UTL 208 amp/hr.
  • ken_white's avatar
    ken_white
    Explorer
    Sep 11, 2014
    Go with the Sam's club EGC2 made by Duracell - much more reasonable and on par with the A-H specifications.
  • Salvo's avatar
    Salvo
    Explorer
    Sep 11, 2014
    Yes, I'll raise the voltage some. Half the time I'm not camping. I don't think I want a 15.3V daily charge during this time of inactivity.

    pianotuna wrote:


    So will you "tweak" your solar charger to those numbers?

  • landyacht318's avatar
    landyacht318
    Explorer
    Sep 11, 2014
    If I'm not cycling my 31 then it certainly does not need the daily 15.3v for hours
  • mena661's avatar
    mena661
    Explorer
    Sep 11, 2014
    smkettner wrote:
    Looks like 13.2 float. Odd to charge the last 5% on float. What does that take... another week?

    Interstate does have a 62 pound GC2. GC2-RD-UTL 208 amp/hr.
    That is weird. Sounds like an a$$ covering to me on their part. Take that 15.3V all the way out to 100%. Depending on the amps, it's probably only going to take another 15-30 minutes anyways.
  • ken_white's avatar
    ken_white
    Explorer
    Sep 11, 2014
    ken white wrote:
    Go with the Sam's club EGC2 made by Duracell - much more reasonable and on par with the A-H specifications.


    Belay my last, I didn't know you already purchased these...

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