"New" Sam's GC batteries showing 6.17V.

softdown
softdown Solar Expert Posts: 3,925 ✭✭✭✭
edited August 2022 in Off Grid Solar & Battery Systems #1
They had 5/22 stickers on them. The voltage, I would think, should be closer to 6.35V or more. 6.17V demonstrates either:
1) High self discharge rate or
2) Older batteries that were relabeled as 5/22.

The resistance is ~3.5. Not good, not bad. Readings with a full charge will be of much interest.

Or they may have new mgmt that decided they could save .25/battery by shipping with a lesser charge. While saying it was the "green thing to do". For tax credits?

Thoughts?
First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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Comments

  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    3 months on the shelf is about the limit without some charging.

    I passed on some 3 and 4 month old ones at a local Sames club last time I bought GC batteries and drove 100 miles to get some that had the same date and a month out.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • MichaelK
    MichaelK Registered Users Posts: 236 ✭✭✭
    #3
    What I would do is get them fully charged, then check each cell with a hydrometer.  If each and every cell is not somewhere around 1.270, that's when I'd think of returning them.
    System 1) 15 Renogy 300w + 4 250W Astronergy panels,  Midnight 200 CC, 8 Trojan L16 bat., Schneider XW6848 NA inverter, AC-Delco 6000w gen.
    System 2) 8 YingLi 250W panels, Midnight 200CC, three 8V Rolls batteries, Schneider Conext 4024 inverter (workshop)
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  • softdown
    softdown Solar Expert Posts: 3,925 ✭✭✭✭
    #4
    They both showed 6.17 volts which is reassuring though low.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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  • softdown
    softdown Solar Expert Posts: 3,925 ✭✭✭✭
    edited August 2022 #5
    Charging them did not change resistance. I am guessing these batteries are about average in quality. Based on the idea that better batteries have lower resistance values. No idea why I almost always forget to check the resistance when buying.

    Have not seen bad batteries at Sam's. I have seen bad Interstate batteries at Costco. Quality manufacturers do not release batteries with resistance over 5. Though I have seen 4.5 at Sam's, that is quite a bit better than the 5.5s sported at Costco - in some of their batteries.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
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