Costco Interstate vs. Sam's Duracell deep cycle GC2 batteries?

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softdown
softdown Solar Expert Posts: 3,821 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
Posting up because these outlets often have the best GC2 (golf cart deep cell) prices. Costco switched manufacturers a few years ago. They used to offer a carte blanche 7 year warranty on all automotive batteries. Last time I bought an automotive battery the "cashier" asked about the application. I said Prius and he promptly voided the warranty.

I keep buying Costco Interstate batteries showing a resistance over 5. Good manufacturers will not release batteries with a resistance over 5. I returned both. Very good batteries may show a resistance of  only 1.5. I bought another Prius battery from Sam's, they sell Duracell. The resistance is 4.5 - still a disappointing number. But the CCA is measuring 650 instead of Costco/Interstate battery showing a bit over 500.

Not saying that Sam's batteries are a better buy. They are a little more expensive and have a 3 year warranty instead of Costco's 5 year. Talking about auto batteries here. Has anybody recently compared their golf cart batteries?

I have Napa Gold batteries in my International bucket truck. Resistance is a very low 1.5 in spite of being stored with low voltage a few times. My vans solar batteries also measure a low resistance of 1.5 - they are pricey European batteries.

I feel that a resistance of 3.5 or lower is acceptable. Measurements over 4 are a disappointment. I return batteries measuring over 5 in resistance. Quality manufacturers do not release batteries with a resistance over 5.
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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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
    #2
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    What tool are you using to measure resistance?
    It sounds more like 0.005 Ohms vs "5" and what units?
    Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,144 ✭✭✭✭
    edited February 2022 #3
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    Concorde (AGM only) publishes their "internal resistance" in milliohms. The numbers are all over the board ranging from 0.24 to 6.77. It would appear to me that battery design and construction have a tremendous impact on internal resistance.
    As an example, their 12v 30H size is enormously successful in the field. It is a true deep cycle battery with a 150 ah C/20 rating, 700 CCA and a rated internal resistance of 5 milliohms.
    I always have more questions than answers. That's the nature of life.
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  • softdown
    softdown Solar Expert Posts: 3,821 ✭✭✭✭
    edited February 2022 #4
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     Bad old batteries generally show resistance over 7 and I've seen resistance over 13 on a toasted battery. The measurement always goes up as batteries age and deteriorate. My battery tester simply gives me numbers like ~1.54 to ~5.6 on new batteries. Quality manufacturers do not release new auto starter batteries showing resistance over 5 according to a battery quality video I watched.

    What I was trying to determine is - Has someone tested the difference between Interstate and Duracell GC2s?

    My tester looks somewhat similar to this but is different. [shortened link--BB.]

    https://www.amazon.com/Kzyee-Battery-Analyzer-Cranking-Charging/dp/B07KP8GCWG

    Coincidental but interesting that my 2012 Group 51 lead acid and 2019 Group 51 AGM have almost identical numbers in CCA and resistance. CCA - 370  Resistance 7.5   2022 Group 51 resistance ~ 4.5 and CCA 650

    I believe I can say that resistance increases as a battery deteriorates.
    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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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,746 ✭✭✭✭✭✭
    #5
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    Both of those batteries are in my opining for emergency use when a bank dies unexpectedly. That is the reason they are easy to get. Especially now in C19. I would never use them for Offgrid in a cycling application that would stand the test of time. Good Luck !
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • softdown
    softdown Solar Expert Posts: 3,821 ✭✭✭✭
    #6
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    FWIW and mostly on topic. Sams has recently started charging $120 for all of their FLA auto batteries. A big jump on the smaller batteries. And I keep finding unacceptable resistance levels with Costco batteries. I've heard that Home Depot may still be reasonable?

    NAPA Commercial batteries seem good. I once called them Napa Gold not long ago. Resistance of 1.5 which is very good. 
    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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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #7
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     Sams in my area still have gc battery’s for around the same price , I saw these today they have a fresh pallet in
     stock . 
      They cost 87 to 97 ish it has been going up and done for a few years .
        I’ve been getting good service out of them . 
     I have one system that I set up in 2015 and the battery’s will need to be replaced soon .
       My main system has 16 of these gc battery and are going into there 4 season and the sg is still allmost as new .
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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