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Suggestions for 30kwh

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  • Suggestions for 30kwh

    I currently have 8 golf cart batteries at 6v 230ah. Want to upgrade my system to 30-40kwh batteries. Wondering if I should take 2500 and get more golf cart batteries and make 3 strings of 8 for my required 48v or get new batteries altogether. Having a hard time finding batteries that are not 30k$.
    any suggestions? On different batteries or on my idea of more golf cart batteries
    eta: i know adding batteries shortens the life of all of them. The new batteries would be dated within a few months of existing ones. If I can't find similar dates I'd get brand new of same type since they seem like decent price
    Last edited by morton.bia; 11-28-2021, 03:53 PM.

  • #2
    Going with multiple parallel strings can be an early death for some or more batteries due to uneven charging and discharging.

    If you really want to build a high amp hour system then I would spend the money on low voltage (2v ,4v or 6v) 1000Ah batteries and wired them all in series to achieve the desired system voltage.

    You can spend less money more often or get a quality system for a little high cost.

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    • #3
      Originally posted by SunEagle View Post
      Going with multiple parallel strings can be an early death for some or more batteries due to uneven charging and discharging.

      If you really want to build a high amp hour system then I would spend the money on low voltage (2v ,4v or 6v) 1000Ah batteries and wired them all in series to achieve the desired system voltage.

      You can spend less money more often or get a quality system for a little high cost.
      Thanks. What are your thoughts on refurbished electric vehicle batteries?

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      • #4
        Originally posted by morton.bia View Post

        Thanks. What are your thoughts on refurbished electric vehicle batteries?
        I have never had refurbished batteries last long so I will never use them in a solar/battery system or any system that I need to rely on having power when I need it.

        Having older batteries makes it hard to determine how many cycles you can get out of them. Sure you might spend a lot less on used batteries but you will end up getting another set much sooner then you want and have to spend more money again.

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        • #5
          30kwh @ 48V = 625ah

          Is 30kwh a "rounded up " number, or what you actually need ? Floor scrubber 6v batteries are in the 400ah ballpark, and might be an option.

          While scrapped EV batteries sound like a great idea, ( not needing the big power surges that an EV requires ) they are still used and you are relying on the seller having tested and being honest about how much life is left in them. Also, I hope in the next few years, there will be huge advances in charging choices and BMS for Li batteries, that don't exist now. Maybe getting a set of floor scrubber batteries, expecting 3 years out of them and then see what market has for Li options. ( I said this a couple years ago, and so far, only "integrated solutions" have appeared.
          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

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          • #6
            Originally posted by Mike90250 View Post
            30kwh @ 48V = 625ah

            Is 30kwh a "rounded up " number, or what you actually need ? Floor scrubber 6v batteries are in the 400ah ballpark, and might be an option.

            While scrapped EV batteries sound like a great idea, ( not needing the big power surges that an EV requires ) they are still used and you are relying on the seller having tested and being honest about how much life is left in them. Also, I hope in the next few years, there will be huge advances in charging choices and BMS for Li batteries, that don't exist now. Maybe getting a set of floor scrubber batteries, expecting 3 years out of them and then see what market has for Li options. ( I said this a couple years ago, and so far, only "integrated solutions" have appeared.
            30kwh is an average. When we were living in a fully electric apartment (no gas at all, even stove and water heater were electric) we used about 1000kwh a month in Florida heat with AC blasting all day and night. Figured on our mostly propane setup (drier, stove, water heater and heater) and smaller tiny house (about 1/3 of the size) we should be ok with the average in NV which has cooler nights than Florida so ac won't work so much in summer. There was 1 day we used 40kwh in Florida.

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            • #7

              I've seen/read/heard good things about these batteries. 6 of them would be about your "30kwh". They have them in 12v, 24v, & 48v configurations.

              Please do not include posts selling anything on this Forum.
              Last edited by SunEagle; 01-31-2022, 04:29 PM.

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              • #8
                In 2000 I purchased 42 kWh of LFP cells from China for $125 per kWh. The price is probably higher today but one vendor has a warehouse in Houston for customers who do not want to deal with the uncertainties of overseas shipments. Indeed there are issues with paralleling Pb batteries. There are not the same risks with paralleling LFP when it comes to large packs. I have a 3P16S pack and know others that have 4P16S packs with no issues. In my opinion the larger the pack the more economical LFP becomes.
                There are many alternatives depending on one's risk return profile.
                Last edited by Ampster; 02-01-2022, 12:44 PM.
                9 kW solar. Driving EVs since 2012

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