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Amp Hours to Kwh

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  • #16
    Re: Amp Hours to Kwh

    Originally posted by Unregistered View Post
    John,
    I have a question about battery banks .
    If I have 6 100 AH batteries configured as 3 banks of 24v ( 2 -12V in series in each bank)
    what is my total watts and AH.
    I know the 3 sets of 2 batteries in parallel wil still be 24V but is each set of 2 = to 200AH and do I add the 3 sets that are in parallel together to get 600AH.
    rb
    So each battery is 12 V, 100 Ah?

    Two batteries in series will be 24 V, 100 Ah
    Three such banks in parallel will be 24 V, 300 Ah
    The total stored energy is 24 V x 300 Ah = 7200 Wh or 7.2 kWh

    In series, voltage adds, no change in capacity (provided both are the same).
    In parallel, capacity adds, no change in voltage (they have to be the same voltage)

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    • #17
      Re: Amp Hours to Kwh

      What a helpful thread!
      So, I have 8 batteries rated at 375Ah (20 hr rate) wired in 2 parallel series of 4. Which means I have 750Ah, correct?

      I was reading another article online and according to it's calculations, I should be able to draw a 15 Amp load for about 24 hrs (Down to 60%). That's 750 Ah x 80% (rough reduction for size of load) = 600Ah / 15A = 40hrs x 60% = 24 hours. Does that sound right?

      Because I'm lucky to make it 8 hours... I believe the batteries are 6+ years old and have lived a hard life (due, in part, to my learning curve and from neglect prior to my arrival). I'm finally equalizing them properly today for the first time since I've been here (14 months).

      I've used a hydrometer a couple times lately to log the results but I'm not sure of the optimal conditions in which to test. Any suggestions?
      THANKS!

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      • #18
        Re: Amp Hours to Kwh

        Originally posted by Unregistered View Post
        What a helpful thread!
        So, I have 8 batteries rated at 375Ah (20 hr rate) wired in 2 parallel series of 4. Which means I have 750Ah, correct?

        I was reading another article online and according to it's calculations, I should be able to draw a 15 Amp load for about 24 hrs (Down to 60%). That's 750 Ah x 80% (rough reduction for size of load) = 600Ah / 15A = 40hrs x 60% = 24 hours. Does that sound right?

        Because I'm lucky to make it 8 hours... I believe the batteries are 6+ years old and have lived a hard life (due, in part, to my learning curve and from neglect prior to my arrival). I'm finally equalizing them properly today for the first time since I've been here (14 months).

        I've used a hydrometer a couple times lately to log the results but I'm not sure of the optimal conditions in which to test. Any suggestions?
        THANKS!
        Six years old, especially a hard six, you may be seeing rather normal aging. All rechargeables gradually lose capacity with repeated charge discharge.

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        • #19
          Re: Amp Hours to Kwh

          ok.. the calculation you are doing is right... but you don't have taken in consideration the discharge level of the battery, if i'm right ..so

          if a normal battery is lets say 12v 200A, then if is a marine battery with a discharge level of 20% then we could use from that battery only 40A until is considerate discharged

          so lets say we have 4 battery's in series we have 12v and 4x200A = 800A from where we get that we could use only 160A = ....wh...kw ecc..


          i'm right or i have understood something bad?

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          • #20
            Re: Amp Hours to Kwh

            Originally posted by Leon View Post
            ok.. the calculation you are doing is right... but you don't have taken in consideration the discharge level of the battery, if i'm right ..so

            if a normal battery is lets say 12v 200A, then if is a marine battery with a discharge level of 20% then we could use from that battery only 40A until is considerate discharged

            so lets say we have 4 battery's in series we have 12v and 4x200A = 800A from where we get that we could use only 160A = ....wh...kw ecc..


            i'm right or i have understood something bad?
            You are right that state-of-charge must be considered if less than 100%.

            Also, the battery should NEVER be fully discharged as it shortens battery life. For deep discharge lead acid batteries, it is recommmended NOT to go below 50% state-of-charge, if you wish to optimize battery life.

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            • #21
              inverter

              good day

              how can i design a pv system for my camera using a 12v batt that will last 13hours, and which inverter i will used?

              fred


              fc.logan@yahoo.com

              Comment


              • #22
                Re: Amp Hours to Kwh

                Stumbled across this thread looking for something more technical (Battery R&D guy)
                The basic conversion is very easy (a lot will already know this).

                wh = volts x Ah(amp hours)
                Kwh = wh / 1000

                It helps if you give battery bank capacity in Ah at a voltage.
                eg 200ah @ 12v because this will only store half the power of 200ah @ 24v.
                Whereas a 2000w solar array is producing the same power regardless of voltage.

                If you are converting battery bank to kwh you can calculate them individually regardless of bank voltage.

                From previous example of 8 x 375ah 6v batteries but in different configurations;
                375Ah, 48v Bank = 1bank x 375Ah x 48v = 18000wh = 18kwh
                750Ah, 24v Bank = 2banks x 375Ah x 24v = 18kwh
                1500Ah, 12v Bank = 4banks x 375Ah x 12v = 18kwh
                6v singles = 8 x 375Ah x 6v = 18kwh

                In regard to the daily depth of discharge (DOD) forget the 50% rule. The deeper the DOD the fewer cycles you will get. Professional off grid systems are usually based on 20% DOD where budget allows, combined with proper solar batteries this gives 5000cycles/15+ years service life.
                The same batteries at 50% DOD might only do 1500cycles/5 years. Select a commercial deep cycle battery and your probably back to 1000cycles/3years, marine 600/ 2years, automotive - 6months?

                Comment


                • #23
                  Re: Amp Hours to Kwh

                  "In regard to the daily depth of discharge (DOD) forget the 50% rule. The deeper the DOD the fewer cycles you will get. Professional off grid systems are usually based on 20% DOD where budget allows, combined with proper solar batteries this gives 5000cycles/15+ years service life.
                  The same batteries at 50% DOD might only do 1500cycles/5 years. Select a commercial deep cycle battery and your probably back to 1000cycles/3years, marine 600/ 2years, automotive - 6months? "

                  I'm glad to finally see someone address this issue about 50% DOD. I saw a Trojan Battery Data Sheet for their L16RE battery and it said that 20% discharge would give 4000 cycles. 40% discharge would give 2000 cycles and 80% discharge would give 1000 cycles.
                  Go to Trojan Battery RE website for the PDF sheet (sorry no links allowed for new users).

                  This shows that a battery only has so much total power available to store and you can either use it up in under three years or use it over ten plus years. 20% of a 370 AH (at 20 hr rate) is 74 AH*4000 cycles = 296,000 total AH available. Figure a 100% discharge would be 800 cycles and that is what their graph shows.

                  The way I look at it there is no reason to have thousands of dollars in batteries sitting on the floor when you could invest that money in the stock market and maybe pay for a new set of batteries in three years. I also believe a battery accepts charge easier up to 80 or 90% where that last bit to full takes higher voltages to force it into the battery. One more thought, if the house burns down or someone steals your batteries (happened to me) the money is gone sans insurance.

                  My new set of 8 Trojan T105''s will be discharged to 20% DOD regularly and a full charge every 10 days with an equalize every thirty. BTW I'm charging right now with a generator until I get my panels.

                  Any thoughts?

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                  • #24
                    Re: Amp Hours to Kwh

                    Originally posted by Montmarions
                    Amp Hours to Kwh Convert and Calculate. ... Does anyone know how to convert KwH to Amp hours? Or maybe better, if I have 8 360 amp hour ...

                    ---------------------
                    Mont Marions
                    seo consultant
                    Multiply by voltage for watt-hours, divide by 1000 for kilowatt-hours.

                    Comment


                    • #25
                      I am trying to get some answers for calculations on my 8 x 6 volt golf cart batteries I am using for my solar panels. I am told I will only get 5000 watts at 50%. Is this correct?

                      Second, If I want to increase my available watts how many more batteries would I need to achieve 10,000 usable watts at 50% rating?

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