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2 x batteries or 4

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  • 2 x batteries or 4

    Hi my question although you probably been asked a thousand times is if you run 2 batteries say 300ah to run your camp and you have good results should you get 2 more to add to the battery bank ....does that increase your actual run time or does it remain the same and you are just flattening 4 batteries instead of 2

  • #2
    Apologies 2x batteries in series to 4x batteries all identical in series parellel for a 24v system


    • #3
      Adding more batteries will usually increase the Ah rating of the system as well as be able to generate more kWh. The problem is if you increase the battery system Ah rating you also need to increase the amount of charging amps proportionately. That means more solar panel wattage and more than likely a bigger or more efficient charge controller.

      On "con" side, by wiring batteries in parallel you increase the chances of unequal charging/discharging which usually leads to one or more batteries doing the most work and failing sooner then what they should have been able to live.


      • #4
        Simple Rules and Answers.


        1. Never Ever Parallel Batteries. If you need 300 AH, buy 300 AH batteries period. You should never need more than 800 AH at any battery voltage
        2. Use the highest voltage possible within equipment limitations. This will minimize cost and maximize efficiency. 12 volts for less than 500 watts, 24 volts for 500 to 1500 watts, 48 volts for 1500 to 4000 watts.
        3. Size your battery correctly. For part time systems like a camp site, 3 day minimum. For a home or other application use 5 days. Example if you need 1 Kwh per day,, then you need a 3 Kwh battery for a camp site and 5 Kwh for a home.
        4. A battery has minimum and maximum charge current requirements. Generally a FLA battery minimum requirement is C/12 and maximum is C/8 with C/10 being perfect. Example a 100 AH battery minimum charge current requirement is 100 AH / 12 H = 8.3 amps, Maximum is 100 AH/ 8 H = 12.5 amps, and perfect is 10 amps.
        5. Live below your means, and you will be rich at any income level. .


        1. If you match everything to work with each other following the rules above, life is easy and works.
        2. 12 volts @ 400 AH = 4800 watt hours.
        3. 24 volts @ 200 AH = 4800 watt hours.
        4. 48 volts @ 100 AH = 4800 watt hours.
        5. If you earn $50/day and spend $100/day you are a fool and bankrupt.

        Choose your battery voltage, battery capacity, and panel wattage wisely. A 1 gallon beer mug does no good if you all you have is a quart bottle to fill it with. You need a Keg.

        Any questions?
        Last edited by Sunking; 06-20-2017, 09:53 PM.
        MSEE, PE