Anonymous
Anonymous asked in Home & GardenMaintenance & Repairs · 7 years ago

How far can I push on a 120AH deep cycle 12v AGM battery with 120w solar panel?

I have read about not discharging deep cycle battery to below 50% state of charge. Is this a strictly no-break industry rule? I have read that people discharge down to 25% or less.

My intended setup for a remote camping situation:

- 120w solar panel with MPPT duo-battery charge controller (17A/1A)

- 120AH AGM 12v deep cycle battery

- 300w inverter (non sinewave)

My intended purpose daily use of up to 6 hours for:

- 1 laptop (power adaptor 19v @4.75A) drawing actually between 20w - 40w during use.

- 1 light bulb (240v x 20w).

- 1 car battery (12v @ 800CCA) requiring trickle charge in a parked camping scenario for days at a time.

My intended setup has taken into consideration the size of solar panel that I can place of my car rooftop and the weight of the deep cycle battery not exceeding 40kg.

I thought this setup would be more than enough for my intended use, provided solar panel does not experience too many rainy days.

I would like to know if this is enough or any other better solutions would help. Thanks.

8 Answers

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  • Anonymous
    7 years ago
    Best Answer

    Your projections seem to me to be pretty much on target. Your load is less than 6A for 6 hours, that makes about 36 AH per day, which is less than 30% of your battery's capacity. So you would have plenty lf reserve for not so sunny days. Deep cycle batteries are concipated to be able to handle repeated cycles of discharge averaging down to 50%. Occasional deeper discharges are not a problem. However consistent deep discharges below 50% will shorten the usefull life of the battery.

    The 120W solar panel will give you 8A max charging current - that is at full sunlight at noon when pointed stright at the sun. For the rest of the day you can expect an average of maybe 50%, so that woiuld be roughly 4A. If you got 10 hours of sunlight, that would give you 40 AH, which is about what your load at night would be, and considering the efficiency of the system (say about 80 to 90%) my conclusion is that you could use a somewhat larger solar panel to keep you battery charged enough.

    Wnat to learn more about DIY solar systems, go to http://www.DIY-Home-Energy-Answers.com

  • Anonymous
    4 years ago

    This Site Might Help You.

    RE:

    How far can I push on a 120AH deep cycle 12v AGM battery with 120w solar panel?

    I have read about not discharging deep cycle battery to below 50% state of charge. Is this a strictly no-break industry rule? I have read that people discharge down to 25% or less.

    My intended setup for a remote camping situation:

    - 120w solar panel with MPPT duo-battery charge controller...

    Source(s): push 120ah deep cycle 12v agm battery 120w solar panel: https://tr.im/QuRR9
  • Capri
    Lv 4
    4 years ago

    For the best answers, search on this site https://shorturl.im/avZ0E

    A 400 W supply doesn't really say what the average power consumption is. But if we assume that you are operating somewhere near 400 W total, including losses due to the inverter and battery, then this is 1200 WH. You probably won't get more than the equivalent of 6 hours of direct sunlight per day, which means that you would need about 200 watts of solar panels. This would not account for variations in sunlight, which could significantly reduce the stored energy. But you may not be using a full 400 W, so you may not need quite that much either. If possible, it would be MUCH better to use a laptop versus a desktop computer if you need to run it off solar power, since the power consumption is far less. And the lathe might add another 400 WH or so, so for that you would need at least another 70 watts of solar panels, probably more due to inefficiencies.

  • Anonymous
    7 years ago

    Deep cycle batteries are designed to repeatedly discharge down to 50% or lower and then recharged again. The 50% is meant as your average discharge, not the maximum. So you design your system such that on an average day your battery would be discharged no more than 50%. Then there will be days where it would be discharged much more, which is fine. This is to get the maximum lifspan out of your battery.

    So after quick calculations, it appears that you have it well figured out. The only thing I would change is to increase the size of your solar panel, if possible. Maybe you can figure a way to put a second panel somewhere else, if your rooftop is too small.

    Wnt mor info on Solar Systems? Check out http://www.DIY-Home-Energy-Answers.com

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  • spirek
    Lv 4
    3 years ago

    120ah Deep Cycle Battery

  • 3 years ago

    Guide To Solar Power : http://Solar.eudko.com/?ySj

  • Mark
    Lv 7
    7 years ago

    google " vandwellers " there are bunch of people living off the grid. if you search a little you will find a group that talks extensively about your subject.

    edit ,, i just went to check which one is best for you , google ( VanDwellers.org ) lots of info you there. you have to enter it exactly as i typed it with a capital V and D or will get the wrong site.

    hey ! and as a bonus .. i think the guy that has the site is Brit and sounds like you hahha.

    he even speaks 240 volts a Kg`s .

    his name Ramano i think. He would love to hear from you as most people on his site are us ugly Americans haha We know you hate us ;( ,,,, but we still like you. ;)

    your welcome and happy off griding !

  • A B2
    Lv 7
    7 years ago

    no problem.

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