Putting my system to bed for the winter

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Endurance
Endurance Solar Expert Posts: 40 ✭
in Off Grid Solar & Battery Systems #1
It is time to put my boat in mothballs for the winter season of about five months. My biggest concern is proper care of my battery bank -- six L-16 AGM batteries. One thought would be to disconnect my batteries from my solar panels and let them self-discharge for several months. I could visit the boat and bring things back to full charge one or two times in the winter if you all think it would be a good idea. My thought with this plan is that the batteries would see this as two or three cycles over the winter season.

An alternative plan would be to leave everything on and charging. Sure, there would be a cycle every day, but it wouldn't be much of a cycle since there is little to no power draw with my inverter off and all my DC breakers turned off. I could leave all the solar panels on if you tell me that is best. My panels are wired in parallel, so I could turn off all but one at the combiner if I want.

Any thoughts on which of these plans will best protect my batteries and other equipment?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: Putting my system to bed for the winter

    What I do: disconnect inverter. Make sure batteries are charged and electrolyte is up. Leave panels & controller connected. Come back in six months to perfectly charged batteries.

    Caveat: it's cold up here and Winter days are very short. So there's little battery self-discharge anyway and not much charging power available. Enough to keep things good for half the year.

    In a warmer climate you may want to reduce the Absorb Voltage a couple of tenths. Be sure to have the RTS on, shut down any automatic EQ program. If you have the WhizBang Jr. on your MidNite Classic that should handle things just fine.

    Note that with certain other charge controllers the Absorb cycle is a fixed time, not varied with the length of the Bulk cycle. Without that flexibility your best bet is to charge up and disconnect everything and take your chances with self-discharge over time. Otherwise the daily Absorb input could cost you a lot of water and come Spring you could have exposed plates.
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  • Mountain Don
    Mountain Don Solar Expert Posts: 494 ✭✭✭
    #3
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    Re: Putting my system to bed for the winter

    Is the self discharge rate of an L-16 AGM low enough to not be concerned about the batteries sitting for a couple months at a time? Our ATV's have AGM's and they do quite well sitting for a few months of winter. (anywhere from -20 F to 40F, up and down, day in day out)
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Putting my system to bed for the winter
    Mountain Don wrote: »
    Is the self discharge rate of an L-16 AGM low enough to not be concerned about the batteries sitting for a couple months at a time? Our ATV's have AGM's and they do quite well sitting for a few months of winter. (anywhere from -20 F to 40F, up and down, day in day out)

    AGM self-discharge rates are usually lower than their FLA counterparts.
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