good charging schedule

palausystempalausystem Solar Expert Posts: 73 ✭✭✭
General questions:
How often should batteries be brought back up to a full charge? If there is 15% discharge overnight, how important is it that they be brought back to full the next day? Is that the ideal scenario? Do the good inverter/chargers accomplish this unattended? or do they wait for a 30% discharge and then kick in - or is there a time factor involved?
I have experience with our set-up only, but am curious how other systems behave.

As pointed out to me before, we have inverter/charger that may be more geared to grid tied than the off- grid that we are. Also that we have too much battery and not enough PV. But we're working with what we got.

Off-grid 48v, 3 kw PV, Sunny Island 5048U, SunnyBoy, US Battery RE L16XC  6v, 800ah, Genset: Kohler 8.5 RES propane.


  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: good charging schedule

    What is important is that they do not spend extended periods of time below 75% SOC. If you recharge to 90+% daily they will last for as many years as if 100% daily (there are so many other variables that factor in that the total SOC becomes a minor attribute at that point).

    A well-designed system can achieve 100% SOC daily without any trouble and with power to spare, so it is usually not an issue. Nor is there any problem from achieving this goal (the batteries will not suffer as a result).

    An inverter-charger can do the same thing, but since the power source is usually a generators it is far less efficient (the cost per Amp from running the gen goes up and the charge rate by necessity goes down). That's why when you get in a "no sun" scenario one usually only does the Bulk stage (perhaps with partial Absorb) from generator. Of course if the no sun period lasts too long you'll want to bite the bullet and do a full recharge once a week or so. If the no sun lasts longer than that you may want to consider moving to a different part of the world - somewhere that gets sunshine. :D

    Too much battery and not enough PV is the #1 problem with systems in my experience. It necessitates using the gen often and as such is something you want to avoid.
  • westbranchwestbranch Solar Expert Posts: 5,123 ✭✭✭✭
    Re: good charging schedule

    If you do not get them fully charged once a week you have to use your charger.
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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