Maybe a stupid question

97TJ
97TJ Solar Expert Posts: 68 ✭✭
in Solar Beginners Corner #1
Maybe a stupid question and not sure if this is the place to post this, but I am picking up some batteries tomorrow for a summer install at my cabin. I have a power max charger. Should I be hooking up the power max charger to keep a charge on these batteries until I am ready to do the solar install this summer and just leave it or should I discharge the batteries from time to time and let them recharge?
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #2
    Re: Maybe a stupid question

    Always leave the batteries fully charged. Batteries in storage will self discharge, and after a while will begin to degrade due to lack of full charge. Fully charge them, and then put them on a regular float charge regimen.

    Read ( and understand) the following links,,they will help you maximize battery life span.

    http://www.batteryfaq.org/

    http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

    Tony

    PS. There are no stupid questions,, only stupid answers!

    T
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,642 admin
    #3
    Re: Maybe a stupid question

    It depends...

    Does the Powermax charger have a float mode/setting?

    One thing I do with 120 VAC chargers--Is a get a (heavy duty) lamp timer from the hardware store and set it to charge one hour per day--That keeps the batteries charged (if no load) without having a float charger and/or remembering to plug the batteries in one day a month for charging. And reduces gassing/distilled water use a lot.

    If you have a hydrometer (or if this is a store, have them do the measurements) and these are flooded cell, I would take a reading on each cell and make sure they match (within 0.030 units) and are near full charge. Ideally, log the resting voltage and specific gravity readings for (possible) future reference.

    Too many stories out there today of people getting "dead cells or dead batteries" that were supposed to be brand new.

    Don't let them sit discharged (my recommendation is don't let them go below 75% SOC without recharging back >90% state of charge). But don't let the batteries "cook" at >14.0 volts while in storage either. Your battery mfg. may have a float recommendation of 13.2-13.6 volts if the charger is left plugged.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Thomas
    Thomas Solar Expert Posts: 291 ✭
    #4
    Re: Maybe a stupid question

    I belive if you have the time in between regular usage, then slightly working the battery correctly can make it stronger for the times of usage, Float charging, or light controllers/ diversion controllers can do this.
    Always troubleshoot with adequate sunlight.  Hi Ho Hi Ho
    2.3kW [10] Enecsys SMI-240-60 micro inverters

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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #5
    Re: Maybe a stupid question

    Hi 97TJ. The Moderators on this form know what they're talking about. I'll leave it at that and wish you good luck with your project.
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