Need advice/opinions on unused system

newguy
newguy Registered Users Posts: 5 ✭✭
in Off Grid Solar & Battery Systems #1
Hi,
Thanks for the wonderful forum and to the knowledgeable people that post here!

I have just purchased property with a system that won't be used for a couple years.
It has 2100 watts of panels on a tracker system with a 48v. battery bank (8 16L in series) The batteries are 5? years old and 1 currently has a dead cell. Full charged voltage runs 7.1- 7.3 on 7 batteries, 5.3 on the suspect one. I will not be able to go back there for several months. I will take a charger and hydrometer to try equalizing charging all the batteries then. Hopefully nothing will get any worse before then!

Should I lower the voltage settings to avoid overcharging the other batteries?
Should I just disconnect and remove the batteries?
Should I disable the tracking system?
Any other ideas?

Thanks in advance for your advice.
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Need advice/opinions on unused system

    Welcome to the forum.

    I'd say pull the batteries and keep them charged somewhere that you can keep an eye on them. One is bad already, and it won't come back just being left alone with the rest through standard charge cycles. If you can equalize the bad one with a good charger (not just automotive type) it might be salvageable. Left in series with the others and they'll all be dead in two years. Multi-stage chargers: http://www.solar-electric.com/bach1.html

    Since the batteries are already 5 years old and your not planning on using the place for two years, expect to buy a new battery set. If not at first, then soon after. Seven years is getting close to death for even a well-maintained set.

    What kind of trackers? If they are electro-mechanical and you pull the batteries there's no power for them to track with. Make sure all the moving parts are properly lubricated and hope for the best. No machinery likes to sit doing nothing!
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    #3
    Re: Need advice/opinions on unused system

    If they are Wattsun's about all that goes wrong with them over decades is not letting them track. It is also not hard to replace the azimuth motor.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • newguy
    newguy Registered Users Posts: 5 ✭✭
    #4
    Re: Need advice/opinions on unused system

    Thanks for the quick replies.
    The tracker is a Wattsun 225.
    I was hoping to use these batteries at least for house construction with a little help from a small generator for larger power tools. I think we'll need a larger bank when we move in so I don't want to replace anything yet.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #5
    Re: Need advice/opinions on unused system

    Good plan. Unfortunately that one bad battery makes the whole system non-viable. If you could bring that one back up to near normal it should work, but chances are it has failed internally (one out of string having very low Voltage, others high).
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    #6
    Re: Need advice/opinions on unused system

    If it were me and I did not need this battery system for serious power I would replace the bad battery with a golf cart battery from Costco. Be aware that the same thing that killed one of your batteries is probably still at work. Good Luck.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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  • Peter_V
    Peter_V Solar Expert Posts: 226 ✭✭✭
    #7
    Re: Need advice/opinions on unused system

    Your current sent of batteries is almost certainly toast at this point. They were old to begin with and the "good" ones haven't been charged properly since the stinker developed a short.

    Don't put a new one in that pack, it won't last very long and neither it or the old ones will get charged properly with a mixed pack
    You can try replacing the stinker with another old battery.

    Make friends with a guy that maintains the golf carts and see if you can get some batteries in decent condition.

    Since it's not a good idea to mix new batteries with old ones, when one goes bad in a golf cart's pack they normally replace the whole pack. The other 5 batteries in the pack should at least be as good as your batteries.

    Note: Mixing GC and L-16 batteries is generally a bad idea because they have different capacities. However, in this case you should be able to limp along for a while at very little cost.
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  • newguy
    newguy Registered Users Posts: 5 ✭✭
    #8
    Re: Need advice/opinions on unused system

    Thanks to everybody for your input. Next time I'm there I'll see if the battery can be salvaged. If not, maybe parallel 2 T105 sized batteries to fill the gap in the string temporarily to be nearly equal in capacity at the lowest price. If they survive, they could be used in the camper later.
    I'll let you know what happens and I'm sure I'll have more questions later!
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  • jcgee88
    jcgee88 Solar Expert Posts: 154 ✭✭
    #9
    Re: Need advice/opinions on unused system
    newguy wrote: »
    I have just purchased property with a system that won't be used for a couple years.

    I wasn't sure if you meant, "hadn't been used" vs "won't
    be used" for a couple of years.

    If it is truly the latter, and you have the ability to hook to
    the grid and do net metering, if I were in your shoes I'd
    disconnect the batteries/charger, and just do a standard
    grid tie. That way, you'd be racking up credits or money
    for two years.

    John
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  • newguy
    newguy Registered Users Posts: 5 ✭✭
    #10
    Re: Need advice/opinions on unused system
    jcgee88 wrote: »
    I wasn't sure if you meant, "hadn't been used" vs "won't
    be used" for a couple of years.

    If it is truly the latter, and you have the ability to hook to
    the grid and do net metering, if I were in your shoes I'd
    disconnect the batteries/charger, and just do a standard
    grid tie. That way, you'd be racking up credits or money
    for two years.

    John

    Thanks, it wasn't very plain but I meant both. I wish I could go grid-connect! That would be the best plan, if possible. The system is now 5? yrs. old and has only been seasonally used to power a RV. One battery is bad in a 48v series string of 8 L16s. I'll probably be building a house over a two year period, starting in one or two years and will need the pv system along with a generator for construction. I believe I will need a battery bank 2-3 times larger for the house once built, so I hate to spend much now on batteries only to be replaced in a few years.
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