Best way to equalize batteries off-grid - Cheap Generator?

cdre
cdre Solar Expert Posts: 78 ✭✭
in Off Grid Solar & Battery Systems #1
In the past, I've used a 2 stroke 1000w generator run for 12 hours or so to equalize my 12v RV sytem with 4 12v batteries.

Shifting over to a 48v system and trying to ensure I take care of my batteries, I'm wondering what the most cost effective way to equalize is... I wonder if I can get away with the same small generator idea...

How are you guys doing it?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,649 admin
    #2
    Re: Best way to equalize batteries off-grid - Cheap Generator?

    What is the AH rating and voltage of your battery bank?

    A good quality power factor corrected AC battery charge mated to a good quality genset of appropriate size is still not a bad way to go for charging/backup power.

    Ideally, for most generator you want to run them at a minimum of 50% load for good fuel efficiency. The Honda eu2000i can run down to 400 watts / 25% load at good fuel efficiency because of the inverter/generator (allows engine to throttle back to a lower speed when power requirements are low).

    But, this all has to match your battery bank + battery charger for optimum cost and fuel usage.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • cdre
    cdre Solar Expert Posts: 78 ✭✭
    #3
    Re: Best way to equalize batteries off-grid - Cheap Generator?

    I'm looking at a Northstar Trifuel 6.6kw generator for typical use (surge loads and bulk charging), but thinking a smaller gen would be better for long equalization (float) runs... Battery bank likely to be 16 T-105s in two 48v strings with an Outback FX3048T.

    I always keep a smaller generator handy as a backup anyway, but wondering if I can get away with the 1000w disposable chinese generator for a monthly battery burn. I'm not sure if it would have enough power to supply that equalizing charge.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,649 admin
    #4
    Re: Best way to equalize batteries off-grid - Cheap Generator?

    Your choice on the small generator... How many hours do you expect on the 1,000 watt guy vs the 3,000 hours +/- that you could get on the much more expensive (and quiet) Honda eu2000i (1,600 watt rated).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • cdre
    cdre Solar Expert Posts: 78 ✭✭
    #5
    Re: Best way to equalize batteries off-grid - Cheap Generator?

    I've actually had 2 of those units, and I can't complain too bad... The biggest problems I've had is carbon buildup at the exhaust (too much 2 stroke oil) and pull cord failures. Carbon bulidup occured after about 6 months of 2 hours or so daily (before I went solar). If I'm running the generator very infrequently I won't be pulling on the cord all the time (less starting wear and tear).

    While the metallurgy on those little engines isn't comparable to a honda engine, as long as you buy them knowing they are disposable, they are very handy.
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