Generator plus battery charger

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Just Me
Just Me Solar Expert Posts: 48
I searched, but didn't find what I was looking for.

I have a TriMetric to watch my two Trojan T-105s and 96W panels for my toy hauler. If my batteries get to 20% DOD, and I fire up my generator and also have a Smart Charger hooked to the batteries and set it to equalize, will it charge them better and quicker than if I just let my inverter charge them?

I did find that whatever is putting out the most current, will take over from the lesser charge. What is the best way to charge my batteries.

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,439 admin
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    Re: Generator plus battery charger

    Bulk charging (battery is more than ~10-20% discharged)--is just putting current into the battery and anything is OK as long as the maximum charging current and maximum charging voltage is not exceeded.

    Once the battery is ~80-90% full (state of charge)--then any charger will begin to cut back on current. Depending on the battery type, too much charging current at this point can overheat the battery (plus use more water) and cause sealed batteries to vent gasses.

    You should not be equalizing ever time you charge--for flooded cell, typically only 4-12 times a year. Excessive equalization is damaging to the battery.

    By the way, are you discharging to 80% DOD (depth of discharge) all the time? This is pretty hard usage on the battery bank and they will not last that long (depending on the battery brand/model, perhaps around 500 cycles or so).

    Don't get me wrong that you are "abusing" your battery bank... But be prepared for replacements (i.e., 2x the number of batteries will last roughly 2x as long--still the same rough costs for battery power).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
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    Re: Generator plus battery charger
    Just Me wrote: »
    will it charge them better and quicker than if I just let my inverter charge them?

    Dunno - you didn't say what the inverter is, or what the charger is. Some are better than others.