Bulk/abs chg with XW-MPPT60-150

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Brent
Brent Solar Expert Posts: 64 ✭✭✭✭
in Grid Tie and Grid Interactive Systems #1
I have a 840A/H, 48 volt battery bank and every morning the charge controller cycles through the Bulk [57V], Abs [59V] and Float [53V] charge profile [voltages recommended by mfg]. The batteries are not discharged frequently so stay pretty much fully charged.

My question is that the batteries gas quite a bit during the bulk and abs cycles. Is this ok for the long term health of the batteries and since the batteries gas is this a substitute for periodic equalization.

Thanks,

Brent


PV:6500W, [2] XW6048, [2] XW-MPPT60-150
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
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    Re: Bulk/abs chg with XW-MPPT60-150

    How long is the battery in each stage ?

    Some gassing is needed to keep elelctrolyte stirred, and since you are not discharging much, you don't need much EQ, so this is likely good, if you've checked each cell for gassing.
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Brent
    Brent Solar Expert Posts: 64 ✭✭✭✭
    #3
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    Re: Bulk/abs chg with XW-MPPT60-150

    The charge controller abs chg is set for 10 min. The bulk charge can't be set but typically stays in bulk for 20 - 60 min depending on solar output.

    Brent
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #4
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    Re: Bulk/abs chg with XW-MPPT60-150

    What loads do you have on the system that pulls the battery down nightly?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

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  • Brent
    Brent Solar Expert Posts: 64 ✭✭✭✭
    #5
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    Re: Bulk/abs chg with XW-MPPT60-150

    When not in the sell to grid mode the system is in the AC feedthru mode so there are no loads on the batteries unless the grid goes down.

    I guess my real question is, since the batteries are always charged and in float for most of the day, would it make sense to set the bulk and abs voltage to say 55 volts until the time comes when the batteries do get discharged then I can raise the charge voltages.

    This would prevent unnecessary gassing which I understand is hard on the batteries over the long term.

    Brent
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