ISO 2 volt high amp battery charger for single cell balancing.

wild01wild01 Solar Expert Posts: 100 ✭✭✭
Does anyone know of an affordable 2 volt efficient battery charger that i could use to balance individual cells in a lead acid agm stack. I have a 36 volt 1100ah stack made up of 2v individual cells, because it's AGM equalizing to balance is problematic. I think a 20+ amp 2 volt charger would be ideal. If and of you know of one I would greatly appreciate a link/name of where I could obtain one.

Alternately if any of you electrical engineer types could cobble one together quick it would be worth a couple hundred to me😉.


  • BB.BB. Super Moderators, Administrators Posts: 33,002 admin
    Here is a 0-50 volt @ 20 & 30 amp adjustable lab supply:

    And, on the low cost side 15-20 amp down converting adjustable switching regulator:

    Either should work... Note that the second two may not have "isolated outputs" (i.e., the Vin negative is directly connected to Vout negative..

    The lab supplies should be isolated outputs (from the AC input). However, you need to verify if the AC ground connection is also connected to the DC negative connection (should be, but don't know).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • wild01wild01 Solar Expert Posts: 100 ✭✭✭
    Thanks Bill, you've given me a great starting point. Sometimes it's just about getting the right Google phrase.  (Adjustable power supply)Haven't checked yet to see if my AC ground it connected to my dc neg but was aware that that could be an issue- Every since I wired a msw inverter into a camper with a bonded neutral and discovered that they make msw 120v with split phase 60 volt. When I grabbed the door knob to leave the sensation was not pleasant.

    I definitely don't want to short a 40 kwh battery bank.

    Thanks again wasn't getting anywhere googling 2 volt battery charger.
  • BB.BB. Super Moderators, Administrators Posts: 33,002 admin
    I started with "adjustable step down power supply 20 amps":

    You could sub "step down" with "buck" and/or "converter".

    Ebay seems to have "tons" of DC to DC power converters (if you do EBay).

    One thing to watch out for... Many electronic power supplies (for computers and such) can include a "crowbar" on the output circuit (typically these supplies are not adjustable). A crowbar is set to short the output if the voltage goes to high (like a failed regulation circuit).

    You do not want a "crowbar" protected output on a battery bank (aka, shorting the battery bank with the crowbar protection). For example, a 12 volt power supply may have a 14 volt crowbar.

    I do not believe any of the "classes of supplies" I gave links for, have a crowbar circuit (no crowbar--ok/good for battery charging).

    Many supplies are just voltage regulated... For battery charging, you want one that also can regulate current (i.e., limit to 20 amps from 0-2.3 volts, and limit voltage at 2.4 volts.

    Converters/power supplies without current control, they will over current and be damaged--Or simply shutdown for over current.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mcgivormcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    Seen these 2v cell ballanceing devices never used them though. Connecting all the cells in parallel and leaving them for some time overnight perhaps will also ballance the voltage, or discharging the high cells to match  the voltage of lower ones would work. The thing is, every cell is unique, there may be slight variations in voltage, the question is how far apart are they? Even if they were ballanced, as soon as they are charged in series, it's likely the cells will drift back to their previous values. 
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
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