Looking for 12v AC-DC battery charger recommendation.

terracoreterracore Registered Users Posts: 10 ✭✭
I'm looking for an AC-powered DC battery charger for supplementing my battery array on cloudy days.  I am not looking for an inverter charger, or anything that starts a generator.  I have smart and dumb chargers but all the smart chargers I can find are tailored for maintenance free automotive batteries, not an array of golf cart batteries under load. 

Basically what I'm looking for is a charger with thresholds I can set.  Like it doesn't do anything unless the battery voltage drops to 11 volts and then it kicks on and begins charging until it reaches 13v and then goes back to sleep until/if it's services are required again.  Or whatever voltages I set.  Because the solar chargers are doing the heavy lifting and just need help every now and then when the clouds roll in.

This seems like a no-brainer product that should be easy to find but I haven't been able to find it, just a bunch of DIY "workarounds".   If anybody can make a recommendation I look forward to reading it.  Thanks.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,509 admin
    edited May 20 #2
    The Xantrex TC-2 series is pretty nice. They are Power Factor Corrected for their AC input, and are much "friendlier" for gensets-though not cheap (they are "effectively" more efficient on gensets vs non-PFC--Can discuss in detail if you are interested).

    https://www.solar-electric.com/residential/batteries-battery-storage/battery-chargers.html?manufacturer=101 (scroll down on page)
    http://www.xantrex.com/power-products/battery-chargers/truecharge-2-2.aspx

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • terracoreterracore Registered Users Posts: 10 ✭✭
    Thanks for your reply!  Maybe I'm not technically savvy enough to understand these products- I don't see features that allow the user to set the voltages at which the chargers turn on or off. Please school me if I'm mistaken!
  • BB.BB. Super Moderators, Administrators Posts: 29,509 admin
    Terracore,

    You are correct, the TC-2 has fixed charging voltages--Depending on battery type and 2 or 3 step charging cycle chosen.

    Here is another thread with a charger from Full River that appears to have a wireless charging interface and potentially high programmability:

    https://forum.solar-electric.com/discussion/352285/ac-battery-charger/p1

    http://www.fullriverbattery.com/series/chargers/fullriver-fr1-chargers

    In the same thread, there is a Concorde programmable (to what degree?) charger too (designed for aircraft charging, probably not cheap):

    https://www.aviationpros.com/engines-components/aircraft-airframe-accessories/product/10771553/concorde-battery-corporation-battery-accessories
    http://concordebattery.com/otherpdf/BC_8000.pdf

    Some of the most configurable chargers I have read about seem to be the Inverter-Chargers--I know you don't need the inverter, but it may be cost competitive compared to the few other programmable chargers out there.

    What is it you are looking for? Cycling golf cart batteries are not unusual and even the "simple" Iota chargers with the IQ-4 charge control module seem to keep most people happy...

    https://www.solar-electric.com/search/?q=iota

    Many (most/all?) have an internal 10 turn pot that can be adjusted to change base charging voltage (you have to remove an external cover to access the pot).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • bill von novakbill von novak Solar Expert Posts: 850 ✭✭✭✭
    terracore said:
    I'm looking for an AC-powered DC battery charger for supplementing my battery array on cloudy days.  I am not looking for an inverter charger, or anything that starts a generator.
    Because I am cheap I'd use a Meanwell 12V power supply with a voltage controlled timer.  Below 11.5 volts it turns on and supplies 13.8 volts, and then shuts off after four hours.
  • terracoreterracore Registered Users Posts: 10 ✭✭
    Thank you again everybody for your comments.

    "What is it you are looking for?"   Example:   Solar panels produce 1000 watts.  Electricity needs are 500 watts.  80% of the time, everything is peas and carrots.  20% of the time, dark clouds roll in and solar panels produce 250 watts.  Since I have access to the grid, it makes more sen$e to occasionally replace 250 watts with grid power for a short period of time than buying a huge battery bank. Sometimes, it might be longer.  But whatever the case, simply looking for a plug-and-play gizmo that will sense a programmable battery level and begin charging, and then shut off at whatever programmable level I choose.  It doesn't seem like rocket surgery, and it also seems like nobody makes such a gizmo.

  • BB.BB. Super Moderators, Administrators Posts: 29,509 admin
    There are "hybrid" inverters (inverter-chargers) that can do this (I think) from Schneider, probably Outback, and others. No standalone charger that I can think of (I am not in the solar biz--So that opinion does not mean much).

    In general, cycling batteries runs your cost upwards of $0.45 to >$1.00 per kWH (battery replacement costs, inverter/charger/etc. hardware costs, lower system efficiency, etc.)...

    So, for most people with utility power, the cost of utility power is cheaper than the added wear and tear on your battery bank. (in California, my summer afternoon peak power costs can exceed $0.46 per kWH--So close to breaking even).

    https://www.pge.com/tariffs/assets/pdf/tariffbook/ELEC_SCHEDS_E-6.pdf

    If you wanted to estimate state of charge with a simple voltmeter (i.e., when battery falls below ~12.3 volts or so--ref 12 volt bank), and turn on the charger until the battery is >14.4 volt volts or so-->~80% SoC from utility charging)--Not the most difficult thing to do with a modern Raspberry Pi or Arduino or other single board computer connected to a 120/240 VAC power contractor for the external power supply AC input.

    You can also go with a shunt based battery monitor and set the "alarm contact" to 50% on and 80% off (suggested values)...

    https://www.solar-electric.com/search/?q=battery+monitor

    Some of the Victron and Xantrex Battery monitors have the programmable "alarm contacts".

    I am sure that there are other good ideas out there too...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • EstragonEstragon Registered Users Posts: 3,962 ✭✭✭✭✭
    It seems to me a simple float charger set to just under solar charge controller float voltage might do what you want.  It would hold battery voltage at 13.x if need be, but otherwise do nothing. To the extent possible, the solar controller would hold battery voltage higher and supply loads.  If a cloud rolls by, battery voltage would drop and the AC charger would kick in to hold float voltage.  The battery would only cycle if grid power was lost - essentially a UPS?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • terracoreterracore Registered Users Posts: 10 ✭✭
    Maybe I'm overthinking this?  I'm currently using one of these units that detects low voltage and switches to grid until the batteries recover.  I was thinking it might be easier on the batteries (extend their life) if I didn't let them drop so far in voltage to begin with.  I think he unit can be reconfigured to turn a dumb charger on/off as well but I didn't want to lose the primary function of the unit or buy a second one if there was a charger on the market that was configurable.


  • EstragonEstragon Registered Users Posts: 3,962 ✭✭✭✭✭
    At 11v, you'll be taking the battery down to near dead, which will reduce expected cycle life considerably.  If it's likely this only happens a handful of time over the chronological life of the battery (eg. 5-10yrs), that's not a big deal (as the battery will likely die of old age before it dies from cycling).  If more frequent cycling is likely, shallower cycling should give you more cycles.

    With true deep cycle batteries, we use 50% as a rule of thumb balance between long life and system size / cost.  This would be about 12.1v.  

    Fully charged is generally ~12.7 (may vary some depending on the battery).  
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • terracoreterracore Registered Users Posts: 10 ✭✭
    I have my system to switch to grid when batteries are about 50%.  The primary reason for installing the switch was to make the batteries last as long as possible, and also I didn't want to be stuck with nearly dead batteries if the grid power goes out.  I have another transfer switch set on a timer so the system will never try to use DC power when the sun isn't out unless the AC power fails.

    I've looked for a programmable float charger... no dice.  Anybody have a recommendation?
  • tabbycattabbycat Solar Expert Posts: 51 ✭✭✭
    The Sterling Procharge series of chargers seem to have everything you need. They are marine rated so should be reliable.
  • mcgivormcgivor Solar Expert Posts: 3,073 ✭✭✭✭✭
    tabbycat said:
    The Sterling Procharge series of chargers seem to have everything you need. They are marine rated so should be reliable.
    Translation, Marine = Expensive  :D
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery bank 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • EstragonEstragon Registered Users Posts: 3,962 ✭✭✭✭✭
    Agree that "Marine = Expensive".  Sometimes the extra cost does have some utility (eg. better circuit board coating, water-tightness, vibration resistance, etc), but that utility may be of limited value in a non-marine application.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
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