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Thread: Charging 24 volt system with a 12 volt charger-

  1. #1
    Join Date
    Oct 2006
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    Edgewood, New Mexico
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    Default Charging 24 volt system with a 12 volt charger-

    Let's say I have two 12 volt batteries in series running my 24 volt inverter. Could I use a 12 volt battery charger applied to the correct posts on ONE of those batteries to successfully charge both batteries?
    Current setup: Xantrex SW4024 inverter\2220 watts of PV:6 Evergreen 180 panels and 6 Canadian Solar 190's\Outback FlexMax 80 Charge Controller\Prometric charge analyzer\Large bank of Trojan batteries\ (2) 800 watt 24v wind generators. Craftsman 5600-watt gas generator for backup.

    WWW.GOIN-GREEN.NET My interview website for off-grid living! Please feel free to e-mail the website with your stories and pic's: Goin-green@live.com

  2. #2
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    Default Re: Charging 24 volt system with a 12 volt charger-

    Quote Originally Posted by rickeolis View Post
    Let's say I have two 12 volt batteries in series running my 24 volt inverter. Could I use a 12 volt battery charger applied to the correct posts on ONE of those batteries to successfully charge both batteries?
    In theory, if its a deep cycle capable charger (15V vs 14V), it could work, if there are no loads on the system. To insure against reverse charging the other battery, by a load running, you should disconnect the load, till all charging is done.
    http://tinyurl.com/LMR-Solar
    http://tinyurl.com/LMR-BigLug
    http://tinyurl.com/LMR-NiFe

    Grundfos 10 SO5-9 with 3 wire Franklin motor (1/2hp 240V 1ph # 214505 ) on a timer for 3 hr noontime run - Runs off PV
    Powerfab poletop PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe battery | 15, Evergreen 205w "12V" PV | Midnight ePanel || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT

  3. #3
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    Edgewood, New Mexico
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    Default Re: Charging 24 volt system with a 12 volt charger-

    I know that the charged battery(s) will have more amperage than the uncharged one, but will the flow of power simply go towards the lesser charged battery?
    I am on a 'time of use' measured system and am thinking about setting a timer to run a small charger during the off-peak times in that manner. Basically, at night when the sun is not feeding the solar array.
    (I know my elect. provider would have a cow if they found out)
    I've looked around and can't seem to find a 24 volt battery charger anywhere.
    Current setup: Xantrex SW4024 inverter\2220 watts of PV:6 Evergreen 180 panels and 6 Canadian Solar 190's\Outback FlexMax 80 Charge Controller\Prometric charge analyzer\Large bank of Trojan batteries\ (2) 800 watt 24v wind generators. Craftsman 5600-watt gas generator for backup.

    WWW.GOIN-GREEN.NET My interview website for off-grid living! Please feel free to e-mail the website with your stories and pic's: Goin-green@live.com

  4. #4

    Default Re: Charging 24 volt system with a 12 volt charger-

    Links to basic 24 V chargers with optional "IQ" smart controller:

    http://www.iotaengineering.com/24vdc.htm
    http://www.iotaengineering.com/iq.htm
    http://store.solar-electric.com/bach1.html

    HTH,
    Jim / crewzer
    120618: System off-line for a while...

  5. #5
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    Default Re: Charging 24 volt system with a 12 volt charger-

    Quote Originally Posted by rickeolis View Post
    I know that the charged battery(s) will have more amperage than the uncharged one, but will the flow of power simply go towards the lesser charged battery?
    No. What will happen, is that the more charged battery, will, if you have a load on it, will eventually reverse charge the weaker battery. So you have to disconnect load, charge battery A, switch leads, and charge battery B. Or get a 24V charger.

    Are you using deep cycle batteries, or car starter batteries ?
    http://tinyurl.com/LMR-Solar
    http://tinyurl.com/LMR-BigLug
    http://tinyurl.com/LMR-NiFe

    Grundfos 10 SO5-9 with 3 wire Franklin motor (1/2hp 240V 1ph # 214505 ) on a timer for 3 hr noontime run - Runs off PV
    Powerfab poletop PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe battery | 15, Evergreen 205w "12V" PV | Midnight ePanel || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT

  6. #6
    Join Date
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    Edgewood, New Mexico
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    Default Re: Charging 24 volt system with a 12 volt charger-

    Mike, I see what you mean. I drew a little diagram of what I am looking at doing, and the weaker battery won't get the higher charge, it will try to pass through the inverter and reverse charge the weaker battery. Not good!
    I guess I can look into a 24 volt charger, thanks guys!

    -Rick-
    Current setup: Xantrex SW4024 inverter\2220 watts of PV:6 Evergreen 180 panels and 6 Canadian Solar 190's\Outback FlexMax 80 Charge Controller\Prometric charge analyzer\Large bank of Trojan batteries\ (2) 800 watt 24v wind generators. Craftsman 5600-watt gas generator for backup.

    WWW.GOIN-GREEN.NET My interview website for off-grid living! Please feel free to e-mail the website with your stories and pic's: Goin-green@live.com

  7. #7

    Lightbulb Re: Charging 24 volt system with a 12 volt charger-

    I am on a 'time of use' measured system and am thinking about setting a timer to run a small charger during the off-peak times in that manner. Basically, at night when the sun is not feeding the solar array.
    Rick,

    Doh!! You can do this with your SW4024 and not buy/connect any additional equipment. From page 69 of the SW manual:

    INVERTER/CHARGER MODE

    IN BRIEF

    The SW Series Inverter/Charger is capable of automatically transferring AC loads from the inverter to a utility grid or generator. Once transferred, the inverter can recharge the battery. The inverter/charger can transfer upon the availability of AC power (FLT mode), either at a specific time each day (using the GRID USAGE TIMER (18 ) menu heading), or upon a low battery condition (LBX mode)
    So, just go into your SW, and set it up to connect to the grid for a few hours at night to run your AC loads and charge your batteries. Voila!

    HTH,
    Jim / crewzer
    120618: System off-line for a while...

  8. #8
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    pittsburgh, pa
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    Default Re: Charging 24 volt system with a 12 volt charger-

    "weaker battery won't get the higher charge"
    actually if you only charge 1 of the 12v batteries the other receives nothing unless the charger wires are taken off of the charged battery to be placed on the other battery yet needing a charge. there are difficulties in doing this and though it can be done there is a larger margin of errors that can occur to ruin the batteries and could be considered the ultimate in unequalized batteries. you were advised correctly on getting a proper 24v charger.
    NIEL

  9. #9
    Join Date
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    Edgewood, New Mexico
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    Default Re: Charging 24 volt system with a 12 volt charger-

    Hi Jim,
    I actually tried that method out a couple of months ago and it went OK for about 5 days and then the 4024 turned itself off due to low battery voltage. Apparently I use too much power during the day to make use of that method. It should have run the battery charger automatically when the batteries got low but it didn't. I have gone back to the default mode and things are OK again for now.
    Niel, you're right, I was hoping I could use something I already had, but I guess not! Thanks-

    -Rick-
    Current setup: Xantrex SW4024 inverter\2220 watts of PV:6 Evergreen 180 panels and 6 Canadian Solar 190's\Outback FlexMax 80 Charge Controller\Prometric charge analyzer\Large bank of Trojan batteries\ (2) 800 watt 24v wind generators. Craftsman 5600-watt gas generator for backup.

    WWW.GOIN-GREEN.NET My interview website for off-grid living! Please feel free to e-mail the website with your stories and pic's: Goin-green@live.com

  10. #10
    Join Date
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    Location
    Willits, CA
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    Default Re: Charging 24 volt system with a 12 volt charger-

    Why not say exactly what you are powering, what are you trying to do ?

    I know it's some sort of load shift, to offload an appliance at peak hours, and recharge the battery at night.

    Whats the power draw of the device , and for how many hours ?

    It's easier to be helpful with all the info at hand.
    http://tinyurl.com/LMR-Solar
    http://tinyurl.com/LMR-BigLug
    http://tinyurl.com/LMR-NiFe

    Grundfos 10 SO5-9 with 3 wire Franklin motor (1/2hp 240V 1ph # 214505 ) on a timer for 3 hr noontime run - Runs off PV
    Powerfab poletop PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe battery | 15, Evergreen 205w "12V" PV | Midnight ePanel || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT

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