Multiple charge controllers for one battery bank

larynx
larynx Registered Users Posts: 1 ✭
in Caravan, Recreational Vehicle, and Marine Power Systems #1

I currently have one 330watt solar panel hooked up to a MPPT controller that is charging a 12V 300AH LifePo4 battery bank in my camper conversion. Would it be possible to connect a second MPPT charger controller to a second (smaller) solar panel and charge the same battery bank with both charge controllers efficiently? 


​​​​​​​Thank you

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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #2

    Multiple charge controllers on a bank is done often, and is generally not a problem.

    One issue that can arise is when the controllers don't communicate (generally just the large, higher end ones do), they may get a bit out of step in charging. Typically, one sees a bit higher voltage than the other, but with a lithium bank and fairly conservative voltage, it shouldn't be an issue.

    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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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #3

    Be sure your battery preservation system (BMS) and charge controllers are all going to play well together, you don't want to cook anything

    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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  • Reed
    Reed Solar Expert Posts: 55 ✭✭
    #4

    Larynx -

    Our 19' Roadtrek has very limited real estate. Our son was able to get a 100 W and a 315 w panel installed. This required two controllers to the 4.5 kW-hr 12 V nominal battery suite. It has worked well on trip to Labrador (1000 km of fairly rough gravel) and Newfoundland and two trips to Yucatan. Battery suite is below bed with a blower that sends warm air from cabin to the battery box when temperature drops below 40 F (5 C). Scared the heck out of it the first time it did this at outside temp of 18 F (-8C). It never got above 85 F ambient in Yucatan.

    We got leary of line power when we went up west coast of Mexico. Two RV sites in a row had very bad electricity: no ground. This resulted in shock when touching frame. So went just used solar the last four weeks of trip. We have since installed a ground cable to frame along with a thick copper rod pounded into earth. On beach of Yucatan, we put a pailful of sea water onto sand by rod.

    Reed and Elaine

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