Lithium Battery Complications

Crosscut
Crosscut Registered Users Posts: 5 ✭✭
in Caravan, Recreational Vehicle, and Marine Power Systems #1
Greetings all.  I'm new to solar and wish to install a system on our travel trailer.  Sitting down yesterday with the RV service guy, I realize I'm not yet ready.  I had intended AGM batteries, now I'm considering Lithium.  My immediate questions are these:

1) It seems I now need a solar controller intended for lithium batteries.  Is that correct? 

2) Victron advertises its batteries as having just four cells.  Of course I don't want a battery consisting of a hundred smaller cells.  Which battery brands do you recommend? 

3) Can two separate Li batteries be wired in parallel?  I read that there are inherent troubles with this. 

4) Finally, if I find myself with cold-soaked Li batteries...let's say 15 degrees fahrenheit...what sort of power would I have?  Enough to run a heater blower long enough to warm the trailer/battery?  (2X Battle Born 100Ah 12VLiFePO4)  How cold is too cold for cold soak?

5) Is it true that a Li battery should never be charged below 32 degrees F?

FYI:  4X 170-watt solar panels in series, Victron MPPT 150/60 TR controller, AIMS 2000 watt 70A inverter/charger, 2X Battle Born 12V LiFePO4 batteries

Thank you for responding.


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


    1) It seems I now need a solar controller intended for lithium batteries.  Is that correct? 

    A controller with requisite programmability (absorb voltage, etc) could be used, but one with pre-set charging profiles would need a specific profile suited to the battery chosen.

    2) Victron advertises its batteries as having just four cells.  Of course I don't want a battery consisting of a hundred smaller cells.  Which battery brands do you recommend? 

    3) Can two separate Li batteries be wired in parallel?  I read that there are inherent troubles with this. 

    I believe some are designed to work up to some limited number of parallel connections.  Lots of parallel connections can be an issue with any battery bank, not just lithium  .

    4) Finally, if I find myself with cold-soaked Li batteries...let's say 15 degrees fahrenheit...what sort of power would I have?  Enough to run a heater blower long enough to warm the trailer/battery?  (2X Battle Born 100Ah 12VLiFePO4)  How cold is too cold for cold soak?

    My understanding is discharge is okay at moderately cold temp (eg -10°C) and small currents (eg 5-10% of capacity).

    5) Is it true that a Li battery should never be charged below 32 degrees F?

    Yes.  Hard plating can occur if charged at sub-freezing temps, which is irreversible.

    FYI:  4X 170-watt solar panels in series, Victron MPPT 150/60 TR controller, AIMS 2000 watt 70A inverter/charger, 2X Battle Born 12V LiFePO4 batteries

    Thank you for responding.



    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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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited December 2018 #3
    The Battleborne batteries are intended as drop in replacement for lead acid 12V, they consist of multiple  small cells in parallel to form a cell block, 4 blocks are connected in series to achieve 12.8V nominal,  a built-in  BMS protects from over charge, over discharge and so forth.They can be connected in parallel but not series, the BMS would most likely include temperature protection, contact Battleborne directly to get answers, they are very helpful. Using them, or any battery for that matter, to provide heat is not advisable.
    Battleborne kit https://battlebornbatteries.com/shop/adventure-in-a-backpack-200ah-amp-lithium-bundle/
     This link https://forum.solar-electric.com/discussion/352589/lithum-battle-born-battery-claims-of-peformamce-and-origin#latest is where I previously contacted Battleborne asking some general questions.
    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.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • OldMan
    OldMan Registered Users Posts: 128 ✭✭✭
    edited December 2018 #4
    Crosscut said:
    Greetings all.  I'm new to solar and wish to install a system on our travel trailer.  Sitting down yesterday with the RV service guy, I realize I'm not yet ready.  I had intended AGM batteries, now I'm considering Lithium.  My immediate questions are these:

    1) It seems I now need a solar controller intended for lithium batteries.  Is that correct? 

    Yes.

    2) Victron advertises its batteries as having just four cells.  Of course I don't want a battery consisting of a hundred smaller cells.  Which battery brands do you recommend? 

    If you want to waste your money, buy Victron.

    3) Can two separate Li batteries be wired in parallel?  I read that there are inherent troubles with this. 

    Yes. Many have done this, look around youtube.

    4) Finally, if I find myself with cold-soaked Li batteries...let's say 15 degrees fahrenheit...what sort of power would I have?  Enough to run a heater blower long enough to warm the trailer/battery?  (2X Battle Born 100Ah 12VLiFePO4)  How cold is too cold for cold soak?

    I don't know. Wouldn't be much. 

    5) Is it true that a Li battery should never be charged below 32 degrees F?

    Correct. Head to Arizona. 

    FYI:  4X 170-watt solar panels in series, Victron MPPT 150/60 TR controller, AIMS 2000 watt 70A inverter/charger, 2X Battle Born 12V LiFePO4 batteries

    Thank you for responding.


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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #5
    ) Can two separate Li batteries be wired in parallel?  I read that there are inherent troubles with this.  

    Yes. Many have done this, look around youtube. 


    Blanket statements can be potentially dangerous, Li batteries  ( a collection of cells or cell blocks connected in series to achieve a desired nominal voltage ) can be connected in parallel as long as there is a separate BMS for each battery. Without a BMS the potential for disaster is greatly increased. Over and under voltage can damage cells, the rate if voltage change at the knees of the charge/discharge curve is very rapid, a couple seconds is all it takes to destroy the battery without protection. 

    There are way better resources for information than youtube by the way.
    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.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • OldMan
    OldMan Registered Users Posts: 128 ✭✭✭
    #6
    mcgivor said:
    ) Can two separate Li batteries be wired in parallel?  I read that there are inherent troubles with this.  

    Yes. Many have done this, look around youtube. [/quote]
    There are way better resources for information than youtube by the way.
    Well since you're not dishing the 411, I have no interest in you.
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