Charge controller low temperature shut off

icarus
icarus Solar Expert Posts: 5,436 ✭✭✭✭
Working on a design for a system using LoPo batteries.  This system may well be un attended for months at a time of cold weather.  Victron batteries allow storage to ~-40c but limits charging to ~+5c.  

My question is this: Is there a reputable MPPT controller that you can field configure to shut off when a BTS says the battery is too cold?  I know that you can configure most controllers to shut off with too high a battery temp, but I’m unaware of one that will shut off at a pre set low temp.

Thanks for the help,

Tony

Comments

  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    Because most, if not all, charge controllers are primarily designed for lead acid batteries which have no need for such a feature, makes me think it's unlikely to find one with low temperature cut-off. Making a device would be simple with the use of a thermostat and a couple of DC contactors, one to disconnect the PV and a second to disable the controller, the latter to prevent the controller itself from drawing current unnecessarily when the PV is disabled.,should you need assistance in design I would be happy to assist.


    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.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Thanks MC...I may be in touch.  I have contacted Victron to see about simply “pulling the plug” and not worrying about a charge regimen while gone.  Clearly I don’t want to risk an expensive battery on a beta.  I suppose I could simply by a small LiPo and set it up for a winter, but bottom line is, I need to replace the T105’s come spring any way.  Tony
  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    icarus said:
    Working on a design for a system using LoPo batteries.  This system may well be un attended for months at a time of cold weather.  Victron batteries allow storage to ~-40c but limits charging to ~+5c.  

    My question is this: Is there a reputable MPPT controller that you can field configure to shut off when a BTS says the battery is too cold?  I know that you can configure most controllers to shut off with too high a battery temp, but I’m unaware of one that will shut off at a pre set low temp.

    Thanks for the help,

    Tony

    Hi Tony,

    The MidNite Classic CCs have two sets of Aux terminals,  one set is output only,  the second (Aux 2) does input and outputs.

    One Aux 2 function causes the CC to Rest when these terminals are active (Settable active high or low).

    One trade off would be,   that the MN Battery Current Monitoring accessory (the WbJr),   also needs to use Aux 2.   This would probably not be an issue for a system that needs two,  or more CCs.

    FWIW,  Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • mike_s
    mike_s Registered Users Posts: 155 ✭✭
    A Morningstar Prostar MPPT will do what you want:

    The ProStar MPPT has a Low Temperature Foldback option which can be used to protect lithium batteries from being charged in cold conditions.... The High Limit defines the lowest temperature at which the controller will deliver 100% of the controller’s rated output charging current. The Low Limit defines the temperature at which the controller will stop providing battery charging current. The charge current is tapered linearly from the High Limit to the Low Limit.


  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,142 ✭✭✭✭
    mike_s said:
    A Morningstar Prostar MPPT will do what you want:

    The ProStar MPPT has a Low Temperature Foldback option which can be used to protect lithium batteries from being charged in cold conditions.... The High Limit defines the lowest temperature at which the controller will deliver 100% of the controller’s rated output charging current. The Low Limit defines the temperature at which the controller will stop providing battery charging current. The charge current is tapered linearly from the High Limit to the Low Limit.



    Thanks for the info, Mike.
    I always have more questions than answers. That's the nature of life.
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Thanks MIke...

    Tony
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Interesting.  Read up a (tiny) bit on the MS Prostar.  Looks like it will do the trick. Wish it were a bit bigger for head room.  (I am also designing a much bigger system that also will be laid fallow for cold winter months.  Probably on the 3kw size). I suppose it is only a matter of time before Midnight designs this into it’s line?

    T
  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    Looking and thinking a bit further, this won’t work either.  Any controller has some self consumption current draw.  So in my case, if the batteries go “dark” because of cold, they may stay dark for months. The .6 watt draw day and night, for months on end will draw the battery to zero quite quickly.  I need to figure out a way to allow the CC to wake up once the battery temp rises enough.  I’ll keep thinking about this.

    T