can a deep battery of say 400ah at 12v be charged by a car?

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  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    edited August 2019 #32
    Some of the newer li batteries have built in BMS with over charge, over current and over discharge built in.  To the point where it physically will internally disconnect the battery from the terminals on the battery.  They are more expensive but that is one way to do this without any worry.  I believe Battle Born and Simplphi  have this and I believe a couple of others as well.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,639 admin
    #33
    Don't know any specifics... And it may be true that Balmar and others do not have a "minimum current" output by design. And I do not have any recent experience alternator systems (many decades since I have needed to touch one).

    I am not any sort of expert on Li Ion batteries... But most (all?) seem to be very susceptible to damage if overcharged (over voltage while charging).

    -Bill "don't know" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • m151
    m151 Registered Users Posts: 39 ✭✭
    #34
     A little off-topic, but 25% of the energy in an engine is wasted through the radiator. Instead of a battery I have always brainstormed the idea of having a 30 to 50 gallon water heater in back of the truck tied into the cooling system with a heat exchanger inside the water heater. This could be plumbed just before the regular water heater  to use free energy. The weight of the water heater would of course take more energy to haul around. But on a six or 7000 pound pick up truck it may not amount to that much.  A valve  with quick disconnects could be plumbed into the garage. Anybody tried this?  Heated water is an energy hog. 
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #35
    Something similar is sometimes done with stationary generator systems.  I think it needs a bit of engineering to, for example, make sure coolant temp gets to and stays in the proper range. 

    Exhaust is also a potential source of heat, but also needs to ensure backpressure isn't excessive, etc.  I do a crude version of this to warm the ground under my genshed.

    I'm not sure of the economy of doing it for a mobile application though.  I assume you're somewhere always warm (repeatedly winterizing would be a PITA).  A preheat tank painted black sitting in the sun might be more bang for the buck.
    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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