Lithium Iron Phosphate Battery question?

QuinnQuinn Posts: 7Registered Users ✭✭
Can anyone suggest a good supplier / brand for a 12vdc 35ah Deep Cycle battery? The web is full of cranking / starting LiFePo batteries but a true 35ah deep cycle for solar charging I cant's seem to find. I'm planning on hooking it up to a Renogy 100W portable solar suitcase charger to power a new type of stove I'm planning to buy. Thx  
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  • BB.BB. Posts: 27,433Super Moderators admin
    I am not sure that there is a "difference" between a "cranking" vs "solar" LiFePO4 battery in that a "cranking" battery designed for heavy starting current still cycles just as well as a non-cranking designed LiFePO4 battery.

    LiFePO4 batteries are designed to be more "stable/safe" vs some other high density Li chemistry (such as laptop computers). And LiFePO4 batteries are less "dense" (kWH/cubic inch) and higher internal resistance (less surge current).

    So, as long as you are looking at LeFePO4--I would suggest that any of those batteries (well designed and mfg. batteries--all else being "equal", which it rarely is) should be fine for your needs.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • QuinnQuinn Posts: 7Registered Users ✭✭
    Hi Bill thanks and that's what I thought until I called Shorai about using their LiFePo Motorsport cranking batteries for deep cycle.  Their reply was negative telling me that Shorai batteries where not suitable for Deep Cycle use and that the recommended depletion was much less then a Deep LiFePo Cycle battery. I don't remember the specifics but I did get that Shorai is not designed for deep cycle applications. Having said that I have noticed that the majority of LiFePo so called Motorsport batteries are small in dimension and at an almost unbelievable light weight for the advertised capacity. It gets confusing when the marketing folks crank up the fluff. 
  • QuinnQuinn Posts: 7Registered Users ✭✭
    I just found this little tidbit on a battery question and answer page that might help

    Shorai batteries are rating for starting purposes. If you draw power on one like a deep cycle battery, you‘ll find about 1/3 of the capacity. Therefore, the 18AH battery would have the perceived capacity of a 6 AH battery. We recommend not discharging a battery more than 50%, so that translates to 1 hour of safe runtime for the 18 AH Shorai battery under a 3 amp load. - See more at: https://www.batterystuff.com/kb/frequently-asked-questions/powersports-batteries-faq/lithium-iron-faq.html#sthash.TD8QOTvq.dpuf


  • BB.BB. Posts: 27,433Super Moderators admin
    Interesting--There are some folks here that have experience with LiFePO4 batteries--Hopefully, one of them can help.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Raj174Raj174 Posts: 586Solar Expert ✭✭✭✭
    Hi Quinn,

    Stark Power has LiFePO4 12 volt deep cycle batteries in various sizes from 6 AH  to 125 AH. This is the link... https://starkpower.com/shop/
    Take a look at the Lithium 101 menu, some good information about their products and lithium batteries in general. 

    Rick

    12 x 300W Renogy PV, MNE175DR-TR epanel modified, MN Classic 150, Outback Radian GS4048A, Mate3, 54.4V 207AH HI Power LiFePO4 no BMS, 4000W gen.
  • QuinnQuinn Posts: 7Registered Users ✭✭
    Hi Rick,
    I spoke with the owner of the company that makes the stove I am looking at about batteries. And he said the Stark Power specifications look good but he had no success in contacting them by phone or email. I will check with him again. He suggested Valance LiFePo batteries which I am sure are great but a bit pricey out of the gate. Maybe I will end up getting Valance but not without looking for cheaper options first. Thx 
  • oil pan 4oil pan 4 Posts: 669Solar Expert ✭✭✭✭
    Why not just use propane? 

    Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

    Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

  • karrakkarrak Posts: 275Solar Expert ✭✭✭✭
    Fabulous, a new term "Pb Eq AH" to confuse everyone. If you see this, divide the figure by 3 to get the real AH rating.

    This battery might be of interest.
    https://www.bioennopower.com/collections/12v-series-lifepo4-batteries/products/12v-40ah-lfp-battery-black-pvc-pack

    Another cheaper option is to make your own battery using four 40AH 3.2 volt cells from Winston or CALB or GBS. To do this you need enough technical knowledge to know how to operate the battery without a BMS or be able to install a BMS from a third party.

    With any LFP battery with an inbuilt BMS make sure that your solar charge controller can work and will keep the charging voltage regulated if the BMS disconnects the battery from the battery terminals. In other words make sure the charge controller can keep the voltage regulated with no load on it.

    Simon
    Off-Grid with LFP (LiFePO4) battery, battery Installed April 2013
    32x90Ah Winston cells 4p8s (24V), 4kW Latronics Inverter, 1160W of Solar Panels, homemade MPPT controller
    Homemade BMS https://github.com/simat/BatteryMonitor
     

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