| Re: Li batteries [message #367121 is a reply to message #366428] |
Sun, 10 October 2021 07:01  |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
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Senior Member |
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LiFePO4 (LFP) batteries cannot be charged below freezing, but they can be discharged and stored. They do live longer at temperatures at temperatures from about 10 to 45C. I installed my LFP batteries in the clothes closet so they are right beside the electrical cabinet where my charger/inverter lives. This reduces the length of wire from the charger to the batteries for minimal voltage drop.
There are LFP batteries rated for charging in freezing temperatures. The Battery Management System (BMS) of these batteries will use the available charging current to warm the battery with an internal heating element to above freezing before applying the charge current to the battery cells.
LFP batteries live longer when stored with only a partial charge. So charge (or discharge) your LFP battery to about 60% then bring it into your house for the winter. Do NOT recharge over the winter! The self discharge rate is very low on LFP batteries at about 5%, so even after storing for 6 months you will still have about 30% state of charge.
You cannot permanently parallel batteries of different types, but you can temporarily connect them... That is what the BIM charge controller is doing. A BIM connects the house and chassis batteries together for 15 minutes, then disconnects for 20 minutes to allow the alternator to cool. Since LFP batteries are not designed for extremely high currents (this is more the BMS maximum current rating rather than the cells) I would suggest to press and hold the Boost switch for several minutes to allow the chassis battery to recharge a bit from the LFP house battery, then try starting. This will reduce the maximum current being drawn from the LFP house battery by the starter.
Again, this is a very good article on LiFePO4 batteries:
https://marinehowto.com/lifepo4-batteries-on-boats/
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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