Preliminary report on LiFePO4 batteries

blars · Dec 25, 2013

I've been carying around a set of LiFePO4 batteries I intend to install as my house battery, and for now have them under my motorhome hooked in parrellel to my golf-cart batteries. After I fixed the cheap "jumper" cables (soldered #8 wire to replace the poorly crimped #16) they are working very well -- in the mornings I'm at 13.0v or better after not being conservative with my use, falling to 12.8v with my furnace on, that bounces back when the furnace goes off. (so it's wiring loss) When I get them wired up properly without the lead-acid pulling them down, I expect to do better.

The set of 260Ah 3.25v cells cost me $1200, about the same as a set of four 220Ah AGM 6v with about the same usable power. They should last at least twice as long. Read the series on Technomadia.com for their research and experience (they have had LiFePO4 for over two years), if anything they tend to understate the advantages of LiFePO4.

I'll have a pair of used 6v golf cart batteries for sale at the RTR cheap.

AltTransBikes · Dec 25, 2013

Thanks for sharing this, looking forward to your updates and assessment as you get everything dialed in. Certainly not cheap but you should get a massive amount of charge cycles out of them and a lot less weight. I haven't used a big pack like that for something like a MH but have used 15 and 20Ah LiFePo4 for electric bikes and would not use anything else.

ccbreder · Dec 26, 2013

Your batteries will not like being connected to a bank of different chemistry. It will shorten the life of the lifepo. It may be dangerous with the lead acid, but can't find that reference.

blars · Dec 27, 2013

It's a temporary hookup, and I do not think it is damaging either bank. (The wiring is limiting the current enough to not make it a problem.) I'm more worried about the engine battery and I intend to disconnect the relay that connects it when the house battery is charging.

ccbreder · Dec 27, 2013

There are two or three very long threads about using LiFePo batteries as house banks. A lot of good information along with links to more. It will take a while to read through, but I think it is worth the effort.

http://www.cruisersforum.com/forums/f14/

Good luck with your bank. Please keep us posted as hands on is better than theory.

blars · Dec 29, 2013

Thanks, the cruisersforum has some good information, and I'm less than 1/4 way through one thread. (Maybe 10 hours of reading.) I've already changed how I programed my solar controler differently than I had planned based on the info there, and have decided I do not need to replace my converter/charger. The more I learn about LiFePO4 the better the seem.

The golf cart batteries have been removed and the LiFePO4's installed. They are performing at least as well as expected.

blars · Dec 29, 2013

Balqon.com is offering free freight to the US until the end of the year (so two more days), that was about $100 of what I paid for my set of four 260Ah cells. The box was over 100 pounds, so be prepared and package acceptence services may not accept it. (Heavy wooden box around the 80 pounds of batteries.)

blars · Jan 30, 2014

After using the LiFePO4 as my only house battery for over a month, I'm very happy with them. While I stiill have a lot of energy conserving hablits, I no longer have to worry about power. When I ran out of propane, I ran my refrigerator (320w) on inverter for a night, and the LiFePO4 were at 12.8v, just starting the sharp downward edge. (So nearing discharge.) It took 5 days to recharge them from the solar panels, with a couple of them being overcast and so about breaking even with my usage.