Ramblings of a Techno-Viking

LiFePO4 After almost six months

While I can't say that it is a completely fair comparison due to sunnier weather this year and more than twice the usable amp-hours in my LiFePO4 bank than I had in my lead-acid one, the LiFePO4 have exceeded my expectations. On sunny winter days, I was able to fully charge the bank and then run my propane/electric refrigerator (320 watts) on an inverter several hours during the hot part of the day without depleting the batteries. In the late spring, back in the same spot I was last year, I can use the solar panels only to recharge my batteries except when there are several cloudy/rainy days in a row. Last year I was having to run my generator frequently since I only get a few hours a day of strong sunlight due to trees.

The higher efficiency of the LiFePO4 batteries and the ability to accept almost any charging rate until they are full make LiFePO4 much superior to lead-acid when charging from solar panels. On average, I think I am getting 50% more usable power from my solar panels, not including the extra savings due to being able to power an extra load on sunny days.

While I should also see much better performance when charging from a generator, due to my converter-charger not being well designed for them and I have not been able to find the "high-voltage" plug for it, they do not charge quickly from the generator. I also have to turn the converter-charger off on the rare occasions I am plugged in to shore power to avoid overcharging the batteries. With a properly selected converter-charger, the generator runtime to charge the LiFePO4 batteries should be much less than with lead-acid.

As far as I can tell, LiFePO4 have less need of per-cell automatic balancing and automatic over voltage and under voltage cutoffs than lead-acid ones do in a RV house battery where the maximum charge or discharge current is less than one half the rated capacity and it is a "12v" four-cell pack. Overcharging needs to be avoided on LiFePO4, but chronic undercharging (but not to zero) is not a problem for LiFePO4. The latter is much more likely to occur in boondocking situations where solar and generator are used as the main charging sources. Checking cell balance needs to be done occasionally with LiFePO4 if it is not handled automatically , but it is much less of a chore and needed less frequently than checking fluid levels on flooded lead-acid batteries.

My only questions are "Why aren't converter-chargers optimized for LiFePO4 in RV house batteries readily available?" and "Why aren't more people using them?" They are about the same cost as AGM, and should last much longer, making the life-cycle cost less than flooded lead-acid and much less than AGM in addition to the other benifits of LiFePO4.

Posted Wednesday 18 June 2014 23:41 UTC
Last edited Wednesday 18 June 2014 23:41 UTC