Ramblings of a Techno-Viking

The Best Battery for Full-Time Boondocking: LiFePO4

For use as a house battery for a full-time boondocker, prismatic Lithium Ferric Phosphate batteries have huge advantages over Lead-Acid (including AGM and Gel). Half as many amp-hours have more usable power, you don't need as much solar to charge them, and generator run-time for when that is needed is reduced by a lot. Lifetime is much longer as well, but how much is difficult to know since there have not been long-term studies at "low" charge and discharge rates yet and no one has had them long enough to wear them out without mistreating them. (For use as a house battery, seven to ten years is a reasonable expectation.)

While not everyone will agree, I do not believe a BMS is needed for this usage. Anyone that can handle a Lead-Acid bank should have no trouble avoiding over-discharge, and charging at 1/2 C or less tends to put the cells into balance. (For multiple C charge or discharge, a BMS may be a good idea.)

Rarely mentioned is that you can get by with less solar when using LiFePO4. Besides them being more efficient batteries, they do not need the slow finishing charge of Lead-Acid, and they prefer not to be fully charged rather than having their life reduced by not being fully charged. While it will vary depending on your usage, you can probably have a happy battery bank with 25-50% less solar than would be needed for Lead-Acid.

Unless the battery temperature is near or below freezing, LiFePO4 can be charged from "empty" (10-20% of rated capacity) to full rather fast. 1/2 C for my 260 Amp-Hour pack is 130 Amps, which neither my solar or converter-charger can supply. Combined with not needing to get the pack to full, this means much less generator run time is needed when the solar is not able to keep up.

LiFePO4 is not the same as other lithium batteries, and should not be lumped with them. They perform better (but differently) at fractional-C applications than at high-current ones like electric vehicles, so the recommendations for that use should not be used as a guide how to treat them for house batteries.

What is critical for a long-life LiFePO4 house bank setup is properly set charging equipment. They are not drop-in for Lead-Acid, and will be prematurely killed by treating them as one. For solar charging, I recommend 14.0 volts maximum with 1/2 hour hold time and 13.4 volt float. This will charge them near full then not discharge much during remaining daylight. For a converter-charger I would use 14.2 volts maximum (higher voltage because of the higher current) and 13.2 volts as the float, since LiFePO4 does not like being left for long periods fully charged. With my current converter-charger, I just turn it off after the battery is fully charged.

The lifepo4-resources page I have is updated as I find new information. After a year of use, they are out-performing what I had hoped for them.

Posted Saturday 03 January 2015 23:35 UTC
Last edited Saturday 03 January 2015 23:35 UTC

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

Virginia City, Nevada

Virginia City Nevada was a silver and gold mining town that is now has tourism as what it sells. There are many small museums, and lots of gift shops and saloons. The first Friday of the month admission to most of the museums is free.

The "Way it Was" museum has mining equipment from the area and the best overall history of the area. The firehouse museum has examples of horse-drawn fire-fighting engines and ladder trucks. The police museum has a large collection of badges from all over the country.

Posted Tuesday 06 May 2014 22:05 UTC
Last edited Tuesday 06 May 2014 22:05 UTC

Red Rock Canyon Campground

Red Rock Canyon Campground is located close to Las Vegas, it's only about three miles to the closest grocery store and restaurants. The Red Rock Scenic Loop is a couple of miles in the other direction. Camp sites are $15/night, 14 days maximum. There are over 70 camp sites, some tent only, some RV only. A couple of dozen sites have gazebos over their picnic tables. The campground does fill up even on weeknights during the spring/fall. The city lights and noise are mostly blocked by the hills. Verizon signal is poor, TV is moderate. The sign was missing coming from Las Vegas, turn on the road the BLM fire station is on. (It is about a mile off of highway 159.)

Posted Friday 18 April 2014 22:21 UTC
Last edited Friday 18 April 2014 22:21 UTC

Big Wash Road BLM

Big Wash Road is a maintained, but in places rough, dirt road about 20 miles Northwest of Kingman, Arizona. Dispersed camping is allowed on the unmaintained side roads starting about a mile from US 93. (The section by US 93 is on state land and has different camping rules.) Trailers and large rigs are not recommended on the steep switchback section starting about six miles from US 93. Verizon signal was marginal. Several sites were occupied when I was there.

There are two developed campgrounds along this road after the steep section. Packsaddle is free, has four tent sites uphill from the parking areas, a vault toilet, and trash can. Windy Point has 7 sites, is $8/night, and the camping areas are closer to the parking places. Some have good views down the canyon, but I bet it lives up to its name at times. There is a BLM web site for these campgrounds. Both campgrounds were empty early Saturday afternoon in mid-April when I looked at them.

Posted Sunday 13 April 2014 00:00 UTC
Last edited Saturday 12 April 2014 23:48 UTC

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