"Cheap" LiFePO4 drop-in update

[sailorboy1]

Just an info update:

I have now had my $306 100Ah LFP drop-in Power Queen batteries 11 months (they are cheaper now). They are still babies really for LFP batteries and I have 4 of these for a 400ah house bank. These batteries have mostly only been charged by solar. They of course charge via the alternator while motoring and once in a while they get charged via battery charger either using shore power or my Honda EU2200. For the most part they operate in the range of 60-100% state of charge. So far the biggest problem turned out to be the idiot that installed them (me) not tightening all the terminals.

Since it has been cloudy for 4 days it seemed a good time to test them for the first time before heading out again in couple of months. So I just let them run down a couple days and then hurried the discharge along today by turning on every DC load I could. I finally stopped after -342Ah, which works out to be 14.5% charged by the math and was 19.6% by the battery monitor that has a PF of 1.05 programed into it. Voltage after a 10 minute wait with all DC power off was 12.67V, which works out pretty much to be about 15% SOC on most curves.

So my cheap batteries look good!!! they may have gone up in voltage more, but I wanted to turn the lights back on. In normal operation I never would have let my batteries get so low and the only time would be if I was gone a long time and solar failed or it was cloudy 4 days.

And to note I made NO changes to my electrical system at all changing from acid batteries to the LFPs. I had a "cruiser" type system already and all I did was change the various setpoints. Right now the charger is running on an AGM setting that will charge back o 14.1V and then float at 13.4V. That probably wouldn't be 100%, but who cares and I probably will turn it off once batteries are back in the 90% range.

Now I will say this, the same great things could have been written about my last set of FireFly carbon foam acid batteries at this time of use. Those lasted 2.5 years and then died a death that exactly matched partial state of charge problems they were not suppose to have.