Charging performance lithium phosate batteries

[Elkman]

The lithium phosate batteries are supposed to charge at a faster rate than standard FLAT or even AGM batteries. In theory that means that whether the current is coming from the alternator(s) or the generator this charging should require less time to get them back up to 100% SOC.

Does anyone have any direct experience with recharging their lithium house batteries with the alternator or the generator or after connecting to shore power?

[tinglett]

I'm not exactly sure what you are looking for, but earlier today I did an experiment in charging a single 100Ah Battle Born LiFePO4 battery from 17% SOC (-83Ah) to full. The experiment involved connecting with short 4 AWG cables to the charger and I got 53A. Normally with my rigs long cables it starts out at about 40A and quickly drifts down to 30A. It took me a bit to figure this all out as I had a second battery in parallel in the past and it turns out that one was bad.

I checked on the battery a few times. It was at 34% SOC (-66Ah) 21 minutes after starting, 77% SOC (-23Ah) 74 minutes after starting, and was already full up when I looked 2 hours after starting. Battle Born's 100Ah batteries can produce sustained 100A, or so they say, and they can be charged at that rate, but they highly recommend a max of 50% (so 50A for my single battery) for longevity of the battery. So it should take about 2 hours to charge from 0% SOC. If I just do simple ratio math, that 77% SOC reading tells me it did 60% in 74 min which would translate to 83% in 102 min (which is full -- remember I started at 17%). A full 100% would be 123 min. Pretty much right on schedule.

And yeah, this is pretty easy for a generator. We are only talking about 700w or so to generate that 50A. The tricky bit that I've learned is that you need a charger that can do it (mine is 55A) AND you need a cable of fat enough gauge to deliver it. My rig's cable is 6 AWG and that limits my charging rate significantly.

[Elkman]

That is great information and exactly what if am interested in knowing. With AGM batteries taking so long to charge a generator would need to run for hours. At 50% SOC it would take 4 hours to bring the charge up 100%.