LFP on Shore Power with Inverter/charger?

I enter the nominal battery capacity for my bank into my BMV-712 and enjoy, no real need for any further shenanigans.

If you want to measure your battery capacity, charge your battery full, turn on a load (the current doesn't really matter) and then run until the BMS cuts off. Look at your battery monitor to see how many Ah came out, and that is your capacity.

There is a tendency to make this way more complicated than it needs to be.

BFL13 wrote:
How's this for a plan then?----

FWC was careful by saying, "the resting voltage is 13.2-13.3 " He did NOT say that was the "full resting voltage". He did say that as soon as a load is applied to a full LFP, the voltage drops to 13.3.

So 13.3v means anywhere from 99-89% SOC in effect. Then the voltage/SOC table time2roll posted (from BB's) could be used (except very difficult to get proper voltage with the temperature making that so sensitive, per FWC's note on that)

Then time2roll makes a very important point--you can see where the lower knee starts by watching your voltmeter.

How to use your AH counting monitor or smart shunt?

1. You get the battery as full as you can using its charging specs and guide for that.

2. Pick a number for your amps draw since Peukert is near 1 (FWC again) say 10 amps and hold that constant as you can while your AH counter counts down and you keep an eye on the voltage.

3. When voltage starts to drop off, stop!

Now you have your AH "allowance" that you can operate within. Using a variety of amp draws while camping, you still have the same total allowance. ( which is why the 20 hr rate doesn't really matter with Peukert at 1)

What do you enter as your "full" capacity on the monitor? Doesn't matter as long as it is more than your "allowance". Set your low voltage alarm at that voltage you saw where it started to drop off.

While camping, you can watch the AH counter count down and remember your allowance. You can do the math in your head to tell when you are half way down or three quarters the way down, etc.

OR, if you make your AH allowance your "full" entry on the monitor, and it reads your percentage SOC, you can use that. Just remember to zero/sync the monitor whenever you get the chance when the batt is as full as you can get it.

TA DA! Is that what you LFP guys do? ( Itinerant1 has a more complicated monitoring system that does include some cross-checking, but I am wondering what LFP guys with a simple system do)

jaycocreek is looking for suggestions and I suspect time2roll is suspecting he will now need more than just his voltmeter too, so over to you LFP guys on what to do----