Controller puzzle - Float for LFP on solar (long post)

[Almot]

Preamble - for those who are interested. I'm trying to set EPEVER MPPT controller for LFP battery. Custom charging profile for LFP requires connecting laptop with proprietary cable (not included) and downloading and installing EPEVER software. Procured the cable, installed the software, controller is not recognized. Software Read-me and Help files are in horrible Chinglish. I am not new to controllers but had to read each phrase several times, comparing to interface screens and buttons, going back and forth again and again before could understand what they meant. Had to dig into Win 10 Control Panel and change Port COM number, delete ports, add ports, delete and create custom profile 10 or 12 times, uninstalled and re-installed the entire software a few times - after 5 or 6 hours it works now.

Battery specs:
charge Full to 14.2V, set Absorption to 0-10 minutes, avoid Float or set Float as low as possible 12.8-13.6V.
BMS: LVD= 10V, HVD= 14.6V.

Objective: keeping battery being charged all the time unless it's Full, because this is solar, North Pacific - sun today, gone tomorrow.

Can't set Float to lower than 12.9V.

Custom charging profile that I've set:

Charging limit: 14.2
Over voltage disconnect: 14.4 (why do I even need this when charging stops at 14.2?)
Over voltage reconnect: 14.2 (don't ask me what this is)
Equalize: 14.2V, duration 0.
Boost charging (aka Absorption start): 14.2V, duration 10 minutes (thinking changing to 5 minutes)
Float: 12.9 (can't be set below Boost Reconnect)
Boost Reconnect: 12.8
Low voltage reconnect: 12.7
Under voltage warning reconnect: 12.7 (don't ask me what this is)
LVD: 12.6
Discharging limit: 12.6 (why do I need this when LVD= 12.6?)

As said, Float can't be set below Boost Reconnect, and there are other mandatory relations, ex. LVD>= BMS LVD+0.2, OVD> BMS OVD+0.2 (not sure about the latter, could be a typo). Complete list of requirements below (pain in the ars, told ya :). PCM means BMS, but other than that, controller manual is in good English. Software is not.

I. Over Voltage Disconnect Voltage > Over charging protection voltage(Protection Circuit Modules(PCM))+0.2V;
II. Over Voltage Disconnect Voltage>Over Voltage Reconnect Voltage=Charging Limit Voltage >= Equalize Charging Voltage=Boost Charging Voltage >= Float Charging Voltage>Boost Reconnect Charging Voltage;
III. Low Voltage Reconnect Voltage > Low Voltage Disconnect Voltage >= Discharging Limit Voltage;
IV. Under Voltage Warning Reconnect Voltage > Under Voltage Warning Voltage >= Discharging Limit Voltage;
V. Boost Reconnect Charging voltage > Low Voltage Disconnect Voltage;
VI. Low Voltage Disconnect Voltage >= Over discharging protection voltage (PCM)+0.2V

[Almot]

Some glitches in forum interface, typed post is being messed up when I try.

[Itinerant1]

All the info out there with LFP and still "new" comers wanting to Neuter the cells.

[jaycocreek]

This is a chart I picked up on DIY solar forums for my lithium battery.and solar controller..

[FWC]

12.9V for float and 12.8V for reconnect is too low.

For example: say you use relatively little power overnight, the sun comes up in the morning and solar gets the battery through bulk and absorb by 10am. The solar controller then switches over to float but isn't providing any power as the float voltage is lower than the resting battery voltage. You then start using a bunch of power, the solar won't help out until the battery voltage is below 12.9V, which is almost flat for a LiFePO4 battery. Furthermore, it won't kick back into bulk charge until you get down to 12.8V, which means the battery is flat. As a result you missed out on a whole day of solar charging, used an unnecessary cycle on your batteries and go into the night with a flat battery.

If you set the float for 13.3V, the solar charger will carry for as long as there is enough solar power available.

[time2roll]

12.8 boost reconnect and 12.9 float seems reasonable while in use. I don't think you don't want to be dropping lower as the sun sets.

[pianotuna]

almot,

"Float: 12.9 (can't be set below Boost Reconnect)"

Set the boost reconnect to zero.

[FWC]

Set the float voltage to 13.2 - 13.3V. This is the resting voltage of your batteries and with the float set this low it will carry the parasitic loads on the batteries, but will not charge the batteries beyond about 30% SOC.

You want to set the boost reconnect higher as well, or the charger will never go back into charge unless the battery is completely flat. Otherwise the settings look good.

[StirCrazy]

can you lower the low voltage reconect, discharge limit and under voltage warning. Or are you trying to set it for that high, I would use 12V as my bottom end but thats just me. as for float, if your only using solar your not going to have a lot of float. I tend to think the float they say not to have would be when its pluged in and sitting for weeks on end. with solar and being out camping if you use a fair pit of power depending on your solare size your not going to see much, we are talking about hours not weeks. and every night it will just shut off. so myself I would set it up at 13.4.

Steve