DIY build, way to cutoff inverter at low voltage and compatible mppt info?

[williamsk913]

DIY power station build. I have a high frequency inverter that limits low end to 10v plus or minus .5 and that has a high limit of 16.6v. I am using what I think are Lishen 272ah batteries with a 120a smart JBD bms (think overkill solar 120a... I bought before overkill began carrying the 120a version). My questions are: any way I can get inverter to cut off before 10v (to keep wear and tear off bms). Solar charge controller recommendations? I have a Li Renogy Adventurer charger, but because it is not mppt afraid voltage will not play nice with inverter. Any MPPTs that will charge battery but stay lower than inverter cutoff? Thanks in advance.

 

[snoobler]

If an inverter doesn't have programmable LVD, you're stuck with it. Rely on the BMS settings. If your inverter has an alarm voltage, setting the BMS LVD just below that would at least give you a warning. I would not be concerned with "wear and tear" on the BMS in that regard. Flowing current is more "wear" than not.

I don't understand your concern about 16.6V. You don't want your batteries getting anywhere near there, so PWM or MPPT needs to be programmed to 14.6V or less boost/bulk/absorp and 13.6V or less for float with no equalization, or equalization set to 14.6V or lower and time as close to zero as permitted.

 

[williamsk913]

If an inverter doesn't have programmable LVD, you're stuck with it. Rely on the BMS settings. If your inverter has an alarm voltage, setting the BMS LVD just below that would at least give you a warning. I would not be concerned with "wear and tear" on the BMS in that regard. Flowing current is more "wear" than not.

I don't understand your concern about 16.6V. You don't want your batteries getting anywhere near there, so PWM or MPPT needs to be programmed to 14.6V or less boost/bulk/absorp and 13.6V or less for float with no equalization, or equalization set to 14.6V or lower and time as close to zero as permitted.

Looking into charge controllers because there are reports with some setting off the high voltage alarm. I read an answer to a similar question on amazon where the seller recommended a "real mppt" solar charge controller. Perhaps an mppt lowers the voltage that goes into the system to charge it. My thought process is that an mppt might bring it below this limit, versus a simpler on off charge controller. I was wondering if there was a simple low voltage disconnect, maybe something that just turn the switch off to inverter if it gets too low versus handling the entire amount of amps the inverter uses.

 

[snoobler]

Defective or malfunctioning charge controllers can go over voltage. MPPT is better in many ways, but there's no real concern in your situation.

Some charge controllers have load ports and can take actions based on battery voltage. You could power a relay that kept the switch in the inverter on position. If voltage drops below X, cut off the load port, relay opens, inverter switch off.

Or you could just let the BMS cut-off. Hopefully, you're designing your system such that this is unlikely to occur on a regular basis.