Pre-charging microinverter capacitors?

[greymda]

Hey community, hope your wisdom can help. I have a HM-800 inverter and building a DIY 1kwh battery for start (16 lifepo4 20Ah cells in 1 series) and i am finding contradictory information on the internet. Somewhere it's stated that pre-charging capacitors are needed only for 2000W+ like here

You need to precharge any inverter 2000W or above. It’s important to do this any time that you’ve disconnected the batteries for a prolonged period. Smaller inverters have smaller capacitors that charge even quicker than those in larger inverters. This means that the current flow slows quickly enough to avoid any BMS damage and large sparks. Therefore, it’s safe to connect your inverter directly to your busbars.

somewhere that it's a must have!

What is this community experience and consensus?

[schlimmchen]

Always pre-charge using a resistor and be safe 👍

Have a loot at #528

[schlimmchen]

You will find them by yourself. Have this example: Chose an overvoltage protection value that is safe for your cells, but set your charge controller to charge only to less than that. You overvoltage protection should never trigger unless something goes south.

[swingstate]

Act before the BMS has to. Basically switch off the Inverter before you hit the zone where the BMS would kick in. I use Homeassistant for some automations in that area and also the DTU to enable/disable the inverter.

[greymda]

gotcha, but how about if during night the battery gets drained out? as we're speaking about something around 1kwh max. will this be a problem?

[swingstate]

switch the inverter off at for example 15 or 20% SoC or the Voltage equivalent - depending on your battery. 16 cells sounds like a 48V Battery. I used these charts for the PowerQueen I was using prior. https://cleversolarpower.com/lifepo4-voltage-chart/
At the end, you should measure the voltage of your cells and switch the inverter off at e.g. 3.1V / cell respectively at 48V. But that's just one example. Other people might tell you different things.

[greymda]

I think i understand. it will be 16 cells EVE C40 40135 - 20Ah - and a JK BMS.