Pre charging capacitors in all-in-one inverters.

[Electrobob]

I have a couple Growatt 3000 24v Solar inverters and when I need to change out batteries or connect batteries to them after being disconnected I want to avoid the spark during the final connection. I have tried attaching a Brightstar 50 watt 6 ohm resistor between the last cable end and battery lug before making the final connection, but this isn’t working. What happens is the Growatt will turn on for a moment, then long beep and then turn off. I hold it touching together for a while but when I attach the cable I still get the spark. The Growatt has a 60 watt idle consumption so I suspect I am just a little shy on the resistor watts. Do you agree? What wattage resistor would you recommend using, or is anything above 60 watts suitable? Could there be another reason this is occurring? Sorry for the newbie question. Thanks for your help!

 

[nc73]

20 ohms I thought. I used a 10 on my lvx6048 and no spark at the inverter. I think an incandescent light bulb will also work.

 

[brclark82]

25W 30 Ohm resistor is what Will uses in his how to pre charge capacitors video with pretty much your exact setup

 

[meetyg]

I have a couple Growatt 3000 24v Solar inverters and when I need to change out batteries or connect batteries to them after being disconnected I want to avoid the spark during the final connection. I have tried attaching a Brightstar 50 watt 6 ohm resistor between the last cable end and battery lug before making the final connection, but this isn’t working. What happens is the Growatt will turn on for a moment, then long beep and then turn off. I hold it touching together for a while but when I attach the cable I still get the spark. The Growatt has a 60 watt idle consumption so I suspect I am just a little shy on the resistor watts. Do you agree? What wattage resistor would you recommend using, or is anything above 60 watts suitable? Could there be another reason this is occurring? Sorry for the newbie question. Thanks for your help!

The problem is probably that you are leaving your inverter ON while connecting the battery again. This discharges the capacitors immediately.
Try turning OFF the inverter first, then connect with a resistor for a few seconds, and then quickly connect the battery.
After that, no sparks should appear and you can turn ON the inverter.

 

[Electrobob]

Got it. Thank you!