Hand Truck Portable Power Station Issue

[Kmartin]

Hey all. As the title suggest I just built a portable power station. Its a vatrer server rack battery and powmr 5k low frequency inverter.
I'm having an issue where I believe the BMS is cutting off and will not start the inverter unless I connect grid power first.
From my limited investigation it's because the inverter is pulling too much power to charge the capacitors so I possibly need some sort of pre-charge circuit. It works fine if I connect AC power first but I don't want to have to do that obviously. Any help would be appreciated. Just need to know if I should return this inverter. Thanks

 

[Supervstech]

It is a fact of life that higher voltage inverters require precharge resistors to facilitate connecting the battery.

Does the setup have a switch to turn on the battery? Add a pushbutton to bypass the switch with a resistor. Hit it for 30 seconds or so before you turn on the battery.

ANY inverter you get will behave the same way.

 

[timselectric]

Yes, if you are turning the battery on and off, you will need a pre-charge resistor.
Assuming that your battery doesn't have one built in.

 

[Zwy]

Hey all. As the title suggest I just built a portable power station. Its a vatrer server rack battery and powmr 5k low frequency inverter.
I'm having an issue where I believe the BMS is cutting off and will not start the inverter unless I connect grid power first.
From my limited investigation it's because the inverter is pulling too much power to charge the capacitors so I possibly need some sort of pre-charge circuit. It works fine if I connect AC power first but I don't want to have to do that obviously. Any help would be appreciated. Just need to know if I should return this inverter. Thanks

Use a push button and 48V light bulb for precharge. Hold the button in until the bulb goes out.

 

[Kmartin]

Use a push button and 48V light bulb for precharge. Hold the button in until the bulb goes out.

Thanks. That helps but I think I should not have went with a low frequency unit on this build. All the videos I've seen from others have not had this issue although they were using high frequency 3000 watt all in one units. Might have to return and get another unit. I need this thing ready to go when I flip the switch.

 

[timselectric]

Thanks. That helps but I think I should not have went with a low frequency unit on this build. All the videos I've seen from others have not had this issue although they were using high frequency 3000 watt all in one units. Might have to return and get another unit. I need this thing ready to go when I flip the switch.

Both have capacitors, it doesn't make a difference.

 

[Supervstech]

Thanks. That helps but I think I should not have went with a low frequency unit on this build. All the videos I've seen from others have not had this issue although they were using high frequency 3000 watt all in one units. Might have to return and get another unit. I need this thing ready to go when I flip the switch.

The only way they wouldnt have the issue is if they used a 12v system.
12v can disconnect the battery with a small spark. 24 and 48v the spark can be beyond the bms ability.
Why turn off the battery? Connect once, be done.

 

[Q-Dog]

I see several folks stating absolutes that just don't hold true in my experience. I run 2 different 24 volt systems and have never used a precharge resistor on either.

 

[timselectric]

I run 2 different 24 volt systems and have never used a precharge resistor on either.

I don't need a pre-charge resistor either. Because my battery bank (BMS capacity) is large enough to accept the capacitor surge.
But I doubt that a hand truck buid can accommodate that.
You either need a battery with a built-in pre-charge, or add it externally.

 

[Kmartin]

I don't need a pre-charge resistor either. Because my battery bank (BMS capacity) is large enough to accept the capacitor surge.
But I doubt that a hand truck buid can accommodate that.
You either need a battery with a built-in pre-charge, or add it externally

The only way they wouldnt have the issue is if they used a 12v system.
12v can disconnect the battery with a small spark. 24 and 48v the spark can be beyond the bms ability.
Why turn off the battery? Connect once, be done.

I guess I can just leave the battery on and inverter off. Theres nothing wrong with that I guess. I'll only be using it when the power goes out. Just went through Helene in western nc and was without power for 7 days and my little portable power station was not cutting it so it was time for moar power!

 

[timselectric]

I guess I can just leave the battery on and inverter off. Theres nothing wrong with that I guess. I'll only be using it when the power goes out. Just went through Helene in western nc and was without power for 7 days and my little portable power station was not cutting it so it was time for moar power!

Are you sure that your battery doesn't have a built-in pre-charge circuit?