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Install done, power up fail…..

J

JTB321

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So, complete the install and come to power up off batteries to set up inverter. Two batteries each measure 13.2v as supplied, series connected giving 26.4v as expected. No AC mains or PV enabled. Closed power switch and one battery dies to <3v. Not a good start. Complete system is an LV2424 and relatively straight forward. now need to figure out if I have a faulty battery or it is just not fully charged. After three attempts the battery recovers to around 12.5v slowly. Going to call Shop Solar Kits and see what they think. Disappointing to say the least. Any one with suggestions or comments?
Cheers, John
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It may have something to do with the capcitor inrush to the inverter tripping the bms overcurrent protection.

Depends on what switch you mean. If it’s a battery disconnect switch that isolates battery from inverter, you would get inrush when you close that switch. Look up ‘precharge resistor’ or precharge circuit for context. If you just mean the power switch on the inverter that would not cause this as the inrush would have occurred when you connected battery to inverter, even if inverter was off.
 
Last edited:
The switch I was referring to is the inverter on/off switch. Should be photos in the initial post showing the battery wiring. I’ll research the inrush issue, thanks.
 
Glad your fuse held. What’s it’s rating? 200A?

The inrush should have happened when you connected the battery leads, did you check voltage at the DC terminals after you made connections and before flipping the switch?
 
No inrush when battery connected to inverter. Only when I turn on the inverter power switch does one battery ‘die’. With the batteries connected I get the full 26.4v at the inverter terminals.
 
JTB321 said:
Only when I turn on the inverter power switch does one battery ‘die’. With the batteries connected I get the full 26.4v at the inverter terminals.
Click to expand...
So if you then switch the inverter off, the "dead" battery comes back to full voltage?

Are you sure all the loads are off (or disconnected) from the inverter?
 
JTB321 said:
The switch I was referring to is the inverter on/off switch. Should be photos in the initial post showing the battery wiring. I’ll research the inrush issue, thanks.
Click to expand...

I don't see anything like a 200A switch (that would complete circuit between batteries and inverter).
A little rocker switch, which signals to the inverter time to power on?
 
Initial connecting of the batteries to the inverter showed no inrush/spark. Full battery voltage measured at inverter terminals. Closing the small inverter power switch causes the battery issue.
I did not charge the batteries before use, don’t have method to do so?
as per the photo, the AC input is not connected and thr are no loads on the AC output.
going to try contacting Shop Solar Kits this morning. Could be a faulty inverter. Nothing in the install instructions details needing to use the resistor current limit when the batteries are connected. I expected to see a spark but didn’t?
 
The manuals of units like MPp and Growatt usually do not mention start up procedures or precharge resistors. I just got scolded on YouTube by a commenter who said "read the manual" (as if I didn't) when I was doing start up testing to develop a starter up sequence for my daughter.

Growatt literally takes 30 words in the manual to describe start up. And even though there is a power saver mode on the switch. It's not mentioned.

I'd precharge.
 
Last edited:
InRush can do some interesting things to a BMS. Can you access the BMS via Bluetooth and see if you have error codes in the log file?
 
TomC4306 said:
Then do that.
Especially series connecting pre-made batteries.
Click to expand...
Don’t have a charger, wasn’t expecting to have to need one once the system was running. I’ll feedback what info I get from the supplier.
 
I doubt it's the inverter. It's mostly likely the BMS shutting down the battery. Do you have a couple Led acid batteries to test power up of the inverter?
 
Lol
JTB321 said:
Don’t have a charger
Click to expand...
Perhaps it might be a good tool to have around a 12v charger...
You know, if you are going to play with 12 volt batteries...

Your problem is not the inverter.
Nor is it a battery problem per se. You need to charge these two batteries that you have connected in series to the same place.
I guarantee they did not arrive identically charged
 
TomC4306 said:
Lol

Perhaps it might be a good tool to have around a 12v charger...
You know, if you are going to play with 12 volt batteries...

Your problem is not the inverter.
Nor is it a battery problem per se. You need to charge these two batteries that you have connected in series to the same place.
I guarantee they did not arrive identically charged
Click to expand...
I have auto battery charger, not sure if it is compatible? Still don’t understand why no inrush observed?
 
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