LV2424 and Growatt 3000 won't turn on with 24V from bigbattery

kxy

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First my simple set up,
One LV2424 connected to four 24V bigbattery connected in parallel, connect to solar input and grid input and output.

I have been working at this issue for over 2 month now, I thought it was a bad inverter, now I am not so sure. This setup has been running fine for over a year, then one day the inverter just turned off and won't turn back on.

I contacted the manufacture in China and replaced the mainboard, then the control board and then finally the mptt board. None of those resolve the issue. I then went ahead and bought a Growatt 3000 just to test. Same issue, Growatt turned on for a few seconds and showing 16.4V reading on the front panel then it turned off and now it won't turn back on.

Next I troubleshot the battery. However all batteries reads around 26.4V(LED reading on the battery itself), also measured it using a multimeter. Contacted big battery, they suggest resetting BMS.

1. I tried connect each battery individually to the unit
2. I tried resetting the BMS of the battery by disconnect them over 12 hours and connect them back on.

Finally, I took the multimeter and measured at the ring terminal connected to the inverter, the reading is at 8.7V. Why so low?

I am pretty sure it is not inverter at this point, can all four batteries be bad, can the LED display be bad and misleading? What should I troubleshoot next?
 

Bud Martin

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"Finally, I took the multimeter and measured at the ring terminal connected to the inverter, the reading is at 8.7V. Why so low?"
That looks to be like the battery BMS is not on, when you read the battery without load connected, it may show correct Voltage but when load is connected the Voltage drops down.
Do you have two 12V car head lamps connected in series so you can test the Voltage of the battery when the lamps are connected?
BTW, do you also have battery charger?
 

kxy

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I will double check the BMS connections. I do not have a battery charger. How can I test with the 12V car head lamps? Is this something I can get from wal-mart or autozone?
 

Bud Martin

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You just get two 12V car head lamps (round or rectangular shape) from auto store and connect them is series using good size wires and connectors.
 

kxy

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BMS cable looks ok, multimeter reads 26.5V at the battery


battery.png
 

kxy

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Connected two 12V car head lamps in series, 26.5V pulls around 5 amps.
 

Bud Martin

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So it also shows 26.5V dc at the lamps wires?
If it is then the BMS is not in the shutdown mode.
So you have the clamp-on dcA meter for measuring the current?
What current and Voltage do it show when connect to the LV2424 without the Inverter ON/OFF switch turned on?
 

kxy

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So it also shows 26.5V dc at the lamps wires? Yes
What is shutdown mode?

Yes, I used the clamp on meter.

Connected to LV2424, turning it on. Current is at 0.07A, 4.9V (this dropped from last measurement)
 

kxy

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If I purchase an Ampere Time 24V 100Ah LiFePO4 battery (to rule things out), would it be okay to connect this battery with the 24V LiFePO4 Powerwall from bigbattery (they advertised 3KW, so 125Ah) via bus bar? I was told it is bad to mix brands of batteries.
 

Bud Martin

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So it also shows 26.5V dc at the lamps wires? Yes
What is shutdown mode?

Yes, I used the clamp on meter.

Connected to LV2424, turning it on. Current is at 0.07A, 4.9V (this dropped from last measurement)
How about if the switch is turned off? Can we see the picture of your setup? It does not make any sense to see 4.9V and only 0.07A of current draw unless there is high resistance in your wiring such as poor connection, bad circuit breaker, etc. So we need to see the picures.
 

kxy

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"unless there is high resistance in your wiring such as poor connection"

Thanks Bud, you are the BEST! It was a bad loose crimp on the connector. I wouldn't never thought a cable would be bad since I bought the cable "professional" made. I put in a new connector today and it boots up.

Going back to my other question about batteries, it is bad to mix brands of batteries with different Ah though a busbar?
 

Bud Martin

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Glad to hear that is just simple bad connection, may be you should check them once a year to make sure they have good connection and clean.
100Ah and 125Ah batteries will not be problem mixing them together.
 
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