JK-BMS turned off and won't turn on

[brainwashed]

I have the B1A20S15P hooked up to a bank of 16 LPF cells, has been running great for months now. It suddenly shut down and won't turn on. I can briefly force it on using the LCD button but it then shuts off after one second. The bank voltage is 56.8, temperature sensors are not tripped, there was no overcurrent or anything else. Since I monitor the entire status in Home Assistant, checking out the graphs nothing jumps out. The phone doesn't have enough time to connect via BT so cannot check the BMS logs, but the rPi can sometimes manage to connect via BT4 and retrieve the values, when I force it on.

It has been sitting now for 1h, still nothing. Temps are at around 38C, well below the tripping point. Cell delta is 1mV.

EDIT: tried hooking up a jumpstart cable between the BMS terminals but the inverter still doesn't register the battery voltage, very strange. It also seems to be shorted inside since I am measuring 30 ohms or so between the terminals and a diode drop of 20mV both ways.

EDIT: the inverter battery fuse seems blown, I can measure the full battery voltage across it:


Adding for reference some inverter and BMS graphs:








Around 5:10pm there is nothing going out of the ordinary. The BMS temperature suddenly jumps from 37 to 38, but that's all. Looking at the detailed load, charge and discharge charts everything is very stable.

Odd to have two failures back-to-back.

 

[brainwashed]

Found the inverter spare fuse, installed it and got huge sparks when I tried to connect the battery. Seems that the battery-side of the inverter went down, shorted and also took down the BMS. The AIO is still able to run on solar but this is the last straw with this inverter. I will try to get a replacement and sell it and never going back to MPP Solar / Axpert / Voltronic.

 

[kommando]

Thanks for the update, sticking to my old 2nd hand Sunny Islands.

 

[KB9RKU]

To

 

[Boron]

WOW that is scary. The general wisdom is that Inverters are a weakness in a Solar system. They have a limited life expectancy AFAIK. Perhaps more expereinced members might comment here? At least JK performed as needed full marks there.

 

[brainwashed]

There are plenty of people running successful setups for many years, even here on the forum. Though I read yesterday about another inverter failure on the battery side, also a rebranded(?) Voltronic. The person initially wanted to change the power semiconductors but decided instead to replace the board. I don't have the link at hand.

The BMS acted as a very expensive fuse. After replacing the inverter 150A fuse and trying to connect the battery without BMS, I got some great balls of fire. Never doing that again without full-face protection. The 150A fuse is in series with the BMS, which is rated for 125A, so I wouldn't give it full marks yet. But I don't know the overload curve for the fuse nor for the BMS.

Already ordered a replacement Deye inverter, which I would have wanted in the first place, if I knew it existed. Hopefully it has better customer support as well.

 

[Boron]

In my emergency back up post I omitted to mention that you should never connect a cable up to a lfp directly without a fuse link (unless you expect the cable to be your fuse (like a 20AWG test wire)