Hi, today i found a problem, batteries was in alarm mode. 
i have 2 parallel inverters, everything connected like it supposed to be, but one of the inverter has continuity in both + and - on the input of the battery. 
the other one is good. 
 

any ideas how this is possible?? 

13 hours ago, Tsmithf said:

but one of the inverter has continuity in both + and - on the input of the battery. 
the other one is good. 

This is unfortunately not unheard of. Usually, some transient on the battery bus will cause one of the MOSFETs to fail shorted; when its opposite number turns on, there is a dead short across the battery, frying the second MOSFET (or set of 3-4 MOSFETs in parallel). The resultant current surge can often take out IGBTs as well, and also gate driver components as the gate melds with the source and drain.

One common way that this happens is that the battery bypass capacitors (there are usually 4 of them) dry out with heat; they protect the MOSFETs from switching transients. are only rated for about 2000 hours at 105°C. If the inverter runs at 65°C, that's 4 x 10°C difference, meaning that the capacitors will typically last about 16x longer than that, or 32,000 hours. That's less than 4 years. Often the temperature will be lower, but problems can start occurring at around 5-6 years.

How old is the unit that failed?

Is it a well-known brand?

Another possibility is that it's got even lower quality parts because it's a clone. They could fail in a much shorter time span.

Or it could just be bad luck. A colleague of mine  had an inverter explode its MOSFETs when operating a vacuum cleaner nearby. On examination, he found mysterious dark marks around the pins of the IGBTs. It seems that some sort of partially conducting material was there from the factory. When this was cleaned up and the IGBTs replaced, it worked well for years.

3 hours ago, Coulomb said:

This is unfortunately not unheard of. Usually, some transient on the battery bus will cause one of the MOSFETs to fail shorted; when its opposite number turns on, there is a dead short across the battery, frying the second MOSFET (or set of 3-4 MOSFETs in parallel). The resultant current surge can often take out IGBTs as well, and also gate driver components as the gate melds with the source and drain.

One common way that this happens is that the battery bypass capacitors (there are usually 4 of them) dry out with heat; they protect the MOSFETs from switching transients. are only rated for about 2000 hours at 105°C. If the inverter runs at 65°C, that's 4 x 10°C difference, meaning that the capacitors will typically last about 16x longer than that, or 32,000 hours. That's less than 4 years. Often the temperature will be lower, but problems can start occurring at around 5-6 years.

How old is the unit that failed?

Is it a well-known brand?

Another possibility is that it's got even lower quality parts because it's a clone. They could fail in a much shorter time span.

Or it could just be bad luck. A colleague of mine  had an inverter explode its MOSFETs when operating a vacuum cleaner nearby. On examination, he found mysterious dark marks around the pins of the IGBTs. It seems that some sort of partially conducting material was there from the factory. When this was cleaned up and the IGBTs replaced, it worked well for years.

Hi thanks a lot for the reply, but my kit is 2 months old, the inverters are voltronic axpert max II - 10kW 

On 2024/09/01 at 12:23 AM, Tsmithf said:

my kit is 2 months old,

Wow, that's soon even if it's a clone. 

On 2024/09/01 at 12:23 AM, Tsmithf said:

the inverters are voltronic axpert max II - 10kW

As far as I know, none are actually branded Voltronic, though some recent ones might (finally!) say that they are manufactured by Voltronic. I imagine that the cloners would be happy to copy that, though.

If you post a photo of the sticker on the side, I can probably tell if it's genuine. Block out the last part of the serial number if you wish. 

Now you are scaring me! Hahahaa, here is the pic 

14 hours ago, Tsmithf said:

Now you are scaring me! Hahahaa, here is the pic 

Hmmm. MPPT Solar is a known clone brand (hoping that people mistake it for the genuine MPPSolar brand). A genuine MPPSolar inverter will never say "Made in China", always "Designed in Taiwan". Yet the sticker looks legitimate to me.

Is it branded "MPPT Solar"? If it's branded something else, then MPPT Solar inverter is a reasonable summary of what it does.

The inverter with the short on the battery input: Does it smell of parts burning? Sometimes new inverters have a faint "hot resistor" whiff.

If the MOSFETs have blown, you can sometimes see evidence of this by shining a torch into the holes in the cover on the right hand side, for example cracked MOSFET cases or legs blown off. Though the MAXs possibly use the larger transistor case, which may behave differently under severe overload.

Thanks a lot, i took it to service yesterday, so i will wait and see what happend there 

Was a bad board. The change it for free, thankfully, so now im running fine. But getting sometimes error 72