Hi all,

I recently repaired a Growatt 5000 ES with a Warning 02 (overheat) that turned into an Error 02 that shut it down.

I'll post the cause and fix in another thread but suffice to say it was a connector and track to the thermistor on the MPPT board that was corroded by the salty Garden Route air to the point of giving false readings and eventually created an open circuit in the track leading to 02 error.

When I put the inverter back in service I noticed it started up showing a ridiculous Eskom AC input voltage in the 350-380 range. It did so before but settled down quickly. This time it also started jumping all over the place and eventually came down to threshold level and jumped between 180 and 250 and the inverter kicked the relay in and out repeatedly. It was a bit scary as it clearly was very confused what to do and just kept cutting in and out. No load at this point. I shut it down and put it back on the bench.

By the way it works perfectly from battery only.

I then fed it from the output of another inverter at exactly 230V measured with the multimeter at the terminals. It showed 350V and slowly came down until it settled at 240V a few minutes later. 

Then I switched to Eskom again and still showed 240 with actual input of 225V.

I left it switched off for 4 hours or so and now it started up AC only at around 280V on an actual of 232V. When I switch the inverter on, it does the clicking in and out again and there is a disconcerting sparking sound coming from inside.

Starting up on battery works fine and bringing in AC shows 410V (yes!) dropping to 270V and staying there.

Any ideas? Could it be the AC measurement circuit that has a faulty component and any suggestion where on the board to look for it?

By the way I fixed another Growatt with weird behaviour by just cleaning the board from the salt build-up. Looks like when the salt gets wet from high humidity it conducts and throws the sensors off. Not in the latest case though... already sparkling clean.

Rudie

Solved!

Here's the cause if someone else runs into it.

There is a string of 4+4 330K sense resistors that feed the AC voltage to the processor.

These guys are really close to the intake fan and something seemed to have corroded away the pad on the PCB. Probably the salty air here at the coast. Makes sense because another corroded track was the cause of the Error 02 as well.

Because the track was not completely broken, it sometimes worked and sometimes not. With temperature or humidity fluctuation, it would magically start working or stop working, you never can tell.

I repaired it by re-soldering the resistors and repairing the track. All good and stable for 24 hours on the bench now.

PS. This is a typical "replace the motherboard" problem, solved for a couple of Rands and a bit of time. Fair and well if under warranty but expensive if not. Not to mention the perfectly good electronics going into landfill and killing the sea turtles. I really think all of us have the responsibility to try and repair something before we rip and replace it. It's not only good for the pocket but also for the environment.

PPS. Growatt needs to attend to this. It is not the first inverter I found with salt damage and it is dangerous. I saw it kick in at 260V and supply the load with the high voltage - enough to fry something (in a non-foodie way). There is a protective coating over some areas of the board, but quality control failed you here because the coating was very spotty in this area. Put more moisture protection in the area by the fans please. People in my area are throwing out Growatts and putting in SunSynks by the truckloads because the SunSynks are IP65 and weatherproof and the Growatts lose their marbles when it rains for stupid reasons like this.

 

 

 

 

 

 

Rudi can you please share how fixed the 02 Fault. I did clean the inside of the inverter but with the rain around it still showing the fault.