Enginer converter sparky noise

hi folks,

I just sent this email below to Jack, but I thought to share it here as well as to solicit any comments from the experts:

"I think there is a problem with my converter. I have a 4kwhr system, buddy paired, with 2 cellog monitors, connected to a loud siren for low & high cell alarm. My wife reports that she never gets an alarm while driving, and I notice that one of my buddy pair reached full charge rather quickly, way before the rest of the pack. I also notice that the system doesn't require very much charge, less than 1 hr each evening.

Finally this morning, I turned on the system, with a fully charged pack, while checking the cellog voltage and there is an intermittent sparking sound inside the converter and all cell voltages are pulled quite low, around 2.8 - 2.9v, with my weak cell 6 being the lowest. Upon tapping the converter, the sparking sound sometimes goes away and the cell voltages come back to around 3.2xx. But then the sparking sound comes back, and the pull of the cell again. Please advise."

 

Neither red or green LED is on now. Upon checking the phone jack at the converter, one of the pin is all blackened. I tried cleaning it with contact cleaner but still no LED. The spring loaded contact may be bad with intermittent bouncing, creating spark and thus increasing impedance and finally become opened circuit.

I will pull out the converter to inspect the phone jack's pin. These type of pressure contact are probably not very robust for high vibration environment, such as the back of a vehicle. Crimped and socketed pin, such as DB connectors, are probably better.

I just hope that the cells are still ok.
-Pb

 

Update:

cleaned out those tiny brass contacts on the phone jack, one was particularly black. Sprayed contact cleaner, reassembled and powered up. Green LED ! checked output float voltage to be 246vdc, good enough.

so, it was those tiny spring loaded contact. I think it'll happened again. I am a bit surprised that no one has reported this problem before.

thanks, Pb

 

It is very strange with these funny noises. I have opened up the converter and it's all solid state in there. I can understand hums and high frequency switching, but the sizzling is kind of weird.

There is also something else going on: I turned on the system in Park and in EV mode, I can see the pull of the LiFePo pack, some cells are lower than other: between 2.9 - 3.2 volts spread. But after a minute or two, the current pull is lessened and all cell voltages go back to around 3.3. Then a minute or two later, the pull happened again, then eased off. My OEM pack increased from 4 to 6 blue bars, but never get to a green 7th bar. I may have to increase the converter output voltage a bit, it's at 246vdc unload.

The sizzling noise may just be only when the converter is warming up. I have to check again when it is already warm.

-Pb