Finally I found the time to open up that box and take a look.
Besides the melted connector, nothing else seems to have been affected.
Findings:
- My plug connector was fully inserted. I was able to verify this when removing the connector.
- This really seems to be a design flaw. My unit was stationary, a full charge each day (discharge to ~10%).
- After replacing the plug with XT90 connectors I’ve looked at the connection with a thermal camera - the cable from the power brick reaches ~45 °C, the XT90 Connector is steady at 31 °C
- Wires from the charger and the connected cable inside the unit to the baseboard do not seem to be copper but aluminum
- Wires really could be better/thicker. The howllow plug gets converted instantly on the inside of the unit to an XT30U connector with reaaally thin cables. They also heat up quite a but (~40 °C) at normal room temperature. I do not want to know what happens if the unit is coocking in direct sunlight or inside a heated tent.
- It seems the charger does NOT have any sort of “soft start” - I left the unit open while testing and each time the charging starts you can more or less hear a sound reminiscent of some kind of input surge. And no: I am NOT talking about the relay that switches.
And I guess this is the root cause: when not moving the unit at all, a certain point of the round plug will have to transfer the surge current. Over and over again. Until the connector starts to degrade on that spot. Then the next best point of contact will have to handle the load and again degradation.
Until the connection becomes so bad it heats up and starts to melt…
Also: the charging brick itself is horribly prone to collect dust. I’ve had my unit charge for ~160 full cycles by now. When i’ve opened up the charger (screws are located beneath the rubber feet) I had tons of dust built up on the inside. You should really go ahead and clean your charging brick right now. (be aware that touching the wrong components on the inside may kill you dead. )
Here are a few impressions: BluettiPowerstation — ImgBB