Battery charging error Deebot Ozmo 950

@jozsefkazs48209 @welsonjr before digging into the motherboard, I would consider this an error of the battery controller board. Remember that these are smart batteries. They usually "report" the state of charge etc to the charge controller. Those parts "talk" to each other (smarter than some people right ;-). I would at least try a new battery to see if that resolves it. There are no schematic for the battery controller, so troubleshooting would be difficult.

the 950 has a pile of charging circuitry on the motherboard near the tiny plug where the power comes in from the 2 metal fet, but on the underside of that socket.

The mosfet q10 (labled NL9345 but not a part number i can locate) appears to be a p-mosfet in charge of switching power to the battery for charging. it needs 14v on its gate (pin 4), which is controlled by a pile of transistors / biased by a few resistor networks.......

Check gate pin voltage of that mosfet, if its around 20v / loosely aligned with input voltage then thats why its not charging / why signal isnt reaching mosfet. in my case it was caused by r89 being opened. There are 3 resistors next to that mosfet - r97 > 57 ohms, r88 -> 57 ohms, r89 -> 2.2kohms, confirm those are correct values. if they look right and you still not getting right voltage at mosfet gate, then possibly something else around that area of the board has gone bad(he tiny transistors around there? the diodes or the mosfet itself or one of the many fuses between the power in and the battery)

ultimately the mosfet pin 1-3 are the input power (20v) from the base station, pin 4 is gate and should be ~14v, pin 5-8 is battery voltage (~12v if battery is low, ~16v if battery is fully charged).

if mosfet is bad, try looking for something that will fit the "outer pads, be much easier to solder and to buy.... (sorry i dont have a recommended part but above voltages should give you an idea)

remember.... attempt to fix at your own risks, batteries are dangerous etc standard disclaimers

I had the same problem with mine, I replaced the resistors but now it charges intermittently. There is something else left. Next to the 2k2 resistors I found almost all bigger size resistors faulty (0603 and 0805). I replaced them all but still no charging yet. I wonder what makes the resistors to fail.. it's the first time when I see resistors failing in this way. Probably was a bad batch or poor quality resistors.