yes, sounds like the battery temp sensor( The temp sensor is an LM335 IC on a little board with a capacitor ). See my thread on my 2002 e825 and scroll back to where you see pictures of the sensor repair Just purchased 2002 e825-4 where to start rejuvenation?
What I did while I waited for the part was to unplug the sensor wire/plug from the Zivan and I think it might charge ok without the indicator and sensor plug plugged in. But I also peeled back the heatshrink and cut the wires back enough to leave colored insulation on the temp sensor part so I knew what went where after repair and I could work in my house on it. Mine still didn’t work after the IC was replaced but I found a big SMT capacitor on an old circuit board and changed out the capacitor and then it worked. Or at least it would act like it was working.