I’m guessing you are talking about the temperature sensor which is usually up near the front 2 batteries.
I’ve had mine get wet and fail and the result was it wouldn’t charge but by unplugging the “keyboard” connector from the Zivan charger it would charge but without the sensor and without the charge indicator LED.
If you know anything about electronics and soldering you can probably fix it. I posted about how I repaired mine. link to info I posted: Just purchased 2002 e825-4 where to start rejuvenation?
And the Zivan does automatically shut off only it will not provide a float charge unless sent in and modified to do so. You’re might if it was already reworked.
One more thing, you need to learn how to use a volt meter to test what your batteries and battery charger are doing. Otherwise you will be replacing your batteries every 6 months because you killed them by over discharging them or letting them go with fluid level too low etc. Lead acid batteries are not maintenance free, not even close.