I like the idea of just disconnecting the sensors and keeping everything else alive. Still I will need to protect the rest of circuit from surges.
I'm not sure what you call a surge, but surges (as I know them) are incurred whenever the load on a supply (eg. your battery) changes - small change => small surge and v.v. Disconnecting a load, you will have a surge, relative to the load current.
That's why you need to know what your sensors will safely deal with (I have never heard of IR sensors that were particular frightened of surges though).
Soeren: I am not aware of soft start and disconnect mechanisms. Can you please point me to some?
Not without knowing the specs, as such things need to be made for the circuit in question.
As for the battery charger, it is a charger specifically made for charging NiMh batteries and has detections for overcharging and sensing the existing charge levels so all I need to do is to connect the battery to the charger once the robot is docked.
If it has got 4 leads running from the battery (2 supply wires and 2 sense wires) it might work, but if it's just 2 wires and you extend the wires between the battery and the charger, don't count on its reliability without thorough testing.
If I put a 1A protection diode across the battery charging circuit, wouldnt this prevent current surges?
A diode is not a current surge suppressor. It can keep the voltage within Vcc+0.7V (or Vee-0.7V), but in a 12V system, a surge can be from eg. 5V to 12V.
But perhaps we're talking about different things?
I suppose SmAsH is right as my charger stops the charging once the battery is charged so disconnecting shouldnt be a problem. I need to try this out.
I wouldn't count on it, as mentioned, without extensive tests.