Hello, I am working on this "Robot presence" which is a robot much like one of thoose https://www.google.fr/search?q=robot+presence&espv=2&biw=1375&bih=761&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMIo5W6_o3nyAIViUoUCh3hZwE3 except for the graphic design maybe :(
The robot stays on all the time.
Most of the time it is plugged to the wall, but when someone wants to wander around the house of course we switch to the battery.This is the diagram i made with the welcomed help of OldSteve and others here.
Now what i would like is to have a circuit to recharge (cleverly) the battery knowing that it stays on the wall most of the time (maybe 95%) The battery i have for now is a cheap 3800mah NIMH. I might change for a better quality one but it will stay arround 3k-4K mah.
There is loads of resources online about how to charge those battery going from a simple resistor to a whole circuit detecting heat on the battery.
I am not sure what direction take. I can detect heat easily enough with the arduino but i doubt this is a good idea ( what happen if arduino goes down?) Maybe the simple trickle charger with a resistor would do just like on this page
What do you think?