Ive been scratching my head on this for awhile. So I have an arduino telepresence bot project and I need to come up with a method of remotely recharging the batteries without someone manually doing it. I was thinking of a roomba style AC contact point but I need some advice on the best way to go.
The format is an rover 5 chassis with an arduino uno r3 + L293D Motor Shield , at first i tried 6x 1.2v NiMH 2400mah AA's but the voltage didnt seem high enough for the motors (Motor rated voltage: 7.2V) which seemed sluggish so I added another 2 AA's and it seems to be fine voltage wise. All up 8 AA's now.
So I need to remotely recharge these, being telepresence i cant manually open up the robot to pull the batteries out and recharge them every time so I wanted to come up with a relatively cheap way to recharge them via an AC point. The first bit of advice I got was that Lipos are no good for recharging while still pulling power to the arduino which needs to stay on through everything. I gather a charge controller circuit is required however most of the ones ive seen eg http://www.adafruit.com/products/259
are for sub 5v. Id like 12-24hrs running time between recharges. If someone can suggest a good relatively cheap way to go id be very grateful.
I had a rough/cheap idea, I bought an 8 bay AA recharging bank like this http://www.ebay.com/itm/131218125319
and I was thinking of placing all the batteries within it and then running a wire from each + and negative to the +/- on the motorshield. The AC power cable goes to the contact station to recharge the batteries and the power should continue into the motor shield. I was planning to put a diode on each AA + wire to make sure they dont all connect up at the motorshield and trip the charger which seems to cut out when the batteries reach a certain voltage.
Apologies for my lack of basic battery / power knowledge.