Re: Battery Power and handyboard. I am currently using nickel hydride AA cells in two 4-cell battery boxes and so
far during my construction and testing of the board they have not needed
recharging yet. I didn't have access to a mains power supply most of the time,
so after checking that the power circuits worked from the mains I used an
external 8cell battery box for the batteries and connected into the power
socket. As you can imagine powering the comms convertor and hb during the
construction and testing phase is a reasonable time so personally I would
recommend using the nimh cells to increase running time. The nickel hydride
batteries that I am using are rated at 1300mAh (1.3Ah) so are significantly
larger in capacity than the Nicad battery packs. If you need more capacity, the
C cells are rated at 2200mAh (2.2Ah) which should be enough for most
applications. They are more expensive though as they were bought as packs of two
cells (actually I got 4 with the wall-wart charger).  If you bought the 'tagged'
style of cell you could effectively build your own 9.6 volt battery pack using
nimh cells to fit into the base of the hb the same way as the normal pack.

The problem you need to watch for when you put battery packs in parallel is that
the cells of each pack will be slightly different in their charging/power
characteristics. Preferably have both packs completely discharged before
connecting them together (away from the hb) as the packs could have slightly
different voltages and you could get a reasonably high current flow from one
battery to the other. Assuming that both packs are discharged, when they are
connected together and connected to the hb they will both charge up to the same
level so any differences should have no effect. Obviously the charge time will
be higher than before (probably up to twice as long). Be careful with this
configuration though, as the supply to the hb will now be capable of sending
double the amount of current though your board in the event of a short circuit.

Hope this helps.

John


