AXE120 power options
Coin12 stated in his first post ”I have axe120 microrobot it runs with 4 AA batteries”.
And direct from the AXE120 datasheet:
The micro-robot base unit consists of a plastic enclosure (120 x 80mm) which houses the 4 AA batteries
And
Also required (not supplied):
• 4 x AA cells alkaline recommended - part BAT002)
Dropping to 4 x Ni-MH AA’s giving around 5.00 V after removal of the “safety” diode on the AXE120 will be slightly worse as the motor volts will be down and torque is proportional to the square of the voltage. If down from 5.3V (6V-0.7V for diode) to 5V (94%) reduces torque by 12% compared to a fresh set of alkaline 1.5V AA’s.
Two 3.6/3.7 V Li-ion batteries will help keep the power up but as others have indicated a 7805V regulator will be needed for the PICAXE chip to prevent from damaging that.
A possibility could be 3 x 3.6 V Li-ion cells and two regulators:
- 7805 regulator for 5Vdc for the PICAXE side,
- 7809 regulator for the XBEE if that runs of 9 volts (not familiar with XBees)
- As the L293D can handle up to 36V, modifiy the PCB and run the motors across 2 Li-ion cells for 7.2 Volts. Could the motors handle 3 Li-ion cells at 10.8V ? Certainly more likely to burn out.
This will reduce the battery set to 3 cells instead of one or two sets of 4 AA’s (depending how XBEE powered at present), It would mean some serious mods to the AXE120 robot PCB.
PLUS the need for proper charging of the Li-ion batteris as others have already mentioned.