What happens if I go above 13.5V? Immediate damage? Life reduced from 10 years to 3 years?
I’m currently using 8 AAA NiMh cells to power my controller & robot.
Right now I use VBat to power the motors and use software to compensate for the fluctuations is motor voltage.
I would like to use 12 AAA cells, and then power the motors via a fixed voltage provided by the integrated adjustable DC-DC converter. The specs say that the DC-DC converter can deliver up to 80% of the input voltage. With 8 AAA cells, 80% of 8V (worst case is too low - considering discharge state AND considering that the voltage dips somewhat during high load). Hence my desire to go to 12 AAA cells.
12 x 1.4V (fully charged Nimh) = 16.8V (for a relatively short period of time). What will happen?
In general, if the voltage rating of a chip or board is exceeded, it could be damaged immediately. The 13.5V limit comes from the TB6612FNG motor driver IC used on the Orangutan SVP. By default, the driver is connected to VBAT, but you can disconnect it from VBAT by cutting the labeled traces on the bottom of the board. You can then supply the motor driver with VADJ (like you mentioned) or some other power source. You can read more about this in the “Module Pinout and Components” section of the Orangutan SVP user’s guide.
Additionally, VBAT is connected to BATLEV of the PIC on the Orangutan SVP (as seen on page 5 on the schematic diagram. You will have to either cut a trace or remove a resistor to prevent the BATLEV pin from exceeding 5V. You can follow the trace coming off of pin 7 of the PIC to determine where those resistors are.
With the motor drivers and BATLEV isolated from VBAT, you should be able to power the Orangutan from 16.8V; however, you should make sure the VBAT line does not exceed 18V (the step-down regulator’s input voltage limit).