I’m trying to increase the run time of the 3pi and at the same time reduce the weight. I’d like to replace the 4xAAA battery with a pair of lithium ion cells. I see that the maximum voltage specification is 7 volts. I noticed that this is the same as the “low voltage” version of the power-on switch, Pololu item #751. A pair of lithium cells would average around 7.4 volts, with a peak after charging of 8.4 volts. Would this be too much voltage for the power switch circuit? What about any of the other circuits attached to Vbat?
This has already been covered here, buried deep within the extreme line following thread (so I’m not surprised you didn’t find it). The short answer is that the 3pi will not be able to handle this, because certain parts of the power system cannot handle the 8.4 V of a fully charged pack. You could try a single cell, though performance of the motors might be adversely affected.
You might also try to use 2 diodes in series to drop roughly 1.4V. These would have the additional benefit of reverse polarity protection. Test this with a load resistor (maybe 100 ohms, 1/2 watt?) before connecting to 3pi.
