V2.0 board note:

Thanks to Mark Spiegl I have realised that the resistor that's used t charge the pryo charge cap (R2) is too small (watt wise) for people who are using larger voltages. If you are using 6v on +V then everything is OK, for 9v you should probably replace it with 2 240 ohm 1/2 wat resistors in parallel, and if you are using 12v you should replace it with 3 390 ohm 1/2 watt resistors in parallel.

In a related note - this resistor is shorted to ground through T1 most of the time - when the firing circuits are not armed. This is mostly to make sure that power on transients don't cause the pyro circuits to fire. If you are not using the pyro circuits you should arm them to save battery power.