Alpha.s1

A small life is what i use, http://www.componentshop.co.uk/9-9v-1000mah-20c-lifepo4-mini-stick-battery.html , though that 1 is very tight, better 1 to use would probably be this one http://www.componentshop.co.uk/9-9v-750mah-20c-mini-lifepo4-battery.html Any way its done except PEQ box will be really tight, and a nightmare to change.