Hi I use 1000 mAh 2 cell LiFe batteries from Component Shop. I solder my own xt30 on but he will put xt30 connectors on for you.
https://www.componentshop.co.uk/6-6v-1000mah-lifepo4-receiver-battery.html
Hi John I happen to have a Titan Tornado surplus to requirements and needing a good home to go to if interested. It is one of the later models that use a 3 cell LiPO battery.