I placed one large lipo bag inside an identical bag and put two Bonkas inside. Then I pushed a small lipo bag in between the Bonka packs as a firewall. The whole assembly is really tight. The two zippers can not be closed all the way on one side because the battery cables are sticking out but it is better than no protection. The non zipped opened section could perhaps act as a vent if something bad was to happen. Just guessing, but it gives me a little peace of mind. The same setup can be duplicated for additional two Bonkas - there is enough room on the back plate.