Drilled all the parts to the FW and FW support angles. The bottom battery support and side hinges are tied into the horizontal support angle which is tied into the vertical angles. I haven't riveted the .032 aluminum sheet to the hinges yet, I plan to Engine Turn the sheet first, then bend and attach to hinges. I plan to use solid 3/32" flush rivets with the heads on the inside. WIll dimple the sheet aluminum and countersink the .040 hinge.
I'm sure the battery case added at least1 lb to the airframe but I don't think that will be an issue. I would rather have the piece of mind knowing the battery isn't going to tear the FW or fall off in flight.