ORIGINAL: Jeff489

Tamiya makes a little Y adapter for hooking up one battery to two loads. It's sold with their King Tiger kit and Pershing kit (maybe others too, I just don't recall right now). I'd use just one high quality battery (the battery you have in there is just fine (I've got a few and am impressed by how they charge up). One battery saves weight (which is your enemy).

As for charging batteries in your tank, I charge mine inside using the aforementioned charging system. Yes, they can overheat if improperly charged, but they haven't in many years of doing this. I follow a few common sense rules. I currently use NiMH batteries. I replace my batteries every 2 years (I magic marker the date first charged on the battery before installing) and charge them at a reasonable amperage (3.5a) with a high quality peak detecting charger. They get warm, but not hot when charged.

My basis for doing so is that I choose to run the remote risk of a meltdown instead of enduring what I consider to be a sure thing of turret ring damage and stripped gears from continually removing turrets for maintenance. Time savings is huge too, as it is very convenient to recharge tanks. Many other tank club members do this too. One might not realize it, but we charge batteries inside plastic stuff every day (such as our vehicles, laptops, cellphones, RC transmitters, etc.) without meltdowns. Why not a tank application?