YouTube User [Vuaeco] has come up with a novel idea, combining power tool battery packs to double the capacity.

Starting off with two slimline 2.0Ah compact battery packs, [Vuaeco] wanted a larger 4.0Ah rebuilt drill battery pack. These battery packs are different in size so it wasn’t just a case of adding in more cells in empty slots, instead he goes on to show us how to connect the batteries in parallel using some thin nickel strips. Once completed he modifies the battery casing so it fits another stack of batteries. He does this by bolting the top and bottom together with long screws, and insulating the otherwise exposed battery terminals with insulating tape. The final product isn’t as aesthetically pleasing as a real battery pack, but it looks good enough.

There are a few things we might have done differently, for instance providing some hard plastic around the insulation so should the battery get knocked in an awkward position it would still have a hard shell protecting it. Also, instead of combining the batteries together fully charged as the video suggests, we might have done the opposite approach and fully drained them, avoiding unnecessary risks. If you try this, how about giving it a 3D printed case?