A1278 battery in A1342

Unibody 2009 - 2012 MacBook Pro 13" and 2009 - 2010 MacBook batteries are electrically compatible but have incompatible enclosures. After an expensive NewerTech battery failed in under two years, I decided to modify a cheap used OEM A1278 battery for my MacBook7,1. Here are some photos in case they may help someone else.

cells

I carefully cut the enclosure off the A1278 battery. This completely destroyed the plastic, but seemed less risky than prying the cells out. I also extricated a piece of black rubber from under the wires, since it made that side too thick.

shell

I removed the cells and electronics from the failed A1342 battery. The plastic had to be trimmed slightly to fit the new circuit board.

assembly

I hot-glued the cells into the enclosure and installed it in the MacBook. It is fully functional.