My trimmer came with green Suppo batteries. I have found a good replacement on Amazon (HyperPS 1.2V AAA 600mAh Ni-MH Rechargeable Battery for High-Drain Devices, Quick Charge (Flat Top w/Soldering Tabs)). They fit nicely in the housing and I was able to solder contacts without issues. It was not the best soldering job but there were charging and providing power to the trimmer. Not the best capacity but much better than then original. I bought a 4-pack as I might replacement again sometime later.

https://www.amazon.com/gp/product/B07BX4...