No Standards for battery operated power tools.
Voltages have crept up,
having started at 3.0 v, then 4.5, 6, 7.5, 9, 12, 14, 18.......
Every time I've looked for a replacement battery,
it's cheaper to buy a new tool !
I feel bad "tossing" a perfectly good power tool head.
And, of course, no battery will fit any other brand tool.