It's unfortunate there are no standardized rechargeable battery
packs for portable devices. This might have been doable when
they were powered by AA and C cells, but modern devices are
so small, and the battery is so tightly mechanically integrated,
it isn't possible.

There's a reason why nobody standardizes on battery packs. Battery
packs are a major profit center. It's the razor blade model. Give
away the razors, and sell lots of blades. For example, Motorola makes
it policy of requiring a new battery, microphone, antenna, charger,
and other accessories with every new model handheld radio and cell
phone. Even models that are very similar, have intentional lumps and
holes to make the previous generation of accessories incompatible.
Same with some HP LaserJet cartridges.

You can still get LaserJet series-4 cartridges with no problem.

Oddly, companies /neglect/ to take advantage of profits they could make on
batteries. Palm no longer provides parts or service for the Tungsten T3 --
which is illegal. Had they charged (no pun intended) $50 to replace the
battery, I would have sent the T3 to them. I replaced it myself for $6. If
it lasts two or three years -- and batteries are still available -- I'll be
happy.

"Unless and until" some "ultimate" battery technology is developed, it's
unlikely there will ever be a universal battery system (or systems).