One-button menus must die.

[Firecrow]

I'm no expert but it could be nice. Not sure if it's possible, tho. Only place I've seen such features is on rather high-end battery chargers intended for RC hobbyists and such. Even with those I think it's only possible to get an estimation of internal resistance while charging.

(I will slowly try to back off of this limb I suddenly found myself on. Again, I'm no expert.)

Perhaps someone with more technical knowledge will chime in and remove you from the branch