Re: help-echo from battery-mode-line-string fails

[Richard Stallman]

    For some reason, the help-echo property on `battery-mode-line-string'
    doesn't have an effect in the mode line.  It works in 21.3 and if you
    insert the string in a buffer.  I can't see what's special about it.

batter-mode-line-string needs a risky-local-variable property.
I will add that.

    By the way, battery.el should provide a minor mode that can be turned
    on via Custom (using `display-battery').  I think it has to cancel the
    timer and update global-mode-string when turning off the mode.

I agree.  Would someone like to do it?