David Brodbeck wrote:

I'm not surprised. I have a cheap one and it reads 10% low on the
voltage scale when the batteries get low. The LCD has a low battery
annunciator but it never comes on. Poor design. My job doesn't
require a very accurate meter so I just check it against the line
every so often and replace the batteries when I start to see
suspiciously low readings. In my job there's a fairly substantial
chance that sooner or later I'll drop it off a ladder and break it,
and I'd rather break a $40 Chinese meter than a $300 Fluke.

Thank you for your response!
The new meter that I would purchase is only for my personal use, not for
work, and it should be used only by me..I think that it can "live" for some
years..I don' t use it in "difficult" ambient, or with the possibility that
it can fall down.
The battery of my cheap ones is fully charged (also my meter had a low
battery indicator..and I never had seen it turned ON, when the battery in
low!!)..I think that they are "at the end" of their life...or, simply, they
aren't the right meter for the work (at this moment,my PC monitor repair)!
Thank you!