Was just given a Starrett 722. The only thing the display will say is
"test" (at least that's what I think it says, the "t"'s are a bit funny
The batteries were about 1.4v each - is that not enough?
And there's a little three-pin connector inside - what's that for?
My 721 uses a pair of CR2032 cells, which are nominally 3V each,
and the current pair measure at
3.005V and 3.020V
Note that the calipers keep drawing current when the display is off, so
your battery life may not be as good as you would like (just a few
What I do is slide the battery housing toward the jaws just a
little bit before putting them away. This disconnects the batterys from
the little pin which carries power into the electronics. This means
that I will have to re-zero the unit (the push of a button) when I slide
the battery housing back into place -- but it also means that the
batteries are not being drained while I'm not in the shop using them.
This results in a major improvement in battery life.
I don't have that, but yours is the 722, not the 721, and I
think that is designed to connect to a remote set of electronics for
doing statistics on a production line -- measure every part off the
line, and note trends in the dimensions which may indicate that a tool
is wearing enough to need the insert replaced, or something like that.
I don't have it, and I don't miss it, as I am not doing production work.
Overall, I am quite pleased with my calipers, other than that
battery life feature. but it is so simple to disconnect the batterys
during storage that it is no problem. The 12" Mitutoyo calipers that I
have give longer battery life (over a year), and have a real "off"
button. But since disconnecting the batteries involves unscrewing a
cover to access the batteries, disconnecting them to get even more life
would be a real PITA.