Lots of people use the rechargeable batteries and report no problems.
One that is listed at only 12 charges is likely some type of rechargeable alkaline
battery.. I don't consider that a true rechargeable..
One that is spec'd at a few hundred charges, like a ni-cad, nickle hydride, lithium, etc,
is what I call a rechargeable.
They save money if you do lots of constant hunting.
But.. I prefer to use alkaline batteries that I get cheap at the dollar store, and I
usually change them out at about 1/2 way on the indicator.
The reason, is I prefer the higher voltage that you get from the alkaline cells,
vs most of the rechargeable cells.
I feel there could be a slight depth edge when using the higher voltage.
The Ace 250/350's are designed to run on 6 volts. Which is the voltage you
get when using four alkalines. "4 x 1.5 volts".
If you run rechargeables, most do 1.2 volts per cell. So instead of 6 volts, you
would get 4.8 volts.
Of course, the alkalines will drop when they see some use, and the rechargeables
tend to hold the voltage a bit flatter when they discharge, which is why I change about
1/2 down. I'll have to see what my voltage is when half run down.. I've never checked it..
New alkies will actually be a bit higher when new, and no load.. 1.6 volts a cell is
not unusual. When a alkie discharges, it's a real gradual, but steady decline.
Most rechargeables stay fairly level until the end, and then they go kaput real fast.
I often use the Ray o Vac "Gold" alkalines.. I think that's the brand anyway..
I get them two for a buck, and my machine seems to like them.