Quote Originally Posted by mtngael View Post
Interesting that the extra .5v of the 675 batteries doesn't make a difference in meter accuracy but one more volt does! I found 675s at the local supermarket at $10.99 for an 8 pack. Definitely more economical than the Wein cells!

Am I correct in believing that unlike the old mercury batteries, which maintained a steady voltage till death, that the 675s would gradually fail, and thus start giving meter inaccuracy with the dropping charge? I'd probably just replace them at a set interval anyway but my geek side is interested.

Thanks for all the info!
The 675 hearing aid batteries are zinc-air technology, so they too maintain a steady voltage until discharge.

The difference is that they don't nearly as much capacity as the mercury batteries, and they have a tendency to lose capacity even when not under load. So they don't last as long.