>Every year or so I replace the batteries in the Performance Monitor (PM). Not because they are flat, but to reduce the chance of them leaking and killing the P

>Every year or so I replace the batteries in the Performance Monitor (PM). Not because they are flat, but to reduce the chance of them leaking and killing the PM. Lithium (primaries non-rechargables, not Lithium-ion) batteries don't leak (or freeze, fwiw) and store a similar amount of energy as Alkaline batteries. They are considerably more expensive, but IMO a better overall choice for important applications.