15 of 15 people found the following review helpful
One of the highest-capacity 9V rechargeables...,
This review is from: Ansmann 9v 250 Mah Rechargeable Battery (Accessory)
but there are some drawbacks.
Unfortunately, 9V NiMH batteries only have about 1/3rd the capacity of a standard 9V alkaline. While that doesn't matter so much for my needs (it just means I swap batteries out more often, and I have plenty of warning that the battery is starting to run down) this could be a problem for uses where the equipment draws a lot of current--such as wireless mikes.
These batteries aren't really 9V, they're only 8.4V. Depending on what they're being used for this may be an issue. Most equipment doesn't care, but I believe paintball guns (among other things) really want a 9V battery.
The Ansmanns are slightly larger physically than a standard 9V. Again, this may make a difference; I've run across equipment where the Ansmanns just won't fit (though the same equipment is also picky about alkaline batteries). If most standard 9V alkalines are a tight fit, it's unlikely these will work.
If you need a "true" 9V battery, or size may be an issue, the Powerex 9.6V battery is a good alternative. They're slightly smaller than a typical alkaline 9V battery so size isn't a problem, and they put out 9.6V so they will work in almost anything. The one drawback is that they don't have nearly as much capacity as the Ansmann batteries.