This is I guess the update post to a previous post of mine... (sorry for the wall of text guys, but I figured it might be handy to know.)
you can read the previous post in this thread for full details, but we've been running now since 08 at least on rechargeables for all our shows and techs. the batteries have been more or less faultless. (any batteries showing issues are detected at charging
phase so we notice before we put them in the packs).
Those wanting to use rechargeables, the best thing I can say is do your own research. buy a pack of rechargeables and test them on your equipment and see how you like it. it's what I did, and it's what I still do if i need to
switch brands to keep pricing good or if there's new technology.
I have now gone through testing with duracell, energizer, sanyo (2500mah and the new sanyo "eneloop" long lifes, and ansman. our initial
purchase was sanyo/duracell. energizers I've tested at home. Ansmann were bought to replace the duracells but once we found issues with them, we changed to the sanyo eneloops.
the batteries have been used in Sony's WRT wireless handhelds, and
shure's UR1 series lavs. (and misclaneous "non pro" gear)
it breaks down (by brand) ike this for us...
duracell's quick chargers suck. don't get them. they charge too fast and break the batteries (or shorten their life.)
energizer seems good but their life isn't as good as sanyo's series of batteries.
(Note:those 2 make sense, why would the larger manufacturers of alkalines screw themselves by bringing out a product capable of doing damage to their main lines.)
Ansman... if you see these batteries, don't use them in pro gear. they cheat their manufacturing tolerances so they're millimeters too large to get the
power output they want. this means they strain the packs and can
bend connectors. By the way, this is apparently fairly common, and the reason why i say *test your own systems on rechargables before commiting*.
There is 1 company I've noticed who's manufacturing tolerances match "real" AA batteries without fault. Sanyo.
Sanyo: 2500 mah and "eneloop" series. of the batteries we've tested, 3 years down the
road there are still sanyo 2500mah batteries in service with us. we do 5 plays a year on a roughly 7 month schedule with shows on most days. I've past the "1000 charges" lifespan Sanyo claims they can hold charge for and some have given up, but over 70% of their
line has held now 3 years later. they are hands down the best company i've seen with the NiMh batteries so far.
the eneloop series from sanyo is a relatively new "long life" NiMh. they say the batteries stay charged for over a year without discharging to an unusable state. I've used the eneloops in full runs and techs without any problems. they reliably stay charged for over 3 months and can still pull enough battery life to run a pack for about 4 hours (so if you just need a battery right now to do something fast and you have these in a drawer, the eneloops are fantastic. try not to rely on their "long life" characteristics for show runs, but certainly for rehearsal it is reliable. and at least for me, don't push too much past 3 months before making sure to charge them before use to guarantee their performance. their long life characteristics do not affect their standard "charge and use" for us.) regarding battery life on a full charge, they last over 8 hours a charge for us (eneloop and the older 2500mah AAs). Battery size tolerance seems to match AA alkaline standards exactly.
Others are correct in that the battery life bars of much equipment shows these batteries acting strange. NiMh batteries, as others have said, have a different
power discharge curve. As I understand it, no pro gear has a
power curve table specifically catered to NiMh (though there was a post on here saying the UR1s do..) test your own equipment and see what the graph does... for us, 5 (full) bars drops to 4 bars pretty fast, and even to 3 still means it has over 7 hours on its life. at 2 bars it means you have between 1-3 hours left, at 1 bar change them out within the next hour or risk failure.
regarding chargers: look around, there are a lot of chargers on the market and as long as you're using a good multi charger, it does not necessarily need to be the same manufacturer. It is much more important *how* the charger charges the battery and what it's protection circuitry does when things get to "full" or don't work. there are good "mass charging stations" out there that can do between 8 and 16 batteries easily with really nice charge and protection circuitry. it's how we know which batteries to watch for. Strangely, while annsman's batteries are absolutely garbage (due to manufacturing tolerance. their life and
power usage seems fine), their chargers are not bad and very easy to tell if batteries have problems or if there's an issue with the charger.
9v NiMh batteries are still too costly for their use with us. I replaced our full
line of batteries this year with the new eneloops for about 50 bucks and used our multipurpose NiMh battery chargers with them from previous batteries. and they'll hold us for the next 2-3 years on over 150 shows a year, not including techs.
Our present inventory has the eneloops as our "main batteries", all the other batteries from previous years (verified still working) as rehearsal/testing batteries, and a pack of alkaline "oh crap" batteries incase something goes horribly wrong. in 3 years I've dipped into the alkaline stash twice. our board operators forgot to charge the batteries, and put in the alkalines instead of charging them for that night and had the rechargables ready for the next night.
Really sorry for the wall of text guys.. hope the info was at least useful!