I recently purchased 2 x Tenergy Centura's and can say they are absolutely EXCELLENT (too bad I can't say the same about their AAA 1000 mAh, but I digress...).
I've been using them in my Extech HD450 light meter and RS DMM. They hold their charge well and last much better than the Engergizer's (non-LSD, 7.2V 150mAh) I purchased a while back.
They're charged in my universal AA/AA/9V Energizer charger but I think it's just a dumb slow charger that doesn't ever truly stop charging so I usually monitor the charge and yank them off after a few hours. They come of the charger around 9.2V or so.
I've tried just about every PP3 rechargeable (Also MN1604, PP3-HP, 006P, 6LR61, 6LF22, 6LF62) on the market with my assorted meters and none of them give trustworthy results.
My only use for these batteries is in meters so i buy bulk packs of good alkalines for them. If i could get reliable rechargeable ones I'd buy them in an instant.
I own a lot of them that can't be trusted for meters.
In general meter readings tend to be off when the voltage is low. However, as mentioned my Tenergy's come off the charger around 9.2-9.3v whereas I could never get the Engerizers above 8.3v or so. Not sure what devices you'll be using these in but if it's meters and the readings will be critical then I'd recommend getting some good quality 9V Lithiums.
For me personally, I haven't experienced any adverse readings with either these or even the Energizers.
Won't the meter alert for low battery in this case?
Otherwise how is this different from using slightly discharged primaries?
I use 9v for: IR thermometer, ultrasonic distance meter, DVB-T signal strength meter, luxmeter.
I currently don't have any multimeters that use 9v (well, I do, but it's the crappy 3$ meters I don't use), but I have one that uses AAAs. So I shouldn't use it with rechargeable AAAs and stick to primaries? And if so - does it make any difference if I use alkaline or lithium primaries?
I guess 9.6v batteries (like the Imedion LSD 9.6v) can be useful in voltage sensitive situations, but they're expensive compared to the 8.4v LSDs, so do I really need them? Arrggh, decisions, decisions... :)
I think they were the cheapest at the time I purchased this but definitely look around. For just under $9 for two, it's certainly worth a try to see if these will suit your needs.
Basically self-discharge and I suspect grossly overcharging them at some time in the past. While I disapprove strongly of disposable batteries, I couldn't trust the numbers I got from several meters - they'd read the same on alike/lithium cells but would give different readings with the NiMH 9V cells - which always seemed to be flat when I wanted to use the meters. I've not bought any LSD ones or tried them in the meters though. The low battery warning is for the gradually declining alike/lithium curve, not the "fall off a cliff" typical NiMH discharge.