Ansmann9V Rechargeable Batteries 300mAh pre-Charged Low Self-Discharge NiMH 9 Volt Battery 9V Battery (2-Pack)

I've been using rechargeable batteries in wireless mics for years. I've usually used Ansmann products, but the Tenergy 250mAh one had great reviews. Also, my go-to Ansmann 250mAh was not available. I read some negative reviews on the Ansmann 300mAh so I wanted an alternative.I was dismayed on Sunday when using my new Tenergy battery (fully charged of course) my mic quit before the end of the service. I had gotten about 2.5 hours of use out of it between the rehearsal and two song services. I've never had one quit on me in that short a time.I ordered two other batteries and did a shootout. I put all the batteries in identical mics (Shure ULX Beta87's) and left the power on sitting on a desk. I believe that using the mics actively would shorten the times but be harder to compare accurately.Here are the mics I compared:Tenergy 4 pieces of 9V 250mAh NiMH high capacity rechargeable BatteryAnsmann 50354539V 300 mAh Low Discharge Rechargeable Battery (this product)Maha Powerex 9 Volt Size Rechargeable NiMH Battery [8.4 Volts, 300mAh](I've had issues with Powerex before because the voltage was too high for the mics. However, this one is the 8.4V model and did just fine.)I also had a brand new Ansmann 250 mah on hand to compare.Here are my unscientific results:Tenergy 250mAh - 3.5 hoursAnsmann 250mAh - 5.5 hoursAnsmann 300mAh - 6.5 hoursPowerex 300mAh - 6.5 hoursThe two 300mAh batteries died within seconds of each other, so that's a draw. Either of these would be a great choice.I've owned 9v batteries from both of Ansmann and Powerex in the past and I have never had a quality issue. If I encounter any issues I'll update this review down the road.******************************Update:Lately I've had issues with the Powerex batteries not working in the Shure mics. I believe they actually get charged over the voltage tolerance of the mic. I'm placing another order for the Ansmann batteries today. You may not have issues depending on your application, but for me I'll stick with the Ansmann brand.******************************If size is an issue because you have a tight fit, please note:The Ansmann is the widest and longest followed by the Tenergy then Powerex.The Tenergy is the fatest follwed by the Powerex then the Ansmann.Charging was done on the Maha 10 bay charger:Maha Powerex MH-C1090F 9V 2-Hour Battery Charger for up to 10 Rechargeable 9V BatteriesI've purchased several of these and have been very happy. My batteries last a long time.I hope this review saves you some time. If you think I've missed a comparable product or have other input, please comment.

The best rechargeable batteries for wireless microphones.

So far these batteries have worked well in the sensors they are installed in.Not enough time yet to know how they will hold up, but so far they look like they will be ok and I will be buying more as needed.

I works well, but I had hoped it would give me more hours of usage per charge for my wireless microphone than it did. I wanted to use the microphone four or five times over the same number of weeks for about one and a half hours each time without having to charge the battery. That was how much usage I had experienced with 9V alkaline batteries. I used the microphone once for 1 1/2 hours with the Ansmann battery and used it again a week later without having charged it. It lasted about one hour the second time. I called customer service and the man I spoke to was very helpful and courteous. He explained that four or five hours per charge was a realistic expectation, and suggested I charge it after each usage.

These with my charger have saved me a bunch of money in my scarecrow sprinkler set up to keep the neighbors cats from defecating in my lawn. I keep that sprinkler set up all year when it is above freezing and I have to change the battery about once a week. They last long enough for me.

I got 4 tenergy 200mAh at $4.5 each, a powerex 300mAh at $12, and this 300mAh at $15.This and the tenergy's were right at 200 mAh, the powerex at ~270mAh. So per dollar, this is by far the worst value, and the farthest from rated capacity. The tenergy are the only ones that hit rated capacity, and they're the cheapest.Tenergy aren't high quality either, 1 of my 4 was straight up bad (like 50mAh on first cycle, up to ~150 after 3 cycles) so make sure to cycle yours a few times right when you get them to weed out the defective ones.After lots of searching, as far as I can tell nobody makes a good NiMH low self discharge 9v at this point. If you don't go through a lot of them (like just smoke detectors), get Energizer Ultimate Lithium and trash when they fail. Hopefully 9v's go extinct entirely or someone makes a rechargeable that isn't junk..

Never have had a problem with Ansmann batteries in our professional usage of them however, the last two we ordered Corroded in the charging unit and became non-functional after minimal usage

These are high capacity 9v batteries. If you have electronic devices that draw a lot of power, or ones that are a pain to swap out batteries, then you want these. Pricy? Yep. Worth it? Yep.I use these in a high output T.E.N.S. unit, a bed alarm, and a metal detector. The amount of life between recharges is nothing short of amazing. They seem to be well constructed, and I foresee no problems with them. If that changes in any way, I will edit this review.