MaximalPower 9 Volt Li-Ion Rechargeable Battery HIGH CAPACITY 550mAh 9V Block

This is an excellent battery, very well built (at least it looks so) and I'm using 2 of these, one for a Nady 4 channel stereo mini mixer, and another for my danelectro electric guitar mini amp. Both with great results.Beware you will need a Li-Ion charger, because this kind of batteries need pulses of current for charging correctly. I own maximal power 9 volt battery charger which I also recommend and it comes bundled with 2 of these bateries.

I use this battery to power specialized equipment used in Paranormal Investigations, namely, REM-Pods and Shadow Detectors. Once charged, they do in fact hold their charge over time, but there is one significant problem with their design that complicates their use. In many 9V applications, either the battery lead itself or the battery must be brought together with significant force in order to get the terminal sockets to engage and lock into one another. With this particular battery, it's not a solid little mass, like an alkaline version of a 9V would be. So using force to press the terminal sockets into each other results in the top of the battery depressing back into its own casing, slightly. They still work, but it is a concern. It's been a few months now that I've been using them in spite of this issue and they're continuing to work just fine. Given how few choices there are in the market for rechargeable lithium based 9V batteries, these will do.

i decided to try these out because my six *p*w*r 520 mah batteries (~$23 each) started to go. those batteries were good for three years plus. i use 9v batteries for my church's handheld shure mics (those mics are 10+ years old). used alkalines, ni-cad (very briefly), ni-mh, and now li-ions/polys. li-ions are the best by far next to good ol' alkalines. these maximal 9v have held up so far the past month without any failing when run for 4+ hours. sorry, can't be more specific because i let the singers and other sound tech's change them out so i don't know how long a fully charged one actually lasts. i'm using the *p*w*r 4-bay fast charger because i didn't want to purchase another charger unless i had to. i haven't seen and problems using the maximal 9v batteries and the charger...so far so good. i have the charger on a 7-day timer set at different intervals throughout the week; the maximum time the batteries are charged is no more than 4 hours per day...about 10 hours if the battery is left in the charger the entire week. time will tell if they last over 3 years. great price and good lasting charge.

I purchased this thinking this would be a great high capacity 9v battery. Received it quickly thanks to Amazon. Charged the battery using my 9v batt charger, charge was done and I tested with my multimeter and battery read 8.4v so I placed it on my charger again thinking it stopped too soon...charge finished after about another 8 hours and checked again with multimeter, read 8.4v! Thanks to Amazon's great return policty I wasnt stuck with a dud battery. I also purchased a Lenmar 200mAh 9v and its been great! Sure the battery doesn't last as long in theory but at least it works. Another issue with the maximal battery was the size, its a bit bulkier than a regular 9v. The Lenmar was just right. Hope this helps anyone else.

I use these in a set of clinical instruments that chew up 9V batteries and had some bad luck with single-use lithium batteries. These rechargeable Li-ion batteries have worked very well for about a year. They hold their charge well between uses (we use the equipment heavily for a week at a time, but only twice a year) and we get a lot of use with each charge. I am guessing the 550 mAhr rating is honest.

I'm sure this battery is a great rechargeable but its rounded shape and large connections made it awkward and it does not "snap into" the charging ports on my 9V charge. It has to very carefully sit upside down on the charger or be taped to maintain the connection long enough to charge whereas other batteries simply snap in, and stay in when the charge is in the wall.

I use these in my Meier Corda Step Dance portable headphone amplifier with great results. This amp is known for being power hungry and I have had no issues with power delivery with the battery lasting about 30hr of play before fading and needing a recharge, which is about the same as a good alkaline disposable. Definitely a cost saver in my case.

I bought four. One was a bum. Partially charged the first time. Quickly died, and wouldn't charge again.