EBL 9V Li-ion Rechargeable Batteries (2PC) and Smart 9V Battery Charger

I picked these up for my TENS devices. I was sick of running through 9 volt batteries while trying to keep up with TENS therapy schedules. It's already hard enough to keep motivation going for long term stuff, and buying batteries was quickly becoming an unwelcome chore. After some poking around on Amazon these seemed like the way to go. And sure enough they perform perfectly. They charge fast. They quite frankly last longer than standard 9 volts in my TENS units. I am thoroughly satisfied with this purchase.If I had to nitpick I would say they're a tight fit. They're like the tiniest millimeter larger than a standard 9 volt. So fitting them in can be tight and removing them a little more annoying. On this note, the shrink wrapped plastic label will eventually take damage I imagine. Not that I'll forget what they are or anything. But it's mostly a non-issue in my situation. I just gotta make sure the pull ribbon is situated well.Long story short; I had a specific use. These work perfectly for it. In fact, they exceeded my expectations. I feel like I already got my money's worth out of them with the amount of cycles I've done. If they died tomorrow, I'd be disappointed but probably buy them again. Of course I have no reason to think they'll run out of juice any time remotely soon. Already saved me money, and I believe they'll continue to save me lots more.

Purchased this based on other reviews for use on a tens unit. The IF mode drains the battery so you would have to change it out every day.! These rechargeable batteries work great

A few months earlier I had purchased the 4 battery kit that came with a 4 slot charger, and recently needed an additional 2 batteries. Furthermore, I also wanted an additional smaller charger that would take up less space in my bag, thus I purchased this kit. The batteries are the same, thus you get the same benefits of a direct output from 2 3.7V (4.2V full charge) li-ion pouch cells wired in series for an 8.4V output. As with the nature of this setup, you will not reach a true 9V output but since most products that use these batteries can work down to the 6V range, you can still enjoy pretty much all of the capacity these batteries have to offer.Compared to quality alkaline 9V batteries, these have a higher capacity at 600mAh rather than the 450mAh that you would get from expensive premium alkaline 9V batteries, thus if your device can operate down to at least 7V then you will get a longer run time from these batteries.If your device needs a higher voltage where it cannot make full use of the capacity of these batteries, then I recommend looking into 9V rechargeables that use a single 3.7V cell and a DC to DC boost converter. Those will offer a fixed 9V output until the battery is drained to its minimum voltage. While it will mean that your device will not be able to estimate the battery level or warn of a low battery, those will give a longer run time for devices with a higher minimum voltage requirement. The only downside is if the device that needs a higher voltage, also works with any kind of audio capture or analog audio output (that isn’t a basic beep or set of tones), then a DC to DC boost converter will introduce noise into the audio (thus not recommended for any musical instruments, mics, or anything dealing with audio in general).The size of the 9V batteries are within the size limitations of the IEC 9V battery standards, with a height (including the terminals) of 47.9mm, width of 26.14mm, and depth of 16.78mm. In my review I included a diagram detailing the measurements I took with some calipers.One thing to keep in mind is that the operating range of a alkaline 9V battery is 9.5V to 5V, thus if a device has a battery gauge built in and can operate down to 5V then the battery gauge will be completely inaccurate with these rechargeable batteries.Pros:Direct battery output with no DC to DC regulators to introduce line noise into a circuit.More capacity than a quality alkaline 9V battery.No DC to DC switching noise (no DC to DC regulator), thus great for audio equipment.Cons:Lower fully charged voltage of 8.4V compared to a fresh alkaline 9V battery.Devices with a battery gauge that are designed for alkaline battery use will be inaccurate with these batteries. If you need to rely on the battery gauge of a device, then monitor at which point of the battery gauge the device shuts off so that you will know how it correlated to the rechargeable battery.

UPDATED (SEE BELOW) I wish I had read more reviews before purchasing this. As others have said, this battery is just a bit taller, wider and thicker than a standard 9V battery. Who knows why they would stray from the standard size battery. I bought this because I wanted rechargeable batteries for my guitar that has a Sustainiac pickup that drains the battery if left plugged in. This battery fit pretty snugly into the battery compartment but trying to pry it out was a task. I give this item 3 positive stars because the batteries seem to do the job and the charger worked well enough (had to charge the batteries for about an hour upon receiving) but I have to deduct some stars for the poor design of the battery size itself. If you have a more spacious battery compartment then these should be ok for you but buyer beware. I'm returning this item.UPDATE 3-18-23: I DID NOT return this item. The seller reached out and addressed my concerns and I'm impressed by their customer service. FOR GUITAR PLAYERS (like me) or others who have tight battery compartments, since the battery fits snugly into the battery compartment in my guitar, it works fine but needs to be pried out (risking damage to the battery or battery compartment) so I came up with a not-so-elegant solution but one that works quite well.I purchased a roll of 20 lb. fishing line for $3.29 + tax (link below). I made a loop with approx. a 3" diameter and tied it securely, tying the knot multiple times to be sure it stayed and strung an old plastic button from an old shirt through it before I tied it so it wouldn't "disappear" on my desk. I place the loop of fishing line around the middle of the battery before inserting the battery and, since the line is thin enough, the plastic battery compartment door closes fine without having to cut notches in it for the line (although you may have to). When I need to remove the battery, a gentle tug on the fishing line loop and it pops right out. I hope this helps. Link below for the fishing line I used:https://www.amazon.com/dp/B0000AUW91?psc=1&ref=ppx_yo2ov_dt_b_product_details

I really like my new rechargeable batteries, with just a short charging time they were able to work while the other one was charging. I have other EBL batteries and love them because they are long lasting and recharge pretty quickly