HW 9V Li-ion Rechargeable Battery, 9 Volt/1000mAh(9000mWh) Long Lasting Rechargeable Batteries with Micro-USB, 1000 Cycles Charge, 1.5 Hrs Fast Charging, LED Indicator, 2 Packs

A year ago I purchased a small practice amp for my guitar that runs on either a single 9V battery or on a 9V power supply. Because this amp rapidly used up the energy of a new Maxell 9V battery I bought for it, I purchased a four-pack of Amazon alkaline batteries so that I would have a fresh battery to replace the existing battery when it became drained. This was only a short-term solution because I knew I would use up the power of all four batteries in the space of one week.I decided to find a power supply to run the amp without batteries. While I have several power supplies that produced 9 V, none of them worked because the connection on the amp is the reverse of the plugs that go into the amplifier. I got back on Amazon and look for a power supply with the connections reversed and found that electronic keyboards use power supplies like the one I need. I ordered that power supply and it worked great. However, if I wanted to play my guitar on the beach, at tailgating parties or anywhere else where 110 V outlets are unavailable, I would need longer lasting 9 V batteries.I wondered if I should be using rechargeable 9 V batteries instead of single use batteries that would be costly to keep replacing both to my wallet and to the environment. While looking for a traditional battery charger, I came across this self-contained battery/charger for the price that was slightly more than what I paid to buy the four alkaline batteries. I was still skeptical that this would work, but to my surprise it charged up quickly and lasted as long as the standard batteries did (which is to say not very long). Of course the difference now is that I no longer have to send useless batteries to the landfill.The battery comes with a short connecting cable where you take its large, male USB-A plug and insert it into your smartphone charger's large female USB-A port. The small, male USB-A plug on the other end of the cable is inserted into the small, female USB-A port located on the bottom of the battery. Note that cables with USB-C connectors - the ones that have no top side or bottom side - will not work with this battery). When the charger is inserted into a standard 110v wall outlet, a small light on top of the battery will glow red when it's charging and turn blue when it's fully charged.I can't tell you how long this battery stays charged because I always connect the charger after I am done using the battery and since it is lithium-ion, there is no need to worry about memory effects of charging a partially filled battery. I highly recommend this battery.

I use this rechargeable battery for my tens unit. It's already paid for itself more than a few times. I also like the fact that I don't have to be without my tens when the battery dies because this charges very quickly. Great price for a great product.

These batteries are fantastic. They charge fast and hold charge for a very long time. I tried to use them in my acoustic guitars that have the "LR Baggs Element" pickup system. I was getting a lot of hum and saturation and finally figured out it was the batteries. Once I went back to a regular 9v the guitars worked great.These are fantastic in multiple other applications, so not a knock on the product or quality. Just beware in sonic applications.

Fits battery compartments on guitars abd equipment. Other brands I tried were slightly too big in at least 1 dimension and were getting stuck in my things.These batteries don’t stick inside battery compartments. They are the ‘correct size’ for guitar battery boxes and other musical equipment.Charge fast and have long life. Very durable. All of mine are still in use after several recharges.Highly recommended for acoustic guitars. I have noticed zero noise. Most importantly, they fit without sticking. Same size as energizers.

Great rechargeable battery for a toy that eats batteries. I'm no longer throwing away a dead alkaline battery every few months, I just remove this and it charges back up in a few hours via the built-in USB port on the side, and put it back in. It's nice they included a cable. I have several battery chargers, but none of them charge 9-volt batteries so having the built in port on the side is what sold me on this battery. It holds a charge for a long time. I am pleased with this.

Bought this for an old digital clock radio I use. The disposable batteries don't last very long on it, so I decided to give this a try. Now I can just charge it whenever it rans out and put it back on the alarm clock. It will save me money buying disposable batteries, especially when they don't last too long. And charging the battery itself doesn't take long either. Very convenient and effective. Highly recommend!

It charged up fine, read the correct voltage when done. Does take a while to charge, but that's no problem for me. What was a problem is that it is slightly larger than a regular 9V battery. 9V batteries were mainly built to power transistors in items containing electronics. As such, many of these items use pretty tight spacing to slide a 9V battery into. What I bought this for, it didn't fit. Slight too wide, slightly too long. That's just slightly too bad for me :-( but I'll find something I can use it in I suppose. Cheers

Initially I chose the two pack so that I could have one charging while the other is in the smoke detector. I mean, how many things use 9Volt right? Well I was thankful for the second when my husband got sick and come to find out, our forehead thermometer uses 9Volt. Was great to have a second one available. So far the performance has been great! Cant wait to just have to recharge rather than throw away!