HW 9 Volt Batteries 4 Pack, 1400mAh Rechargeable Lithium Battery 9V with USB C Fast Charging Cable, 1600+ Cycles Square Baterias for Smoke Detectors, Fire Alarms, Remote Controls, Clocks and More

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 love these rechargeable 9v batteries. They work great and hold their charge well and don't take a long time to recharge. A super money-saving deal.

Don't waste you money buying normal batteries, these batteries are rechargeable and an excellent value for your money, the 1400mAh charge Capacity is more than enough to power your devices and when the power run's out, just recharge them, excellent product.

These batteries have good capacity & super convenient charging, but beware they introduce a ton of noise when used in sensitive audio equipment. They're so light you may think they're fake but they really do work. They last about as oong as alkalines have for me. Conventional 9v battery meters won't read correctly. My device reads full charge all the way up until it dies. I bought this pair for my guitar pedal, LR Baggs Venue DI. At first I couldn't tell what was causing the new noise because it's a unique sound. I believe there's some sort of BMS or switching controller in the batteries operating at very high frequencies causing the noise through my amp and PA's to sound like soft whistling, almost like air. They may work fine for other types of devices. Understand this is a newish technology & does not completely phase out regular batteries. Just like with tube amps.

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.

Works as expected

This is very convenient for an electric guitar with active pickups. Just don't lose it...which i did lol. And now im going to buy it again.

Excellent product and great shipping time. Product was delivered in excellent condition.