- SHENMZ 4-Pack 9V Rechargeable Battery, 1300mAh 9 Volt Lithium-ion Long Lasting Power, USB-C Recharge with 2 in 1 Charging Cable for Smoke Alarms,Multimeters,Microphones,Walkie-Talkie,Toys

I needed a 9V battery for some guitars with active pickups and some guitar pedals. Buying batteries in bulk and never knowing when they will die is annoying and stressful for me. I can't tell you how annoyed I can get when I forget and leave a cable plugged in to a guitar all night and the next day I've got a dead battery.These things are a lifesaver. They don't charge super fast... but having a built in USB-C (nice!) charging port means I can pretty much get one juiced up wherever I am in a pinch. No more wasting batteries! Heck, I even bought some for friends and made them a believer.I would (and will) buy these again. I can't attest to their longevity in more demanding 9V situations, but for Guitar Pickups and Pedals, these things Rock!

THESE BATTERIES ARE A GAME CHANGER FOR MUSICIANS... LOVE LOVE

Was disappointed that it wasn't a true 9 Volt battery. They are OK, To make things right, this seller refunded me. So thanks.

They don’t hold a charge very well… they ended up in my junk draw, last resort option… not exactly the finest specimen of the technology… put them on a charge, light turns green. Oooo weeee! Let them sit for a while, deader than a hammer. Somewhere somebody is just a laughin’ because of the printed specs they claim

In my opinion, lithium-ion batteries that recharge via USB cables are a true game changer.These SHENMZ 9-volt batteries are the third type of USB rechargeable batteries that I’ve gotten recently, the others being AAs and AAAs. They all performed extraordinarily well where I’ve tried them, such as, for example, in smoke alarms, a garage door opener and as backup power for a clock radio and an irrigation timer.The USB charging cable included with these batteries is eight inches long and has a standard USB plug on one end to connect to a charger (not supplied, but any that you have lying around will work, or just plug the cable into a computer’s USB port or a power bank) and two USB-C plugs on the other end to interface with the batteries. A tiny but eye-searingly bright LED near the USB port on each battery glows red when it's charging--check out the pic; it lights up the whole end of the battery!--and turns green when it's fully charged. When unplugged, there’s no indication of the state-of-charge.These batteries are exactly the same size as non-rechargeables. They fit perfectly into every device in which I tested them. If you’re a techno-weenie, you should read some of the other reviews that describe the up-conversion circuit in each battery that’s used to bring the lithium-ion chemistry up to slightly over nine volts. This circuit drains a tiny bit of power, which may affect the charge longevity, and also can create electronic noise that render the batteries unsuitable for some applications, such as audio devices.But for everyday use in typical household gadgets, they’re perfect. I haven’t used them enough to know how long they’ll last compared to non-rechargeables, but right out of the box I give them a most enthusiastic five-star rating.

These 9V batteries charge much faster than some 9V rechargeable batteries I've used before. Something I also like very much about these batteries is the way they indicate a full charge; the bottom of the battery lights up brightly when fully charged. If the battery is low, there is a small (red) light on the bottom that illuminates once the charging cable is plugged in. These batteries also remain cool to the touch during the entire charging process.As for performance, I have so far been able to obtain about 5 to 6 hours of continuous use of the battery in an effect pedal device (phase shifter). A perfect choice for performing musicians who don't want to further complicate their pedal board setup, or have any more wires or cables than necessary.Specifically, some effect pedals require a continuous 7 to 9v supply to operate correctly. Other pedals can drop a little lower than 5v before noticing a degradation in output. After about 2 hours, my test battery was still holding at 8.9v Once fully charged, I read the initial overall charge voltage to reach 9.14vdc.Note: if you unplug these batteries after a full charge cycle and then plug them immediately back into the charger, it will take a few minutes for them to indicate a full charge once again.I haven't compared these batteries to similar products available, but I do know that if I am able to get at least 2 or 3 uses from these batteries, they will have paid for themselves in comparison to the price you'd pay for name brand, non-rechargeable, alkaline batteries.

Chirp, chirp, chirp! Seem like every few months one of the smoke detectors installed around my home would need a battery change. Guess them being triggered multiple times a week (My wife thinks smoke adds needed flavor to everything she cooks) reduces battery life considerably. At times it is hard to find a replacement 9v battery lying around that was fully charged.Thanks to these SHENMZ rechargeable 9V batteries I’m able to bring a dead battery back to life by using the included USB-C cord (Able to recharge two 9V batteries at the same time) in about 6 hours. Batteries have a built-in port for charging so you won’t need spend extra money on a standalone one. LED lights clearly indicate power status.So far been able to use them in several smoke detector brands, a pocket size transistor radio, and toy HESS truck I keep displayed on my knickknack stand. Everything powers on with no problem at all. Seems to hold a charge for quite a while (Been using them for about 3 weeks now without needing to recharge.)I’m never going back to using regular 9Volt batteries again. Excellent rechargeable battery that has delivered well past my expectations.

But I was confused about the whole USB-C cable thing.