12V 5.2Ah DC5521 Connector

This was the perfect thing to turn my wife’s spectra S1 breast pump into basically a portable unit. Apparently this battery is so strong it lasts twice as long and doesn’t lose its power compared to the much more expensive portable version( the S2)

Nice battery. As others have said, no relevant instructions on charger, but research elsewhere suggested, and experience now confirms, that it's basically plug into power outlet, connect battery and wait until led on charger changes from red to green to show full charge. Battery life and longevity as yet unconfirmed.

I wondered if it would work for the M12 jacket and it does. Works great! Will update with longevity if i remember.

I have 2 of these in 2 different sizes and while they work and do charge to 12.6v they seem like they must be made from extremely old or reject cells possibly because they do not hold a charge even when not used very well. So you have to charge each time you want to use and the runtime is lackluster. These are not rated at what is claimed although I did not do a thorough test. Sadly I am going to attempt to start making my own battery packs with quality batteries because there are so many scam pack out there. Stay tuned perhaps soon I will be making custom quality packs for your devices that are as good as they can be!!!

I ordered this battery, got it quickly. Charged it up using the supplied trickle charger and noticed the input and output terminals presented the same voltage. Found their customer support email in the instructions booklet and asked if I could use either terminal to source my 2 Amp power. They answered Yes after just a few hours. Because other reviewers said NO!, I asked the seller for more details and again quickly got the confirmation I wanted. These batteries repeatedly pump out an initial 2 amps from either set of terminals for at least 2-3 hours. Powers my 12V electric gloves great, light and compact, super easy to use. I bought another battery for extended backup ‘cause the first one works so well. Hope to get good reliability too.

Using it for a motorcycle to bicycle headlight conversion and fits my application perfectly.

The battery is fully charged. Actually came that way but I put it on the included charger anyway. I am trying to use it to power a small radio (a HAM radio transceiver). The radio will not power on. I checked the battery voltage with a meter and it is good. If I put the battery on the charger then the radio will power on and I can then disconnect the charger and the radio stays on. I tried other radios with the same result. A little AI research seems to suggest that the batteries BMS might be faulty and "tripping out" on initial in rush current. I don't know except I can't use it for my purpose and will return.

So far it works great. Only thing I don't like is the cheap charger. The battery should be charged at 12.6V 1Amp but the charger is giving it 13V at 400mA. It charges all the way to 13v. It does at least use constant current constant voltage. Nice little battery pack though. Love the barrel jack connectors, perfect for what I was doing.