Rechargeable AAAA Batteries for Surface Pen, Rechargeable AAAA Battery for Active Stylus, Ni-MH 1.2V 400mAh with Storage Box, 2 Count

Have worked as intended.

The charge is holding up well. Only question now is on the longevity of the battery.

If you have a computer stylus or other device that uses a AAAA cell or cells as its battery, the ANVOW low self-discharge NiMH AAAA cell can spare you the risk of alkaline leakage while letting you use rechargeable rather than throwaway power. If you've ever seen what happens to an aluminum flashlight when alkaline cells leak in it, and if your stylus or other device has an aluminum body, then you already know an important reason to consider other battery types.Key hint: These are true LSD (low self-discharge) cells, so buy twice the number of cells your device uses, and have the charged-and-ready spare(s) at hand for immediate use whenever you drain the in-use cell(s). You'll never have to go looking for a battery for your device again.There are, however, a couple hurdles to deal with: charger (un)availability and false low battery indications.AAAA cells have been much less common than than their larger AAA and AA counterparts, so chargers able to contact such a small cell and with low enough current for such a small cell's necessarily lower capacity can be a bit difficult to find. Finding a nonbanked charger (one that charges individual cells, not pairs nor larger groups), important for proper care of your cells, can also be a bit difficult. The two options I've found are buying a customized very slow charger such as this one for "overnight" use (be sure to remove the cell(s) yourself) or using a ~2 mm thick metal object to allow a controlled and low-current AAA charger to handle the smaller cell. I've used a '3/16"' ("small" size) female quick-connect as a spacer to allow charging of AAAA's in both a Powerex Maha MH-C9000 analyzer and a Panasonic BQ-CC17 charger.Low battery misindication is a standard inconvenience for using any NiMH in nearly anything that expects alkaline cells. I have electronic clocks that display "low battery" for most of a NiMH's discharge, so I've learned to ignore the false indication and swap cells when _function_ begins to suffer (e.g.: an LCD clock's display starts to fade out). So it is here, too. For instance, a ThinkPad Pen Pro I tried indicated low battery (via its companion ThinkPad Pen Low Battery Notifier software) above 1.2 V (about the nominal for NiMH) on a cell which then proved to have nearly 70% of its capacity remaining. So, the same workaround applies: don't replace|recharge the NiMH battery until impaired function indicates need. Whenever using alkaline, however, get the darn thing _out_ of any expensive or hard-to-replace equipment, _especially_ aluminum-bodied equipment, at the first indication of "low", to prevent leakage.I've done some performance testing on my Anvow AAAA cells and, like another Amazon reviewer, got results indicating lower capacity (about 350 mA*h) than the 400 mA*h claimed. One should note, however, that capacity claims are usually based on 10-hour discharge and the analyzer I used can only go as low as 100 mA, not the 40 mA that would yield a 10-hour discharge for these cells. Thus, the small difference between claimed and (mis)measured capacity doesn't concern me.My testing has verified the low self-discharge (LSD) characteristic of these cells. At 4 weeks from charge I've seen almost 15% self discharge, while at 10 weeks I observed about 17% self discharge. Thus, the cells exhibit some initial self discharge and then "settle" to a much lower self discharge rate that can preserve usability for quite a while.

I really like this product

Great

Works

I bought these for a Surface Pen and they last only a few months per charge. I use this pen constantly and don't always have another with me.

So far so good. I've only been using them for about a week but they are holding up. The price of them was great and I hope they stand up to the test of time.