3.7 Volt Rechargeable Battery 18650 3.7V Battery 2 Pack 9900mAh High Capacity Batteries for Flashlight (Flat Top Type)

I bought this to replace the i o 6 Oral B battery. Out of the 4 batteries, 1 was dead.

Es muy buena

long and strong light in my head lamp

After receiving the 4 pack of batteries, I replaced two cells in my solar lights and measured their voltage to determine their charge state and put them out in the bright daylight sun to be further charged. The terminal voltage indicated they were at least at 80-85 percent charged before further charging them in the sun for almost a day.A 2500 mAh cell that’s 80 percent charged would be what… 2000 mAh.. but, even if it had only 1000 mAh worth of charge, my run time would be doubled over a charged 500 mAh cell.The next morning they were not lit as I was hoping for. They replaced 500 mAh batteries and the lamps only needed a couple more hours of run time, so a charged 750 mAh cell would probably have worked if it really had that capacity when charged.So, long story short, these cells don’t have any where near their stated capacity, just can’t be.Also of note, I weighed each battery and found that two cells weighed much less than the other two of the 4 pack. So now I’m in the process of charging them up to see if their capacity may be different/better.

Got a 4 pack and 2 Flashlights. Difference in brightness is noticable for sure. Light enough to carry extras if needed in my backpack. Not sure I got the best charger, but does the job.

I replaced a solar string battery that died with one of these. The battery was a 2000mAh and would run my lights all night in the summer. New battery is rated at 9900mAh and in theory should run 4x as long. I would take this to mean roughly 4 full nights on one charge. Got one full night, cloudy day charge, ran partial night. Not even two full nights. Best guess without an analyzer, maybe 2500mAh.I bought an analyzer charger and as you can see 964mAh

Item description says 25￵00m￵A￵h. Actual is about 1/10th of that, measured with a high-quality rechargeable battery analyzer (IQ-338XL Universal LCD Smart Charger/Analyzer). Both the capacity discharge, and the capacity charge are measured. Both at 500 mA. I test all of my rechargeable batteries as soon as I receive them. Worst rechargeable battery purchase I've ever made. Pathetic. Totally pathetic. A waste of my valuable time.

One was dead on arrival. The other died after first use. Look elsewhere.