Cree 8.4v Rechargeable Battery Pack For Bicycle Lights & Headlamps Li-ion PCB Protected Battery Spare Replacement (4 x 18650 batteries equivalent) - XM-L T6 - U2 - P7 - L2 LED - Universal Fit With Cree, Magic Shine, Gemini Bicycle Lights - 2 Year Manufacture Warranty (Choose 6400 or 8800 mAh)

First of all, the housing and the rubber strap mounts built in are brilliant and beautiful. So much better that the loose nylon pouch of the cheap battery that came with my light. Never could get it tight enough not to bounce around and always ended up scratching my glossy paint job on my bike too. This just goes on quick and sticks in place solidly.However, I spent the extra money to get the 8800 mAh rated pack only to find out that it rated near 2500mAh when I meter tested it and did multiple run time tests in cold wind environments to prevent overheating of the lights. I’ve found with multiple brands including expensive ones that 18650’s are at best a true 2600-2900 mAh each (whatever they false advertise on the labels), but are at 3.7v working voltage with a max voltage for a very short when freshly charged at 4.2v. To get the 8.4v out of 4 batteries you’d have 2 in parallel and 2 in series. So at best you’d have a runtime of 5-6mAh with only 2 cells in parallel. Ok fine. I’ll live with that. But to get only 2-2.5 mAh is pretty sad. I almost wanted to buy some legit batteries and send them to the guy to get him to install it and wire it into the case because it’s so good. Funny that they sell a light splitter cable to use the battery with two lights. Better be small lights to last very long. I got 40 mins running two lights on high on it totaling 2.2 A of draw from a freshly charged pack. Hmm. Math doesn’t add up much does it?But still better runtime I’d say than the really cheap batteries that come with some of the light bundles.

I commute by bike and it is often dark when I ride in the winter. I need a battery I can depend on. This one fits the bill, unlike the one that came with my Cree light (the light was an excellent buy, but the battery it came with was awful). When my light is in the flashing mode, I'm confident that the battery will stay charged for at least 2 1/2 hours. The waterproof case is excellent - even if one is not planning on riding in the rain, one can sometimes get caught unexpectedly; it is good not to have to worry about a wet battery.Update - The battery does degrade over time. The Care instructions indicate that it should only be charged to 80%, but when charging the battery, there is no way to tell when this point is reached. I have a fairly long ride in the dark and cannot take a chance on the battery not being charged sufficiently; I therefore charge it until it is fully charged, as indicated by the light on the charger turning green.

The execution of idea is great, with one major flaw. The battery they use is rather poor quality. With most Cree light, the battery run time at full power is less than an hour after 20-30 charge cycles.If the battery they use is better quality, this would have been a winner. They should use either Panasonic or Samsung cells even at the higher price. I'd buy this again if the battery quality is better.

So far so good. Two real mountain biking rides and the battery stayed put and powered the Cree light at low & medium intensities for 1.5 hours each time.I tested the battery when I got it and it is definitely better than the one I got with my knockoff Cree lamp. It powered it for 3.5 hours at low intensity so I'm comfortable on longer night rides.We ride in mountain lion territory so a dead light could be very bad!I have a cheap battery I use with my helmet lamp but when it dies I will replace with one of these.Another option is getting my hands on the Fenix 2 battery case & using high quality Panasonic batteries.

Arrived on time and as advertised. Purchased as a replacement for my original $20 light and batt pack. Higher capacity so it does take longer to charge. I've used it for 3-4 hours so far and haven't ran it down, so I'm happy with the battery life. Build quality is excellent. Probably overkill. The only problem I've had: The plug-in connector wasn't real secure when plugged into either light I have. I had to wrap a piece of tape around it or it would jiggle out over bumps. The fix was easy, I just trimmed some of the rubber off the top of the battery's connector, maybe an eight of an inch, and it works just fine now.

6 month update. Used dozen times. This morning it lasted just 30 minutes. The capacity is GONE and it decayed quickly. I have 2 other lights with different batteries that are OLDER but maintained the same way ( never left dead, never left on the charger for days, used 2-4 times a month) and they are FINE. This one that I paid extra for gave it up, way too soon.My original post is below.Great capacity to start with and that is a good sign. Nice strap and appears to have high quality of workmanship overall.

It is compatible with my 1st generation Magic Shine. I replaced my original Magic Shine battery (which was from GeoManGear since there was a Lithium Battery recall) after using it for 6 years. I used the original battery for a one-hour session twice a day (I recharged in between sessions) and for about 150 days per year. I hope this new battery lasts as long.The rubber straps work fine on my hardtail bike and have never got loose even with the bumpy LA roads.The power cable is much longer than my original battery (three or four times longer) and it helps make it easier to charge

This is a solid alternative to the cheap chinese batteries which usually go bad soon after using them.The owner has put a lot of thought into this battery pack and it shows. A stout casing combined with builtin straps help keep it secure and waterproof. The connection is your standard connection and works with my light even though mine has a screw top. As for the battery itself I've been getting great run times with a constant power draw. A much better deal than the Magicshine or name brand competitors. Highly recommended.