1 X Replacement 8.4V 6600mAh Rechargeable Battery Pack for Headlamp & Bicycle Light

I have been working on getting good lights on the front and back of my wife's bike since she was head on-ed a year ago by a woman who ran a stop sign "not seeing" my wife. I have therefore bought many T6 crees and batteries. The problem is she rides centuries taking about 7 hours... and she will not stop to have me fool around with the battery. NO need anymore! I bought two of these batteries and charged them for 24 hours. I plugged lights up to one battery each and timed the results. The T6 tail light with a red lens ran for more than 13 hours! By the clock, no bull. The headlight ran for more than 10 hours. Both lights were in strobe mode. I am charging them up again to confirm and will note results soon. I think finally I have found the answer to real battery duration. The lights remain very very bright and get constant comments from other riders on group tours. She carries these batteries in a smallish seat bag with holes for the wires.9/4/2013: update. I have found now that with a 12hr charge these will push a head light or tail light (cree style "1100 lumens" for about 15 hours. I would take that to mean that an hour charge would power a light for about 1.25hrs, but need to investigate. Also, do not know yet if the batteries have a memory. Overall these batteries are fantastic. Highly recommend.

I get a week of commutes out of this pack, morning and night. I have found in general that some of the cheap 18650 cells stop holding charges after a few hundred charge cycles. And capacity degrades. I can't say about these until I've had them for a year, but so far no problem.The one minor gripe I had with this pack is that the connector was so loose fitting with my light that it would randomly drop off. I crimped the round connector a little with a pair of pliers which helped some, but I wound up having to rig up a latch for it to hold the ends together.

I want to note that the product I received was different (and better) than the reviewer who showed a picture with two "unconnected" cells- see the picture below, I took mine apart and all six cells were connected, and mine had a different connector than the one shown in that reviewer's post- see mine below. The love is that this is a cheap rechargeable set that works with my ridiculously bright bike light. The hate is that I've had to buy several of these because (I assume) quality control isn't that great. They all worked perfectly out of the box and held a charge for a long time (6+ hours of use with several days of standby plugged in, when they are powering the LED button on the bike light). Within a few weeks/months the charges wore down. I still have several of these and use them, but now I unplug them when they are in standby, and I probably get 2 hours of use in between charges. If you're using this charger to power a product, I'd have to recommend getting some respectable rechargeable batteries instead of this power pack. I have a feeling this is a Chinese manufacturing issue; poor battery components and cheap charging regulators. With that said, still stand by four stars given that it's relatively inexpensive and still works, just have to charge it once a week or so. Again, while the other reviewer may have received a charger with two unconnected cells, I can attest that all six of mine were connected, see the photos below.

I purchased this light about a month ago and the only thing still working is the lamp itself: http://www.amazon.com/gp/product/B00AOEH4J2/ref=oh_details_o06_s00_i00?ie=UTF8&psc=1The original 4-cell battery that this one is replacing had a short in the connector that gradually got worse until it failed after just a few weeks of ownership. Pathetic.Turns out there's a considerable difference in the design of the the two battery connectors. The end on the 4-cell was so thin that I could pinch it closed with my fingers. The metal on this one is noticeably thicker. It looks as if it will hold its shape and endure many, many reconnections. No shorts in this one...yet. The stock charger also works just fine with this battery. No issues there. Battery life seems to be as rated or better. I didn't recharge the pack until after 4 hours of use (without depleting it).So far so good!

I use it for inside glowing light pointed to the ceiling at night for reading and using a high-end bike light bulb set on lower setting which is still quite bright and it stays on for about 4 hours!!

I ordered this battery for early morning mountain bike rides which I take weekly. The battery was on a charger between rides. The first ride was great, it lasted for my entire hour-long ride. The second ride was also fine. By the third week and third run it didn't last the entire ride and by the fourth ride it lasted about 20 minutes.Not good.

I fully charged the battery pack overnight, then ran the light, a CREE 1200, on the high setting. The result was 2 hours of constant light.That's about what I expected.. What I didn't expect was the run time I got on the lower light setting.I should mention that the light I used for the test had only 3 light settings: High - Medium - Strobe.On the medium setting, still a very bright light setting, I got 9 hours and 20 minutes! That's amazing!I tested it twice to make sure I hadn't made a mistake or that it was a fluke.I'll update this review in a few months and report on the longevity of this amazing run time.17 months later and it's finally starting to weaken. Now when I fully charge the battery pack, the charge only lasts a day or two of riding before the indicator light turns red. Still, that's not bad.All 6 of my cells were wired.