I can not find long lasting battery
 

I have bright light my problem is the battery. I have a 8.4V 4400mAh and a 6600mAh and they both only give me only 35-45 mins on low. I need a battery that will last 1 1/2 - 2 hours for my night rides. Do battery brands make a difference?

What light do you have? You probably need a better light. Most lights last 1.5-2 hours minimum even on high.

More modern lights are generally more efficient.

That must be some helluva light to pull a 6600mAh to dead in 45 minutes. Most all-in-one lights of 700-1000 lumens will run for 90 minutes on a dinky, sub-4000mah 3.7v cell.

It's probably cheaper to buy the next brighter light and run it on medium than to buy a bunch of batteries. Just saying.

Sounds to me like old batteries. Li-ions start to lose capacity from old age fast after about 3 years or 500 charge cycles. Both of those specs drop faster if the batteries are not high quality batteries to start.

j.

One battery a year old and other is 2 years old.

I have Sahara sailor 800 lumens and bright eyes 1200 but I don't use either of them on the high light.

Buy a battery case and choose the best batteries for it
 

You can buy an empty case that holds four 18650 Li-ion batteries and then fill it with NCR/Panasonic 3400 mAh batteries. This is the battery most recommended on a flashlight site that I often visit. The last time I bought them a pair was $11.50 postpaid on eBay but the price has gone up a bit since then. There are several US vendors and again the flashlight site often mentions an eBay seller called genuinecells. When I compared the Panasonic batteries to a couple of different Chinese cells fictitiously rated as high as 5800 mAh the Panasonic cells ran about 5 times as long in a two LED 1300 lumen bike headlight. https://cimg2.ibsrv.net/gimg/bikefor...c610a88a44.jpg
. https://cimg3.ibsrv.net/gimg/bikefor...e6ec23405a.jpg
Link to Genuinecells offering on eBay https://www.ebay.com/itm/2x-AUTHENTI...1vQR:rk:3:pf:0 The seller is in Florida so there is no way to know if he was affected by the storm. Alternate seller in NJ https://www.ebay.com/itm/2x-Panasoni....c100505.m3226 but I haven't ordered from there.

Just for reference, I have a cygolyte 850 Expillion and the single 18650 lasts many hours on low. So I wonder about your lights

There are a lot of cheap Li Ion batteries out there on Ebay and other websites that are close to worthless. I agree with those that recommend Panasonic. You should buy from a vendor that has very good reviews. There are counterfeit batteries out there too, so shop carefully.

Agree.

fwiw been having very good performance since 1/23/17 from this

Magicshine Bike Light Battery, MJ-6102 high Capacity 6 Cell Li-ion Rechargeable Battery for Bike. 7800mah Waterproof Battery for Mountain Bike Lights | Round Plug

Most of the bike lights and batteries on Amazon are junk. This guy, Jim IIRC, has been in the bike lights business for at least a decade. I have bought from him 5 or 6 times, different lights, batteries, chargers, etc. Never sold me any junk - in fact his Li batteries outlasted others I bought going back to ~2004 by years, highly recommended:

https://www.action-led-lights.com/

If you want to try individual 18650 cells in holders, here's a great source I have bought from several times over the past three years:

https://www.imrbatteries.com/

Be aware there has been a thriving business in counterfeit cells for several years, widely sold (even on Amazon). IMRbatteries in Houston sells genuine cells - I know as I've bought and tested them. 18650 cells used to be a lot of junk, Panasonic being the exception, but it was difficult to find genuine cells for less than $15 each. Thanks to all the kids now vaping (many vaporizers use 18650 cells), places like IMR exist and sell a wide selection of genuine cells at great prices.

If you go with the 18650s-in-holder solution, in addition to cells you'll need cell holder(s), proper cables and charger and perhaps some DIY work with solder, tape, shrink tubing, etc. If this is not for you, then look at Action LED lights, linked above. Their basic Magicshine light is not terribly expensive and the bundled batteries are much superior to those sold on Amazon. Jim knows his lights and batteries, and he hasn't stooped to selling junk in all these years. FYI, most bike light sellers go out of business in 2-3 years or less because all the junk they sold comes back as hordes of disappointed, complaining customers demanding refunds.

series adds up the voltage , parallel increases the battery amp hours ,
so series-parallel wired cells .. can be both..

http://adventure-ev.com/wp-content/u...rallel_v01.jpg

8.4 is 7 1.2 v cells in series..

I made up a 5 D cell series, battery pack to run my 6v head and tail lights
for an hour long commute in ..1990 ni cad, back then..






...

This is why brands matter -- because of their quality control. In many cases, they make them in the same factory but only put their names on the good one. The generics get the leftovers which can still be good...or not. Brands are also better at refunds and may guarantee the name brand product they're in as well.

If you are buying individual 18650 cells, you may need to figure out if you want protected or unprotected cells. I suspect that others on this forum could describe that much better than me so I won't try to explain it. So, if there are any experts out there, ... ...

I have also found that some of the grossly low capacity ones that I bought were much lighter in weight, in other words the factory intentionally made them without a lot of the important stuff inside of them while they labeled them as having a lot of capacity.

Interesting. I found it on ebay. $12,99 ain't bad. LINK

Sometimes the 2S2P packs have two dummy batteries.

Kai packs were one of the better deals on high capacity batteries last time I looked.
http://kaidomain.com/search&search=KBP-18650B

Lower the load demand (w) and the battery amp / hour capacity, can last longer.

Also a battery charger can be at fault. Sometimes they only charge partway and show charging complete. Only way to tell is test your batteries after charging and see what they are holding.

Do you have a link to where to buy the battery case pictured?