I just bought a pair of Orbtronics 3500maH 18650 batteries, charged them up, and put them in my light. These things made my light look like a lighthouse. I'm afraid to use them on the road as they'll blind anything oncoming now. They can provide current that the weaker batteries usually supplied just can't. I haven't tried them yet for longevity, but my guess is they'll last longer too. I'll report back when I do, but taking a ride for over an hour in the dark isn't usually something I do, but maybe over a few rides. Now that I have gps tracking too I can see how long one lasted before I needed to swap to the other.

What light are you using? Most decent lights these days are highly regulated to put out a nearly constant amount of light until the battery is almost completely discharged. A battery with higher capacity should make the light last longer per charge but not affect the brightness.

I usually run my light on dim, but will bump it up to medium on some bike paths, or high on some fast descents.

Mine has a rubber band mount, and I'll often still focus it down when a car comes, unless the car blasts me with their high beams.

This ^

My lights are both getting old, but both are still extremely bright. One is a Lezyne and the other is a cheap Chinese light. My guess is the Lezyne is old enough to not be regulated, and the Chinese light definitely isn't.

When these batteries are fully charged, the voltage is somewhat higher, and the current available is definitely higher. I still wonder how long they'll last.

The Orbtronic 18650 batteries are made by Panasonic. From the Orbtronic company website description - 3500mAh Protected 18650 Battery Li-ion 3.7V Rechargeable Orbtronic 10A Dual Protection (Panasonic-Sanyo inside),For High Performance Flashlights, Case Included.

There are quite a few people who post here who recommend the Panasonic batteries. I recently bought a new light that has two CREE XPE LEDs and runs on a pair of 18650 batteries. I wanted to see how long it would run on the Panasonic batteries so I bought a pair of 3400 mAh batteries. I had been using any cheap Li-ion battery since they seemed to work OK in LED flashlights and camper's headlamps. There was a startling difference between the batteries. The light was run in flashing mode that I will use as a daytime headlight. The results:
Panasonic 3400 mAh cost $11.48 a pair 13 hours 20 minutes continuous flashing
Trustfire "4000 mAh" rated cost about $2.50 a pair 3 hours 20 minutes
Trustfire "5800 mAh" rated cost about $2.50 a pair 2 hours 4 minutes
All were freshly charged before use. I weighed the batteries because I noticed the bike light was heavier with the Panasonic cells. The TF 5800 weighed 27.4 grams, the TF 4000 35.7 grams and Panasonic 45.7 grams. Just shows how much the Chinese battery capacities are overrated. They obviously contain less battery material than the Panasonic batteries. I will still use them for some things but for a longer run time, the Panasonic cells win out hands down. There was no noticeable difference in the lumen output with the cheap cells, just a much shorter run time. I confirmed that with some DIY bike lights that I also use.

I've never seen anyone who has weighed batteries! Interesting. Any single 18650 battery that claims to be above 3500 mAh, is lying and is junk. Any single emitter LED flashlight that claims more than 900 lumens is also lying. And in reality, that is probably 900 lumens from a bare emitter. In reality, after losses through the lens you probably get more like 750 lumens. I like to purchase batteries online from Mountain Electronics.

budgetlightforum.com is a great resource for flashlights, batteries, chargers, and DIY modding.

These batteries can provide more current than the older type batteries, and sometimes your lights are current limited by the battery. It won't make them last longer though if you use more current to get more light. Let's say your light can draw 3 amps at 3.7v, but your battery can only provide 2 amps, then the light will be limited to what it can get. At 2 amps with a 2600maH battery you'll get just over an hour of use. With a battery that can supply 3 amps, at 3500maH, you'll get about the same runtime but a much brighter light.

You can buy cells that were developed for use in a Tesla, or you can buy cells that were developed for use in a cheap laptop. Which do you think will be better? I'd go with Elon Musk, even though I think he's a huckster. Whether they are better for the light you own you'll have to find out for yourself.

I have both the Orbtronics and Panasonic, and they perform similarly in my lights, because Orbtronics us a relabeled Panasonic, as vegastriker explained above.

But the 3400mah are different from the 3500mah, whether made by Panasonic or Sanyo, relabeled or not. It may seem like a trivial difference in capacity, but the 3500 can deliver higher current. For our use in bike lights the difference may not matter. For use in cars or airplanes it is a very big difference. That said, I perceive a brighter light with the 3500 Orbtronics, but I'm not comparing it to a 3400 Panasonic, but to the cheap Ultrafire batteries that came with the light. I'm assuming they'll last longer just based on the mah rating unless they draw more current to get a brighter light as I pointed out above.

The batteries of the same voltage will put out power for a longer time with more milli amps, not more voltage. They will just last longer before being recharged.
Radio control uses lipo batteries for their power in a lot of their motors. A 1 cell lipo puts out 3.7 volts. A 2 cell puts out 7.2. As you go to higher cell count, add 3.y volts for each cell. The milli amp designation is how much power the battery can hold. So, if your lights are brighter, then the voltage is higher, not the amount of power the batteries can supply in milli amps.
Your lights may last for a while with the increased voltage, but I would be cautious on applying more voltage than designated. This would be like running a 6 volt bulb on 12 volts. won't last too long.

I highly recommend getting something with a good cutoff. Running an IQ-X off my hub generator now, the light output is simply astounding. If I put my Planet Bike "2 watt" LED headlight on high, and point it towards the road, I can't even tell it's on because it gets lost in the B&M beam. Even if I point the Planet Bike light level (so it's blinding to oncoming traffic since it has no cutoff unlike the B&M), you STILL cannot see the Planet Bike light because there's not enough above level to reflect off of.

A light with a good cutoff isn't blinding AND provides far more illumination.

Actually, I have the B&M Cyo Premium, which is the standard I use to measure my battery lights. I find that the beam of the battery lights mostly gets lost in the field of the B&M light, but mostly because the battery light beam is so unfocused. You don't really notice it until you get somewhere that is truly dark, all of the NYC streets are so well lit that it is hard to tell sometimes.

There are several good battery powered cut-off beam lights available:

• Outbound Lighting Focal Series ---- Discussion ----- Mtbr.com
• TRELOCK_Katalog-2018.pdf#page=6
• AXENDO 60 USB - Spanninga
• supernova-lights.com/en/products/battery-lights/airstream/
• bumm.de/en/products/akku-scheinwerfer.html
• lupine.de/products/bike-lights/road-bike-lights
• specialized.com/us/en/flux-expert-headlight/105390

... move the light lower, closer to the road surface, then what ever light you have, will seem brighter..

and blind every incoming driver/biker.
https://swhs.home.xs4all.nl/fiets/te...-bundel-hoogte
https://swhs.home.xs4all.nl/fiets/te...html#lamp_hoek

yea,yea, I've done that too... When I use my battery lights now I always put them on low and point them down. I've gone over the Manhattan Bridge on the bike lane and the oncoming bikes can be blinding. When I see that, and I have my super flasher light on, I'll turn on the flash so they get the message. That's why I like my Cyo light, it doesn't blind people, and it puts the light where it's needed. And when I come up behind people on the bridge, they always get a little nervous about that huge road beam that they otherwise don't see. It is all on the road in front of me. I feel like I'm the only person in NYC with a STZVO type light, except for maybe Noglider. (We met a few years ago and compared lights.)

An 18650 - I think it was a 'Startfire' brand - that came with some Chinese electronics was labeled 4000 mAh. Measuring runtime against a Panasonic 3400 mAh I reckon the Startfire is in actuality no more than ~700 mAh!

I'm personally big on bike lights that use replaceable, interchangeable generic 18650s rather than proprietary batteries or 18650s molded into proprietary holders. One can use commonly available top quality, highest capacity batteries in the light and purchase a second backup battery for a dime on the dollar of proprietary batteries.

That's a great collection of links. Most of them are very expensive though probably worth the prices. The Axendo is NOT expensive and looks good, too.

The Axendo is the Philips Saferide according to a post on CPF: Philips LED bike light - Page 6 The price is very low. If only the shipping from EU were less than the price of the lamp. The US distributor only sells to bike shops :-/ There seems to be a "reputable" seller in germany on ebay, but only has the non-usb version.

Well, actually shipping 1kg from germany to USA is 10€ insured&tracked (500g = 6€).
eBay Deutschland Versandvorbereitung

The Axendo 60 USB without box weights 220g. So it is possible to ship 3 lamps for 10€ safe over the sea.
Maybe some european member would do that

Fenix, PDW and Raveman also offer battery headlamp models with vertical cutoff, ya' know, depending on what you want out of life.

It's a soft cutoff, so more marketing than a real competition to a correct adjusted cutoff light.
Also the LEDs are direkt visible, increasing the visible brigness and blinding effect.

Topic is like a good webcam with low noise, sharp images and high resolution. If you use one, others have the advantage.
In case of lighting it's more a safety issue than comfort/quality.
Incoming riders with bright glaring lights gives to safety problems:
You can't exactly tell speed, position and left space on the lane towards the rider and the outer side of the way.

By the way, did you compare the pseudo-cutoff with an real cutoff light already?