Are USB-rechargable lights any use ?

Because it is.

OP their is another light thread where I listed a link to a light with a runtime of Many hours

I have a few USB rechargeable lights and they are OK - the low battery indicator works OK. I'm not an expert on lights but I've never heard of that brand - so expensive or not I'd stick with brand names (Cateye, Garmin, Lezyne etc...) . If you want a small "be seen" front light then the Bontrager ION RT 200 automatically switches to a lower power output when the battery reaches a certain %.

That behaviour has never happened on any rechargeable lights I have ever owned. You either have a faulty light or a crap manufacturer - or quite possibly both.

The nature of modern rechargeable batteries be it drills, impact drivers etc is you have full power until you have no power. These bike lights are most likely the same.

The lights I have at the moment deplete progressively, going from a visual blue indicator (> 75%) to a yellow (25-75%) and finally a red (< 25%). When showing a red light the flash modes are significantly reduced from 7 to a single operational (eco) mode. When red I have about 1 hour in eco mode before the light will give up.

I only use burst mode in urban riding so the light is never on continuously. In the flash mode I prefer - which is a quasi-strobe mode - I get about 6 hours use before hitting red. That's 3 days commuting 45k / 2 hours per day. Re-charging is 2 hours on main adaptor or 3 hours from usb power source so you're never really stuck.

I have two sets of them so even if I forget to charge I always have a fresh set handy. If I let both run down - well then that's on me.

They are really small and light and use durable rubber clamps so they are on & off the bike in seconds and fit all bars and seat posts - no brackets or mounts.

Similar to MojoMaker, my lights have several battery indicator lights (green, yellow, red, red flashing) and on red flashing only a solid but very dim light is on which lasts about an hour I believe so I'm never stuck.

I charge it after 2 days as I won't get a full 3rd day so I'm never really caught without it. Can't say I've had any quality issues from a series of CatEye AA/AAA lights or my current front and rear Lezyne rechargable lights.

I'm old school on this, prefer the traditional battery operated lights. Yes it's a pain in the arse having to replace batteries every so often, but it's equally if not more of one having to plug in the yoke into your PC or wall socket every few days (if you're a daily cyclist, less often if only occasional one).

I use a rechargeable USB pair from decathlon that cost about 30€ and find them good. An indicator turn red when they are running low, like have 2 have charge left. They seem to last about 20 hours in flashing mode. Delighted with them.

If people are unwilling to recharge their lights regularly, they are hardly going to feel any different about ensuring that the power bank is adequately charged.

See sense front light for daytime

Two Aldi Cree (?) front lights for night

One Cat eye rear light

All are usb charge and given a full charge after each use to avoid the dreaded dead battery. The key for me is to know how long each will last before heading out on any spin.

Sorry but no you didn't. €30 isnt a high end light.

One is not like the other.

220Mah @ 4.2v = 0.924Wh

1000Mah @ 1.5v = 1.5Wh

So yes in theory the AAs have more capacity but any light using 220Mah LiPo cell is going for size/weight not endurance.

Decent lithium based lights are grand. You should get one that goes amber at <40% and flashes at <20%. Then you have plenty of warning. Honestly you just bought a dud. Its likely the thresholding in the chip was never set/set wrong so it's detecting say 4.1v as near empty making the indicator useless.

Any I have had switch to dim or go auto flash when low. They all had some form of charge indicator too.

I do miss the battery powered ones but good ones are very hard to find now

A detachable USB-rechargeable LED front light came with my ebike (and a built-in rear light). The battery lasted quite a while on the front light as mounted under the front carrier, the vibration made it switch off after every bump! Moved it to the handlebars and it's been fine - green LED for when it has sufficient charge, switches to red LED when it's low on power, output isn't effected. Sounds like the one you have is defective. I picked up a spare front light from the Dublin Cycling Campaign one evening there where they were giving them out, so I've backup in case I do run out of juice.

Slightly bemused by this post, if USB lights were of no use then they would not be a market for them.

I've used USB lights for commuting and for overnight rides. A few tips I'd give are:

(a) Get a powerful light and run it at 20%-50%. For example, I have a Halfords 1000 lumen light, but I never run it at max. At a lower setting, I'll get 8-10 hours (night-time country riding), or 24+ hours of flashing (commuting)

(b) Find one with that tells you what time you have left in the current mode instead of some type of colour indicator. The last thing you want to do on a night ride is to try to remember if flashing red means 1 hour or 10 minutes.

(c) Dont pay too much attention to stated run-times. Cold weather can reduce run-times.

(d) Regardless of whether you use USB or battery lights, have a small backup light. I use one good light, but also have a second light that will last 1-2 hours (e.g. Aldi light). If first light fails, then I just switch to the backup to get me home. If commuting, I'll use this light once a week and recharge it along with the main light.

I have the 1000 lumen version of the light below. I run it at a lower setting (200 lumens?) on overnight rides on the flat and uphill, switching to a more powerful mode on descents. Whatever mode I pick, it tells me roughly whats left in the battery in hours - no trying to remember what a flashing red icon means and if I can get home on it.

https://www.halfords.ie/cycling/bike-accessories/bike-lights/halfords-advanced-1600-lumen-front-bike-light-253334.html

I could live with a USB headlight, and might yet have to, as decent-ish focused AA headlights seem to becoming rarer all the time.

I've found that very good for last 2 or 3 years, use regularly on fairly challenging country lanes, and have used for 3-4hr spins in the dark.

€51 without charger and batteries, but worth it for the charge and batteries; you can just leave them in the light.

Hard to find much under that price bracket

I've got knog , lezyne, cateye and some other less well known rechargeable lights and they all go from 100% to 0% which is not ideal. However they are all much more powerful than most lights I've used which run on disposable batteries. Also the disposable battery lights can still be 'working' for years without changing the battery but the light output can be very poor as the battery runs low.

The low battery indicator on the rechargeable lights is generally ok and I might get a few trips before charging, but if I'm using them daily I just get in to the habit of recharging daily. Also ideally I use a second set as back up. There is huge variation in battery life depending on power setting though.

The rechargeable lights are usally smaller and lighter and easier to throw in the pocket.

Edit: dynamo light for the win

Actually the rechargeable Exposure Maxx shown in the attached image and bought in 2009 is still going strong and fades gracefully. There are 3 different brightness levels and it switches to lower levels once the battery goes low.

Back in the day this was the Rolls Royce of lights. Expensive and heavy compared to what you get thesedays. The tech and price has come on a mile since. Bought it for night time mountain biking, did a thing back then called the Ballyhoura Spook with it.

I've a lezyne microdrive, bought as a recommendation from a work colleague. I think its 1000 lumens but as above I don't run it at full power. its a great light, has given no bother in 1.5 years. It was around 60 or 70 euro at the time but I think it has paid off.

I have some ebay lights I bought for mountain biking which need to be revived with new battery packs. The lights themselves were of good build quality to be fair.

This thread has been interesting as it has confirmed my suspicions of cateye being basically overpriced.

Sure, and if it works for you that's what matters. just relating my experience which is that cateye generally cost a lot more than 20 euro back when there were fewer brands on the market. They've probably had to up their game.