Opinions on this bike light driver please

I’d be grateful for any comments on the innards of this $20 eBay bike lamp:

It runs on a battery pack containing two 18650s, presumably in parallel, but has a USB connector and is brighter at 5 V. Is that what you’d expect from the components visible in the driver?

It claims 1000 lm with the supplied battery pack, and I believe that. But output drops after a few minutes. Is there a mod that would maintain the output for longer? It’s a chunky aluminium case but the star doesn’t seem to be attached securely (no glue or thermal compound). The driver faces the opposite way and I think the leads pass through a kind of bulkhead between the driver and the star, if you see what I mean. I wondered if some thermal compound would help.

I couldn’t photograph the emitter very well. It looks to be absolutely plain, with no little dots or grid pattern. I’d be surprised if it were a real Cree but it’s bright enough and the reflector is nice.

Thanks for any ideas.

Is that true while the bike is in motion? I think a lot of this type rely on air speed for cooling.

A sensible design decision, but in this case the output soon drops even at 20-25 km/h and winter temperatures. When the bike is moving the housing stays cool, whereas in still air on turbo it’s at least 40°C. Which I suppose reinforces the case for improving heat transfer from the emitter to the housing.

would be nice to have a link

i have used several of the 4x18650 cheap bike lights
i think a 2 cell solution would not have enough energy for the riding i would do

a 4 cell only runs about an hour on turbo 1000 lumen +

it is pretty easy to find a decent 4 cell for under $30

just do not expect any of them to have a decent light color - at best they are cool white, at worst, purplish-blue nightmares


Thanks wle.

It’s the Te-Rich 1200 Lumens CREE XM-L2 (as a Brit the name makes me think of a popular kind of biscuit).

I wouldn’t recommend it. It works OK and the narrow beam suits me, but it gets poor reviews for water resistance and having taken it apart I can see why. The charging system is a bit eccentric, too: a double-ended USB-A male cable with an embedded voltage regulator, so not easy to replace. Would be easy to mod, but I guess you could say that about many bike lights.

If there are any particular lights you can recommend, please do. I don’t need more than 1000 lm – this is mainly for dark country roads and a disused railway line that’s straight and level, not technical mountain biking. I’d also like a beam shape that won’t blind oncoming traffic, but I’m guessing that’s unlikely to be available in a cheap light.

I’m a newbie, but won’t 4 x 18650 deliver 1000 lm for 4 hours or so? At say 2.5 A (cool white) and 2500 mAh per cell?

Also because I’m a newbie I’m not very sensitive to light colour. Perhaps when I get around to seeing a high-CRI light in action I’ll understand what the fuss is about. That said, I’ve managed to avoid blue tints so far and I should think that would be nasty.

something like this is a classic:


i have had 2 or 3 of them - when the cells fail i just get a whole new one, light and cells and all

can;t vouch for this exact one - they tend to look similar

i would not worry about blinding cars, they aren;t that bright or beamy, really

this is another design i have been seeing for years
3 leds


they also usually mis state the mah, ignoring the fact that the cells are in series-parallel and run at 8.4v

as far as 4 hours on high, i would doubt that


Thanks! That first one looks to have several advantages over mine, notably the waterproof plug. Mine has a shrouded USB connector but still people report that water gets in – or perhaps it’s via the switch, which has nothing really to keep the rain out.

I thought long and hard about this, and have ordered a Magicshine Allty 1000. Enough light for me, I think, in a tough and simple package, easily pocketable, and a Garmin-style mount. At three or four times the price, I know. But thank you for helping me focus on what I needed. It’s appreciated.

the cheap 4 cell battery packs are never water proof, no matter what they say

you can just stick it in a plastic bag

the magicshine should be waterproof - it costs 5x as much(i see now you also said that)

the cheap ones will also usually have PWM which bothers some people
if you are going to be picky you can;t have that for $23


I’ve been really impressed with a couple of the low-cost lights mentioned here on BLF: I have a Lumintop Tool AA with a 14500 battery and a Sofirn D25 headlamp, both of which are excellent for the money. A Convoy S2+ will join them if that ever makes it out of China. But I guess bike lights are quite demanding in terms of form factor, UI and especially mounting systems, even ignoring the electrical and optical side.

That first lamp you mentioned seems to have a big O-ring for mounting, and since it’s compact and probably quite lightweight I expect that works well. The one I have mounts via a tripod thread, which isn’t a bad idea, but the part that goes on the handlebars isn’t up to much. And to go from low to high you have to pass through “off”, which isn’t ideal at speed on a dark road.

I did think about using the Convoy on the bike, but good mounts for round-bodied lights seem to be in short supply. Perhaps there’s a market opportunity there.