Much the same story as the 1600.
It starts off at an impressive 1187 lumens. After 10 minutes it’s down to 630 lumens. With a cooling air flow over it, it won’t drop so drastically in use.
At £40, I don’t think anyone would be unhappy with it.

Why would it drop so dramatically and so quickly? I have the 1600 and can’t say I’ve noticed the output drop off – although I’m obviously using it in the evening in the winter and tend to cycle between full power and one down to make the battery last longer (not that I’ve ever got close to running out). The light output is also a good colour and flood.

Ive mentioned it before and don’t want to carp on, but why do some of them cut out repeatedly?
I really liked them until this issue made them unusable and I know others have had similar problems.

My 1600 has stopped working. Totally dead. It hasn’t even been outside yet.

My 500 cut out a few times on a cold ride, first it’s happened. I warned it up for a minute with my hands and it kept working for another hour or so the cut out again. Warning it up just briefly seems to help a lot.

Ive mentioned it before and don’t want to carp on, but why do some of them cut out repeatedly?

I can only assume Quality Control hence the low price. It does seem to be a bit of a lottery but if they are happy to replace it then you will get a good one, it doesn’t seem to be particularly prolific a problem.

Anyone opened one up? Mine felt more like a loose connection than cold – I’d be surprised if they had a low temp cutoff. Perhaps something contracts internally below a certain temp.

Mine did seem to coincide with rough roads but it’s hard to be sure as the road was rough a lot.

Lithium batteries don’t like the cold, although I would have thought the heat off the light would have kept the batteries at a reasonable temperature.

That’s what I was thinking too. The climb on which it happened was a series of frost hollows in a narrow valley so possibly the coldest point – but it was fine over the top and fast down the other side. But it was only around freezing, hardly extreme cold. And the battery voltage indicator was on full the whole time.

With mine it was about minus 4 and they were both turning off every 60seconds. The only way I got home was to turn one on, wait 30s and turn the other on, then when one went the other was working while I turned it on again. And they stayed in synch all the way home. You could turn them straight back on, no dimming and showing full power. Both seemed fine next day at home.

Last night was a similar cold ride, around 0C, and the light didn’t turn off once. Weird.