How to convert lux into lumens

[Custom24]

Hi
The Lidl lights I use are pretty good, even off road. They are rated 30lux. Most off road MTB lights are rated in lumens. I want to know if they are likely to be much better in terms of light than the Lidl ones.

This page http://www.ledrise.com/shop_content.php?coID=19 says you need an angle and distance for the conversion.

What distance and angle are manufacturers using when they quote their lights in lumens?

Thanks

 

[Custom24]

OK, tumbleweed...

I'll ask the question in a different way. Does anyone have experience of how the Lidl lights compare to something "better" in terms of light output?

 

[Scoosh]

Moved to Bikes, Accessories etc as this is where the Knowledge should be about lights ...

 

[Wobblers]

You can make a rough estimate of the lumen output. What batteries does the Lidl torch use, and how long do they last. What LED does it use (I suspect it'll probably be a Cree XR-E or XP-E)?

 

[Custom24]

It uses 4 AA batteries. I use 4 rechargeable Energizer batteries of the stay charged type, I think they are 2000 mAh. On full, I get about 3 hours from them but I am not sure.
Can't find any info about the led.

 

[Kies]

Emitter type is the key, then we can make an educated guesstimate

 

[Custom24]

On the bottom of the torch, the following is written. Google doesn't help, but maybe someone here will recognise the emitter / LED from some of it;

Inter Union Technohandel GmbH
Art. No. 97331
Model: XC-116/L-SWITCH
Batteries: 4x1,5V AALR6
1W IAN 73445 IP 44

And on the lens, K894 is written

 

[Wobblers]

From your runtimes, we can estimate that the current going into the LED is 0.6 to 0.9 A. Making a few hand waving assumptions, that would suggest you're getting about 150 lumens out the front for a XP-E driven at 0.6 A (a bit less if it's actually a XR-E LED, though those are quite old now and have been superseded) or about 250 lumens for a XP-G driven at 0.9 A.

 

[Custom24]

Thanks all. They were so cheap that I was wanting to be convinced that something more expensive would be better. They have a pretty poor beam pattern for off-roading, but apart from that, there is no particular reason to replace them - I use two together and they have also been completely reliable.