LD20 R4 turbo

Its my first post Originally I just wanted to buy a bike light for commuting and ended up lurking on here getting totally addicted and spending lots of $$ so thanks very much for that Anyway...

I have a new Fenix LD20 R4 that I mount on my helmet, and 2 questions...

1) I've seen vague references to Fenix recommending not using turbo mode for > 10 minutes perhaps only in older versions of this torch (L2D or LD20 Q4???). I assume this does not apply to LD20 R4 as it doesn't appear anywhere in its instructions?

2) Am I going to affect reliability or led life/brightness by using turbo continuously for 40 minutes a day? From what I've read on Cree's website, the XP-G R4 goes to >400 lumens, with turbo being 205 lumens on ld20 this seems to be a huge safety margin right? Or is it just about how good the ld20 is at getting heat away from the led?

Thanks in advance!

Hi, i've got a Fenix LD20 R4 and i often use it at max for many minutes (about half an hour) and it produces a moderate heat. I think it's safe to use LD20 at max for 40min. Outside temperature is an important factor to considerate. You must be more careful in summer due to highter temperature ( for example).

If that LD20 R4 sits on your helmet when you ride, there will be no problem with overheating at all because the airflow will be more than enough to cool the light, assuming the ambient temperature isn't something like 40C (it'd be crazy @40C at night) and you are riding the bike, not walking it. Obviously, the faster you go, the cooler the light will stay.

I use it in my helmet about 1 hour in the night without problems in Turbo mode. Don't worry, it's safe and the heat is cooled by the airflow. The only problem is the weight, but you will be accustomed.

Thanks for the advice guys. Nobody seems to have seen any advice from Fenix to say don't run it on turbo either.

Teobaldo, to be honest I don't really notice the extra weight of it on my helmet, its not that heavy - which is great.

I run mine that much all the time. No issues.

if you have a constant stream of air running past the light it should do ok:welcome:

i shouds read more im like the third person to say this

bbb74 said:

1) I've seen vague references to Fenix recommending not using turbo mode for > 10 minutes perhaps only in older versions of this torch (L2D or LD20 Q4???). I assume this does not apply to LD20 R4 as it doesn't appear anywhere in its instructions?

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Great choice for a first quality light!

Fenix used to put a sentence in their instructions as to the fact that they do not recommend using turbo mod for more than 15 minutes IN HOT ENVIRONMENT. That would mean something like 30 Celsius and no wind. I have never ever heard of anyone killing a flashlight because they used turbo for too long, so you're safe.

bbb74 said:

2) Am I going to affect reliability or led life/brightness by using turbo continuously for 40 minutes a day? From what I've read on Cree's website, the XP-G R4 goes to >400 lumens, with turbo being 205 lumens on ld20 this seems to be a huge safety margin right? Or is it just about how good the ld20 is at getting heat away from the led?

Thanks in advance!

Click to expand...

If you succeed in killing it, you will have spent a lot of money on batteries first. 40 minutes a day on turbo should not affect your light at all unless it's really hot outside. I still would ask myself if high mode is not sufficient for my use and therefore change the batteries less often.

The LD20's power (output) is limited by many factors, most of which is battery power. To get to 400 lumen you'll likely need more amps and/or volts than 2 AA batteries can offer. The size of the head also limits how much heat can be dissipated, therefore how much output your light should have, but I believe the LD20's head can still dissipate more heat than that.

Fenix tends to have fairly standard runtimes on turbo, so that was probably their first consideration for calculating what output should the LD20 have