L91 with Fenix LD20 issue

[Quiksilver]

Hey, first post.

I'm currently using a Fenix LD20, and using NiMH rechargeables for every day use.

When I go out into the bush I bring along a spare set of L91s just incase. When I've used these though, I lose the Low and Medium brightness levels. Meaning I cycle through the UI and get High-High-High.

I've heard that I get longer runtimes out of L91s, that's why I carry them. I'm interested in having the Low level brightness for many outdoor night tasks, and am concerned that since the L91s seem to run my LD20 on High only, that I'm actually losing runtime as a result.

Can anyone confirm this, or know of a way to utilize the Low-Medium output with L91s?

Thanks


(ps tried a search came up empty)

 

[John_Galt]

Re: L91 issue

It's a common issue with the lower-voltage Fenix lights. My LD20 does the same thing.

It's because the driver is only a boost driver, not a boost/buck driver (allowing for higher input voltage than the LED forward voltage). So the light does go into direct-drive for a while with fresh Li AA's. I've found using the light on Turbo for about 15 minutes is enough to drop the voltage to allow the return of the lower modes.

 

[parnass]

Re: L91 issue

It's a common issue with the lower-voltage Fenix lights. My LD20 does the same thing.

Luckily, the 2AAA Fenix LD05 still provides 3 distinct brightness levels when powered with Energizer Lithium AAA primary batteries.