Fenix LD20 Turbo problem.

are you using fresh batteries? alkalines toward the end of their life don't handle the high drain turbo mode well on the LD20.

If you are using alkalines, the internal resistance is causing the voltage to sag under that much of a drain, thus causing the driver to drop out of regulation, and reduce output. This can be compounded by nearly depleted cells.

Also, human eyes perceive light in a logarithmic manner (not linear). That is to say that it takes ~4 times the output to appear twice as bright (assuming two light sources are identical other than output. Thus, the doubling in output from High to Turbo may not be very noticeable in daylight, or indoors.

When I first got my LD20, I used alkalines before I purchased a rechargeable Ni-MH system (definitely worth the expense, especially if you have multiple lights that require the same battery). I usually got 20 minutes of runtime (in turbo) with Duracells, about 50 minutes on high. The extra runtime afforded by Ni-MH and Lithium AA's is really worth the added expense.

To both John & Luke,

Thanks for both of your replies, you guys are really good at understand batteries and Flashlights. *Bow* I'll be getting a few Energizer Lithium batteries in a few days time.

I had the same problem, and it was embarassing because I was showing off my new flashlight to some mates. Just because I was using old batteries. Definately go for the NiMH's, if you spend a little on them at first then it's definately worth it in the long run.

John_Galt said:

The extra runtime afforded by Ni-MH and Lithium AA's is really worth the added expense.

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As I see lithium they're only for very special purposes (a light very rarely used in a car etc.) and backup purposes.

NiMH might be expensive at first. But has people forgotten the simple math?
Don't know the general prices in US etc. but where I live the price of an eneloop 4-pack is approx. the same as two packs of Duracell or other brand names. Then count in that the precharged pack of eneloops will power your high power flashlight for at least twice as long as a pack of Duracells.

Then a charger is needed. A decent charger for AA/AAA can be bought for like 2-3 packs of Eneloops _if_ buying the _right_ charger. In that price segment there's a lot of crap too and the difficult thing - especially for a novice - is to pick the right thing - or else rechargeables will be disregarded as crap even if it's just the crappy charger (which might already have trashed the NiMHs).