Problems with LD20's regulation.

[KevinPJ]

First of all, I'm new here so hello :wave: and I hope that I posted this in the right forum.

A few weeks ago I bought a Fenix LD20 R4 (the 205 lumen version) and it was all awesome. I tested all the modes and they all worked.

Then, about 10 days later, the turbo mode stopped working. When the flashlight is on and I tighten the bezel to go into turbo/strobe modes the flashlight now gives a flash of I guess 205lumen then goes down to what appears to be it's high setting.

Then, after using the flashlight for maybe 10 minutes the high mode doesn't work. When I try to go into high mode it will just flash and go to medium mode. At this point I tried going into the turbo mode thinking it might flash and go to high mode but it instead went all the way down to medium.:shakehead

I thought maybe the batteries (Alkaline duracell procells) where bad so I checked the voltage but they seemed OK at 1.2 volts (each).

I have not used this flashlight in temperatures under 20ºC and never had it turned on more than 15 minutes.

I then put some fresh batteries in and everything worked until the batteries discharged to 1.4volts (each). Then the turbo mode was unavailable.

I've cleaned the contacts with alcohol on a swab like Fenix says you should on their tutorials.

Is there anyway I can fix this? I live in a pretty remote place and sending it to fenix or amazon is going to cost me quite a bit.

Thanks.

 

[jonnyfgroove]

:welcome:

I believe it's due to the use of alkaline batteries. Alkalines do not do well in high output led lights. Do you have any NiMh rechargeables to try?

 

[carrot]

:welcome:

I believe it's due to the use of alkaline batteries. Alkalines do not do well in high output led lights. Do you have any NiMh rechargeables to try?

This seems like the most likely answer.

 

[John_Galt]

It's your batteries.

Change them. Stop using alkalines. They suck (search why, tons of threads). Use either Ni-MH rechargeables, or Energizer Lithiums for best performance.

 

[KevinPJ]

Do you have any NiMh rechargeables to try?

I'll be buying some tomorrow to test it.

But shouldn't the regulation kick in at 2.4volts and make it 3volts or is it because of the mAh of the battery?

I'm quite a noob

 

[jonnyfgroove]

If you have the time, poke around the battery forum for a while before you make a purchase (batteries or charger). :thumbsup:

 

[Jash]

A batteries voltage will sag under load, so the 1.2 volts will be a lot less than that and as such you won't get your required output.

Nimh sag lots less than alkaline and therefore can keep up the voltage for longer. Lithiums more so.

Alkalines are like unfit people, they will move for a long time at a slower rate no problem, but don't ask them to run. Nimh are like keen amature athletes, they can run for a good while but need to stop and recharge. Lithiums get to go to the Olympics as their performance is second to none, but once they're done, they're done. Nothing more.

 

[carrot]

A batteries voltage will sag under load, so the 1.2 volts will be a lot less than that and as such you won't get your required output.

Nimh sag lots less than alkaline and therefore can keep up the voltage for longer. Lithiums more so.

Alkalines are like unfit people, they will move for a long time at a slower rate no problem, but don't ask them to run. Nimh are like keen amature athletes, they can run for a good while but need to stop and recharge. Lithiums get to go to the Olympics as their performance is second to none, but once they're done, they're done. Nothing more.

Clever analogy. Where does NiZn and CZn fit in?

 

[tandem]

Hey KevinPJ, no shame in being a noob or asking questions -- and welcome to CPF!

Your issue is almost certainly battery related, so the good news is you can take your time and get properly set up with good rechargeable cells. If you want to see the difference in performance between alkaline and rechargeable cells (Sanyo Eneloops in this case), you could do no better than to read the excellent review on the LD20 in this thread. Here's a runtime chart on alkalines, and the same on NiMH rechargeables you can buy in most cities. Quite a difference!

Your light is capable of great output and runtime on max, when fed with the right cells. It is also one of the best on the market for running on alkaline cells -- but as you've discovered, alkaline cells can't keep up with good NiMH rechargeable cells in a foot race. 15 to 30 minutes into the run and they are wheezing like asthmatic turtles, while the NiMH jack rabbits are still hopping along merrily. (Jash, your running analogy is fantastic, well done!)

Definitely spend some time reading the battery sub-forum here before you spend any money. You can buy the right cells once and actually not spend all that much. Over the long run your operational costs should be quite low. My runtime outlay is in the pennies per recharge, all costs in (well, all but lights!).

What part of the world do you live in? Many of us track good deals and sales and such on high quality cells and known good rechargers. Stick around and ask more questions!