Fenix P2d/lwith Li-Ion, only turbo mode?

Hi everyone!

After reading here for a couple of months I'd like to introduce myself:

I started with some MagLites 25 years ago, and recently updated them with Terralux dropins. They became really nice. However, that didn't stop me. I just had to buy a Fenix, but couldn't decide between the P2D Q5 and the L1T v2.0, so I bought them both ...

Using Li-Ion rechargables, most posts I've seen here states that they only has one state, turbo, but I do get two stages, turbo and high (or more exactly about 60% of turbo mode). In turbo mode both gets quite warm, but if I drop down to high, there is no problem to run them for a long time without any heat problem.

Is there anyone else seeing two modes on rechargable (3.7V nominal) Li-Ion batteries?

I'm not really sure. This may be the first thread on this topic that specifically applies to the Q5's, as the previous ones seem to have been for Rebels and earlier Cree XR-E's. So far, I have not tried my own P2D on "normal" 3.7v batteries (well, really 4.2v). (actually, I don't have a full P2D; instead I have a P2D body and an L1T/L2T RB80 head, but I have tried my L2D RB100 head with the P2D body, and no Q5)

The P2D uses a boost circuit to increase voltage to what the LED needs to operate. "3.7v" Li-ion rechargebles come off of the charger at 4.2v and have too much voltage for the lower modes to work properly. As the battery is drained, at some point the voltage will drop low enough for the lower modes to function.

I have, however, used a pair of J.S. Burly's early protected Li-ions from about two years ago. These come off the charger at around 3.9v (this was, I believe, an unsuccessful attempt to make actual "3v" Li-ions; we now have some Li-ions that are in the low 3v range). Using these batteries, I can get all modes of operation with both the Rebel 100 (Digital series head) and my Rebel 80 (LxT series head). Unfortunately, runtime is VERY short at only 12 minutes in turbo mode.

One possibility is that your batteries are not getting a full charge. Another is that your batteries are charging all right, but the LED in your particular light can still work partially well even with the extra voltage.

I do think that my batteries (both AW 14500 protected cells, and AW RCR123a, protected) comes of my UltraFire WF-139 fully loaded. When I measure with an old analog instrument my reading is about 4.1 volts. I am going to get a digital instrumet soon, in order to get a more exact reading.

Both heads (P2DQ5 and L1T V2.0 RB80) has those two stages, the higher with the head tightened, and the lower (about 60% of the high mode) while the head is loosened. With the P2D in General Mode, all three, low, med and high are the same strength until the battery is almost depleted, but tightening the head will create the stronger light.

My protected AW 14500 cells was a bit too long in the L1T V2.0 body, so I had to modify the tailcap somewhat in order to get two stages with it. I took the thin washer from inside the rear clickie that came with the L1T, bent it somewhat to a slight conical shape, in order to get to act as a spring, and dropped it into the forward clickie tailcap. This allowed the L1T V2.0 RB80 to get both modes with those longer 14500 cells. To avoid loosing the washer while changing battery, I just remove the head instead of the tailcap.

I am aware that I run both heads with higher voltage than what Fenix recommends, and that they might become less efficient over time. Hopefully, this won't happen too soon. If it does, I'll get a reason to order an upcoming Fenix model to replace them ...

I just tested both heads with newly recharged batteries, and a new DMM bought today.

AW 14500 came off my WF-139 with 4.16 Volts. Fenix L1T V2.0 RB80 on high draws 960mA, and on low 430mA.

AW RCR123a has 4.13 Volts from the charger. P2D CE Q5 in Turbo mode draws 760mA, and on low/med/high 360 mA.

Percieved lumens are - to my surprise - about equal from the lights (P2D Q5 versus L1T V2.0 RB80). Hotspots seems equally bright, but P2D possibly has more spill light, and this might expain the 180 lumens versus the 140 lumens (for the L2T V2.0 RB80, driven from 2AA) Fenix state as output.