Fenix PD35 (2014) Circuitry & Unprotected 18650 Use

Hi All,

I have recently purchased my PD35 (2014) which I love, and currently use Nitecore NL189 18650 protected cells.

I want to buy more cells and understand the caution that comes with using non protected cells as I have read many useful guides off this site.

My question to you all is; does the PD35 have circuitry that prevents the cell from dropping below this limit through normal use, or would I have to keep self checking the cell with a voltage meter? I want to understand how difficult it will be to ensure safe use of non protected cells, and compare this to just paying for more expensive protected cells.

Many thanks in advance.

Hi there, i have never run my pd35's down enough to find out but will tell you as the cell drains then it will not sustain turbo or high, this in itself is letting you know the voltage is getting low. I am sure it does blink when its down to eco mode after the cell is low and will not hold higher outputs.

Unless you trip your protected cells every time you use your pd35 by running the cell down to 2.7v-3v(or what ever the PCB trips) you should have nothing to worry about at all.

Treat the cell the same, knowing the light and rough run time you get, maybe you use for 1hr at a time, maybe 10mins a night. After an hours use, top the cell back up, after a week or so again top cell back up. Thats how i work, i get used to the light at top back off for the next use. I would hate to have used it for say 40 min, then need it for a long duration and have to keep it on a low mode so i dont get left in the dark..........

Get some nice 3500mah cells 10a rated, good value, higher mah............happy days.

Imo unless a total noob(no offence to anyone by that word) or dont want to think about voltages(not the right fuel type if the case), there really is no need for protected cells in single cell lights. Again imo and most of mine are now "naked"(no pcb) unless i am using up spares or reducing rattle in certain lights.

MM's are always a good idea,not a must, but of use to check every so often all is well on the lithium front. Of course they come in handy for many other applications too, so its a purchase(if done right) for life! Can pay for itself in the 1st use! fault finding etc etc........i digress. Other options are chargers that have V readouts, vp1/vp2/vp4/vc2/vc4/bt c3100...........i could go on Very handy to learn your lights V when placing in the charger ......................In fact i will go as far as saying i could now not live without that feature on my chargers.............

One ......ok 2 bonuses of naked cells, fit easier and less stress on the internal spring contacts, also no added potential failure or drain to the cell........

I always lock out with an 1/8th turn of the tail cap, not to stop parasitic drain as n/a with this light being a clicky, but to prevent accidental activation.

:welcome:

I run my PD35 on unprotected cells. I tested the light output at various voltages and it becomes obvious that you need to recharge the light somewhere under 3.0v but well above the critical level of 2.5v.
http://www.candlepowerforums.com/vb/showthread.php?401120-Fenix-PD35-and-unprotected-18650-s

I seem to remember that several tenths of a volt above 2.5v is where you can't get any of the higher outputs..........only the lowest level. The only issue with using non-protected batteries is if you start out on low mode and leave it unattended without the need to run a higher level, which is where you'd be clued in that your battery voltage is getting down there.........when you can't get the higher level.

Many thanks Ven and hiuintahs. I own the nitecore D4 digicharger so am easily able to check the voltages during charging. Perhaps my problem will come from using the lower modes. I often go walking at night and use the low (50Lumens) or medium setting (180 lumens) for several hours at a time. Intermittently I use the higher settings to search for landscape features and so far I have always been able to access these settings.

Do you know what voltage the cell reaches in order to cause the PD35 to start flashing?

Off the top of my head 3v which is low and into the lower last 10% iirc. At 50lm you will know roughly what runtime to expect . After a few hours use when out and about, note the V when placed in the D4, soon get an idea . Take from there, once low as an example 3.3v , you try for a turbo blast and it will not allow it and drop to a lower mode (might blink with voltage sag , not tested that tbh). That in itself is a warning to top the cells back up and ready for the next use . It's always worth carrying a spare cell(heck a spare light really). Granted it's not always convenient , but then again hours away in the dark is more inconvenient! Without going off the 27hrs quoted by manufacturer at around 50lm, let's play extra safe here and say 10hrs use. Unless higher modes are used for really long durations , it's unlikely you will get caught out with a fresh charge done before your outing . As with everything prep is key and a back up cell/light IMHO is a must either way.

Next couple of outings , check V after to get an idea of your actual uses.

Cheers

mountain_man said:

Many thanks Ven and hiuintahs. I own the nitecore D4 digicharger so am easily able to check the voltages during charging. Perhaps my problem will come from using the lower modes. I often go walking at night and use the low (50Lumens) or medium setting (180 lumens) for several hours at a time. Intermittently I use the higher settings to search for landscape features and so far I have always been able to access these settings.

Do you know what voltage the cell reaches in order to cause the PD35 to start flashing?

Click to expand...

My PD35Tac will not hold Turbo below 3.3 volt. I use protected cells as that is one less worry for me. I use the D2 charger. Not sure if the light has protection circuitry.

I own 3 PD35 (2013 version) and recently the new TAC version. Main use for the lights are night strolling to the park and camping. I have a few nitecore 3400mAh and the unprotected Panasonic 18650. When I use the light as a lantern during camping I noticed that when the batteries are done the light will remain at the lowest setting. Then it's time to change the battery. So far all the batteries are still working. I have both the China and US version.