Li-ion PT APEX headlamp

I have been eyeing the PT APEX headlamp for for a long time now. ALthough I really like the fact that it runs on 4AA's I also think that it is a bit big for my ideally perfect all around beat headlamp for every task. I got mint today and within an hour I had this mod implemented.



I used a 7.2V 1200mAh Li-ion battery that was originaly made for a Qualcomm cell phone. It is quite a big smaller and feels much lighter than the 4AA pack. This battery has the same number of watt hours as 4 1800mAh AA cells. with the disadvantage of potentally plunging me in to pitch darkness when the low voltage protection circuit in the li-ion pack trips. Because this light uses a buck regulator it was a perfect choice for usung these packs which I have had for some time now. I was a bit concerned with the potentially high voltage of a freshly charged pack ~8.4V so I contacted PT and they said that it should be able to handle this voltage.



Here you can see the conectors I used. I still have the ability to use the factory 4AA pack if I decide to. I also have 2 Li-ion packs made and can still make a 3rd if I feel the need.



I made the carier for the Li-ion pack out of some velcro that I found in my wifes sowing stuff and I put this together. It works rather well but I think I will design a better one later when I have some better materials and have perfected my sewing skills

Who ever thought my flashlight hobby would leade me to sewing? :shrug:

From what I can see so far this is a great headlamp and I am going to be very happy with it. I live the 4X5mm CS leds they blow my mind and thee lux III on low is as bright as my EOS but has a larger hot spot than the EOS.

Cheers to Princeton Tech for making yet another incredable product at a decent price.

Very nice! :bow:

I wonder what the runtime would be with 2 18650 2600mAh Sanyo cells? Can you measure how much current it pulls in the different settings?

Sure I will do that tonight. I will hook it up to an adjustable power supply and see what the curent draw is at different voltages. Any sudgestions? I was thinking 4.8V, 6V, and 7.2V.

This is by far the best headlamp I have ever had.

Very nice mod !!!

:goodjob:

Will

Brlux said:

Sure I will do that tonight. I will hook it up to an adjustable power supply and see what the curent draw is at different voltages. Any sudgestions? I was thinking 4.8V, 6V, and 7.2V.

Click to expand...

Thank you, I will be interested in both 4.8V and 7.2V.

I ran some tests and this is what I got.

_____Lux HI__Lux LO__5mm HI__5mm LO
7.2V__535mA__151mA__207mA__47mA
6.0V__604mA__160mA__227mA__46mA
4.8V__738mA__181mA__265mA__44mA

Transition
Volatge 3.85V__3.29V___4.27V___3.34V

Transition
Current 765mA__260mA__310mA__48mA


The Transition was the point at which when decreasing voltage I noticed a very slight change in output and then gradual decreasing of brightnes with voltage. It is the point at which the regulating circuits Vin~Vf for the LED at the given drive curent. At this point the circuit is going from a Buck regulator to direct drive. I believe that the current at this point is very close to the actual drive curent of the LED's.

If you look at the drive curent for the 4X5mm leds on high you will see that they are being driven around 77mA each which is quite high. It is believed that they are using the new Nichia CS Led's which can take that kind of abuse (hopefully). But I am really suprised at the brightnes of the 4X5mm on low which are being driven at around 12 mA each. On low it blows away by other 3X5mm led headlamps like the PT Aurora on high with fresh batteries and my Petzl Zipka.

Anyone know how to import a table into a post?

BrLux excellent work with the Apex and many thanks for the readings plus the scoop on the buck regulator :thumbsup:

I have several protected 18650's that I need to put too use and make some new run time plots for the Apex and add them to this thread PT Apex RTP's

Later
Kelly

Nice mod. What kind of connectors are you using? I was thinking of a similar mod but using six Li-Ion 18650's (two sets of three in parallel) for extremely long runtime. I'd like to use connectors that are somewhat protected from the elements and can't seem to find any good ones.

They are Molex headers and conectors Digikey part numbers WM2700-ND, WM2011-ND, and the crimp spring terminals are WM2312-ND.
They are probably not the best choice for this aplication but I had them on hand and they were small and polarized. I contemplated using 2.5mm dc barel jacks which I had a lot of on hand as well. I have been pleased with the decision.

Brlux

I took the oportunity to measure the LED drive currents today when I was puting in a SS P4 and replacing the 5mm with some C0 color bin Nichia CS's.
This was a different APEX headlamp than was used in my previous posts.

The light being powered from 4 NiMH cells and the readings were taken with a Fluke 83III on the 10A scale.

Lux on HI = 890mA
Lux on Low = 260mA

5mm on HI = 300mA
5mm on Low = 50mA

I have found that the APEX runs on a single Li-Ion cell very nicely. It doesn't stay in full regulation long but the low voltage protection circuitry in the cell doesn't surprise you without warning like it does when running 2 cells.
I have been testing it out with an old worn out 18650 that only shows 1000mAh on my CBA. It started out as bright as the 2 cell configuration but 10 hours later it was putting out useful light. The single cell setup is very small and feels as light and comfortable as my APEX Pro. I may find myself using the single cell configuration a lot more often. I will defiantly carry a single cell as an emergency backup when I running the dual 18650 fully regulated setup.

This may be if interest to current or perspective PT APEX users. Princeton Tec has recently within the last few months made changes to the materials and manufacturing methods of the housing.There is no visible difference in the housing but the results are the housing is more crack resistant. This is a problem that they sure took a long time to address and but I think we are going to be happy with the results. I in the past have I been very disappointed to find new in the box APEX's with cracks already in the housings. I have about 2 months on some of my new fixed housings with no signs of cracking. An interesting observation witch may or may not be tied to the housing redesign is all my newest 4AA ones had the weight missing on the front of the packaging (it is still there on the newest Apex Pro). There is just the little box with a G and the image of a dumb bell in it but no numbers. Perhaps this packaging misprint can help indicate weather a to be purchased APEX is of the fixed variety?

I was also told by PT that the newer APEX's are going to be rated at 80 lumen's instead of 60. They must be getting more efficient Luxeon III's? Why they don't get with the program and put in something like a P4 I don't know?
I was told that the APEX's I recently received and subsequently resold on CPFM were of the 80 Lumen variety and they would send me 80 Lumen stickers to put on the box if I wanted. I declined their offer but should have asked if they could make up some 180 Lumen stickers for the now P4 moded ones

I thought I would post some beam shots of upgraded APEX headlamps for others to compare when contemplating upgrades.


This shot is of the Seoul Semiconductor P4 LED upgrade to an APEX. The Particular P4 used was a U flux bin and an SWO color bin. It also turns out that the Stock APEX in the above picture was one of the newer 80 Lumen rated ones.


This is one of my newest modds which replaced the APEX's original 5mm's with some of the Nichia GS 5mm led's. Nichia Part number NSPW500GS-K1
The GS's pictured are C0 color and W flux binned. The changing of the 5mm is substantially more difficult than the Luxeon LED. It requires complete removal of the circuit board and preferably a good solder sucker. Several of the vias have heavy traces and large thermal mass components near them which makes it more difficult to properly perform the work. I used a very nice Metcal rework station with the vacuum desoldering tip to do my upgrade.