Fenix P1 uses 1.7 watts.....

I just received my P1 yesterday, out of curiosity I mesured the current draw and voltage at the battery (3.7 volt protected li-ion) under load while driving the P1 lamp module.

Current: .59 amps
Voltage: 2.81 Volts

2.81 X .59 = 1.659 Watts

So the 3 watt Luxeon is hardly being pushed.

just tested mine on the 10amp range.

tested with an AW 750ma protected battery.

it pulls 780ma, but I had to use crocodile clips, as I was only getting 610ma with the test probes, make sure your getting a good connection.

PS. 2.8volt is pretty low, the cutoff on a protected rc123 is 2.5volt, try again with a fully charger battery, should be around 4.0volts.

regards.

betalight said:

I just received my P1 yesterday, out of curiosity I mesured the current draw and voltage at the battery (3.7 volt protected li-ion) under load while driving the P1 lamp module.

Current: .59 amps
Voltage: 2.81 Volts

2.81 X .59 = 1.659 Watts

So the 3 watt Luxeon is hardly being pushed.

Click to expand...

Only 2,81V is too low. Either you have a bad battery, or it's not fully charged.

I mesured:
0,77A, 3,87V with a fully charged protected r123, oc-voltage: 4,18V

Nothing unusual about that. It's quite typical of most manufactuers - low, medium and high end. They usually spec. how many lumens are being produced. Just because they state they are using a LuxIII device, it doesn't imply they are driving it at any given rate. Besides, what would you rather have - a Lux III driven at 3 watts delivering 55 lumens or a Lux III driven at 1 watt, delivering the same 55 lumens? I'll take efficiency every time.

By the way, don't forget to factor in converter efficiency (for your example):

90% = 1.49 watts
80% = 1.33 watts
70% = 1.16 watts

Being a mass produced, low cost device, the P1's converter could be even less. I've owned three P1's - foolishly gave the first one away - more foolishly destroyed the second attempting to mod it - and I'm not messing with third one. Beautiful tint and superb brightness. Not sure if it is my imagination, but the quality of these devices seems to only get better.

@EvilLithiumMan:
It is an Battery issue. With only 2,81V the relativ low current ist perfect normal.

2.81 volts!?!? OMG.

anyway, you do know how a transformer works right? to get a certain value for both V and A.

the driver will draw MORE current to "make" into voltage to drive the led.

After 15-30min of use, mine draws 2.8v as well on primaries, still in regulation. Maybe part of some normalisation effect/process?
Also maybe it's different cases for disposable lithium and rechargeables.

Make sure u guys are taking the reading from the same points when comparing readings. It's normal for the voltage to lower when measure across battery when used, which is y the regulator pulls more current to compensate (v=ir), if not the battery would last forever.
If u are taking the readings across the emmitter contacts then it should show the regulated and true values of current n voltage driving the lux.

betalight said:

I just received my P1 yesterday, out of curiosity I mesured the current draw and voltage at the battery (3.7 volt protected li-ion) under load while driving the P1 lamp module.

Current: .59 amps
Voltage: 2.81 Volts

2.81 X .59 = 1.659 Watts

So the 3 watt Luxeon is hardly being pushed.

Click to expand...

Thats just the thing, it's not a "3 watt luxeon" it's a Luxeon III. Driven at spec the typical T flux Luxeon III is around 2.4 watts.

Mine draws .93 amp and is incredibly bright.

EvilLithiumMan said:

I've owned three P1's - foolishly gave the first one away - more foolishly destroyed the second attempting to mod it - and I'm not messing with third one.

Click to expand...

LIAR! What an incredible, bold-faced, snake-tongued liar I am! Said I wasn't going to mess with my remaining and fuctioning P1. But curiosity got the best of me. I opened it up and lifted the positive lead of the T bin Lux III. I took volatge and current measurments of both the CR123 and the emitter:

Input power = 2.6V x .87A = 2.26 watts

Output power = 3.30V (Vf) x .390A (If) = 1.29 watts

Converter efficiency = 1.29W/2.26W = 57%

The converter topology is as simple as it gets - 1 ea. IC, capacitor, diode, inductor and resistor. Considering that I have seen converters of this type with 35% efficiency, this one is pretty good. And I've seen many Lux III devices throw out plenty of light at the one watt level. You have to admire the P1. It is a great performer for the cost involved.

57%.
A resistored light can be, and often is, more efficient.
Converters used in the SF KLx, Arc, HDS, and others, goes up to 90% by using sync rectifiers and digital drivers.

The price is the point. The more you use a low efficiency light, the more you are at loss...

Regards

Anthony

I have measured the following values against my Fenix P1 (DMM Fluke 179):

AW's LiFePO4 cell 500 mAh
Open-circuit voltage 3.318 V
Under load 3.201 V, 0.568 A. Thus 1.818 W.

AW's Li Ion protected cell 750 mAh
Open-circuit voltage 4,276 V (fully charged)
Under load 4.101 V, 0.826 A. Thus 3.387 W, but out of regulation from the converter IC.

Caution: These are the values, which were measured in terms of the cell and are not identical with the performance of the LED. The performance at the LED is reduced around the power loss of the converter IC.

I think that are good values for a flashlight of this size.
Anyway I am satisfied with the performance.

Try it again with a CR123. You'll draw way more than that, betalight