MillerMods 3-level Fenix L0P Review

(See post #29 for the measurements on my "fixed" L0P.)

The light: it is smaller than I expected. Even though I knew it is a bit bigger than the Arc AAA, the size still surprised me a bit. I've been carrying it in my left front jeans pocket all day, along with my Arc AAA and I don't really notice it. So I don't forsee any problem once I carry only the L0P

The fit and finish: the machining and anodizing look very good to me. The sharp edge of the notch for the split ring is the only minor problem. The knurling is a bit too smooth but some may prefer it that way. Hopefully the anodizing will hold up to being carried in my pocket with my coins. My Arc has survived 1.5 years in that pocket with only a bit of wear on the knurling on the head. The body has been protected by some clear heatshrink tubing, which I intend to do to the L0P also to protect my teeth when I mouth it.

One hand operation: the light is easy to operate one handed. Almost too easy. I pulled it out of my pocket a couple of times today to find it on (on low). It may be I didn't turn it off far enough or the head may have turned while I fished around for it in my pocket. [Feb 16 update: I have been giving it an extra 1/2 turn in the off direction before putting it into my pocket and haven't had it come on while fishing it out. So problem solved.] Turning it to medium takes more force and to high even more. So I don't think it would ever accidentally get turned on to medium or high. There is a fair bit of rotation between low and the o-ring being visible (1 3/4 turns) so you can turn it off a lot if necessary. If it still comes on accidentally I may try the teflon tape trick that was mentioned in a different thread.

Now for some numbers:

o-ring visible to low: 1 3/4 turns
low to medium: a bit more than a 1/2 turn
medium to high: a bit less than a 1/2 turn

This is very good spacing in my opinion and the spacing is about the same when going from high to medium to low. So I can access the level I want from either direction.

Brightness: I don't have a lux meter, but I do have a photographic flash and ambient meter that can measure brightness in EV (exposure value) units. It has a resolution of 0.1 EV and since 1 EV is a doubling of brightness, 0.1 EV is about 7% increase in brightness. So I measured my (3rd gen) Arc AAA-P against the L0P with a freshly charged Sanyo 900 mAh cell (1.40 volts open circuit). I held the light right against the white dome of the light meter so this is an approximate measure of the lumens the light emits (not the hotspot brightness).

Light -------- EV ---- Brightness # --- Relative brightness
------------------------------------------------------------
Arc AAA-P --- 13.5 ------ 11585 -------------- 1.62x
L0P low ----- 12.8 ------- 7132 -------------- 1.00x (ref)
L0P medium -- 14.2 ------ 18820 -------------- 2.64x
L0P high ---- 16.1 ------ 70240 -------------- 9.85x

With a slightly used no-name alkaline (1.45 volts open circuit):

Light -------- EV ---- Brightness # --- Relative brightness
--------------------------------------------------------------------
Arc AAA-P --- 13.5 ------ 11585 -------------- 1.74x
L0P low ----- 12.7 ------- 6654 -------------- 1.00x (ref)
L0P medium -- 14.1 ------ 17560 -------------- 2.64x
L0P high ---- 15.8 ------ 57052 -------------- 8.57x

I asked Eric for a 30 mA, 90mA and 270 mA (to the LED) current steps and he delivered. With the Sanyo NiMh cell medium is only 10% low from the factor of 3 I requested and high is only 10% high from the factor of 9 I requested (relative to low). The alkaline is very similar but high is not as high due to the cell voltage loading down. Visually they look pretty evenly spaced.

I am very thrilled with this light and would recommend it to anyone who wants a small 3-level AAA-powered Luxeon light.

Greg

Here is the run-time on high. The results are a little puzzling so I did a second run with more readings near the end. So I'm only going to type in the second run. Both runs are using the Sanyo 900mAh cells I charged yesterday, unused since (1.379V and 1.378V open circuit).

Time ----- EV ----- Brightness # ----- Relative Brightness
--------------------------------------------------------
Start ---- 16.0 ----- 65536 ------------ 1.00 (reference)
5 min. --- 16.0 ----- 65536 ------------ 1.00
10 min. -- 16.0 ----- 65536 ------------ 1.00
15 min. -- 16.0 ----- 65536 ------------ 1.00
20 min. -- 16.0 ----- 65536 ------------ 1.00
5m. cool - 16.0 ----- 65536 ------------ 1.00
25 min. -- 15.0 ----- 32768 ------------ 0.50
26 min. -- 14.5 ----- 23170 ------------ 0.35
27 min. -- 14.0 ----- 16384 ------------ 0.25
28 min. -- 13.4 ----- 10809 ------------ 0.16
29 min. -- 12.9 ------ 7643 ------------ 0.12
30 min. -- 12.6 ------ 6208 ------------ 0.09

Needless to say I'm surprised it only went 25 minutes to half brightness. I don't know if this is due to the Sanyo cells or the driver circuit. With the current draw on high of 800mA I expected about an hour. I have a 700 mAh cell charging and may try it later. I also think I'll buy a name brand alkaline and do a run with it.

(The "5m. cool" is a 5 minute cool down I did after 20 minutes. The light was getting quite warm and I decided to let it cool every 20 minutes. Unfortunately I only needed to do this once.)

Greg

-------------
Feb18/06 update:

Runtime on high using Energizer alkaline cell 2011 expiry date, 1.580V open circuit.

Time ------ EV ----- Brightness # ----- Relative Brightness
-----------------------------------------------------------
Start ----- 16.0 ----- 65536 ------------ 1.00 (ref.)
5 min ----- 15.7 ----- 53232 ------------ 0.81
10 min ---- 15.5 ----- 46341 ------------ 0.71
5min rest - 15.6 ----- 49667 ------------ 0.76
24hr rest - 15.8 ----- 57052 ------------ 0.87
15 min ---- 15.3 ----- 40342 ------------ 0.62
20 min ---- 15.2 ----- 37641 ------------ 0.57
5min rest - 15.4 ----- 43238 ------------ 0.66
25 min ---- 15.0 ----- 32768 ------------ 0.50
30 min ---- 14.8 ----- 28526 ------------ 0.44
5min rest - 15.2 ----- 37641 ------------ 0.57
35 min ---- 14.6 ----- 24834 ------------ 0.38
40 min ---- 14.0 ----- 16384 ------------ 0.25
45 min ---- 12.3 ------ 5043 ------------ 0.08
50 min ---- 11.8 ------ 3566 ------------ 0.05
55 min ---- 11.6 ------ 3104 ------------ 0.05
60 min ---- 11.3 ------ 2521 ------------ 0.04
65 min ---- 11.0 ------ 2048 ------------ 0.03

Nice review Greg :goodjob:


I just got one of these from Eric too, and couldn't be happier.

Thanks Dr. Joe. If people want to put their reviews/impressions of the 3-level L0P in this thread that is fine with me.

Greg

CroMAGnet said:

I'd like to see one of these side by side with a Nano from AWR.

Click to expand...

So would I. But I'm number 150-some for my nano-3 so I suspect someone else will do a side-by-side before me.

Greg

I'm up for a side by side if Miller sends me one for eval. I'd pro'ly end up keeping it anyway. My Nano is supposedly shipping this week. And I have a Stock L0P. So :shrug:

I know this must be in some previous spreads, but is Eric selling these directly? If so, how much? Or do we need to buy from 4sevens and ship to him?

wow.... who'd of thought you could get three stages out of this light.

-David

Run-time added to post #2.

Greg

onthebeam said:

I know this must be in some previous spreads, but is Eric selling these directly? If so, how much? Or do we need to buy from 4sevens and ship to him?

Click to expand...

I think he has some pre-modded ones. See this thread http://candlepowerforums.com/vb/showthread.php?t=106533&highlight=l0p%2A

Greg

I didn't get a chance to run any more tests last night. Unfortunately I also forgot to buy some name brand AAAs when I was out running errands today. But I hope to run a test with the 700mAh NiMh cell tonight.

Greg

No new run time tests I'm afraid.

I will mention that I have been giving the light an extra half turn before putting it in my pocket and haven't had any accidental switching-ons since.

Greg

greg_in_canada said:

Here is the run-time on high. The results are a little puzzling so I did a second run with more readings near the end. So I'm only going to type in the second run. Both runs are using the Sanyo 900mAh cells I charged yesterday, unused since (1.379V and 1.378V open circuit).

Time ----- EV ----- Brightness # ----- Relative Brightness
--------------------------------------------------------
Start ---- 16.0 ----- 65536 ------------ 1.00 (reference)
5 min. --- 16.0 ----- 65536 ------------ 1.00
10 min. -- 16.0 ----- 65536 ------------ 1.00
15 min. -- 16.0 ----- 65536 ------------ 1.00
20 min. -- 16.0 ----- 65536 ------------ 1.00
5m. cool - 16.0 ----- 65536 ------------ 1.00
25 min. -- 15.0 ----- 32768 ------------ 0.50
26 min. -- 14.5 ----- 23170 ------------ 0.35
27 min. -- 14.0 ----- 16384 ------------ 0.25
28 min. -- 13.4 ----- 10809 ------------ 0.16
29 min. -- 12.9 ------ 7643 ------------ 0.12
30 min. -- 12.6 ------ 6208 ------------ 0.09

Needless to say I'm surprised it only went 25 minutes to half brightness. I don't know if this is due to the Sanyo cells or the driver circuit. With the current draw on high of 800mA I expected about an hour. I have a 700 mAh cell charging and may try it later. I also think I'll buy a name brand alkaline and do a run with it.

(The "5m. cool" is a 5 minute cool down I did after 20 minutes. The light was getting quite warm and I decided to let it cool every 20 minutes. Unfortunately I only needed to do this once.)

Greg

Click to expand...

The reason for this (The decreased runtime), is because it is difficult for me to get a 800mA draw with my circuit. My circuit at it's lowest setting is pushing the lux harder than the stock L0P. The current draw on high is around 900mA to 1 amp. I tried to get it as low as I could and so far, with the parts I have right now, this was the best I could do. The nice part is, is that it's output on high is a little brighter than the stock L0P. Notice how flat the regulation on the brightness level is for the first 20 minutes Try a lithium, I think the results will be better for the high current draw from such a tiny battery.
I should also mention that with any battery and especially AAA's, as current draw increases, the batteries capacity will rapidly decrease. For example; A AAA 900mAh cell may have that capacity with a 50mA current draw, but the same battery with a 1000mA current draw may only have a 400mA capacity. Heat will also increase a NIMH internal resistance and reduce capacity as well. The stock L0P has a better over-all runtime, but it doesn't have near the regulation that my driver exhibits. With my circuit the heat will cause the circuit to increase current draw from the cell which will also contributes to less runtime but gives you the nice flat output you observed.
I have my 3-stage L0P set to draw 1.53Amps from the cell and I'm doing a runtime test with a Sanyo 900mA cell right now as I type this. I took the cell off of the charger and installed it in my L0P at 7:50. I don't have any kind of true light meter, but I'm using a solar cell with an analog meter that will load the solar cell and give me a pretty good idea when the output begins to decrease.

Greg, somethings weird here. I'm at 18 minutes with no decrease in output yet. At 1.5Amps, I was expecting that my output would have decreased by now if the one I sent you is only draw 2/3rds or less that current and started decreasing at 20 minutes?? Mine is a good bit warm but I'm just going to let it drain the battery. It's been 22 minutes now, and the output is still strong (O.K., the secrets out, I type sloooow). Greg, are you positive your charger is working right? Now at 24 minutes, it appears that the output is starting to decrease, but only slightly. Shoot, I'm getting better results with higher current draw. I'm confused. I'm sitting here waiting as time goes by...........27 minutes(maybe 80% output from start).......29 minutes (still a nice output, no rapid decrease yet)...30 minutes.... WOW, it's doing better than I'd have ever expected....O.K. at 31 minutes I'm starting to see it head down pretty fast. The one I just measured is my 1.5 watt on high model, I thought it would go about 20 minutes at full brightness, and I would say at that runtime, that claim will be easy to up hold.

I don't know if my charger is good or not. It's an Energizer 30 minute 4-bay one. It cost me $70 CDN about a year and a half ago and it came with 4 AA's. So I would hope it is good.

I started a test with an alkaline but had to stop it after 10 minutes. So the cell will get a long rest before the rest of the test. I was hoping that would tell me if the Sanyo cells or my charger are not quite right.

I'd love to try some lithium cells but they are super expensive here. I don't remember exactly but maybe $15 for two AAAs.

I might try to measure the current draw somehow. That would tell me if high setting is way over 800mA draw. I might be able to do it this weekend.

In spite of the short run time on high I am very happy with my purchase. Thanks for creating this Eric.

Greg

Big red flag. NIMH cells as a general rule should not be charged faster than 1 hour, and that's even pushing it a bit. You will only get a partial charge if it's charged in 30 minutes, plus the cell will get very warm, which is not good for the cell at all. The Energizer 30 minute chargers are meant to be used only with 30 minute rechargeable cells.

When you decide to try to take current measurements here's some tips:

The circuit will drop out of regulation if the voltage input is less than 1 volt, so you have to use 10A current range on a DMM to reduce the voltage drop across the current sense resistor in the DMM. You also should make sure the battery is completely charged and don't use a battery holder, as it would drop the voltage some too.
Use a sewing needle to make contact with ground while holding the needle along side of the battery so that the battery is positioned to make contact with the center conductor (+) on the back of the circuit, now just complete the circuit with a DMM set to measure current. This is the way that I have checked the current draw before, and with my Fluke DMM, the results were accurate.

MillerMods said:

Big red flag. NIMH cells as a general rule should not be charged faster than 1 hour, and that's even pushing it a bit. You will only get a partial charge if it's charged in 30 minutes, plus the cell will get very warm, which is not good for the cell at all. The Energizer 30 minute chargers are meant to be used only with 30 minute rechargeable cells.

Click to expand...

I'm confused here, MillerMods. I've been marveling at your knowledge of technical aspects of voltage and lights and impressed that so many are happy with your mods so far.

But, I've looked to Silverfox here for advice on rechargeables. He recommends the Energizer 15 minute charger highly, as do others here. So, I bought it a few months ago and find it simple to use, very effective. The batteries don't overheat.

So, assuming you find the 30 min. charger only useable with 30 minute rechargeable cells (I've never heard of these) then what's they problem using a 15 minute charger?

the one thing i have always missed is Pictures in ANY of MillerMods...

why doesnt ppl post pictures of his mods? are they ugly?

(please... I am getting Negative impressions when reviews are posted without pictures)

Eric posted photos and beam shots of his mods in one of his threads (https://www.candlepowerforums.com/threads/106533). You can see the two springs on the left and right side of the PCB. From the outside it looks exactly like an L0P. The only other thing you can see is the bottom of the PCB in the had. It has a solder blob for the positive contact. For the negative contact ring there are two small metal springs present that are different heights to give you the 3 levels. It's all silver looking and would be very hard to photograph even if I had a decent digital camera. All that said, I will try to get some photos this weekend.

The 15 minute cells are special ones that essentially have a pressure switch inside. As soon as the cell is charged and starts heating the switch breaks the circuit to stop the charging.

I didn't know 30 minute chargers were a bad idea. It came with 4 regular Energizer NiMH AA's and doesn't say you can't charge other NiMH cells in it. The cells do get pretty warm I'll admit. I was thinking that the 1.38V a day after coming off the charger meant that they were fully charged, or close to it.

Thanks for the hints on measuring the current draw.

Greg