XTAR S1 - Test Version and Final Version Review

[357mag1]

I received my S1 and did some preliminary testing.

I will list what I like, dislike and a concern with the light.

Like:
1. Very close to the TK70 in performance on Max setting.
2. Much smaller form factor than the TK70
3. Being able to set my own output level
4. Is built like a tank like the discontinued TK20.
5. Nimh D cells will fit in the tube. I ran it with 3D cells and it worked great. On the bench of course, no way will the length of 3D nimhs fit with the tailcap. Now if we could convince XTAR to produce an extension so we have the option of Nimh D cells.

Dislike:
1. 658u Amps draw when in the OFF position. That will drain a 2600mah 18650s dry in about 5.5 months. Make sure you loosen that tailcap.
2. I have accidentally turned from "Preselect" to "Select" about half a dozen times so far. Which messes up my carefully chosen "Preselect" setting. Wish it had a lock out feature where you had to turn quickly between "Preselect" and "Select" twice to initiate changing the "Preselect" level. This would keep idiots like me from repeatedly going through the ramp sequence to reset my "Preselect" level.

Concern:
Tailcap current with 3 fully charged IMR 18650 cells measured 7.86amps at the tailcap. It is the same with my LG 2800mah cells, some of the best Lithium cells I've tested. Lesser quality cells or slightly depleted cells all read lower tailcap current. This is backwards for a regulated light. Slightly depleted cells should draw more current at the tailcap to maintain the same current through the LED.

So all I can conclude is my light is not regulated like the production versions Selfbuilt and Candle Lamp received for testing. If other purchasers confirm their light does the same we have to wonder why XTAR sent regulated versions to testers and gave the public unregulated versions.

I'm going out on a limb here without all of the facts (perhaps others have regulated lights and mine is a fluke). I can think of at least one reason why XTAR might be inclined to do this (If they did it would still be wrong). The S1 starts out drawing almost 8amps using freshly charged batteries so by mid run on a regulated light it should be pulling over 9amps. This works out to over 3amps per battery and will climb higher further into the run. Perhaps XTAR is worried such a high draw could cause issues with some of the lower/questionable quality Lithium Ion cells on the market.

For those of you who might be a little fuzzy on how a regulated light should function. Lets use my fully regulated TK70 as an example. With fresh cells I measure about 7amps at the tailcap and after the cells have been in the light for about 15 minutes tailcap current has already climbed to 8.25amps and will climb even higher as the batteries near the end of their capacity. That is how a regulated light works.

Without a doubt my XTAR is not a regulated light or at least it is very poorly regulated like the pre-production version.

So does anyone else have a good meter and the ability to verify tailcap measurements on their "PRODUCTION" version XTAR S1?

 

[BWX]

So all I can conclude is my light is not regulated like the production versions Selfbuilt and Candle Lamp received for testing.

Damn! I paid extra to get that regulation, and I only use high quality 18650 cells.
If that's true about the lack of regulation, I'm going to be pissed off.

I do have a digital multimeter, but have never measured current draw on anything with it. I don't even have clips on the leads, just probes.

I haven't received my S1 in the mail yet. I ordered it on the 22nd from hkequipment, who knows when I'll get it. When I do finally get it, if I can, I'll try to confirm what you found with the current draw.

I wonder if you got a pre-production test version? Can you confirm it's the final production version by comparing the machining to photos? Just making sure, I guess it's possible you got a test version in a box and everything by accident? Of course you probably already checked, but ya never know.

 

[BLUE LED]

I have ordered the S1 production version because of the regulation on high quality 18650 Cells. I will not be happy if it turns out to he semi regulated. Please do check the head for the differences and confirm that you have a production S1.

 

[357mag1]

I did verify my flashlight has the machining of the production version. I even contacted the vendor to make sure I was getting a production version prior to purchase.

I sent the vendor an email about my concern with the lack of regulation. His reply was the "The S1 is wired in parrallel, it should drop in current draw".

For those of you who do not have an electronic back ground (I have over 30 years) you may still recall Ohm's Law from school. P=IE Power is found by multiplying current by voltage. Without trying to factor in voltage sag under a load lets use 4.2 volts X 7.86 amps for a total of roughly 33 watts of power. When the battery voltage drops to 4V current must increase to 8.25 amps to maintain 33 watts. At 3.5 volts current has to be at almost 9.43 amps to maintain power out.

Again the above doesn't take into consideration voltage sag under load but should allow those of you without an electronics background to understand why the current draw at the tailcap will ALWAYS climb on a properly regulated light.

Something I forgot to mention last night. When I position the S1 ring to "High" it takes the light about two seconds to come up to full brightness. Not sure why they have that feature, it would be more appropriate on an Ican but perhaps slowly bringing an LED up to full power can help extend it's life as well.

 

[TEEJ]

You can get the latest versions form MD-lightsource, they just got them in.



We get 12% off for CPF members to boot. I think that's only ~ $220 (The list was $299, but MD only charges $249, and the discount is off the $249)

:devil:

 

[357mag1]

I do have a digital multimeter, but have never measured current draw on anything with it. I don't even have clips on the leads, just probes.

You don't need clips. The following procedure applies to most Fluke DVMs.

First some safety information. Safety for your batteries and meter and in rare circumstances the individual as well. We read voltage by connecting the leads across the battery terminals. This puts the meter in parallel with the battery. The meter has a very high internal resistance on the voltage setting so only a trickle of current passes through the meter for it to read voltage. If that wasn't the case the meter itself would add a load to the battery and cause voltage sag giving you inaccurate readings.

When reading current you have to be in series with the circuit. When I move my leads to the current jacks on the multimeter now the internal resistance of the meter is almost zero. The meter in fact uses a piece of precision wire and reads the very small voltage drop across that wire. The more amps going through the wire the higher the voltage drop. So the meter is really still reading voltage but in a way that can supply you with an accurate current reading.

Why have I bored you with this information. I wanted you to understand when setup to read current your meter is acting as a wire. If you forget and connect it across the terminals of a battery it will short out the battery just as if you placed a piece of wire across the terminals. Several things can happen. If your meter isn't fuse protected and the battery is strong enough it will damage your meter. The leads will get hot. If you do this on something as powerful as a car battery your leads can get burnt (arc welded) or melt. Your battery could explode!!! Explosion is unlikely but possible. Please be extra careful when using the current function of your DVM.

So here is the procedure.
Leave the black lead in the "COM" jack and move the red lead to the "A" jack.
Rotate the DVM selector dial to the ma/A position.
Now your Fluke meter is ready to read current, others may require slightly different procedures. Hopefully you have a manual if it isn't obvious after reading the above.

To read current on the S1.
Take the tailcap off the S1 and lay a flat fender washer or disc magnet on top of the batteries. The washer or magnet is just a way to tie the negative ends of the batteries together much like the tailcap itself does.
Now rotate the light switch to "High".
Make firm contact with your red probe (I lay it flat and press down fairly hard) to the top bare aluminum part of the battery tube.
Use the black prove to push down on the washer/magnet you placed on top of the batteries.
Hold it until the light ramps up to full brightness.
Read your DVM digital display.

That is it. You may want to make yourself some short thick leads just for taking current readings like I have. The small and fairly long leads of most meters have enough resistance to affect current reading when getting much above 2amps. You can still check regulation of flashlights by using your meter to complete the current path the tailcap usually does.

Hope this was helpful. I will try to get someone to assist me with some photos though I suspect there are some on this forum if one were to search diligently.

 

[BLUE LED]

Perhaps a regulation test is in order to see if yours matches the S1 reviewed. I will make the time to test mine when it arrives. I have AW, Redilast and Eagletac 18650 3100 mAh cells.

 

[BWX]

Two full seconds to get to max output? I don't remember hearing anything about that either.. but I remember someone saying it ramps up quickly.. I have a light that's like that- the Fenix LD20 premium r4 does that, but very quickly, nothing like two seconds. It sounds like the Xtar S1 that we are getting as a "production version", is different than the "production version" sent to people for reviews. At least the circuit is different anyway. If that's the case, that's deliberately misleading. Not cool at all.

edit
I'll make sure I have the correct type of multi meter and perform the test when I get my S1.

 

[selfbuilt]

Tailcap current with 3 fully charged IMR 18650 cells measured 7.86amps at the tailcap. It is the same with my LG 2800mah cells, some of the best Lithium cells I've tested. Lesser quality cells or slightly depleted cells all read lower tailcap current. This is backwards for a regulated light. Slightly depleted cells should draw more current at the tailcap to maintain the same current through the LED.

So all I can conclude is my light is not regulated like the production versions Selfbuilt and Candle Lamp received for testing. If other purchasers confirm their light does the same we have to wonder why XTAR sent regulated versions to testers and gave the public unregulated versions.

Actually, I suspect the issue is likely with the DMM in the current path.

My production sample (which shows flat output regulation) behaves the same way as yours if I do measures with my DMM hooked up. That is, on partially charged 18650 IMR, I get a lower current draw on my DMM compared to fully charged.

The reason for this (which I can confirm in my case) is that the light is NOT actually running at full brightness when I hook it up to a cell through my DMM. This is why the lower current draw is observed.

Based on some discussion with HKJ in my earlier pre-production review, I suspect this has to do with resistance in the DMM and/or leads (at least in my case).

Note the same goes if you run it for a few minutes - with my DMM hooked up, the current draw drops fairly rapidly (as does the output to match). But if you run without the DMM, the output stays constant.

Something I forgot to mention last night. When I position the S1 ring to "High" it takes the light about two seconds to come up to full brightness. Not sure why they have that feature, it would be more appropriate on an Ican but perhaps slowly bringing an LED up to full power can help extend it's life as well.

Two full seconds to get to max output? I don't remember hearing anything about that either..

Again, this is normal - my sample does the same thing.

I suspect it is to be more "gentle" on the batteries, but it may also give the circuit the opportunity to NOT ramp up to full brightness if it detects an issue with the power source (which may be the case when the DMM is in the circuit path). :shrug:

 

[BWX]

That's good.. I hope that's all the issue is.

 

[357mag1]

Actually, I suspect the issue is likely with the DMM in the current path.

selfbuilt,

First I would like to thank you for taking the time to let us know how your review light acted when testing tailcap current.

I agree the meter can start to influence current readings particularly at these higher current levels. I have taken steps to minimize that by using heavy gauge short leads.

Even if the leads and meter's internal resistance is having an influence on current readings with the S1, I believe it would be minimal and we should still see a rise in current as voltage drops. I have measured powerful regulated lights that draw even more current than the S1 and they all show a rise in current as battery voltage declines during the run cycle.

As I explained above and you probably already know when the meter leads are in position to read current they are connected by a precision piece of wire. With my particular setup the resistance would be extremely small. If the S1 circuitry is truly that sensitive it must be very fragile in design or barely able to do the job. In fact looking at the tailcap I would almost bet my meter and leads have less resistance.

Once again I appreciate you letting us know how your review light behaved. Hopefully my light is truly regulated but the current readings make no sense to me.

 

[BWX]

Oh crap. I ordered it on April 22nd. I look today at tracking..
April 28, 2012, 10:32 pm ------- Processed Through Sort Facility ---------- ISC NEW YORK NY(USPS) -------- Registered Mail™

I've never seen ''ISC NEW YORK NY(USPS)'' ever, so I looked it up. Looks like it's stuck at customes.. or could be.

Might be a while before I can test it.

 

[357mag1]

I don't have a light meter so must rely on my eyes to verify a regulated output. To do this reliably I needed a light close to the output of the S1.

I discharged some Panasonic 3100mah batteries down to 3.85volts and topped off some LG 2800mah 18650s at 4.22 volts.

Then I carried the S1 and a TK70 outside to do some comparison testing. The two lights are very comparable with the TK70 being just slightly brighter and producing a little more throw on the highest settings. Doing side by side testing I couldn't see where the S1 was any brighter with the freshly charged batteries than with the Panasonics at 3.85volts.

I have to thank selfbuilt for the information he provided. It was his tailcap readings that prompted me to think of a meaningful way to test the lumen output at different battery voltages. As stated above I can't see where the light is any dimmer with the lower voltage of the Panasonics or any brighter with the freshly charged LGs.

I'm feeling better about my S1 even though I had no intention of returning the light even if it wasn't properly regulated. By the way, the vendor (sbflashlights) offered to take the light back and provide a full refund if I wasn't satisfied. You can't ask for better service than that.

Just too nice of a light for the size and I really like the rugged build.

I would still love an extension to allow the use of 3D Nimh cells or even 3 Alkaline D cells in a pinch.

 

[candle lamp]

Actually, I suspect the issue is likely with the DMM in the current path.
My production sample (which shows flat output regulation) behaves the same way as yours if I do measures with my DMM hooked up. That is, on partially charged 18650 IMR, I get a lower current draw on my DMM compared to fully charged.
The reason for this (which I can confirm in my case) is that the light is NOT actually running at full brightness when I hook it up to a cell through my DMM. This is why the lower current draw is observed.
Based on some discussion with HKJ in my earlier pre-production review, I suspect this has to do with resistance in the DMM and/or leads (at least in my case).
Note the same goes if you run it for a few minutes - with my DMM hooked up, the current draw drops fairly rapidly (as does the output to match). But if you run without the DMM, the output stays constant.

Again, this is normal - my sample does the same thing.

Many thanks for your time & detaild explanation. Selfbuilt!

I don't have a light meter so must rely on my eyes to verify a regulated output. To do this reliably I needed a light close to the output of the S1.
I discharged some Panasonic 3100mah batteries down to 3.85volts and topped off some LG 2800mah 18650s at 4.22 volts.
Then I carried the S1 and a TK70 outside to do some comparison testing. The two lights are very comparable with the TK70 being just slightly brighter and producing a little more throw on the highest settings. Doing side by side testing I couldn't see where the S1 was any brighter with the freshly charged batteries than with the Panasonics at 3.85volts.

I have to thank selfbuilt for the information he provided. It was his tailcap readings that prompted me to think of a meaningful way to test the lumen output at different battery voltages. As stated above I can't see where the light is any dimmer with the lower voltage of the Panasonics or any brighter with the freshly charged LGs.

I'm feeling better about my S1 even though I had no intention of returning the light even if it wasn't properly regulated. By the way, the vendor (sbflashlights) offered to take the light back and provide a full refund if I wasn't satisfied. You can't ask for better service than that.

Just too nice of a light for the size and I really like the rugged build.

I'm sorry that this was brought to my attention so late. I just saw your #41 reply today, but really didn't know how to explain the reason due to my ignorance.

I can tell you to check the brightness (or output) by using the digital camera as shown in the picture.

Some digital camera has a function to press the shutter every minute or at any interval as you wish by itself. So you can check the brightness difference according to the regulation time.
Otherwise you can take a picture every 10 minutes yourself. (But don't forget to put on your sunglass!) In my view, I think this way is better than seeing with your own eyes.

I don't know this is helpful to you.

KyeongHo,

 

[selfbuilt]

I have to thank selfbuilt for the information he provided. It was his tailcap readings that prompted me to think of a meaningful way to test the lumen output at different battery voltages. As stated above I can't see where the light is any dimmer with the lower voltage of the Panasonics or any brighter with the freshly charged LGs.

Good, glad to hear your light does indeed seem to be regulated for output when run normally.

As for the issue with getting accurate current draws with a DMM (even a good one like yours), I believe the problem comes from the low margin the S1 has for maintaining regulation (voltage-wise). There aren't too many lights out there that can produce this sort of output on a single 3.7V Li-ion source (which is the case here, since the three cells are in parallel). Most other lights I've tested involve a higher voltage battery source (i.e., multiple cells in series). And note by the way that the pre-production version couldn't regulate at all, even when run normally on its battery source. Xtar has managed to adjust to circuit to allow for flat-stabilized regulation on typical cells in the production version, but I'm guessing even the small amount of resistance on the 10A port is enough to drop the voltage down to where regulation won't kick-in (i.e., it is a narrow margin).

Ultimately, the only way to know for sure is to interrogate the circuit directly, with a bench-top power supply. Unfortunately, I don't have one. I wonder if HKJ was sent a production version for testing? :thinking: That would be helpful, since his original voltage sweeps of the pre-production version explained the failure to stabilize on that light.

 

[HKJ]

I wonder if HKJ was sent a production version for testing? :thinking: That would be helpful, since his original voltage sweeps of the pre-production version explained the failure to stabilize on that light.

No, I did not get a production version.

 

[357mag1]

As for the issue with getting accurate current draws with a DMM (even a good one like yours), I believe the problem comes from the low margin the S1 has for maintaining regulation (voltage-wise). There aren't too many lights out there that can produce this sort of output on a single 3.7V Li-ion source (which is the case here, since the three cells are in parallel). Most other lights I've tested involve a higher voltage battery source (i.e., multiple cells in series). And note by the way that the pre-production version couldn't regulate at all, even when run normally on its battery source. Xtar has managed to adjust to circuit to allow for flat-stabilized regulation on typical cells in the production version, but I'm guessing even the small amount of resistance on the 10A port is enough to drop the voltage down to where regulation won't kick-in (i.e., it is a narrow margin).

I think that is the only explanation that makes sense. My meter even with the short leads must be adding more resistance and causing less voltage to reach the regulation circuitry which in turn causes it to assume the batteries are depleted and decreases current draw to the LED. I figured the S1 rotating tailcap would have trouble being lower in resistance than my setup. Apparently that is not the case which means it is well designed (a good thing).

 

[Bruno28]

The test pre-production version was an even better deal.. about $30 cheaper, but with all the improvements, the final production unit was well worth the asking price. $200 for a light like this? Amazing deal.. I thought I'd be spending quite a bit more for a quality flashlight with this level of performance actually. I just can't believe they aren't all sold out already..

Where do you get it for $200?

 

[TEEJ]

Where do you get it for $200?

The pre-production (uncorrected issues) S1's are on sale for ~ $160, and the newest (Corrected/regulated, etc...) versions are on sale for ~ $224, MD-Lightsource has the new ones shipping from the USA for that price with CPF discount.

The Pre-production ones ship from China.

 

[BWX]

Production ver. from hkequipment. Ordered on the 22nd and still haven't gotten it yet and don't know when I will... it'll probably be here by end of this week, could be tomorrow though, who knows. It was $250 with $50 off for CPF/ etc forum. I knew shipping would be longer when I ordered it. I figured it was worth it.