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The Smok ZMax

The Smok ZMax

 

 

Foreword:
This review was originally written for and posted on the ECF on 24 September, 2012. I am reposting it here and will include any updates.

Description:
The ZMax from Smok is a tube style APV that allows the user to select the output voltage from 3.0V to 6.0V in 0.1V increments or the user can select an output power from 3Watts to 15Watts in 0.5Watt increments. It will accept either a single 18650 battery or, with the use of an extended end cap (sold separately), it will accept 2 18350′s.

Packaging:
Nothing exceptional to state except it is nice to get a box. My LavaTube was just in a plastic sleeve when it arrived. However, there was some gunk that was in the lid of my box.

Hard Ware:
When I took the unit out of the box it felt solid and durable. The manual says it can be either Brass or Stainless. Looking inside It doesn’t look coated and it’s not brass colored so I’m assuming stainless I could easily be wrong on that though. The tube walls are a bit on the thin side but under normal use it shouldn’t be a problem. I tend to carry my PVs in a pocket and I haven’t had any warping of the tube due to carelessly sitting down or pressing it against the arm of the chair. Though I have picked up one little blemish that I can’t just wipe away.

The drip well seems nice and deep. I don’t typically use ego style devices. I do have a Kanger T2 and T0 neither of which would fit in the well. That’s no big deal though since both of those are ego threaded and this device has only the 510 connection. The skirt from my CE9 did fit in without issue. The well is deep enough that I don’t think an ego skirted device would bottom out.

The bottom cap threading, when no battery is involved feels a bit loose and it rattles if it’s not snugged up. Once it’s snugged up though, it seems to seat pretty well. The threads appear thin and roughly cut. With such a thin device though it wouldn’t be possible to have deeper threads. When standing the unit on end the wobbliness worries me sometimes. I have had it fall over a couple times and once it rolled off a table. Neither it nor the Vivi Nova that was on it appear damaged in any way and both are still working as designed. I do, on some masochistic level, enjoy the game of get the drop in the moving atomizer when I’m dripping at my desk.

The clear plastic covering the LED display on mine did not arrive flush. It was however attached firmly. So, I thought maybe it was supposed to be that way. The end towards the 510 connector was not pushed in as far and it slopped toward the unit by the button. After using it for a while I felt something shift in my hand and when I looked again it was flush. In both cases it didn’t feel wobbly or loose at all. Then as I was using it I turned my wrist to check the time. When I did so the screen was facing the floor. I heard a tiny little click. It was back to how it was originally but not as pronounced. Still feels firmly seated. There has been no rattle from it at all. You can kind of see what I’m talking about in the following photo.

I like having the button on the same side as the display; but I also would like the button higher on the unit. I don’t see a way to get both of those.

The manual is understandable; but like a lot of devices manufactured overseas not well translated

Battery Installation:
The manual states “Zmax could fit one battery 18650 or add holds two specially designed 18350 High Power Batteries,and reverse connect protection”. It DOES NOT state that this requires high drain and no where does it specify a chemistry such as IMR It does use the term high power when referring to the specially designed 18350 batteries (Where do we get these specially designed 18350 batteries?). I don’t have the extended end cap though so I can’t test this configuration. I started my testing with AW Flat Top ICR Protected 18650 3100mAh batteries (black coating). Inserting the battery was no problem. Getting the bottom cap on with the ICR battery required more force against the spring than I’d like; but I never felt as though I was going to damage anything. The AW Button top IMR battery went in without issue. The thin threads on it cause me to cross thread it about 2/3 of the time and I have to back it off and start over if I want it to sit flush. It’s a bit annoying and I usually just leave it on cross threaded. Noalox helped.

With the AW Protected ICR’s I haven’t had any issues that I could attribute to the battery not being High Drain. In fact, I completely forgot that I had them in there and did a majority of my testing with them. When I put in the IMRs I didn’t detect anything statistically different. However, I would recommend the IMR batteries to provide higher current.

Software:
I did not use a ProVari prior to using this device. I did have one on the way when I ordered the ZMax; but it didn’t arrive before the ZMax. So when the ProVari got here I learned how to use it quickly due to my brief experience with the ZMax. I’m not that fond of one button menus. However, I wouldn’t want to see more buttons on either device so it is what it is. For what it is, it’s easy enough to learn and while I’d like it to be a little less involved to change a setting it works well.

The things it remembers when changing batteries seems arbitrary. If the device is set to Variable Voltage, after the change it will remember that it was set to variable voltage but will reset the voltage to 3.0V. If set to Variable Power it will remember this as well as what the power setting was. After thinking about it, I think they did this on purpose. In Variable Power Setting it’s going to pick an appropriate voltage for what ever atomizer you put on to give a consistent experience. In Variable Voltage you could damage a low resistance atomizer at a higher setting (or even a lower setting, more on that ater). However, if it is a safety feature it’s a little pointless. I’d rather see it reset the voltage when changing the atomizer since changing the atomizer and changing the batteries rarely occurs at the same time for me. Regardless of all other settings it will forget what your display preference was, i.e. Power/Voltage Setting, Voltage read from Batery, or Atomizer Reistance. It will, however, remember weather or not you have the display set to come on while firing (Menu 6. Lo). This feels like either a mistake or just not well thought out.

As far as scrolling through the menus goes, I prefer the ZMax to the ProVari. On the ProVari, there is a “spacer” between each menu. For example when moving from the Pu (Power Up) menu to the Pd (Power Down) menu there is a “–” displayed between each menu, meaning you have to press the button twice to get to each subsequent menu. When I accidentally pause while the “–” is displayed it locks the unit up for about 15 seconds during which you can’t fire the unit or interact with the menus. The ZMax takes you straight to the next menu.

The menu layout could be better. I think menu 5.Ds should have a fourth option. Currently, the settings available are o (Output setting) A or R (Atomizer Resistance) and u or v (Batteries voltage). I think there should be an “of” option and completely replace menu 6.Lo. I think on the Vmax this menu controlled the LED in the fire button (I don’t have a VMax so I’m assuming). Since there is no LED in the fire button on the ZMax and this button controls the display it makes since to consolidate.

The terminology of menu 3.So seems backwards. The “So” according to the manual is “Standby On/Off”. So, I think to my self “If stand by mode is ‘on’ then the unit will be asleep, if stand by mode is ‘off’ the unit will function normally”. That’s not how it is though. Maybe the menu should be 3.Sp (System Power). Also, the placement of this menu right in the middle seems odd. I think it should be at the end or accessed differently such as 5 clicks on/off. I think 5 clicks on/off would work since the menu comes up at 3. 3 clicks, pause = menu. 5 clicks = off/on.

Menu 4.Uc and menu 5.Ds (when set to Du) would be more useful to more people if displayed as a percentage of full with the scale ranging from a new charge at 100% and the lowest voltage at which the device will fire at 0%. It would of course have to auto detect weather you’re using a single 18650 or stacked 18350′s

There is no way to get the unit to display the voltage it has selected for your power setting given the atomizer you’re using. I find that VERY disappointing.

Here’s what I’d like to see the menus look like:

1. Vu/Pu – Voltage or Power Up
2. Vd/Pd – Voltage or power Down
3. Uc – Battery Check (Gives the voltage from the battery as a percentage)
4. Ds – Display Setting
du – display output ( Should display voltage out regardless of VV mode or VW mode)
db – display battery life (as per 3.Uc)
dR – display Resistance ( Shows atomizer resistance)
dO – display Off
5. UP Voltage / Power
PO – Selectable Power Mode
UO – Selectable Voltage Mode
6. Sy – System Power (Or use a different method)
On
Off

I really don’t like having to press the fire button to get a resistance reading from my atomizer. I understand it has to put some power through the coil to take a reading but if it did that internally it could be done with a minimum of power output. Me hitting the button means I have to put more than just a drop of liquid the coil to take the reading. Since I use a lot of rebuildables it means I get juicy fingers trying to fix any shorts or poorly separated wraps that I didn’t see. It’s not that big a deal but I thought it warranted mentioning.

Experience:

As expected, I find things to run hotter than my setting. However, I have been able to find settings I’m happy with as long as the resistance of my coil is at or over 2.2ohms. In VP mode I find the experience to be the same when changing to a different resistance head so it it’s doing a good job at being a consistent experience.

I’ve handed the ZMax to an inexperienced vaper on a couple of occasions and It’s feel and it was very well received. They really want one. That new user experience though has to be weighed against my knowledge of the device and having selected an appropriate setup. As I recall, my ViVi Nova tank arrived with the 1.8Ω head attached. If a new user, not knowing what wattage they liked started on the lowest voltage setting of 3.0V they would likely find it running too hot.

The most annoying part of the experience is the < .5 second delay when releasing the fire button. The unit continues to fire. I thought maybe the coil was just taking a while to cool off. In listening to other units like the ProVari, SilverBullet or twist I found that they also continue to sizzle; but for a much shorter period and the intensity of the sizzle drops immediately on releasing the button. Not so on the ZMax, the sizzle remains at the same intensity during that holdover. I’ve checked on my oscilloscope and confirmed that the power output IS continuing at full strength during that holdover period. This may also be a feature as the display remains lit for the exact same amount of time. Which just happens to be almost exactly how long it takes me to glance at the screen after taking a vape and read what’s displayed. If it is a feature, it’s not well implemented since it occurs weather the display is set to on or off. I’d rather it be removed. if I want to read the display I’ll hit the button.

Technical:

I couldn’t rely on my True RMS multimeter for these readings either because it expects an AC signal (The ZMax and other PWM devices are sending a Pulsed DC signals) or the frequency is too high. After checking with technical support to see if there was a trick to get this to work they recommended a low pass filter. I don’t have a suitable low pass filter at my disposal and I haven’t had a chance to build one. So, In order to verify what it’s putting out I needed to know 2 things. 1) What voltage is being out put during the on period of the pulse. 2) What is the duty cycle. For those that don’t know, duty cycle is the percentage of time spent on vs. off.

To get the Voltage that was being pulsed I put a 2.4Ω coil in my phoenix rebuildable and put it on the ZMax with the coil exposed (just the atomizer base). I then attached leads from my oscilloscope to the posts on the phoenix with the probe clamped on the positive terminal. Here’s what I got:


This was set to 3.0V. With the AW ICR Battery. The scale of the Scope was set to 2V. Meaning that each horizontal line is 2V away from the one above or below it. So on the scale we can see we’re nearly 3 divisions apart. I will call it 5.6V (each little tick is 0.4V

You can see the duty cycle is increased in this next picture when the voltage is set to 4.0V

Note: When I do this exercise with no load the wave form is a good square wave. With a load (the atomizer) on I get a triple line during the “ON” period. This variation changes depending on the atomizer. I won’t go into why this is other than to say it has to do with inductance. Also, without a load the pulse output voltage is 6V

Next I needed the duty cycle. For this I could have done it manually based on this scope but I decided to use my multimeter instead. It has a duty cycle function.

Below is a chart I did based on these values.
For the chart my calculations were:
Vavg = V/Duty Cycle
Vrms = V/SQRT(Duty Cycle)

Where I could not read the duty cycle it was because the display of my multimeter wouldn’t settle on a value. It was bouncing around where you’d expect it to though.

As you can see when setting a value on the ZMax you’re setting the Vavg that will be sent across the atomizer. This is wrong. The Vrms is what should be used to calculate the current through the atomizer. Therefore, the Vrms is what should be used in any ohms law calculations to determine the wattage.

Vrms is the effective Voltage or what the device should put out if it wants to mimic a battery at the given voltage. It is my opinion that all variable voltage or selectable power devices should have the same feel/taste/experience as a direct current at the selected voltage. Using Vavg makes all other calculations (battery life, current, wattage) wrong.

What Vrms is and how to calculate it is explained in this video better than I could do it.

Here is a graph depicting how the Vavg and Vrms get closer together the higher the device is set. This graph is taken from the table above.

The last test I did involved a temperature probe. I set all devices to 3.3V and pressed the button for a count of 5. I then read the value that was held on the screen of the multimeter. The probe was positioned just under the coil on a phoenix rebuildable.

eGo Twist = 267F
Kick on lowest setting = 260F
YoungJune Mini LavaTube = 323F
ZMax = 351F

My coil was 2.3Ω as read by the LT and the ZMax So wattage should have been around 4.7 watts. 5 watts is the lowest setting of a kick.

You can tell that the twist and the kick were in the same ball park. The LT was hotter by far and the Zmax was even hotter than the LT. Demonstrating that different PWM devices don’t even agree with each other.

Conclusions:

The ZMax is hotter than the twist or a kick or a plain old battery at the same voltage. It’s got some minor quality control problems and could use a more well thought out user interface; but it’s not worse off than I would expect from any other product Chinese made or not. As I said before, the few inexperienced people that I let try it out really liked it and thought that it seemed to be of good quality. I’ve been using it quite a bit and having found settings that work for me I will keep using it. I HAVE started wrapping higher resistance coils which can be tricky because the coil gets longer or I use a thinner wire. In either case it makes the coil a bit trickier to install. I always carry a back up. I’d like the settings from one to be portable to the other. That’s not the case here though. I’d have to have two zmaxes; but I won’t buy another.

Follow Up October 10, 2012:
The button performance on my ZMax has been deteriorating since I posted my initial review.

I’ve had several instances where the device has continued to fire after I let go of the button until it reached the 10-12 second cutoff (it seems to change each time I count it off). I’ve had it fire twice while I was just holding it in my hand without my finger near the button. The first time I quickly pulled the battery. The second time I waited to see what would happen and it shut off once it reached the cut off. I pulled the battery at that point so I don’t know if it would reset after some period and then fire again.

Additionally, about 1/4 to 1/3 of the time when I fire it it will light the coil for a second or two, then stop. At first I thought I just wasn’t maintaining pressure on the button. However, when hitting the switch again the vape would be hotter. In checking the setting I find that my wattage has been set MUCH higher than the value I selected. I decided to fire it a couple times while watching it and discovered that it would fire initially then instantly enter the “Pu” (Power Up) menu and scroll the power setting higher as I was pressing the button.

I initially thought this was a button debounce issue; but that doesn’t really make sense since once the bounce settles (within a couple microseconds) the contact should remain constant while the button is held. Entering the Pu menu requires a button-off pause of about 2 seconds followed by the button-on to scroll the setting. So, there has to be something more going on. Maybe a brown out to part of the circuit causing it to read multiple button presses… I just don’t know.

Update On 10 October, 2012 :
The button performance on my ZMax has been deteriorating since I posted my initial review.

I’ve had several instances where the device has continued to fire after I let go of the button until it reached the 10-12 second cutoff (it seems to change each time I count it off). I’ve had it fire twice while I was just holding it in my hand without my finger near the button. The first time I quickly pulled the battery. The second time I waited to see what would happen and it shut off once it reached the cut off. I pulled the battery at that point so I don’t know if it would reset after some period and then fire again.

Additionally, about 1/4 to 1/3 of the time when I fire it it will light the coil for a second or two, then stop. At first I thought I just wasn’t maintaining pressure on the button. However, when hitting the switch again the vape would be hotter. In checking the setting I find that my wattage has been set MUCH higher than the value I selected. I decided to fire it a couple times while watching it and discovered that it would fire initially then instantly enter the “Pu” (Power Up) menu and scroll the power setting higher as I was pressing the button.

I initially thought this was a button debounce issue; but that doesn’t really make sense since once the bounce settles (within a couple microseconds) the contact should remain constant while the button is held. Entering the Pu menu requires a button-off pause of about 2 seconds followed by the button-on to scroll the setting. So, there has to be something more going on. Maybe a brown out to part of the circuit causing it to read multiple button presses… I just don’t know.

I’ve stopped carrying the unit around with me. I may dissect it if I find the time or just give it away with astrong disclaimer.

Update on 17 October, 2012:
I feel like I’m beating this thing to death; but people are still out there buying them so I want to put this information up for all to find.

Like I said in my previous Follow-Up I had set my ZMax to the side uncertain if I should give it away or dissect it. Well the decision was made for me when I picked it up to respond to this post in the New Members Forum.

When I picked it up to see if a drip shield would fit in the well I noticed a rattle inside. Curious, I took off the bottom cap and sitting in it was this little metal ring.

I immediately recognized it as the positive pin that should be attached to the circuit board.

It’s hard to make out in the photo but; you can see on the larger board in the middle of the tube there is a little tab jutting out that this ring sits around. There is a semi circle of solder just above where this ring broke off. You can see some discoloration on the ring in the first picture, that is where it was soldered to the board.

The ZMax has been sitting flat without a battery in it since I posted my last follow up. So, I can’t imagine what force acted upon the pin to break it off other than a bad solder joint to begin with. The ring is perfectly smooth other than the bit of solder still on it. They could have scored it a little to make a better connection. The AW ICR batteries I initially used were a little tight when screwing on the bottom cap. That may have helped the connection come loose. I stopped using those after about a week though and switched to AW IMRs which fit without undue force and everything was fine until the unit started behaving oddly. If the damage occurred early on due to the tight fit of the first batteries it might explain some of the strangeness that I experienced.

So, Let’s take it apart, shall we?
 The top cap is press fit on and was easy enough to take off. I put an old atty on it to help me get a hold of it.
 To get the board to slide up you’ll have to break the glue holding the screen cover to the LED display inside. It shouldn’t take much to do it. In mine it was already broken. Which is why my screen cover had moved a couple times. For the other end I used a small flat head from a precision screwdriver set. Once the screen cover is out of the way the board will slide out easily. Be careful you don’t loose the button because when the board is out there’s nothing to hold it in place. I had to chase it under the desk.
 There are two wires going to the head of the unit. White is soldered to the center pin (positive) on the 510 Connection. Black is going to the body of the head. This is the only place that the board makes a ground connection.
 A Shot of the larger board with the LED display and button.
 The smaller board. Looks like the power regulator circuit
Here’s a better picture of the support tab and broken solder connection and what it should look like when I solder it back on.

I don’t know where my soldering equipment wound up after the last time I moved. So, I’ll have to look around my warehouse at work and see if I can find a soldering iron to get the job done. I’ll update once I get it working again.