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Wismec RX2 21700 Review: How Does it Perform?

Anthony Victor
February 2, 2018

Wismec RX2 21700 intro

The Wismec RX2 21700 is the latest mod in the Reuleaux series from Wismec. It’s almost identical to the RX2 20700 but with a bigger battery door to fit 21700 batteries. And it keeps in line with the original triangular shape of the RX2/3 mods.

Price: ~ $50

Colors: gloss black, gradient white, gradient purple and gradient green

Wismec RX2 21700 specs and features

Kit Content

  • Wismec RX2 21700
  • Micro USB cable
  • Warranty card and manual
  • 18650 battery adapters (2)


  • Size: 46.03 mm 37.10 mm x 81.50 mm
  • Weight: 297 g
  • Thread type: 510 spring loaded connector
  • Cell type: high-rate 21700/18650 cell
  • Output wattage: 1-230 W
  • Resistance range: 0.05-1.50 ohms in TC modes
  • 0.10-3.50 ohms for wattage mode
  • Temperature range: 100-315°C/ 200-600˚F (TC modes)
  • Maximum charging current: 2 A
  • Maximum output current: 50 A
  • Output voltage range: 0.5-9.0 V

Notable Remarks

Initial impressions

The RX2 21700 has a nice shape to it and feels pretty solid without being too big. Again, it’s pretty much the same form factor as the RX 20700 and it uses the same large and elongated hexagonal firing button, and it’s got the same menu layout of the Gen 3. But in general, there’s nothing really new here.

Testing background


I test all mods using an oscilloscope to find out if their ratings are accurate, and how precise and consistent the mod is. Testing for this mod was done with iJoy 5-leg 20700 batteries, since they’re better than the included pair of batteries. When fully charged, the iJoy batteries are above 4.0 V per cell.

Just because a mod is capable of producing over 200 watts doesn’t mean I recommend people vape at such high wattages. This is done in a controlled testing environment and I’m aware of the risks involved and take appropriate precautions. I don’t recommend vaping over 150 watts on a dual-battery mod. Always use authentic 20-amp CDR or higher batteries.

This mod is accurately rated for wattage it can handle. It was able to produce 234 watts with a 0.2-ohm coil, so it exceeds the 230 watts listed. As far as voltage goes, I was able to get 9.046 V with a 0.5-ohm coil so it meets the listed 9 V, and I was able to determine that it has a boost circuit.

The RX2 21700 is listed at 50 amps, like many other Wismec mods. But the results showed it cannot do 50 amps. I was able to get 40 amps max from this mod with a 0.12-ohm coil (at 195 watts). That’s pretty average these days for a dual-battery mod, so no big complaints so far — but they clearly overstate its amp capabilities.

Performance problems


The Wismec RX2 21700 can meet most of its promised output, but it’s too inconsistent for me to assign any numbers to it in good conscience. During my normal usage of the mod, I found that sometimes it would fire fast and hard, while other times I noticed a fire delay or a weak hit. It was pretty rare for me to be able to vape normally and get the same puff each time. It’s a common issue with the RX line of mods that I’ve run into before. More on that in a bit.

During my testing to see what the chip actually does, I created a list of issues that I found. (Note: I had the pre-heat function turned off throughout this testing.)

  • Sometimes it fires at lower wattages to begin with, as if there was a soft preheat setting
  • Sometimes the RX2 21700 doesn’t hold wattage, dropping off during a 3-5 second puff
  • Sometimes the wattage spikes during the puff giving the feeling of a “harder hit”
  • The mod itself gets pretty hot during stress testing, especially the fire button
  • Sometimes it stops reading the atomizer. Taking it off, pressing the fire button a few times and then putting it back on temporarily fixes this
  • Even when firing properly, the signal is shaky compared to most mods

So, what’s the cause of all this? In my experience the one thing all these mods have in common is that they use the actual body of the mod as the ground. Most mods use a wire that is soldered onto the ground of the 510 pin internally, and then soldered into the common ground on the chip itself.

In the case of this mod and quite a few other Wismec mods I’ve tested — like the RX300, the Predator, and the RX Gen 3 — they all had a similar grounding system. The way it works with the RX2 21700 is that the 510 negative threading is secured into the mod, and the body itself has two screws that secure the chip in place. These two screws are located inside the bottom of the mod underneath the batteries.

After removing one screw, the mod still worked, but resistance changed. When removing both screws, the mod reads a short and won’t fire. When both screws are loose, the mod still works, but reads resistance very inaccurately. The fire button is also screwed into the mod which could be the cause of the “hot button,” like you get on mech mods with dirty or poor contacts.

I hope Wismec changes this in the future. They should take it seriously and use the information I’ve provided here to make better products.

As a reviewer it’s my duty to inform the public and give a fair assessment of devices, because in the end it benefits everyone. It allows companies to fix mistakes and to make better products. It also helps vapers avoid wasting money or getting a device that frustrates them, which might cause them to go back to smoking.

Temperature control performance


For temperature control, I’m going to keep this short and sweet. The mod is very inconsistent, and most of the time it winds up kicking you out of TC mode anyway. It’s pretty much not usable as a temp control mod at all.

Other tidbits

  • The RX2 21700 can use 21700 batteries — obviously. It includes a pair of Avatar batteries which are acceptable, but not great. They’re good for battery life at lower wattages, but I wouldn’t try to go over 125 watts with them. And the battery life with the Avatar batteries will be a little less than a triple-battery 18650 mod.
  • I used the iJoy 5-leg 20700 batteries pretty much without issues in fit or performance. You just have to make sure they line up correctly or the mod won’t turn on. You can also use 18650 batteries with the included adapters.
  • The battery door goes on easily, and has a locking latch on the bottom. Without batteries in the mod, it can be a little difficult to line things up as it slides into a railing from the bottom.
  • The fire button is nice – it’s large and clicky. And like other RX mods, the screen is big and bright, and it monitors the batteries individually.
  • The paint job is done well and I don’t foresee any chipping or flaking being an issue

How to use the RX2 21700

The mod follows the standard five clicks to turn on and off. Outside of that, it’s the same old clunky menu system from the previous RX mods. I find it to be outdated and not very user friendly. If you are used to it, it’s probably not going to be a big deal, but if you are new to the RX menu system, it’s going to take time to adjust.

Use three clicks to enter the “menu,” which really isn’t a menu. It will start blinking to indicate what settings you can change. You use plus to cycle through modes, and minus to drop down and cycle between other options like locking the coil, changing power in temp mode, and resetting the puff counter. Holding plus and minus together locks the adjustment buttons. Holding minus and fire toggles stealth mode. Holding plus and fire enters the menu to turn the logo on and off, set up the pre-heat, and screen timeout.


  • Battery life
  • Battery options
  • Paint job and color options
  • Comfortable shape
  • Large bright screen


  • Power mode performance is wildly inconsistent
  • Temperature control mode performance is a dud
  • Clunky menu system is outdated


So, can I recommend the Wismec RX2 21700? If you have to ask, you probably didn’t read the review carefully. The answer is definitely no! There is no way in good conscience I could sign off on this mod. I hope that Wismec takes this feedback seriously in order to make better products in the future that I can recommend to vapers.

I started doing reviews at the end of 2016 bringing a unique amount of data and fair points that has made them grow in popularity. I’m an avid temp control vaper but will vape pretty much any style of vaping. My goal is to bring as much good, fair, and unbiased information to the forefront as I can to aid vapers in making informed decisions to get the best vape for their style. I enjoy helping people really get the most out of their vape and finding their “aha” moment when it all clicks into place.
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5 years ago


5 years ago

Hi, I would like more information about the mod compared to the Wismec Sinuous RAVAGE230 and I would like to know if it works with batteries 20700, excellent article

Anthony Victor
Anthony Victor
5 years ago
Reply to  andres

thanks for the comment. I have my full review coming soon. I just did my testing and took it apart yesterday so I’ll be submitting a review in the next day or so which should be up probably sometime next week. I’d wait until that goes up before making any purchase decisions.

5 years ago
Reply to  Anthony Victor

I read that it does not work with 20700 batteries because the 21700 that it uses (AVB) does not measure 70mm, if not 71.9mm, is it true??

Anthony Victor
Anthony Victor
5 years ago
Reply to  andres

I’ll go over all that stuff in my review 🙂

5 years ago

I read that it does not work with 20700 batteries because the 21700 that it uses (AVB) does not measure 70mm, if not 71.9mm, is it true?

Anthony Victor
Anthony Victor
5 years ago
Reply to  andres

I’ll go over it in my review 🙂

David Naranjo
David Naranjo
5 years ago

Once again, Anthony, excellent technical review! You have saved me from making a purchase I would’ve regretted; my wallet thanks you! I was looking into buying the RX Gen3, but I noticed you mentioned that the Reuleaux line uses the mod body to close the circuit to the 510 connector, rendering temp control useless. It’s beyond me why such a big player like Wismec would keep implementing such a shitty design paradigm. No wonder my RX2/3 would frequently kick me out of temp control mode. I have a hypothesis as to why the Reuleaux line usually gets positive reviews, despite… Read more »

Anthony Victor
Anthony Victor
5 years ago
Reply to  David Naranjo

thanks! always happy to help. I think a lot of the good reviews come from people either not being thorough or not caring (aka out of the box reviewers) or people just not being knowledgeable enough.