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Ok this is really getting on my nerves. i love my tank but i just hit the lid. and i had a problem suddenly last night. it won't close. no matter how much i try to push and slide it won't do it. it didn't fall and i don't know how it happened. i was just randomly changing my coil and it happened. please help?
Between wattage and voltage, which one is the bigger determinant of battery life? I'm currently using a DNA75 with a single 18650 battery. Compare two builds: 5.13 volts @ 25 watts OR 3.9 volts @ 50 watts.
Which build will yield the greatest battery life?
Many thanks in advance!
submitted by /u/siege0626
<a href="https://www.reddit.com/r/electronic_cigarette/comments/5qu9j5/voltage_vs_wattage_in_relation_to_battery_life/”>[link] <a href="https://www.reddit.com/r/electronic_cigarette/comments/5qu9j5/voltage_vs_wattage_in_relation_to_battery_life/”>[comments]
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/U/BrotherAstralius & /U/BrotherLuminous
Hey guys, need your help! so I am using a VTC MINI with lg h2 battery. I am vaping vaporesso coils at 28watts and I have noticed when the battery shows half full on the vtc I get a much weaker vape which is no fun at all 🙁 how do I fix this? Buy a new battery or new mod? thanks
submitted by /u/Speedygonzalees
<a href="https://www.reddit.com/r/electronic_cigarette/comments/5qtxz0/help_regarding_weak_vape_when_battery_half_full/”>[link] <a href="https://www.reddit.com/r/electronic_cigarette/comments/5qtxz0/help_regarding_weak_vape_when_battery_half_full/”>[comments]
Alright, here we finally go on the full test for the RX200 / RX200S! Possibly the most controversial mod in existence for USB charging. I'm expecting this post to be controversial as well! My very first post to ECR was a quick test on the RX balance charge issue but I have not actually ever run the RX200 or S through a full test. I understand this is very late in the game considering the age of these devices, yet I feel this needs to be covered. This is a fairly complex analysis with a lot of points so apologies in advance for the length and incessant rambling. Analysis here can also apply to other non-balancing series regulated devices.
Vapers far and wide passionately claim that charging the RX (and other multi-cell mods) by USB is a crime against everything and doing so will surely cause a rip in the time-space continuum. So why exactly is this? The main points I see are about device failures and safety of the actual charging function – specifically the lack of balance charging. Please keep in mind that these are two entirely separate issues.
This report is therefore broken up into 2 main sections – Actual USB charge performance and Discussion on failures as well as a bonus (??) rant on charge balancing theory. The first section is the physical operation and testing data on a properly functioning device, the second section is some tests and evidence but mainly opinions and theories on failures. The results here are applicable for both the RX200 and RX200S unless stated otherwise.
Here is the disclaimer – the results within are what I have found with the devices available to me and what I believe those results to mean. Deciding whether or not to use the USB charging function on the RX is entirely up to you!
For this test my own RX as well as an original RX200 and RX200S kindly donated for testing by VapourEyes were put through their paces. Massive thanks as always to the crew at VE, you guys are awesome.
Actual USB charge performance:
It is well known that the RX series (apart from the DNA200 version) does not balance charge. The RX like other non-balancing mods simply charges the cells in series as one big cell. It does however monitor each cell individually via a tap in between cells 1-2 and 2-3. This allows the device to perform a charge cut-off based on the high cell and a discharge cut-off based on the low cell as well as check for cell imbalance. Individual cell voltage monitoring is an essential function of any multi-cell device whether it is capable of balance charging or not.
Here is the graph of the total series cell voltage increasing over a typical charge cycle. In this case the total series voltage achieved at charge termination was 12.6V. The cells in this case were fairly close in starting voltage before charging. With imbalanced cells the maximum series cell voltage at cut-off will be lower due to charge cycle termination on the high cell. Both the RX200 and RX200S charged the highest cell to a maximum of 4.22V +/-0.01V (ideal) every time. Under no circumstances regardless of initial cell voltage did either the RX200 or RX200S overcharge a single cell. In a properly functioning device, it is impossible for any of the cells to be over-charged or over-discharged.
The logged USB input current graph is here. The maximum input current recorded was 924mA meaning a 1A or above USB adaptor should be used. A 2.4A supply was used for all of the testing. We can see from the graph that the input current is well regulated and maintained at a very steady level throughout the cycle. No tests were performed with a 500mA adaptor as this would result in a charging current so low as to be practically useless. Don't bother trying to charge the RX on a 500mA PC port either. When manufacturers and other testers quote the “charge rate” of a device, they are almost always referring to the input current. Keep in mind this is not directly comparable with the current rate on an external charger which is the actual per-cell charge current.
Charge current: Here is the actual cell charge current graph. The RX charges at quite a low actual cell current rate at 265mA. Needless to say this is a safe charging current. This low charge rate is due to the boost converter having to increase 5V at 924mA (around 5W) up to the maximum of 12.6V plus some inefficiency. This is also reason why we see the charge current gradually drop as the cell voltage rises. From dead flat it's going to be a very lengthy cycle – well above 10hrs. The current drops to a lower level (less than 100mA) as the cells approach a full charge voltage. I believe the charge circuit in the RX is more or less identical to that of the Cuboid with the addition of an extra monitoring channel.
Charge cut-off / termination:
Upon the highest cell reaching 4.22V, the charge cycle is terminated. The RX does not float charge or discharge the cells in any way after the cycle has finished which is ideal. This is a proper charge termination and I could not datalog long enough to notice any extraneous recharging of the cells which is also a good thing. There shouldn't be any issues with leaving this device plugged in an extended period after full charge as the circuit is inactive. As with any charging device it is still good practice to unplug after a charge cycle has finished. The USB input power is shared to power the standby current of the board after full charge unlike the SMOK Alien and Sigelei / Fuchai 213. This avoids any standby discharge of the cells and subsequently any need to keep boosting the cells to maintain a full charge. The charge cycle cut-off is based on voltage and not current. External chargers commonly terminate a charge cycle on cell current hitting a certain low threshold while at the maximum charge voltage. Terminating on voltage is just as safe (if not more so) but may result in an under-charged cell if the initial charge rate is high. It's so low in the RX that by the time the highest cell has reached 4.22V, the saturation phase has already well and truly occurred and the cells will have a proper full charge. This is about the best method I can think of in a simple charge system without balancing.
Rotating batteries, uneven charging etc:
Pretty much every device I have tested has had its quirks, and here is the RX's. For quite a long time I have been saying that there is no need to rotate cells and that it is impossible to charge cells unevenly in either a series or parallel device. Also that cell unbalancing occurs due to small differences in capacity, internal resistance and self-discharge from cell to cell adding up over time. This all still remains true in a straight series configuration where no current is escaping the series loop. By definition, current can not flow unequally through series circuit elements. HOWEVER, multi-cell mods do in fact have pathways where current can flow out of the series cell loop – via the voltage monitoring taps. These taps are there simply for a reference voltage so the board can tell what the cells are up to, there should be negligible current flow (microamps) as they are high-impedance inputs. Every device tested so far has had negligible current flow out of the monitoring taps and thus the cell loop can be analysed as a straight series configuration. Rotating cells in this case is pointless.
In the case of the RX though, the current flow is not negligible. The RX can in fact unbalance cells during charge and discharge, through the voltage monitoring taps. When the board is active during charging or in use, around 0.8mA of current flows out of each monitoring tap depending on the state of charge. A tiny current flow but not as tiny as it should be and will prove to be of significance. This diagram might make it a little easier to visualise. Starting from the main negative cell connection, 0.8mA of current is flowing out of the connection between cells 1 and 2, and another 0.8mA is flowing out of the connection between cells 2 and 3. This in turn means that compared to cell 3, cell 2 is being discharged 0.8mA more and cell 1 is being discharged 1.6mA more. This also applies to charging but in this case it means that cells 1 and 2 are being charged 1.6mA and 0.8mA less than cell 3. Since the voltage monitoring circuit is constantly active during charging, this slight difference in charge is also happening constantly and does add up. When the device goes into standby when not in use or after a charge cycle has terminated, the cell monitoring circuit is not active and the current flow drops to a very low (negligible) level – around 30.6uA. The cells will not be becoming unbalanced at standby but will be during use or charging. Even with this draw though, the cells will not get noticeably unbalanced using and charging every day by USB for a week.
This is not all as bad as it sounds though, we can actually use the small voltage monitoring current flow to our advantage in that we can change the charge on cells individually just by their position. This is more than enough to compensate for unbalancing effects due to differences in the cells themselves.
Here are 8 consecutive USB charge cycles – cells are numbered 1-3 and are in the same numbered positions in the sled for the first 4 cycles. The cells were not perfectly balanced to begin with as the cells had already done a few USB cycles since being on an external charger. The cells used in this test are Samsung 30Q's, about 3 months of regular use old. After full charge the device was used normally until showing about a quarter remaining charge on the on-screen battery level indicator.
Cycle 1: Cell 1 – 3.59V → 4.17V
Cell 2 – 3.60V → 4.19V
Cell 3 – 3.61V → 4.21V
V-difference at full charge = 0.04V
Cell 1 – 3.60V → 4.15V
Cell 2 – 3.61V → 4.19V
Cell 3 – 3.62V → 4.21V
V-difference at full charge = 0.06V
Cell 1 – 3.58V → 4.14V
Cell 2 – 3.60V → 4.17V
Cell 3 – 3.61V → 4.21V
V-difference at full charge = 0.07V
Cell 1 – 3.57V → 4.12V
Cell 2 – 3.60V → 4.16V
Cell 3 – 3.62V → 4.21V
V-difference at full charge = 0.09V
Cells 1 and 3 were swapped positions so cell 3 is in the sled 1 position, cell 1 is in the sled 3 position. Cell 2 remains in the sled 2 position.
Cell 1 – 3.63V → 4.14V
Cell 2 – 3.65V → 4.18V
Cell 3 – 3.67V → 4.22V
V-difference at full charge = 0.08V
Cell 1 – 3.60V → 4.16V
Cell 2 – 3.62V → 4.19V
Cell 3 – 3.63V → 4.21V
V-difference at full charge = 0.05V
Cell 1 – 3.446V → 4.17V
Cell 2 – 3.466V → 4.19V
Cell 3 – 3.481V → 4.20V
V-difference at full charge = 0.03V
Cell 1 – 3.523V → 4.19V
Cell 2 – 3.526V → 4.20V
Cell 3 – 3.528V → 4.19V
V-difference at full charge = 0.01V
We can see the cell voltages drifting apart for the first 4 cycles, then actually returning back to an almost perfect balance after cycle 8. Since cell position 1 discharges the highest at 1.6mA, cell 2 at 0.8mA and cell 3 is at reference, the cells can be re-balanced by placing the highest to lowest charged cells in order of positions 1, 2, 3 in the sled. Determining the exact cell voltages is best done by multimeter however the built-in voltage checker while not terribly accurate can be close enough. What all this means is that the RX200 and RX200S can in fact charged by USB only permanently with regular cell rotation, never actually needing an external charger. Yes, you heard that right!
Built-in voltage checker:
The built-in cell voltage display function is accessed by 5 clicks to turn the device off, then pressing both the fire button and left button simultaneously until the voltage is displayed. Looking into the battery sled of the RX200/S the left-back position is cell 1, the front single cell is 2 and the right-back cell is 3. The RX200 displays cells 1, 2, 3 from left to right. The RX200S displays the cells 1, 2, 3 from top to bottom. This is also the order they are configured in series with cell 1 negative being connected to the main device negative and the positive of cell 3 being the main device positive. The accuracy on the latest firmware version (3.13) for the RX200 is not as bad as it used to be. Surprisingly though, the accuracy is by far the best on the RX200S with firmware 4.00. Every version after is worse. I thought I was imagining this so I ran through every firmware after 4.00 with pretty much every cell position combination on the RX200S. I didn't test earlier versions of firmware for the RX200 as there's no reason to run an earlier version. Here are some tests comparing my multimeter readings to the mod readings for both the RX200 and RX200S. Cells are deliberately out of balance and are checked in different positions. MM stands for the multimeter reading.
RX200 (firmware 3.13)
RX – 4.20 4.25 3.85 MM – 4.21 4.24 3.83
RX – 3.83 4.22 4.24 MM – 3.83 4.21 4.24
RX – 4.23 3.86 4.20 MM – 4.24 3.83 4.21
Average variance: 0.011V
RX200S (firmware 4.00)
RX – 4.24 4.20 3.83 MM – 4.24 4.21 3.82
RX – 4.22 3.82 4.22 MM – 4.21 3.82 4.24
RX – 3.84 4.21 4.20 MM – 3.82 4.24 4.21
Average variance: 0.012V
RX200S (firmware 4.13)
RX – 4.15 4.27 3.82 MM – 4.21 4.23 3.83
RX – 3.78 4.24 4.21 MM – 3.83 4.21 4.23
RX – 4.16 3.88 4.19 MM – 4.23 3.83 4.21
Average variance: 0.038V
The latest version of the RX200S firmware (4.13) is quite a lot less accurate than the original 4.00 firmware. If you plan on USB charging your RX200S and wish to use the on-board voltage checker as an indication of when to rotate cells, firmware 4.00 is the way to go.
To round all that up: When charging the RX200 or RX200S by USB, you can keep your cells in balance by periodically checking the cell voltages and rotating as required. Put the highest voltage cell in sled position 1, the next highest in position 2 and the lowest charged cell in position 3. Re-check after a week or so. Simply shifting each cell one position every 4-5 cycles would most likely do the trick too.
So what happens if you don't rotate your cells and they become out of balance? Nothing really, aside from an increasingly shorter time between full charge and a empty. At around 0.3V cell difference, the RX will warn of battery imbalance only when plugging in to USB. It will however both fire and charge with any level of imbalance. This may sound like a terrible idea but in reality you could actually put any combination of cells at any starting charge difference and not have a problem. A Samsung 25R at almost dead flat (3.23V) was mixed in with two almost fully charged Subohmcells at 4.11V each. In this case the RX showed just a touch over empty on the battery meter. “Weak battery” was shown immediately when firing as the 25R was already at the discharge cut-off voltage. A very small amount of vapor was produced (the RX will fire at a lowered wattage with near-empty cells) until it refused to fire altogether shortly after. The RX200 will hard cut-off at 3.2V whereas I could discharge a low cell to 3.1V on the RX200S with some effort. On charging these massively imbalanced cells, the RX simply cuts off when one cell hits 4.2V. The same Subohmcell and 25R combination were charged until cut-off with the final voltages being 4.22V, 4.22V and 3.49V. No cells were damaged. To further demonstrate the ability of the voltage monitoring function to prevent problems, here is a pic of an unwrapped (to remove the button top – don't try this at home) super-shitty “Ultrafire” brand cell in an RX with two Subohmcells. All 3 cells are fully charged and the mod was set to 250W. The RX instantly shows “battery low” as the rubbish Ultrafire battery sags immediately to the 3.2V cutoff. No heat, no exploding cells.
Board Quality: The board itself is not bad. Very compact, simple and well arranged. Components seem well soldered and positioned. The rest of the internal construction is crap though. Wires are too small, battery sled is flimsy thin plastic and we all know about the 510 reputation.
Bonus Cell balance rant:
Cell balance is a massively over-estimated indication of safety on a regulated device such as the RX200/S. It is commonly referred to as the deciding feature as to whether a device is safe to charge on or not. The thing is, it's just not that important as far as safety goes. Don't get me wrong, it is always best to have a good matched set of cells at the same voltages in any multi-cell mod. The reason though is for maximum time between charges and not safety in particular.
A few points relating to myths about cell balance:
-Cells in series do not charge each other -Low cells do not get more “stressed” on discharge than the others -Low cells will not be over-discharged when installed with other cells at a higher state of charge -High cells will not be over-charged when installed with other cells at a lower state of charge -A cell will not be damaged by operating in an unbalanced state with the other cells -Cells will not instantly become “unmarried”
This is all due to the independent cell voltage monitoring performed by the device. The upper and lower voltage limits of each cell will never be exceeded under any condition. It does't matter if you try to fire the device with mixed charge cells at the maximum wattage (CDR still applies for each individual cell) – as soon as one cell sags to the cut-off voltage, firing will either be reduced in power or prevented. The low cell will be the limiting factor. Series current flow must be the same through all the circuit elements (in this case the cells) but the voltage across each element can be split in any combination. The voltage of each single cell is not being forced to any particular level by the other cells. Each single cell discharges (or charges) at its own voltage level regardless of the others. Due to the upper and lower voltage limits on a regulated device, imbalanced cells will each be operating in a different voltage range. Let's have a quick look at a simplified example of three cells discharging while being imbalanced.
In this example the device is at “full” charge as one cell is at 4.20V.
Cell 1 – 4.20V, Cell 2 – 3.90V, Cell 3 – 4.10V
Upon discharge at approx. 100W, the cells all discharge at a rate of 8.2A as the series voltage is 12.2V.
At low battery warning (3.2V lowest cell cut-off) –
Cell 1 – 3.50V, Cell 2 – 3.20V, Cell 3 – 3.40V
Due to the lower cell voltages (now 10.1V) at cut-off, around 9.9A was being drawn to achieve the set 100W.
Cell 1 has discharged 0.7V from 4.20V to 3.50V at a current of 8.2A to 9.9A. Cell 2 has discharged 0.7V from 3.90V to 3.20V at a current of 8.2A to 9.9A. Cell 3 has discharged 0.7V from 4.10V to 3.40V at a current of 8.2A to 9.9A.
None of the above cells could care less that they have been discharged with cells in different voltage ranges. They each discharged a total range of 0.7V and at a current of between 8.2A and 9.9A. Overall life between the device showing full and low is considerably lower than if the cells were balanced, however none of the cells have been operated outside their respective safe voltage ranges.
So what happens if the voltage monitoring system of your device fails? In short, your device is broken and would most likely not fire. Cell balance in this fault condition is irrelevant. The device checks the individual cell voltages as well as atomiser resistance each and every time it fires.
The last consideration is long-term wear on cells from operating in differing voltage ranges. In proper use, cells would either be rotated (at this time only needed for the RX, possibly the Cuboid) or charged externally after a certain number of cycles. On average, the wear would be equal. This also comes down to whether (and how much) a lithium cell experiences a different rate of aging depending on the voltage range it is operated in. Theory states that the upper voltage range is more stressful for lithium chemistry. It is plausible that if cells were never rotated or charged externally that some cells would have a resulting capacity loss to a different degree in the long term than the others due to spending more time at a higher voltage. This effect is going to be a fairly minor factor compared to the high discharge rates and frequent cycling we subject our cells to. It's almost not worth considering in my opinion. I don't believe properly using the USB charging function (rotating / occasional external charging) on the RX will “unmarry” the cells in any way. Not a chance in hell over a single cycle. We can go a little further with this and show that even cells which have aged (and lost capacity) unequally are still not a problem. In this case the cell or cells with lower capacity will lose voltage quicker with the same current draw. These lower capacity cells will simply hit the low-cell cut-off sooner than the healthier cell/s in the series set.
Discussion on failures:
There have been many reports of RX200's failing during USB charging. I have not been able to obtain a RX200 or RX200S for testing which had been reported to have failed while being charged by USB. These theories and opinions are based on the tests I have performed on the 3 working units I have as well as anecdotal evidence. If anyone has a failed RX200 (specifically showing a “Check battery” error) that they would be willing to send me, I'd be more than happy to pay for postage.
In order to analyse how and why these have occurred these are the questions I wanted to answer.
Does this device have a design fault with the USB charging function which would result in an almost certain chance of failure which is repeatable, even under a certain condition?
Well, I can't find one. And believe me I have tried. I would conservatively estimate the total USB charge cycles I have performed to be around 200 spread across 3 devices. In the last 3 months I have used my external charger maybe twice. When I had time I would use the discharge function of an iCharger 106B+ in order to have more depleted cells to charge. I have tried every unfavourable combination I can think of. I was basically on a mission to make a device fail. These include:
Wildly unbalanced cells (3.2V mixed with 4.20V and other combinations) Cells of different brand / capacity / age Terrible quality cells – “Ultrafire 4000mAh” with the button-tops removed USB supply up to 7A USB voltage boosted to the maximum allowable of 5.5V Devices left plugged in to USB for over a week Low quality charge cables
As a total anti-climax, all 3 devices are still working perfectly. Personally, I would have much preferred to find a specific condition which could cause a failure. This would have also allowed me to do an autopsy on the failed device and potentially identify a cause. I can't say that your particular RX200 won't fail as a result of using the USB to charge, but none of mine did.
Can we establish that the failures seen are definitely a result of USB charging?
I have no way of knowing which failure reports were genuine charge circuit failures or as a result of drops, rough use, moisture etc. I'm sure some devices did genuinely fail from being charged by USB. I also have to consider that if a device fails and has been charged by USB at some point, this doesn't necessarily mean that USB charging actually caused it. We have no way of knowing if these devices would have failed anyway. The most common failure reported was the “Check battery” error. This means that the main microprocessor cannot determine one or more of the individual cell voltage levels. This is confirmed by devices with this failure often showing 0V readings on the voltage check function with fully charged cells. I have seen the many reports of this error with devices which had been charged by USB, but also with devices which hadn't. The circuits which upon failing that could cause this error are the voltage monitoring circuits. These are permanently energised any time there are cells installed regardless of whether the device is being charged or not. Also, they are not actually affected by charging itself – charging current is being applied via the main negative and positive series cell connections. The voltage monitoring taps don't experience any condition during charging which they wouldn't anyway with charged cells fresh off an external charger. Whether the charge circuit itself has a physical connection with the voltage monitoring circuits is something I also cannot tell without seeing an actual schematic. It's possible if the voltage monitoring circuits are directly controlling the charge circuit operation. If the microprocessor itself is controlling the charge circuit operation based on what it receives from the voltage monitoring, then even a charge circuit failure shouldn't be able to cause a “Check battery” error. Again, I'd love to have a failed device to dig into this further.
Does charging the RX200 by USB result in a “bricked” device every time or even after a certain amount of cycles? I.e. does the RX200 have a design fault?
After as many cycles as I have seen, I can't see how honestly. For there to be a design fault there has to be a condition which would reliably cause a device to fail. There was nothing I could do to make an RX fail while being charged by USB. I also couldn't find a single component which runs hot enough during charging to pose a problem. I can't have the only 3 RX's in existence which somehow just don't fail, electronics don't work that way. Keep in mind, a faulty or even batch of faulty RX's is not the same as a design fault.
Months ago when I started proper research into this issue, I hit up the friendly chaps at VapourEyes to send me a returned RX which had died by USB charging, assuming by reports that they would have many. Nope, not a single one. In fact, the only failed RX they had was one that had been soaked to the board in <a href="http://www.vapininthecape.com/<a href="http://www.vapininthecape.com/eliquid_c_7.html”>eliquid_c_7.html”>juice. I'm not at liberty to say how many units they have sold (and for the record VE is totally impartial on this issue, I'm not in any way representing their opinions), but being one of biggest online vape stores in Australia, it's quite a few. Again, this is pretty much all anecdotal evidence – take it for what it's worth.
Potential causes for failures:
At this point, all the testing and research has led me to my personal opinion that there are 2 possible causes for failures aside from devices which had been dropped or otherwise abused. I do not believe there is a design fault.
Firstly, a short somewhere in the voltage monitoring wiring or connections. These 2 wires coming from in between the cells in the sled are incredibly tiny and snake through the mod. There is a very real possibility that these wires had been getting snagged or damaged during assembly and eventually rubbing through to short out on the case. There is a little too much excess wire just near the board and I did in fact find a small area of insulation (pic here) on one wire which had been damaged, presumably from touching a hot soldering iron while the device was being assembled. The sled itself is also of very poor quality and the plastic seems to crack just near the positive mark on the outer cell position. The monitoring wires are soldered onto the between-cell connections inside the top and bottom pieces of the sled. If one of the voltage monitoring wires becomes disconnected, the device will show the check battery error. If one wire rubs through to case metal and shorts, it will be instantly cooked by the full battery voltage and fail. This would give a burning smell and will also cause the check battery error.
The second possible cause is simply a batch of faulty boards. It is definitely possible that some boards did in fact have faulty components which caused outright failures when using the USB port to charge. Most failures reported happened within a fairly small time frame. Adding evidence to the faulty batch theory is that I've seen very few reports of the RX200S failing, as well as VapourEyes not having any returned units with this fault. Perhaps Australia received an entirely different production run. I don't believe the lack of reported failures for some time now is due to no one ever using USB to charge anymore. It seemed like most failure posts were from new or non-regular members which would lead me to think that if RX's were still failing with USB charging we would see more reports from new users who have not seen all the advice given on ECR.
Once again I'll state that all these theories are just my personal opinion! I can only report on what I have seen in my experiences testing the RX's I have, which is months and months of testing and more cycles than I can count but is still not comprehensive.
To charge by USB or not?
It is, of course, entirely up to the user to decide. The actual operation on a working device is safe. I could not find any design fault which would definitely make an RX fail. As far as failures go however – I would say that if the RX200/S is your only mod and is completely relied upon or you could not afford to replace it, then no, don't risk it. The result of the consumer driving production of devices with the most power and features for the lowest price is always going to result in a certain number of failed units. While I believe the failures of USB charging the RX200/S may be higher than others I also think it has been completely blown out of proportion. Using the USB to charge in any device introduces another point of failure though – there's no way around it. I personally think of it as if never using the headlights in your car will mean you'll never have to replace a bulb. It doesn't mean I'm going to avoid driving at night though. A pretty crappy analogy but you get the point. I also think that if there is an advertised feature on a device which would be a benefit to me, I'm going to use it. I personally detest having to remove my cells to charge them. I've never understood the obsession with external chargers. I can't get through my working day on a half-charge so I need to charge every night. I prefer to have a silicon sleeve on my RX as I'm in a dirty motorbike workshop. I honestly can't be assed taking the sleeve off, plugging the external in, installing the cells, then having to repeat the process in reverse first thing in the morning (I fucking hate mornings) when I'm running late and have precious little time to transform myself into a semi-functioning human to get myself off to work. I'll take the risk of plugging my mod in every time. If it fails, I'll buy a new one. Not to get too dramatic, but vaping has saved my life and the cost of an occasional failed device seems like a drop in the ocean to me.
Max. USB current draw: 924mA
Max. charging current: 265mA
Cut-off voltage: 4.22V (highest cell)
Charge efficiency: Approx. 63.6% at 11.1V
Highest board temp. measured during charging: 44.9degC / 113degF (27.7degC / 82degF ambient)
Restarts charge cycle on plugging / unplugging USB (full cell): Yes
Restarts charge cycle on remove / reinsert cells: Yes
Balance charges: No
Standby current: Approx. 30uA
Overcharge under any condition: No
Protected with reverse polarity cells and USB plugged in: Yes
Charge circuit noise: 0.4mV (Oscilloscope pic)
TL;DR: The actual charging performance of the RX200 and S is as good as possible for a non-balancing system. battery imbalance is not as big of a deal as it's made out to be. Cell imbalance can be completely overcome by rotating the cells on this device. If not rotating the cells, charge externally once per week. Charge rate is slow but safe at 265mA. The maximum charge voltage is 4.22V per cell which is ideal. Under no conditions or circumstances were any cells overcharged and the circuit performs a proper charge termination based on the highest cell. There's no TL;DR for failures, you'll have to make up your own mind on that one!
Disclaimer!! Use USB charging at your own risk. The data, testing and analysis here is taken seriously and all efforts have been made for accuracy – However, please do not take anything here as gospel. Mistakes and assumptions may have been made. I try to make it clear where something is my personal opinion or belief, and hopefully provide enough data so that it is possible for you to do your own analysis and come to a conclusion that suits you. Please let me know if you believe mistakes have been made in either the analysis or testing. It is always good practice to disconnect power from any charging device after your cells are fully charged.
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