# Review: XTAR DRAGON VP4 Plus Charger



## stephenk (Dec 17, 2016)

*Disclaimer*


This charger was kindly sent to me for review by GearBest.
Coupon: GBLED2016 for 8% off. 
No other payment was received for this review, and a free charger does not stop me from being critical when required during reviews. 


*Introduction*


XTAR have a good reputation for quality li-ion and NiMH chargers, and good worldwide distribution. Whilst other manufacturers such as SkyRC, Opus, and Liitokala have had analysing chargers on the market for a while, this is XTAR’s first foray into analysing chargers. Do good things come to those who wait?


Note: this review is based on usability. If you want to read technical tests, please refer to HKJ’s excellent technical review at 
http://lygte-info.dk/review/Review%20Charger%20Xtar%20VP4%20Plus%20Dragon%20UK.html












*Overview*


The XTAR DRAGON VP4 Plus comes in a cardboard box, and includes:


VP4 Plus charger
12V/3A adapter
Pair of probes
3A car adapter
Charger bag
Manual
Warranty card


The XTAR DRAGON VP4 Plus is a 4-bay charger with the following functionality and features:


Charges li-ion cells (to 4.2V only)
Charges NiMH batteries
Charges 11.1V/3s battery packs
Charge USB devices up to 2.4A such as smart phones and tablets from mains, or from cells in charger (powerbank function)
Displays charged current, and % charge
Claimed to handle a large range of cell sizes e.g. 10440 to 32650 and AAAA to D cell
Test probes that can measure the cell voltage and internal resistance (iR)
0.5A/1A/2A charging currents (2A only in slots 1 and 4)
Charge-Discharge-Charge capacity (analysing) “test” mode
Discharge-Charge “refresh” mode
No fan!
Simple user interface
Coloured status lights for each slot
Beeping noise when charge has completed
Can record and playback test results


*Design*


The XTAR DRAGON VP4 Plus is solidly constructed from heat resistant plastic. It is much larger than most other 4-bay chargers which allows for fan-less heat dissipation (unlike the Opus BT-C3100), and makes it much easier to get cells in and out of the slots (unlike the Liitokala Lii-500). The slots can handle long protected 18650 and 26650 cells up to approximately 72mm in length. As with nearly all other chargers, if protected 20700 and 21700 cells arrive on the market, they may have issues fitting. 


There are connections for the 3A/12V power supply, USB output, USB connection for test probes, and JST-XH for 11.1V/3s battery pack. I prefer chargers with 12V power supplies as they are typically more stable than USB power supplies. 






















*User Interface*


The user interface is fairly simple and easy to learn, with just three buttons:
Left - Current/Refresh button - short press will change current, long press will start refresh cycle.
Middle - Display - change between displayed slots, long press will set the display to low brightness, double click returns to main screen.
Right - Record/Test - short press will recall saved test data, long press will start a test cycle, double click will turn sound on/off.
Note: When display brightness is dimmed, the first press of any button will restore it to max brightness.


Each slot/bay has a coloured indicator light:
Blue - Discharging 
Red - Charging
Green - Battery fully charged/reverse polarity/poor connection. 


The screen displays 2 slots at a time, which can be changed by pressing the middle button. When charging 2 cells, the charger automatically displays the slots in use. With 4 cells, this alternatives between slots 1 and 4, and slots 2 and 3. 

The screen can show % charged, mode, charge current, charge current, battery type, and displayed slot. Voltage and iR measurements from the test probes are shown in the middle of the display. The display also had an animated bar effect for charging and discharging. There is no time counter. Unlike some other chargers, the screen is still easily readable when dimmed which is useful. 


When charge mode is complete for each slot, there is an audible beep, and the amount charge display alternates with “FULL”. There are also beeps with each button press. The beep can be quite useful, and can also be turned off if you don’t want to wake anyone up. 












*Operation*


The charging rates are 0.5A, 1A, and 2A (latter in slots 1 and 4 only). These charge rates suit the majority of commonly used batteries, though the lowest charging rate of 0.5A is relatively high compared to other analysing chargers. This should be OK for Eneloop AAA and other AAA NiMH that can handle fast charging. However it may not be good for AAA NiMH cells that are not recommended for fast charging e.g. yellow/green Ikea Laddas have a 0.075A recommended charging current. Newer smaller li-ion cells such as 14500 and 16340 cells should be able to handle 0.5A, though it may be too high for some 10440 cells. Thus, I would recommend this charger only for use with NiMH and Li-ion batteries that can safely handle at least 0.5A charge rates. Only 3.6/3.7V li-ion batteries can be charged (to 4.2V), which is the majority of the intended market. LiFePO4 3.2V (3.6V max) and 3.8V (4.3/4.35V max) charging is unsupported.


The default mode is charge. This starts automatically after around 3 seconds post cell insertion, so it is generally best to select the mode and current before inserting the batteries. However, the charger has a soft start, charging at a low charge rate for the first 10 minutes. Be aware that charge current can be changed during charge by pressing the charge button, and that the charge current defaults to 1A when turned on. During testing, I experienced a brief mains power outage, which was enough to change the charging rate from 0.5A to 1A. XTAR need to change the default charging rate to 0.5A in future revisions. 


All slots/bays have to use the same charge current and mode. Thus you can charge an 18650 in slot 1, and AA Eneloop on slot 2 on the same charge rate e.g. 1A. However, you cannot charge an 18650 in slot 1, whilst running test mode on an 18650 in slot 2. Neither can you charge at 1A in slot 1, and charge at 0.5A in slot 2. This may be an issue for some users, but I personally prefer to charge and test in batches of the same battery type. It is also possibly “safer” to charge this way, so that things don’t get mixed up. Whilst in refresh and test modes, charging can occur in one bay, whilst discharging is occurring in another. 


Batteries came off the charger at 1.48V for NiMH (Eneloops) and for li-ion came off the charger at 4.19V. This was measured using the test probes (see below).


One of the unique features of the XTAR DRAGON VP4 Plus is the ability to test iR and voltage using spring loaded and gold plated test probes, in a similar way to testing voltage using a digital multi-meter (DMM). DMMs can be a bit intimidating to some users, and thus this is an excellent feature. As the functionality and measuring ranges are limited, it cannot fully replace a DMM - for example you can’t use it to test flashlight tail cap current. I have been using the test probes to test iR and Voltage for each cell both before and after charge. It can also be useful to test voltage so as to decide if cells need charging or not, or even test voltage and iR on cells before and after being charged on other chargers (such as a slow NiMH charger). The test probes can be used whilst other cells are charging, but you cannot use them on cells in the slots/bays. The measurements with the probes were fairly consistent (+/-15%) as long as good contact was made, and are in theory an improvement over the measurements on the Lii-500 and BT-C3100 which have to account for multiple objects in the path of resistance. To use, the probes have to be touched together, which zeros the display, then they can be used to test the voltage and iR. The probes are directional (red probe is used for the +ve end of the battery, and the black probe for the -ve end), and thus if polarity is reversed, they record zero. The probes can be a bit fiddly to use with smaller cells. It is also easy to accidentally touch the probes together, making the display change to probe mode (other functions still continue in the background). 







The test (charge-discharge-charge) and refresh (discharge-charge) functions have a relatively low cut-off at 2.6V for li-ion. This did not trip protection circuits on the protected cells tested (two Blazar protected Sanyo NCR18650GA 3500mAh, which has the PCB set to cut off at 2.5V+/-0.1V). Most newer li-ion cells from quality manufacturers should be able to go this low, but some older or poor quality cells may not. Low cut off is 0.85V for NiMH. Discharge current is at least half of the charge current, at either 0.5A (for 1A and 2A charge rates) or 0.25V (for 0.5A charge rates). Capacity results were as expected given the discharge to 2.6V, and thus seem to be accurate. A comparison between the XTAR DRAGON VP4 Plus’s charge and discharge test and the Lii-500 discharge test on four Sanyo NCR18650GAs is below. 
Cell Dragon Disch/Ch Lii-500 Disch
1 3602/3629 3287 
2 3507/3560 3395
3 3556/3559 3388
4 3449/3568 3422












Whilst there is no dedicated discharge for storage mode for li-ion, as on the SkyRC MC3000, it is possible to just use the refresh mode to discharge the cells, and remove them from the charger at around 40% charge. 


There is no fan, and thus when discharging in all 4 slots (tested in indoor 30C ambient heat) the base of the charger was very warm. Despite the large size of this charger I found that handled heat only marginally better than the also fan-less Lii-500. If you have a laptop cooler/chill mat, I would recommend using it, though it is not essential. To select refresh or test modes, the left or right button needs a long press (respectively) before inserting the cells. When the refresh or test mode finishes, the display alternates between current discharged and current charged which is a nice touch. The test record and recall function is also potentially very useful.


The % charge display seems to be reasonably accurate. However, there are some idiosyncrasies. The first is based on its algorithm, and possibly related to how voltage typically rises rapidly at the beginning of the charge from resting voltage. For example I pulled out an Eneloop at 13% full and then placed it back in the charger 10 secs later, which then shown at 58% full. Later during the charges the % charge display returned back to more expected figures compared to the other Eneloops being charged. The same was repeated for li-ion, but with less of % jump. The display also stays on 99% for a little longer than expected during li-ion charging. When discharging, 01% is displayed for quite a long time. This is probably due to the discharge function discharging to well below what is deemed to be an empty battery by the % charge indicators (e.g. the charge discharges to 2.6V, but 01% charge reading may be based around 3.0V).


I don’t have any 3S battery packs to test that functionality. This functionality will be useful for users of RC toys and other devices that use 3S battery packs, and could avoid users having to purchase seperate chargers for li-ion, NiMH, and 3S battery pack charging. The default charge rate for 3S battery packs is 1A. 


The USB output and power bank functionality was not tested in any depth, other than to test that it works. The 0V activation functionality was not able to tested as I’ve never discharged a cell below 2.9V resting voltage during use. 


Reverse polarity detection was tested successfully, "Err" is displayed along with a rapid beeping noise when reverse polarity is detected. 


*Lack of voltage display during charging*


There has much discussion on internet message boards about the lack of voltage display during charing on the XTAR DRAGON VP4 Plus. Whilst there are plenty of popular li-ion and NiMH chargers that do not show voltage, all well known analysing chargers display the voltage during charging. Instead, the XTAR DRAGON VP Plus shows the above mentioned % charge value. It could be argued that users knowledgeable enough about batteries to want to purchase an analysing charger, would also be knowledgeable enough to be able to approximate the charging state based on the voltage alone. It could also be questioned, that users will “trust” a charger more if they can see what it is doing (i.e. if voltage has become stable at around 4.2V near the end of the charge, that it is close to termination). 


On the other side of the argument, is that it is good practice to measure voltage before and after charge with a DMM (or in the case of the XTAR DRAGON VP4 Plus, the test probes). This provides the user as to state of discharge (e.g. if the voltage is below 2.5V you might want to be a bit careful), or how well cells used in series are balancing during discharge. It also allows the user to check that the charger is terminating at the correct voltage. Thus the lack of voltage display may be a good thing if it forces the user to check cell voltage before and after charge using the test probes. 


This subject could be discussed until the cows come home, so I’ll stop now. I would personally prefer voltage display during charging along with the animated bar to show approximate charge progress. However, the lack of voltage display during charging would not stop me from purchasing this otherwise excellent analysing charger. 


*Conclusion*




Build quality is excellent, and the device functioned correctly.
The charger can charge and analyse most newer NiMH and 3.6/3.7V li-ion batteries, as long as they can handle at least 0.5A charging rate, and are less than 72mm in length.
The user interface is fairly easy to use, and record function is useful.
The test probes are a useful and unique feature for analysing chargers.
The lack of voltage display during charging is a bizarre omission. The % charge display has some idiosyncrasies, and default charge rate should be 0.5A instead of 1A.


The XTAR DRAGON VP4 Plus is clearly aimed at those who want to charge and analyse a wide range of batteries, but with a simple user interface, and don’t want to worry about using a seperate DMM to test voltage and resistance. With a relatively high price point, and some limitations (note: no analysing charger is “perfect”), it won’t suit everyone. However with many flashlight users and vapers having high disposable income, I expect that the XTAR DRAGON VP4 Plus will be a very popular product for its intended market. I recommend this charger for users who want an easy to use, simplified, and well built analysing charger.


----------



## OttaMattaPia (Dec 18, 2016)

Thanks for the review.

Almost bought this charger yesterday but decided they would probably make updates to it for the next release that would include changing the percentage voltage to actual voltage readout.

That and the price seemed high compared to competitive products that offered more such as the MC3000 (even though I have written of SkyRC products)

For now I "settled" for a AccuPower IQ338LX since at $39.95 it basically does what the Dragon does and I only need to charge 18650's and D cells. The IQ338LX holds 4 D cells simultaneously.
I hope I didn't mke a mistake buying an AccuPower product since I'm not familiar with them but it had what I was looking for (for now)

Anyway, thanks for the good info. :thumbsup:


----------



## Offgridled (Dec 18, 2016)

Definitely going to get one. Great review!!


----------



## stephenk (Dec 18, 2016)

OttaMattaPia said:


> Thanks for the review.
> 
> Almost bought this charger yesterday but decided they would probably make updates to it for the next release that would include changing the percentage voltage to actual voltage readout.
> 
> ...



I doubt they will replace the % reading with voltage anytime soon, if at all. I think XTAR are purposefully trying to make it "simpler", in a similar way to Apple dumbing down many of it's product for the consumer market (e.g. replacing Aperture with Photos, etc). As I mentioned in my review, I would personally prefer voltage readout during charging, but it wouldn't stop me from buying this product. The XTAR DRAGON VP4 Plus is now my charger of choice, retiring the Liitokala Lii-500. The only exception being for charging some NiMH cells that cannot handle fast charging, for which I use the Panasonic BQ-CC17, but measure the voltages before and after with the DRAGON's test probes.


----------



## StandardBattery (Dec 18, 2016)

Overall this seems like a pretty nice charger. I almost bought it a few times, but don't really need another charger right now unless it is extremely good and this one seems to be a bit over priced. I almost got it on the BF deal, but I think after the excitement dies a bit they won't be able to maintain this high price. I could be wrong, but even so no pressing reason to get it now. Maybe the Russians will release some enhanced firmware and transform that other charger. It could be the technical chargers on the VP2 days are over at XTAR, even as they add more capabilities they get dumbed down. With the IR measurement I think these really are aimed not at the general hobbyists, but at the Vaper community. In that market this charger seems to be well suited and price is likely just fine, so it could be this charger is just not made for the typical market one might think of using LiIon chargers. Sure they tried for some overlap in making it a NiMH and Li-Ion charger, but the extra features were likely targeted at the vap users.


----------



## stephenk (Dec 19, 2016)

StandardBattery said:


> Overall this seems like a pretty nice charger. I almost bought it a few times, but don't really need another charger right now unless it is extremely good and this one seems to be a bit over priced. I almost got it on the BF deal, but I think after the excitement dies a bit they won't be able to maintain this high price. I could be wrong, but even so no pressing reason to get it now. Maybe the Russians will release some enhanced firmware and transform that other charger. It could be the technical chargers on the VP2 days are over at XTAR, even as they add more capabilities they get dumbed down. With the IR measurement I think these really are aimed not at the general hobbyists, but at the Vaper community. In that market this charger seems to be well suited and price is likely just fine, so it could be this charger is just not made for the typical market one might think of using LiIon chargers. Sure they tried for some overlap in making it a NiMH and Li-Ion charger, but the extra features were likely targeted at the vap users.


It is most definitely consumer orientated, rather than the hobbyist orientation of the MC3000.


----------



## Tachead (Dec 19, 2016)

stephenk said:


> I doubt they will replace the % reading with voltage anytime soon, if at all. I think XTAR are purposefully trying to make it "simpler", in a similar way to Apple dumbing down many of it's product for the consumer market (e.g. replacing Aperture with Photos, etc). As I mentioned in my review, I would personally prefer voltage readout during charging, but it wouldn't stop me from buying this product. The XTAR DRAGON VP4 Plus is now my charger of choice, retiring the Liitokala Lii-500. The only exception being for charging some NiMH cells that cannot handle fast charging, for which I use the Panasonic BQ-CC17, but measure the voltages before and after with the DRAGON's test probes.



It has nothing to do with dumbing it down. Charge percentage is a much more accurate way to show charge level. Once a battery reaches the final stages of charge, for instance, it will read 4.20V but, if you arent monitoring when it hit that point it could be anywhere from a minute to 2 hours until charge is complete, there is no way to tell. Percentage readout, on the other hand, is quite accurate on many devices and will give you an idea of charge level through the whole charge cycle. There is a reason why charge percentage is used on most much higher price/quality devices as well. Although I like to have a voltage readout as well, I am finding that percentage readout is much more useful for gauging how much charge time is left.


----------



## Gauss163 (Dec 19, 2016)

Tachead said:


> Charge percentage is a much more accurate way to show charge level [...]



That's only relevant if the device can _accurately _measure charge percentage across the _entire spectrum_ of cells that it accepts. To do that requires fairly sophisticated fuel gauge algorithms, which have not yet made their way into consumer-level chargers. Any claims that the percentage is reasonable accurate are pure marketing hype (the one thing XTAR _does _excel at). Don't believe the hype.

Further, to be most useful, one desires accurate estimates of both SOC and (dis)charge time remaining. I am not aware of any consumer-level analyzing charger that accurately does so (even for one of those parameters). For many chargers it is not even clear what these nebulous displayed "percentages" are supposed to be measuring (since they are often so far off the mark).


----------



## Tachead (Dec 19, 2016)

Gauss163 said:


> That's only relevant if the device can _accurately _measure charge percentage across the entire spectrum of cells that it accepts. To do that requires fairly sophisticated fuel gauge algorithms, which have not yet made their way into consumer-level chargers. Any claims that the percentage is reasonable accurate are pure marketing hype (the one thing XTAR _does _excel at). Don't believe the hype.


Even without more advanced algorithms, it is still a far better way to estimate charge level imo(also, unless you helped design the Dragon you really have no idea how advanced the algorithms it's using are). Voltage readout does very little when it comes to gauging remaining charge time. Especially in the last stages of charge when the voltage stays at 4.2V. 

I can charge the same exact type of cells at the exact same discharge levels, one in my VP2 and one in my Dragon, and the Dragon's percentage readout allows for a far better estimate of remaining charge time imo. 

Now that I have used both kinds of readouts on several different devices, I much prefer percentage readout. I do still like to have voltage readout though to save a step(not having to use a DMM) to see the cell voltage before and after the charge cycle. During the charge/discharge cycle voltage readout is of little use imo because it is not accurate due to the cell being under load/current.

It would have been nice if the Dragon came with both methods of readout.


----------



## Gauss163 (Dec 19, 2016)

Tachead said:


> Even without more advanced algorithms, it is still a far better way to estimate charge level imo



Not true. What is true is that in some cases such heuristics may be better than alternatives, and in other cases the alternative solutions will be better. What works best in any particular context will depend on many factors such as health of the battery, chemistry, knowledge of the user, quality of heuristics, etc, etc.



Tachead said:


> also, unless you helped design the Dragon you really have no idea how advanced the algorithms it's using are).



That's a false inference too. If one is aware of the state of the art in fuel gauge algorithms then one knows well what is attainable with current technology, what the major hurdles are, etc. In particular one can easily distingish marketing hype from reality.

Wild guesstimates about SOC aren't very useful in many contexts, e.g. cells with higher IR that quickly jump to termination voltage (is it a 350mAh cell or 3500mAH cell? The charger has no way to know). Nor does it help when charging to storage voltage (it may be more that 50% off using SOC guesstimates, but the user may know the exact voltage required; being wrong here could be fatal, since it could lead cells to drain too low in storage). Etc, etc.

Generally, given any simple heuristics, it is easy to devise contexts where one is better than the other, and vice versa. Which types of heuristics prove to be more connvient for any user will depend on many factors. None will be perfect. Most will be very far from that (despite marketing hype claiming otherwise). 

None of the consumer charger manufacturers have specific expertise in fuel gauge algorithms. That's a very esoteric area that only much larger companies can afford to invest in R&D. Typically smaller companies gain access to that technology when it percolates down from the larger firms in bundled solutions. But this has not yet happened for consumer-level analyzing chargers.


----------



## Tachead (Dec 19, 2016)

Gauss163 said:


> Not true. What is true is that in some cases such heuristics may be better than alternatives, and in other cases the alternative solutions will be better. What works best in any particular context will depend on many factors such as health of the battery, chemistry, knowledge of the user, quality of heuristics, etc, etc.
> 
> 
> 
> ...



Lol, notice I said in my opinion. I have used both and even compared two Xtar products, one with each method with a number of different age and capacity cells, and I find the percentage readout to be a much better way to estimate charge level and remaining charge time over cell voltage. I realize it is an estimate and accuracy depends on many factors and I am sure that most people do as well but, I find it to be much more useful during the charge/discharge cycle, especially during the final top up when all a voltage readout reads is 4.2V for a long period of time. This is just my opinion and YMMV of course.

No it is not. Have you ran scientific tests to compare Xtars algorithm accuracy to a "large firm" as you put it? Do you design battery percentage algorithms for a living? Do you even know anything about the inner workings of Xtars algorithms? Do you even own a Dragon? Im guessing not on all counts. You are just running your mouth(keyboard) as usual Gauss. Your unsubstantiated claims and trolling, especially in the Xtar threads(havent you been warned about this?), get tiring I bet for many users, including myself, as well as for the moderators of this site. Please just move on, we get you dont like Xtar.


----------



## stephenk (Dec 19, 2016)

I'm surprised it took Gauss163 so long to start trolling another XTAR thread. The black triangle at the bottom left of posts can be used to report trolls. 

Back on topic - as mentioned in the above review the % charge is reasonably accurate. There are some idiosyncrasies based on how it handles the voltage difference between resting and non resting voltages, but that is to be expected.

Whilst I would prefer voltage readout during charging, I would agree with tachead that the % charge allows for a better estimate of how much longer there is to charge. The more I use the Dragon the more I'm liking the % charge readout.


----------



## Gauss163 (Dec 19, 2016)

Tachead said:


> [...] Do you design battery percentage algorithms for a living?



Yes, I have consulted on the design of fuel gauge algorithms so I am quite familiar with the technical aspects.


----------



## SG Hall (Dec 19, 2016)

Thanks for the informative review stephenk. Nicely done. [emoji106]
I purchased the VP2 when it first came out or I'd be all over this probably. 
I am a numbers geek so I personally prefer voltage readout over charge %, but I admit that charge % is what I mentally approximate when I see the voltage!


----------



## stephenk (Dec 19, 2016)

When I get the chance I'll do a % charge vs time charged test at intervals to see how linear the reading is. I'll publish the results here.


----------



## Gauss163 (Dec 19, 2016)

stephenk said:


> I'm surprised it took Gauss163 so long to start trolling... .



Explaining pertinent technical matters is very far from "trolling". I have no vested interest in any particular charger manufacturer, nor any bias. Rather, my intent is to share my professional expertise in order to help user's sort truth from fiction (marketing hype, old wives tales, etc). You are welcome to ignore that if you have no interest in such technicalities. But many readers do.


----------



## kreisl (Dec 19, 2016)

stephenk said:


> When I get the chance I'll do a % charge vs time charged test at intervals to see how linear the reading is. I'll publish the results here.


----------



## stephenk (Dec 19, 2016)

kreisl said:


>


The % charge reading appears to be very linear in that video!


----------



## Bullzeyebill (Dec 19, 2016)

Gauss163 said:


> Explaining pertinent technical matters is very far from "trolling".



You are perceived as trolling by fellow members, in this thread and other threads. Would be good if you stepped away from this thread, and review comments made by you in this thread and others you have made comments in, to see why you are perceived as "trolling".

Bill


----------



## kreisl (Dec 19, 2016)

the progress of biological time depicted in that video is linear: 1 frame taken per 1 biological second, speed 30x, 30 biological seconds = 1 youtube second, 30fps youtube. 8 youtube minutes = ?? biological hours, you do the math


----------



## Gauss163 (Dec 19, 2016)

@kresil It's not clear what the video is intended to imply. But since it presumably starts charging from empty cells, then that is one of the easiest cases, even for naive SOC algorithms, since they already know the exact SOC. Thus if they are matching to some model cell(s) (and the cell is similar) then the results will be very close. That's the trivial case for fuel gauge algorithms.

The harder (nontrivial) case is when you start charging at nonzero SOC (e.g. 30% or 40%), as is typical in normal use. Also one needs to test cells of widely varying capacities, and widely varying IR. That's where the sophisticated algorithms differentiate themselves from naive heuristics.

I was involved in doing similar tests for some professional level chargers, and they are extremely time consuming, so they are typically automated. This is not an easy task for a charger that has no means of automatic control. But perhaps it might be possible to jury rig some sort of automation.


----------



## Tachead (Dec 19, 2016)

stephenk said:


> The % charge reading appears to be very linear in that video!



Yeah, it sure does. Especially since it has no way of knowing the capacity of the cells in it. Seams like Xtar might have a decent algorithm after all lol. What was the starting voltage in that video Kreisl? Thanks for that[emoji106]


----------



## kreisl (Dec 19, 2016)

Starting voltage was 3.0v resting voltage offline.
Old sanyo ncr18650ga.

The YouTube is nothing to imply. It's just documentation.


----------



## TinderBox (UK) (Dec 19, 2016)

I for one like gauss163 comments, i have learned a lot from him as he has suggested solutions to problems I have had and I value his opinion.

But this is not my thread. 

John


----------



## Gauss163 (Dec 19, 2016)

kreisl said:


> Starting voltage was 3.0v resting voltage offline.
> Old sanyo ncr18650ga. The YouTube is nothing to imply. It's just documentation.



Thanks for the info. It would be very interesting to see similar tests for much lower capacity cells, and for cases where the charge starts at nonzero SOC, e.g. between 40-50% SOC.

One common approach is to use interpolation to try to match up to the charge curves for a couple common chemistries (at common currents). This can work reasonably well if your cell is close to these "model" cells, but it can be way off otherwise. How well it works depends on how much thought went into the design. It's possible that they licensed some smart fuel gauge tech from one of the big guys, which might explain the big jump in cost. But there's no way to know for sure without more extensive testing.


----------



## Tachead (Dec 19, 2016)

TinderBox (UK) said:


> I for one like gauss163 comments, i have learned a lot from him as he has suggested solutions to problems I have had and I value his opinion.
> 
> But this is not my thread.
> 
> John



The problem is, he comes into every Xtar thread with nothing but negativity flinging wild accusations about marketing hype and tooting about his vast knowledge of algorithms with no proof and no first hand experience, or actual testing, with the products he is talking about. He clearly has no interest in Xtar and has shown in multiple threads that he dislikes them. Yet, he still comes into many Xtar threads with no motive other then putting down Xtars products and starting arguments with actual users. His negative trolling is disruptive and more then one user and a few mods have asked him nicely to knock it off but, he continues to troll the Xtar threads. He has even been asked to stop posting and/or banned from multiple threads but, still continues.


----------



## Tachead (Dec 19, 2016)

kreisl said:


> Starting voltage was 3.0v resting voltage offline.
> Old sanyo ncr18650ga.
> 
> The YouTube is nothing to imply. It's just documentation.




Thanks Kreisl[emoji106]. Looks like those old GA's are still holding up well. They're good cells.


----------



## Gauss163 (Dec 19, 2016)

@Tachead If, perchance, you find something erroneous in what I posted, then by all means do feel welcome to correct it. I am an equal oppurtunity debunker of marketing hype and other pseudoscience. My critiques here are by no means limited to any one brand. I've probably discussed faults (and benefits) in every popular charger at some point or another.


----------



## Tachead (Dec 19, 2016)

Gauss163 said:


> @Tachead If, perchance, you find something erroneous in what I posted, then by all means do feel welcome to correct it. I am an equal oppurtunity debunker of marketing hype and other pseudoscience. My critiques here are by no means limited to any one brand. I've probably discussed faults (and benefits) in every popular charger at some point or another.



It's always negativity, algorithms, and marketing hype with you isn't it. 

So your just generally a troll, not just an Xtar troll. Noted. 

You should heed the advice my grandma used to give me "If you dont have anything nice to say then say nothing at all" .


----------



## Gauss163 (Dec 19, 2016)

Tachead said:


> You should heed the advice my grandma used to give me "If you dont have anything nice to say then say nothing at all" .



Would you really want to read reviews that only mentioned the positive things? We need to know both positive and negative aspects of products to properly assess them. What good would this forum be if we were excluded from telling others about the marketing hype behind 10000mAh xxxFire cells because many users who purchased them were being offended? (and yes, sadly, that does occur in some other forums).

Let me make it absolutely clear that I would be _thrilled _if it turns out to be the case that the Dragon is the first consumer-level analyzing charger incorporating an accurate fuel gauge algorithm. This would be a great advance for hobbyists. But knowing what I do about the challenges in implementing such, and knowing about complaints about fuel gauges on prior models, I exercise a healthy dose of skepticism until there is enough data to prove otherwise. That has everything to do with logic, and absolutely nothing at all to do with bias against any particular brand. In fact, if it turns out that the Dragon has a good fuel gauge, I may actually consider recommending it to users who could benefit from that unique capability.


----------



## Tachead (Dec 19, 2016)

Gauss163 said:


> Would you really want to read reviews that only mentioned the positive things? We need to know both positive and negative aspects of products to properly assess them. What good would this forum be if we were excluded from telling other about the marketing hype behind 10000mAh xxxFire cells.



The problem is you never have anything but, negativity though Gauss(especially in the Xtar threads). And, you make wild claims based on nothing but, your opinion. You don't even own a Dragon and you have never even tested Xtars algorithms. And, where does all this marketing gimmicks talk come from? Again your head. I don't see anywhere in Xtar's marketing that they use "large firm", as you call them, algorithms or that they're percentage readout is accurate to the nano second/millivolt. In fact, their marketing is very elementary and not even that good really. All they say is the LCD displays battery capacity percentage. I just don't see the gimmicks:shrug:

Maybe you don't realize how negative you are and that you generally fit the description of a troll but, many other people do including the OP of this thread and more then one mod. Might I suggest that you follow BullzeyeBill's(Moderator)advice and step away from this thread. Maybe re-evaluate some of your posts and try and work on being less negative and more constructive. Going from thread to thread being negative and starting arguments will earn you no friends around here, or anywhere for that matter, Gauss. Most people aren't looking for just flowers and sunsets but, they don't want to constantly argue and read slanderous posts that aren't even based on first hand knowledge, experience, or facts all day either. 

Anyway, I think we have derailed the Op's thread enough here. I am terribly sorry Stephen.


----------



## Tachead (Dec 19, 2016)

Gauss163 said:


> Would you really want to read reviews that only mentioned the positive things? We need to know both positive and negative aspects of products to properly assess them. What good would this forum be if we were excluded from telling others about the marketing hype behind 10000mAh xxxFire cells because many users who purchased them were being offended? (and yes, sadly, that does occur in some other forums).
> 
> *Let me make it absolutely clear that I would be thrilled if it turns out to be the case that the Dragon is the first consumer-level analyzing charger incorporating an accurate fuel gauge algorithm. This would be a great advance for hobbyists. But knowing what I do about the challenges in implementing such, and knowing about complaints about fuel gauges on prior models, I exercise a healthy dose of skepticism until there is enough data to prove otherwise. That has everything to do with logic, and absolutely nothing at all to do with bias against any particular brand.*



You edited your post.

I don't think anyone was/is expecting the Dragon to have crazy accurate percentage readout. Nor did Xtar advertise as such. It is meant as a rough gauge, an estimate, and it is a less then $80 charger. The point is it gives a better idea of charge level then voltage readout alone. It is a bonus if it turns out to be quite accurate though. 

I would have preferred it had both a percentage and voltage readout so you can see the voltage before and after the charge/discharge cycle(the only time its truly accurate) but, that is not the case. It's not much of an issue though anyway because the built in DMM is quite accurate and convenient anyway. It just takes an extra step.


----------



## Greta (Dec 19, 2016)

Okie dokie then! I've had enough - Take 10 days off Gauss163. When you come back, I strongly recommend you avoid ALL XTAR threads. Everyone (especially ME!) is sick of your constant trolling and obvious agenda to smear XTAR. Find something else to do with your time while you're taking some time off. :banned:


----------



## stephenk (Dec 20, 2016)

Right, back to sensible discussion...
I'll try and take a few videos over the next week showing some aspects of the operation of this charger. Let me know if you have any requests.


----------



## gilson65 (Dec 23, 2016)

Thanks stephenk for your review very much *appreciated*


----------



## stephenk (Dec 24, 2016)

I've uploaded a short video of the XTAR DRAGON VP4 Plus in action.


----------



## vadimax (Dec 24, 2016)

Once upon a time I'll take the Dragon I guess. Especially taking into consideration that my old like mammoth poop Thrunite MCC-4 gives inconsistent results: the slot #4 always undercharges and the slot #2 started to pass termination voltage (overcharge).

At the same time Xtar SV2 is superb.

One thing I miss so far: if I understand properly the Dragon cannot charge all slots at max current.


----------



## stephenk (Dec 24, 2016)

vadimax said:


> Once upon a time I'll take the Dragon I guess. Especially taking into consideration that my old like mammoth poop Thrunite MCC-4 gives inconsistent results: the slot #4 always undercharges and the slot #2 started to pass termination voltage (overcharge).
> 
> At the same time Xtar SV2 is superb.
> 
> One thing I miss so far: if I understand properly the Dragon cannot charge all slots at max current.


It can only charge at 2A when using slots 1 and/or 4 only. It can charge at 1A using all 4 bays.


----------



## stephenk (Dec 24, 2016)

Review updated with more clarity around discharge rates, modes, and another % charge anomaly.


----------



## doctordun (Dec 26, 2016)

Assuming I am somewhat technical savvy, but not an expert, would I benefit from getting this charger?
I am weighing my choices for an ultimate charger and so far I only have this charger and and MC3000 in my sights.
Should I be considering any other charger and is this XTAR Dragon the best choice?


----------



## stephenk (Dec 26, 2016)

doctordun said:


> Assuming I am somewhat technical savvy, but not an expert, would I benefit from getting this charger?
> I am weighing my choices for an ultimate charger and so far I only have this charger and and MC3000 in my sights.
> Should I be considering any other charger and is this XTAR Dragon the best choice?



This question could be discussed for ages. I would advise reading a few reviews of each charger, before making a decision. 
- The XTAR DRAGON is aimed for those who want a simple to use, well built, analysing charger. 
- The MC3000 is aimed more at hobbyists who want more control over their charging parameters (and thus it helps if you know what parameters you should be using, and that you have the hardware/software to perform firmware updates). 
- Also consider the Opus and Liitokala offerings, which offer excellent value for money, but somewhat debatable build quality (e.g. my Lii-500 has a dodgy LCD display).


----------



## Collins (Dec 27, 2016)

I went with the Dragon because it can do 4 bay at 1amp. And 2 bay at 2 amp.

Also because it was an analyzing charge and doesn't have a fan. Also because Xtar is supposed to be a reputable company.

Before this I was planning on getting the Rocket.


----------



## stephenk (Dec 27, 2016)

Review updated with info on reverse polarity detection test.


----------



## CelticCross74 (Dec 29, 2016)

just got my Dragon today and although quite different from the VC4's I am used to I like it a lot. Being able to charge 1 amp across all 4 slots is really cool. I just scored a pair of Feilong 32650's so should be interesting charging them at 2 amps. I like the overall package it came in. Very nice carrying case lots of accessories and even charging at half an amp it seems to be charging much faster than my now well over a year old VC4. Thumbs up from me


----------



## GTan (Jan 9, 2017)

Hurray, after reading so much about the Dragon VP4, I finally made the purchase. This is my second Xtar charger after the VC4.

I'm trying to understand if my charger is actually defective, I find that if I have a fully charged NiMH Eneloop Pro inserted, I run the battery on the Refresh cycle I get the following result,

Charge 72mAH
Discharge 45mAH

I take the battery out and replace it back into the slow so it goes through the entire discharge and recharge cycle in Refresh and it does almost the same thing again?


----------



## Tachead (Jan 10, 2017)

Since this charger is so new, I doubt there are any fakes but, do any of your Dragon's have the scratch code on them?


----------



## GTan (Jan 10, 2017)

Tachead said:


> Since this charger is so new, I doubt there are any fakes but, do any of your Dragon's have the scratch code on them?



I bought mine from Gear Best, and checked the scratch code and it appears valid. Starting to feel I could have a defective unit.


I've now done a ton of charging and I find the results all over the shop, in Refresh it starts off discharging, then after discharging for a few hours 1,500mAh discharged it goes to charging then after charging 50mAh it immediately switches to Green that it is completed. 


The voltage and IR test says it's at 1.27 volts...it does this to all my Eneloop batteries, new or old.


----------



## Tachead (Jan 10, 2017)

GTan said:


> I bought mine from Gear Best, and checked the scratch code and it appears valid. Starting to feel I could have a defective unit.
> 
> 
> I've now done a ton of charging and I find the results all over the shop, in Refresh it starts off discharging, then after discharging for a few hours 1,500mAh discharged it goes to charging then after charging 50mAh it immediately switches to Green that it is completed.
> ...


Where was the scratch code located?

Yeah, it sounds like you may have an issue.


----------



## GTan (Jan 10, 2017)

Tachead said:


> Where was the scratch code located?
> 
> Yeah, it sounds like you may have an issue.



It's a small card located in the bag, you take it out and you scratch to reveal some numbers that you enter into the Xtar.cc website.
This sucks, returning the charger from Australia to Gearbest is going to cost me much.


----------



## Tachead (Jan 11, 2017)

GTan said:


> It's a small card located in the bag, you take it out and you scratch to reveal some numbers that you enter into the Xtar.cc website.
> This sucks, returning the charger from Australia to Gearbest is going to cost me much.


Thanks, I found it. My other Xtar chargers had it right on the charger bodies, that's what threw me off.


----------



## walterr839 (Jan 27, 2017)

Question 

I have been using this charger for several weeks and am still not sure how to go back to plain charge mode after using either test or refresh.

I have resorted to unplugging it and starting over.

The instructions are not clear to me how to go about this.

Does anyone have a solution?


----------



## stephenk (Jan 28, 2017)

walterr839 said:


> Question
> 
> I have been using this charger for several weeks and am still not sure how to go back to plain charge mode after using either test or refresh.
> 
> ...


Pretty sure you have to turn it off and back on again to get back to charge mode. (Same as some other chargers such as Lii500).


----------



## walterr839 (Jan 28, 2017)

I've read and reread the manual and found the answer 
A long press of the test button to withdraw is how it's worded 

So a long press enters the mode and another goes back to charge


----------



## greenpea76 (Aug 7, 2017)

Any updates on durability of the charger body itself, specifically the charging terminal spring tabs? I had the SKYRC MC3000 and the spring tabs all broke.


----------



## TinderBox (UK) (Aug 7, 2017)

greenpea76 said:


> Any updates on durability of the charger body itself, specifically the charging terminal spring tabs? I had the SKYRC MC3000 and the spring tabs all broke.



Did you get a refund/replacment or did you fix it yourself, have you seen the cable tie fix, It looks good, just waiting for mine to die.

John.


----------



## greenpea76 (Aug 7, 2017)

TinderBox (UK) said:


> Did you get a refund/replacment or did you fix it yourself, have you seen the cable tie fix, It looks good, just waiting for mine to die.
> 
> John.



No, I haven't bothered to fix it. It went into the trash bin after a year and a half of use. It's been used quite a lot. I have not seen the cable fix. It's too late now. It's the use of the full size cells that place too much load for the poorly designed 1.5mm plastic molded pins that cause them to fail.


----------



## stephenk (Aug 7, 2017)

My DRAGON VP4 is getting almost daily use and has had no technical issues since I received it in Dec 2016.


----------



## Kallyfudge (Sep 1, 2017)

I recently got this as my first charger. I like to figure out what's best for me first rather than buying different cheaper things till I find the one I want, to try and save money. I like it although obviously cant compare to other chargers. As a complete NOOB to li ion charging, aside from using built in usb lights, having read the forum aswell before getting into it, this charger seems perfect for me.



walterr839 said:


> I've read and reread the manual and found the answer
> A long press of the test button to withdraw is how it's worded
> 
> So a long press enters the mode and another goes back to charge



Did this work for you? I have tried this after touching the probes together and it doesn't take me back to the charging screen. I have to unplug (probably loosing the charge information?) or wait 10 minutes.


----------



## HKJ (Sep 1, 2017)

Kallyfudge said:


> Did this work for you? I have tried this after touching the probes together and it doesn't take me back to the charging screen. I have to unplug (probably loosing the charge information?) or wait 10 minutes.



From my review: To start IR measurement the probes must be shorted, to leave IR mode double click the display button, the charger will also leave IR mode after about 10 minutes.


----------



## Kallyfudge (Sep 1, 2017)

HKJ said:


> From my review: To start IR measurement the probes must be shorted, to leave IR mode double click the display button, the charger will also leave IR mode after about 10 minutes.



At thank-you very much indeed! I did read your review and missed that/ it didn't go in my brain until I needed it. I really appreciate the work you have done and I have learnt a lot about LiIon batteries through your website the past few days and more to learn in the future. 

Goes without saying but I just tried it and it worked, I think the 1st click turned the screen brightness up, then double click did it. That is very handy to know as before I had to wait 10 mins before I could reassure myself I hadn't increased the charge current.


----------



## stigma45 (Jan 31, 2019)

Hello,
I need help choosing between XTAR DRAGON VP4 Plus and OPUS BT-C3100 v2.2.
I'm mostly interested in charging batteries, everything else is a bonus.
I read that OPUS has problems with power supply unit.


----------

