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Thread: Review: XTAR DRAGON VP4 Plus Charger

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    Flashaholic* stephenk's Avatar
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    Default Review: XTAR DRAGON VP4 Plus Charger

    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.

    Last edited by stephenk; 12-28-2016 at 01:10 AM.

  2. #2

    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    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.

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    *Flashaholic* Offgridled's Avatar
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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Definitely going to get one. Great review!!

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    Flashaholic* stephenk's Avatar
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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by OttaMattaPia View Post
    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.
    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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    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.

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    Flashaholic* stephenk's Avatar
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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by StandardBattery View Post
    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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by stephenk View Post
    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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by Tachead View Post
    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).
    Last edited by Gauss163; 12-19-2016 at 11:23 AM.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by Gauss163 View Post
    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.
    Last edited by Tachead; 12-19-2016 at 11:38 AM.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by Tachead View Post
    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.

    Quote Originally Posted by Tachead View Post
    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.
    Last edited by Gauss163; 12-19-2016 at 12:30 PM.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by Gauss163 View Post
    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.



    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.
    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.
    Last edited by Tachead; 12-19-2016 at 01:37 PM.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by Tachead View Post
    [...] 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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Thanks for the informative review stephenk. Nicely done.
    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!

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by stephenk View Post
    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.

  17. #17

    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by stephenk View Post
    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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by kreisl View Post
    The % charge reading appears to be very linear in that video!

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by Gauss163 View Post
    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

  20. #20

    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    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

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    @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.
    Last edited by Gauss163; 12-19-2016 at 07:01 PM.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by stephenk View Post
    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

  23. #23

    Default Re: Review: XTAR DRAGON VP4 Plus Charger

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

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

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by kreisl View Post
    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.
    Last edited by Gauss163; 12-19-2016 at 05:21 PM.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by TinderBox (UK) View Post
    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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by kreisl View Post
    Starting voltage was 3.0v resting voltage offline.
    Old sanyo ncr18650ga.

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

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

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    @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.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by Gauss163 View Post
    @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" .
    Last edited by Tachead; 12-19-2016 at 05:41 PM.

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    Default Re: Review: XTAR DRAGON VP4 Plus Charger

    Quote Originally Posted by Tachead View Post
    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.
    Last edited by Gauss163; 12-19-2016 at 06:34 PM.

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