Test/Review of Charger Xtar SV2 Rocket

HKJ

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[size=+3]Charger Xtar SV2 Rocket[/size]

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This Xtar charger can charge NiMH and LiIon batteries, it can handle fairly large cells and can also use a both low and fairly high charge current.



I got the charger in a retail cardboard box from. The box has a lot of specifications printed on the back.

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The box contained the charger, a mains power supply, a car adapter a instruction sheet and a warranty card.

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The charger has a DC input socket (5.5/2.1mm) where either the power supply or the car adapter can be connected.

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The user interface is a display, two leds and one button.
A short press on the button will change charge current between 0.5A, 1A and 2A, a double tap (Why?) will change to 0.25A, a long press will turn the display off. With display off a short press or removing/inserting batteries will turn it on again.
The CH1/CH2 leds are red while charging and green at all other times.

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The display shows selected current and how much the batteries are charged. After some time the brightness will be reduced, but it is still easy to read the display and a press on the button will return it to full brightness.

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The charger uses the typical slider construction with a metal rail and works smoothly from about 30mm to 71mm, i.e. the charger can handle long protected 18650/26650/32650 cells.
Notice the long metal bar at the plus connection, this makes it possible to handle 32650 and D cells, it also means that flat-tops with very retracted plus pole may need a magnet to connect (The flat-top cells I tested worked directly).

supportedBatteryTypes.png


supportedBatterySizes.png
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The charger can handle 71 mm long batteries, including flat top cells.
Many high current 18650 can be charged at 2A with only a minor impact on lifetime.



[size=+2]Measurements[/size]


  • When not powered a LiIon will discharge with about 2.3mA.
  • When not powered a NiMH will discharge with about 0.8mA.
  • When LiIon battery is full the charger will charge with 0.6mA.
  • The charger will restart if battery voltage drops below 3.94 volt.
  • Charge will restart charging after power loss, or battery insertion.
  • Charger will charge from zero volt with about 100mA
  • Below 2 volt the charger assumes NiMH
  • Between 2 and 3 volt the charger uses 10% charge current
  • Above 3 volt regular LiIon charging is used.
  • Power consumption when idle is 0.6 Watt (0.9W with bright background light).


[size=+2]Charging LiIon[/size]

Xtar%20SV2%201A%20(PA18650-31)%20%231.png


Nice and fast CC/CV voltage charging with 65mA termination.

Xtar%20SV2%201A%20(PA18650-31)%20%232.png


It is the same on the other slot.

Xtar%20SV2%201A%20(SA18650-26)%20%231.png

Xtar%20SV2%201A%20(PA18650-34)%20%231.png


Other capacities are handled just as fine.

Xtar%20SV2%201A%20(BE18650-26)%20%231.png


Also the old cell is handled as fast as possible, but due to the higher resistance it will spend more time in CV phase.

Xtar%20SV2%200.25A%20(KP14500-08)%20%231.png


Again a good CC/CV curve and the termination current is lower at 35mA.

Xtar%20SV2%200.5A%20(AW18350-IMR)%20%231.png


Also a good charge curve.

Xtar%20SV2%201A%20(2xPA18650-31).png


The charger easily handles two cells at 1A.

Xtar%20SV2%202A%20(2xAWT18650-30).png


At 2A the temperature raises, but the charge curve is the same nice one.

Temp3209.png


M1: 45,3°C, M2: 45,8°C, M3: 48,0°C, HS1: 62,9°C
At 2A the charger is warm.

PowerOnLiIon.png


The charger needs 2 to 4 seconds to start, as can be seen the current slowly ramps up.

CurrentChangeLiIon.png


This is also the case when changing current, when increasing current it is ramped up, when reducing current drops immediately.



[size=+2]Charging NiMH[/size]

Xtar%20SV2%201A%20(eneloop)%20%231.png


The charger start charging NiMH with a low current, then after about 10 minutes it goes to the selected charge current. Termination looks to be on voltage in this case here, followed by a two hour top-off/trickle charge at 50mA (Charger displays done).

Xtar%20SV2%201A%20(eneloop)%20%232.png


It is the same on the other channel.

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The 3 high capacity cells are also handled fine, two of them with -dv/dt termination.

Xtar%20SV2%200.5A%20(eneloopAAA)%20%231.png


I use a lower current here, this also means the top-off charge is done with slightly lower current.

Xtar%20SV2%200.25A%20(eneloop)%20%231.png


With a 0.25A current there is no -dv/dt signal to termination on and it looks like the charger terminates on time.
This is not a fault with the charger, but use of wrong charge parameters for the cell.

Xtar%20SV2%201A%20full%20(eneloop)%20%231.png


The charger takes some time to detect a full cell, first the 10 minutes with slow charging and then a few minutes with full current.
It do also use the top-off/trickle in this case.

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Two cells at 1A is no problem.

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Neither is two cells at 2A, but things are starting getting warm.

Temp3203.png


M1: 46,7°C, M2: 46,7°C, M3: 46,1°C, M4: 57,6°C,HS1: 63,2°C

PowerOnNiMH.png


The charger needs about 4 seconds, before it starts a low current charge.

PowerOnNiMH2.png


10 minutes later it will switch to full current.

CurrentChangeNiMH.png


With NiMH the current do not ramp, but jumps directly to selected value.

TrickleChargeNiMH.png


The top-off/trickle charge is done with current pulses at the selected charge current. The pulse is 1 second wide each 21 second. This gives 47mA at 1A charge current.



[size=+2]Charging LiIon and NiMH at the same time[/size]

It is possible to charge one LiIon and one NiMH battery in the charger at the same time.
As usual the temperature sensor is on the opposite cell.

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In this curve I recorded the NiMH battery, it looks the same as above.

Xtar%20SV2%201A%20(PA18650-31+eneloop).png


The LiIon also looks the same as above.

Testing the mains transformer with 2500 volt and 5000 volt between mains and low volt side, did not show any safety problems.



[size=+2]Conclusion[/size]

This charger can handle from 10440 cells to 32650 cells or AAAA to D cells, the only requirement is that the user selects the correct charge current. The display is rather simple with only current and charge percent.

For a "simple" charger this is a very good charger for both LiIon and NiMH.



[size=+3]Notes[/size]

The charger was supplied by Gearbest for a review.

Here is an explanation on how I did the above charge curves: How do I test a charger
Read more about how I test USB power supplies/charger
 

sidecross

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It appears this is the replacement for the XTAR SP 2 charger.
 

scintillator

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Thanks for the detailed review HKJ very helpfull as usual.
I have been using this charger for about a month now and it is easy to use.
 

Gauss163

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It would be interesting to compare the thermal imaging temperatures to other chargers, e.g. compare this to the Opus BT-C3100. But you don't seem to always list the conditions (e.g. current, ambient temp, etc) under which the thermal imaging was performed, so we could be comparing apples to oranges. Perhaps you could update the reviews with this info if you still have it (and maybe it would be useful to attempt to devise a "standard" context to make comparisons easier).
 
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HKJ

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It would be interesting to compare the thermal imaging temperatures to other chargers, e.g. compare this to the Opus BT-C3100. But you don't seem to always list the conditions (e.g. current, ambient temp, etc) under which the thermal imaging was performed, so we could be comparing apples to oranges. Perhaps you could update the reviews with this info if you still have it (and maybe it would be useful to attempt to devise a "standard" context to make comparisons easier).

I always use highest charge current for thermal imaging. For ambient look for the lowest temp., that will be very close to ambient (You can see it at the bottom of the scale).
I cannot do a standard ambient temperature, in our country air condition is fairly rare.
 

Gauss163

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I always use highest charge current for thermal imaging. For ambient look for the lowest temp., that will be very close to ambient (You can see it at the bottom of the scale)...

How about an example. Using the images in your Opus BT-C3100 review, and based on what you know about your test environment, could you please explain how to infer which charger is heating the cells more, the Opus or this XTAR?
 
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HKJ

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How about an example. Using the images in your Opus BT-C3100 review, and based on what you know about your test environment, could you please explain how to infer which charger is heating the cells more, the Opus or this XTAR?

That would be the SV2, it charges with highest current and has no fan. The cells are around 45C in SV2 at 2A and only about 37C in C3100 (At 1A), both with an ambient around 21C-22C. This is also obvious when looking at the black lines on the charge charts, the temperature is not the same but again the SV2 is warmest.
 

HKJ

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What happens if you charge an Eneloop AAA at 2 amps by mistake?


Probably nothing (Except extra wear), eneloop are very robust.
Anyway an exploding NiMH is not nearly as violent as an exploding LiIon cell. The problem with LiIon is that it will self ignite when above a certain temperature and they contains combustible chemicals.
 

FlashKat

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Now what happens if you charge a 10440 at 2 amps by mistake? Is there any safety features to prevent an accident.
Probably nothing (Except extra wear), eneloop are very robust.
Anyway an exploding NiMH is not nearly as violent as an exploding LiIon cell. The problem with LiIon is that it will self ignite when above a certain temperature and they contains combustible chemicals.
 

HKJ

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Now what happens if you charge a 10440 at 2 amps by mistake? Is there any safety features to prevent an accident.


I am not going to do that test and if you do I would suggest doing it outdoors. :grin2:

With most round cell chargers it is up to the user to select the correct current, there is no safety.
 

Gauss163

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That would be the SV2, it charges with highest current and has no fan. The cells are around 45C in SV2 at 2A and only about 37C in C3100 (At 1A), both with an ambient around 21C-22C. This is also obvious when looking at the black lines on the charge charts, the temperature is not the same but again the SV2 is warmest.

Thanks. Unfortunately that doesn't tell me enough to figure out in general how to use those images to do thermal comparisons. For example, at what time during the charge was the image taken? Do you always use the same cells? If not, big differences in IR could cause big thermal differences. One would have to design a carefully controlled standardized thermal test in order for any sort of comparison to be meaningful.
 

HKJ

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Thanks. Unfortunately that doesn't tell me enough to figure out in general how to use those images to do thermal comparisons. For example, at what time during the charge was the image taken? Do you always use the same cells? If not, big differences in IR could cause big thermal differences. One would have to design a carefully controlled standardized thermal test in order for any sort of comparison to be meaningful.

Instead of all your problems with my test, why don't you do your own.
 

Gauss163

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My remarks were meant to be constructive. With just some minor changes, one could make a first step towards being able to do thermal comparisons of chargers. This would be very useful information to have given that heat plays a significant role both in cell health and safety matters.
 

THE_dAY

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HKJ, thank you for your time and effort on another great review!
Really wish Xtar would make 2A charger with voltage readout for charging/resting voltage instead of the percentage readout.
 

markr6

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Really wish Xtar would make 2A charger with voltage readout for charging/resting voltage instead of the percentage readout.

Yes. That's my requirement for any chargers moving forward. The percentage thing is useless to me. I love my VP2, being able to throw a cell in and do a quick voltage read. During charging it's obviously reading higher, but good enough.
 
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