Charger Xtar SV2 Rocket





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.



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



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



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.



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.



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).








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.



Measurements

• 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).

Charging LiIon



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



It is the same on the other slot.




Other capacities are handled just as fine.



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



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



Also a good charge curve.



The charger easily handles two cells at 1A.



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



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



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



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



Charging NiMH



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).



It is the same on the other channel.





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



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



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.



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.



Two cells at 1A is no problem.



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



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



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



10 minutes later it will switch to full current.



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



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.



Charging LiIon and NiMH at the same time

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.



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



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.



Conclusion

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.



Notes

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