Review Charger Xtar X2

A two slot LiIon and NiMH charge with automatic current selection and both mains and USB power input.

The charger was in a cardboard with specifications on it.

The box included the charger, a mains cable and a instruction sheet.

The charger has input for both USB power and mains power input.

There is a single button on the charger, it can be used to turn backlight on or restore backlight to full power.

During power on all segments will be shown.

No batteries in the charger.

A LiIon and a NiMH battery.

The charger has specifications on the back, with black text on black background.

The connection are the common slider style that can handle from 31.5mm to 77.3mm, this means all batteries will fit.

The slots are marked with current, but the marking leaves out the 0.5A current that is used with short batteries.

The charge current is on the high side for 10440 batteries.

Measurements charger

  • A single long battery in slot #1 is charged with 2A
  • A single long battery in slot #2 is charged with 1A
  • When using both slots #1 & #2 the charge current is 1A on both.
  • Slots change charge current to 0.5A at 55mm length.
  • When not powered it will discharge a LiIon battery with about than 3.5mA.
  • When powered the charge will charge with less than 1mA when finished.
  • Below 2V the battery is assumed to be NiMH, above LiIon.
  • Charger will restart if battery voltage drops below 3.9V.
  • Voltmeter has a minimum reading about 0.8V and will show that from about 0.3V
  • Voltmeter is within 0.04V
  • LiIon can be charged with 0.5A, 1A or 2A, depending on slot and battery length.
  • NiMH is always charged with about 0.5A
  • The display show 0.5A when charging NiMH, but the actual current is around 0.8A
  • Background light goes to low brightness after 60 seconds.
  • USB input will supply some power when charger is mains powered, this is not very good.
  • Mains cable is 32mOhm for each wire, this is fine.
  • Power consumption from mains when idle is 0.42 Watt with backlight on full brightness and 0.25 Watt at low.
  • Power consumption from USB 5V is 45mA when idle full backlight and 24mA at low.

Charging LiIon

A single LiIon battery in slot #1 is charged with 2A using a CC/CV profile, termination current is around 100mA
Display shows 3154mAh

In slot #2 the charge current is 1A.
Display shows 3035mAh

Display shows 1950mAh

Display shows 2599mAh

Charging other LiIon batteries in slot #2 works nicely.
Display shows1950mAh

A high current battery can be charged in slot #1.
Display shows 2902mAh

A short LiIon battery can also be charged in slot #1, due to the shorted length the charger will use 0.5A charge current.
Display shows 572mAh

With two long batteries both slots are limited to 1A charge current.
Display shows 2927mAh 2942mAh

This is valid for both USB and mains power state.
Display shows 2926mah 3015mAh

M1: 37.9C, M2: 38.0C, M3: 41.2C, HS1: 47.3C

M1: 39.9C, HS1: 43.6C

The charger needs about 6 seconds to turn on.

The charger will discharge a full LiIon battery with about 3.5mA.

Charge profile, the charger always start with a low current when voltage is below 2.7V.

The charger cannot work with an unstable USB supply.

Charging NiMH

The charger uses a good -dv/dt termination followed by a two hour top off charge.
Display shows 1989mAh

The other slot is similar
Display shows 1834mAh

The old pro cell get some capacity and terminates.
Display shows 380mAh

This high capacity cell is charged nicely.
Display shows 2399mAh

With the leise the termination is on the slow side, but it do terminate.
Display shows 2970mAh

The AAA cell is charged with the same current as the AA cells, here the 0.8A is a bit on the high side.
Display shows 715mAh

Due to the low current startup it takes the charger about 15 minutes to detect a full cell.
Display shows66mAh

Two cells are charged at the same speed as one.
Display shows 1858mAh 1878mAh

This also goes for USB.
Display shows 1880mAh 1840mAh

M1: 40.5C, M2: 40.3C, HS1: 50.2C

The charger uses the same time as for LiIon, before it starts on the precharge.

As usual the NiMH charging is pulsing, this makes it possible to check the voltage with current off.

Top-off charge 1s at 1A every 20s or an average of 50mA.

The charger handled unstable voltage considerable better with NiMH cells.

Testing with 2830 volt and 4242 volt between mains and low volt side, did not show any safety problems.


This charger works fine for both LiIon and NiMH, there are a few issues, but nothing serious.

I will rate it as a good charge.


The charger was supplied by a Xtar for review.

Here is an explanation on how I did the above charge curves: How do I test a charger