Before I found Xtar battery chargers I had gone through various expensive AA-D size NiMh chargers that were cheaply made and provided poor performance. When I needed to charge my first 18650 battery because I got a fancy flashlight I choose an Xtar battery charger for two reasons. Good product reviews and I simply thought the name was cool. My first Xtar chargers were just able to charged lithium ion batteries. What I use now is Xtar's VC4 & VC2 plus chargers because they can handle NiMh batteries as well as lithium ion. Xtar offered to send me a charger for free to review so I choose the new VC2s because it is most like the older VC2 plus.
- Any USB to micro USB cord can be used to connect the power supply to charger.
- The charger decides which charging current is best for each individual battery.
- The charger can measure each batteries internal resistance in M ohms, and capacity in mAh.
- The display can also show the charging current given in milliamps.
- Best of all the batteries become only slightly warm at most during the charge cycle because the VC2s lowers the current if it senses the battery or batteries are becoming warm.
- The VC2s takes the battery to its maximum voltage. If it's a standard 18650 that is 4.2 volts. But then once the battery is fully charged it brings the batteries voltage down to 4.15 volts. I think to help safe guard any device that uses a lithium battery that cannot handle a full 4.2 volts.
- The charging cycle starts with just a milliamp or two and gradually increases the current to a base current of 500ma, 1 amp, or 2 amps. The charging voltage matches the batteries initial voltage and increases during the charge cycle. The batteries I charged were:A single Xtar 18650 2900mAh 10amp High Discharge Battery.
- The battery voltage the night before the test was 2.46 volts. The day of the charge the battery voltage was back up to 3.00 volts.
- Internal resistance was measured as 81M ohms.
- Battery capacity was measured as 2539 mAh.
- Charging current was never greater than 500ma.
- Time needed to reach a full charge was 5 hours and 39 minutes.
- Battery starting voltage was 3.53 volts.
- Internal resistance was measured as 61M ohms.
- Max charging current was 1.7 amps.
- Capacity was measured as 2704 mAh.
- Time needed for battery to reach a full charge was 3 hours and 20 minutes.
- Cell #1 starting voltage was 3.52 volts.
- Cell #2 starting voltage was 3.53 volts.
- Max charging current for each cell was 1 amp.
- Internal resistance for cell #1 was measured as 49M ohms.
- Internal resistance for cell #2 was measured as 51M ohms.
- Capacity measured for cell #1 was 2139 mAh.
- Capacity measured for cell #2 was 2062 mAh.
- Cell #1 needed 3 hours to reach full charge.
- Cell #2 needed 2 hours and 44 minutes to reach a full charge.
- Starting voltage for both cells were 1.1 volts.
- Starting current for both cells were 200mAh.
- Cell #1 max charging current was 1 amp.
- Cell #2 max charging current was 500mAh.
- Internal resistance for cell #1 was measured as 73M ohms.
- Internal resistance for cell #2 was measured as 100M ohms.
- Capacity measured for cell #1 as 831mAh.
- Capacity measured for cell #2 as 1237 mAh.
- Cell #1 needed 1 hour and 44 minutes to reach a full charge.
- Cell #2 needed 3 hours and 20 minutes to reach a full charge.
- I did not check starting voltage for either battery.
- The charging current for cell #1 was 397 ma.
- The charging current for cell #2 was 331ma.
- Internal resistance for cell #1 was measured as 116M ohms.
- Internal resistance for cell #2 was measured as 190M ohms.
- The time needed for cell #1 to reach a full charge was 48 minutes.
- The time needed for cell #2 to reach a full charge was 50 minutes.
- Batteries do not become hot during the charging cycle.
- Charger does not need a proprietary power cord.
- Charger brings down battery voltage to 4.15 volts.
- Charging current is tailored to each battery. No more guesswork on my part.
My one big complaint about the charger is: It is near impossible to remove any 18650 battery because there is not enough room to do so gracefully. You need a small flat head screwdriver to lift the battery out. However inserting batteries into the VC2s is a breeze and any battery small than 18650 are easy to remove. -
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