January 16, 2019

Xtar VP4+ Dragon charger

XTAR offers the less expensive VC4 charger, which also has 4 bays. It comes without an AC power adapter, and expects to be supplied power via a USB cable, which I find highly questionable for a device that I expect to charge four 18650 cells at anything approaching a reasonable rate, so I passed on this thing. Another option is the SkyRC RC3000, which is also a high end 4 bay charger.

The Dragon

The VP4+ "Dragon" is well reviewed with lots of features.

The main complaint is that it displays percent of charge rather than volts. This is a topic that is hotly debated. I held off on saying anything when I first got it, but now I have formed my own opinion.
This is stupid and by far the biggest shortcoming of this charger. That an expensive high end charger should not display voltage is ridiculous.

I bought mine for $59.99 (free shipping) from Illumination Supply. Amazon was selling the unit for $84

How to use it

If you just want to charge batteries, it is dead simple. Plug the unit in, insert the batteries, and away she goes. Each battery bay has an LED. It is red while charging and green when charging is finished. The LED can also be blue when discharging in various test modes (which we will get to soon enough).

If you want to change the charge current, you have 3 choices. 0.5, 1.0 and 2.0 amps. I generally use 0.5, but sometimes I don't pay attention and end up charging at 1.0. The left button (labeled "current/refresh") lets you change the current.

There is also a right button (labeled "record/test") that you are probably wondering about. Stick with me a bit while I explain the user interface. The buttons do something different if you long press. Most people naturally do a short press, which is what you use to adjust the current setting. Hold the right button down until "something happens" and you have entered test mode. Similarly, hold the left button down until "something happens" and you have entered refresh mode. Refresh and test are quite similar. Refresh will discharge the battery (to 3.0 volts?) then charge it back up.

Test does the same as refresh, but first fully charges it. It also records the mAh to discharge it and then to charge it back up again. When it is done (and the LED is green finally) the display will be showing the discharge and charge ratings in alternation. Not only that, but it saves the information for a number of tests (supposedly 64 can be saved). The short press of the right button (record) accesses this recorded data.

So there you have it. Just be warned that a test sequence can take a long time (figure on all day or overnight, particularly if you select the 0.5 setting as I do).

The test probes

Oddly enough, these plug in via a USB connector to the back of the unit. There are two places to plug them in, so pay attention to the labels. Once you plug them in, you need to know the secret! Touch the probes together until "something happens" and the display switches to meter mode.

Lay the battery on the table and press the probes firmly onto it. This is tricky, clumsy, and obnoxious, but it is what it is. The display will begin alternating a display of voltage and internal resistance.

When you are done, I haven't found a way to return to the normal charging display other than unplugging the unit.

USB charging port

There is a USB port on the back (not the one you plug the meter probes into). You can use this to charge your phone (or whatever), while this is plugged into the AC mains and while charging batteries. It will also work when unplugged from the AC mains, allowing you to use the Dragon as a power bank.

Have any comments? Questions? Drop me a line!

Tom's Battery pages / tom@mmto.org