ISDT K2 Air Review

The ISDT K2 AIR is a two channel (LiPo) battery charger with a lot of very useful (and not so useful) features, let’s have a look, why you might want to consider it as your next battery charger. The pros, the cons and everything else you might want to know.

If you are looking for a 1S charger, have a look at WhoopStor 3 - IMHO this is the best charger for 1S batteries that you can get right now.

For the past years I have been using three battery chargers, the WhoopStor 3 for 1S batteries, the ISDT Q6 Plus and an old Robbe 4S, 3A charger. I bought the ISDT Q6 for two reasons:

The Robbe charger is only able to charge 4S max, I wanted to have the option also to run 6S batteries on my bigger rigs. Further it is only able to push 3A, that’s not great if you are into parallel charging, especially with higher capacity batteries
I thought I want a portable charger that I can take with me and which can be powered from a LiPo if need be. That is something that very rarely happened though.

I power the chargers from re-purposed server power supplies, they can provide 2000W - way too much for those two puny chargers. The external power supply is one of the reasons why I did not care for an integrated power supply in the chargers.

I have used the ISDT Q6 a lot - the counter shows 236 charged batteries, but I did reset it somehow at one point, so that’s not the complete truth, also each of this charges counts for 6 batteries since I basically always parallel charge. It is now at a point where the fan is already giving up and from dropping it once to often, all the screw sockets broke off and it is basically in two pieces. Further the scroll wheel is no longer very precise and tends to skip steps at times. I first thought about repairing it, but then re-considered since my requirements have changed over time.

I have noticed that I would often charge two sets of batteries, 6 in parallel on the ISDT Q6 with 2C. Another set on the Robbe with the max current output, often times less than 2C, sometimes less than 1C. So the ISDT Q6 would finish charging the first batch of LiPos and I would then move over the ones I started charging on the Robbe charger to quickly top them off on the ISDT Q6.

This is less than optimal, so when looking for a new charger, I decided to make 2 channels a requirement.

Another thing I noticed through the years is, that I would not take my quads on holidays: Usually my holidays are only a couple days and it always seemed like a hassle: I don’t have a charger that I can easily power from the wall. I can’t take my server power supply, and I don’t want to take an extra - somewhat - powerful power brick. So the quads stayed home. I am telling myself, that I would take my quads more often if I had a better charging solution, so I add that as another requirement.

Requirements

Before starting the selection process, I gathered my requirements:

Two channel charger
Must be able to parallel charge 6 batteries on each channel with at least 2C - the worst case for me here is 6x 1300mAh, 4S batteries at 2C, so 15.6A or around 200W per channel.
Must have an integrated power supply but also be able to charge from DC
May not cost more than $200
No experiments: Stick with a brand I trust. So either Robbe or ISDT. Since Robbe does no longer seem to sell their own brand of chargers - ISDT it is.

Selection process

When looking at the ISDT line up the following chargers would fit my requirements:

Great, only having to start out with two, makes it easier to find a “winner”.

The K2 Air has basically double the power rating of the K1:

200W per channel when powered from AC
500W per channel when powered from DC

Another thing that I like about the K2 is, that you have navigation buttons per channel. On the K1 you use the same buttons for both channels and have two extra buttons to switch the channel. Seems way more comfortable to me to have dedicated buttons per channel.

The K2 Air also has Bluetooth connectivity (that’s the “Air” part), which is not something I am going to use apart from testing it once…

Also the K2 Air has a USB-C port which can be used for charging your USB-C devices, the one on the K1 only seems to be for firmware updates.

The price difference is quite significant, the K2 is almost 50% more expensive than the K1. Double the power rating and the dedicated navigation buttons are worth it for me though.

Features

Here a summary of the core features of the ISDT K2 Air and basically the main drivers for me to chose it:

2 channels, 200W each when powered from the built in AC power supply, 500W when powered from DC directly
Two separate control panels, one for each channel
“Destruction mode” - allowing for batteries to be completely discharged, so you no longer require an additional LiPo killer to get safely discharge your LiPo batteries to be disposed.

Nice to haves

The ISDT K2 Air has a lot of features that I personally will probably never make use of, but might be interesting nonetheless:

You can set one channel as a constant voltage source, so you can set it at for example 12V and then power whatever device from it - something like a soldering iron for example
USB-C charging: It’s nice to have an additional USB-C charger, but it’s very unlikely that I’ll ever be powering my setup just to use the integrated USB-C charger when I can just plug my phone in next to me on my desk. The USB-C charger is capable of pushing up to 30W
Bluetooth connectivity: You can monitor the charging state of your batteries via Bluetooth. I set it up to have a look at it, it works but I don’t really have a use case for it. I am charging in my office and most of the time I am very close anyway, so to see the charging state I simply turn around. I guess Bluetooth hardware has reached such a low price point, that it’s just thrown into any product, whether it makes sense or not
Parallel task mode allows the use of both channels to charge one battery, allowing to utilize the full power potential. This obviously would only make sense with really high capacity batteries

Conclusion

I really wish, that the bottom case was from aluminum. Don’t get me wrong, the plastic is fine, the device does not feel cheap whatsoever, but after the screw mounts ripped out of my old ISDT charger, I just wish that it was from a more sturdy material.

So far I really like the experience, if you have used a battery charger with a screen before, it is very unlikely that you will need to consult the manual at all.

There are some - for me - useless features, still I think the price (around $140 at the time I bought it) is fair for what you get.

I’ll definitely come back with an update in regards to long term use and if it really made me consider to take my quads with me on holidays more often.

Chris is a Vienna based software developer. In his spare time he enjoys reviewing tech gear, ripping quads of all sizes and making stuff.

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