SkyRC D100 Fundamentals
The SkyRC D100 is a mid-level charger with two independent charging channels. It has a fairly standard user interface that follows the very popular IMAX B6. It does not require an external power supply and can be directly fed either AC or DC power. It has two standard 4mm banana charge outputs, two balance board ports, two temp sensor ports, a USB A charge port, and a USB Micro B data port. It’s a nice step up from simple “4-button” chargers without the big investment into very expensive top-tier units.
The first thing one notices about the SkyRC D100 is its size and weight. It’s roughly 150×150×75mm, and weighs almost 1Kg. That’s quite a bit of bulk compared to most small chargers, and might not be suitable for backpacking. Its basic specs:
- 1S–6S battery support
- Two independent charge circuits
- Supports all common battery types: LiHV, LiPo, LiIon, LiFe, NiMH / NiCd, Pb
- Charges up to 10Amps and 100W per channel (100W total on AC)
- Supports all standard charging modes: Charge, Balance, Discharge, Storage
- Internal resistance measurement
- $100 at the time of writing
In the box:
- The main D100 charger unit
- AC cable (C5 to local standard)
- 2× balance charge boards (2–6S JST-XH)
- 2× balance charge board cables
- 2× 4mm banana to XT60 cables
- 2× 4mm banana to bare wire cables
- 2× ferrite chokes
- Printed manual
The D100 has an internal power supply, so there’s no need for a separate external unit. The cord that came with with mine had the wrong AC plug type, (UK vs. US,) but the AC input connector is a widely standardized C5 type. I was able to quickly find one in a box of old laptop charger cords. A wide AC input voltage of 100–240V means the charger handles a simple cord change just fine if you need to move to another country. The DC input is XT-60 at 11–18V. A car battery is obviously what’s intended here, but it will also work from a 4S Lipo or any external power supply in this range.
If you’ve used an IMAX B6 or any other “4-button” type charger, you’ll be largely familiar with the interface here. That is, it’s not the most intuitive—but there’s generally enough information that you’re unlikely to make critical mistakes, and there are plenty of safety checks as explained later on. In addition to the standard 4 buttons, a 5th changes which input channel you are currently controlling.
To charge, you need to plug in the wide balance charge cable and connect that to the included balance board. Then, plug in the banana cable to the charge socket on the D100. Your battery plugs into both the board and this cable. Normally this charger won’t attempt to charge at all if the balance lead isn’t connected—though this check can be optionally disabled. You’re responsible for manually entering your battery information: primarily type, charge current, and cell count. After a few safety checks, the charger gets underway.
During charging, a pretty comprehensive amount of information is available:
- selected battery type (ex: Lipo 4S)
- charge program (balance, storage, etc.)
- time spent charging
- charge current (in A)
- amount charged so far (in mAh)
- total battery voltage
- target end voltage
- average cell voltage
- each individual cell voltage
- charged capacity (in %)
- charger’s internal temperature
- charger’s input voltage*
- battery’s temperature (with optional temp sensor)
- various safety cutoff conditions (explained below)
The 10A charge current might not seem too strong for parallel charging, but the 10A limit is per-channel. Effectively, you can charge at 20A if you set up both channels.
* Charger input voltage measures the supply to the charge circuit. If you’re using AC power, the internal power supply converts the AC to about 14V DC before feeding into the charge circuit. When using AC power, this will read ~14V regardless of the actual mains voltage.
The charger supports 100W per channel, but the internal AC supply can only output 100W in total. This doesn’t mean you’re limited to 50W on AC; you can configure the split however is most appropriate. For example, you can set one channel at 70W, and the other will have 30W available. Switch to DC power, and you can pull 100W on each side for 200W total. If you already own an external 12V power supply for a computer or other charger, you might be able to put it to use.
Each channel is basically entirely independent. The D100 can charge two different battery sizes, cell counts, and chemistry at the same time. This can be a big benefit if you have different types that can’t be parallel charged together. You can even set up two different parallel charge circuits and do all your 3S and 4S batteries at once. The two channels also do not share internal memory; your saved battery profiles don’t carry over.
There’s actually a 3rd channel on the D100: a USB port provides 2.1A at 5V. It’s not usable for large batteries, but you could charge your phone here or use a USB charger with your micro-quad batteries.
An internal cooling fan uses a fairly aggressive strategy of running almost the entire time a battery is being charged. I appreciate the safety and longevity this provides, but on the test unit the fan was pretty loud. It can be somewhat distracting if you’re trying to do other activities while charging nearby.
This charger does a reasonable job reading internal resistance of individual cells. It can’t do this while charging, so you will have to check your batteries before or after. The readings sometimes varied a little from test to test, but never strayed more than 2mΩ. I don’t have a professional-grade accurate measurement to compare against, but better performing batteries read lower while the worst batteries read higher. It’s usable enough for tracking how your batteries are doing.
TVC allows adjusting the final cell voltage. For LiPo, you can set it to charge each cell from 4.18V to 4.25V instead of the usual 4.20V. This can be dangerous so it is almost a hidden feature, and is for experts only.
There’s an optional WiFi module for about $20 which can connect your charger to an Android or iOS app. We don’t have the module and didn’t test this function. It’s difficult to see it bringing any significant benefit since we don’t recommend leaving any charger unattended, but there would certainly be some added convenience in a simpler user interface.
Two large ferrite cores are included, which are used to reduce electrical noise along a cable. They certainly aren’t necessary for charging operation, but potentially reduce interference to other nearby devices.
The SkyRC D100 can be used entirely stand-alone, but companion software is available for Windows. This software provides a much quicker interface than the onboard menus for controlling charger functions. It makes it much simpler to change settings and cut-off values, view data, and use presets. This software isn’t available for other operating systems.
The software is not without issues. It’s packed as .rar, which Windows can’t read natively; you need an unarchiver like 7-zip installed. On my Windows 10 32-bit netbook, the charger was recognized immediately—but its 800×600 resolution falls short of the expected screen size and many buttons are cut off so that the software isn’t functional. My Windows 10 x64 desktop wouldn’t recognize the D100 via USB at all. I finally got it running on a Windows 7 laptop after doing the plug/unplug shuffle more than should be necessary. The interface was reasonably intuitive, but the live graph stopped updating as soon as I switched to another program. A mouse is required.
The Firmware updater could not find the charger in order to run an update on any of the 3 systems I tried. The factory loaded firmware was v1.18 and the download found on the website was v1.04, so perhaps the updater simply doesn’t have a separate error message for this.
Overall, the software and system connection is a miss. Fortunately, I didn’t find any compelling reason it’s needed as everything is available right from the LCD.
SkyRC impressed me with their commitment to charging safety in the D100. The charger will immediately stop if it encounters any number of poor conditions: a dead cell, reverse polarity, broken connection, abnormal voltage (both input and battery cell), wrong cell count, or even if the internal temperature of the charger goes too high. In addition to these, there are optional and configurable cutoffs that you can set for charge time, total charged capacity, and battery temperature. Battery temperature requires a sensor, sold separately for about $6 each. This sensor isn’t necessary, but monitoring temperature may be your best chance of catching and preventing charge issues before they cause thermal runaway and an outright fire.
One unexpected safety feature was a plastic spacer for the banana plugs which keeps them spaced apart correctly. It also keeps them from touching. If you accidentally have your battery connected to the charge cable without the cable plugged into the charger, this prevents the banana leads from shorting together. (It’s still a bad idea to do this, though; you could cause a short by touching both leads on something else that’s conductive. Remember, the battery is last on and first off!)
- Appears well built, sturdy, and safe.
- All-in-one solution that charges most battery chemistries and cell counts; doesn’t require a separate power supply.
- Large size and weight reduce its portability, and the cooling fan is loud.
- Interface could be improved and some technical knowledge is expected, but users of “4-button” chargers looking to step up will feel right at home.
- PC software doesn’t work well but isn’t necessary.
- Additional features like USB charge port and internal resistance check improve overall utility.