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Mar 03, 2015, 12:53 AM
AMA 1033652
mnemennth's Avatar
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Turnigy Reaktor 300Wx2 Hackage - Get Your Serial Data & TEMP Sensors Back!


One of the best ideas the folks at HobbyKing EVER had was to hook up with the folks at Junsi and start selling their world famous iCharger line of products. Even BETTER was taking the awesome iCharger 206B and stuffing it in an extruded aluminum box with one of its brothers; this is how the Turnigy Reaktor 300W x 2 was born.

Unfortunately, at the same time, they decided to eliminate TEMP SENSOR input and the USB port for Serial Data out to your PC. I'm not sure why; maybe it was due to space restrictions, maybe they didn't want to do support for those functions. But... they're gone.

Well, not entirely. The temp sensor circuit is still there; it's just lurking inside the box. They even left the plug-in header!

As you can see in the above photo; the USB port, however, is NOT there. Worse yet, they left off the USB-->UART transcoder IC on the other side of the board!

However; directly to the right of the empty USB port solder pads is an ISP Header, and it IS live. We can connect to it using an ordinary FTDI USB-Serial Converter. The original circuit in the iCharger 206B uses a Silabs PC2102 IC; there are a number of VERY CHEAP FTDI USB-->UART serial Converters out there based on the same chip. I just bought 3 of them from a US vendor on eBay for $6.13 with shipping; those I'll be using for a future project.

Today's hack will be based on the Silabs FT232 Converter, Commonly known as an "FDTI", since I have one on hand and they are more commonly available with the Micro-USB connector (seen above) for a USB to Micro-USB cable, which we want because it will allow us to make our adapter pigtail nice & short to avoid noise.

Look for one with the MICRO-USB, not a regular USB Type "A" connector.

For connecting inside the charger, these:

fit and are JUST long enough to get to the other end of the case.

Okay; I cannot proceed any further without putting out this warning; now that you have some idea what you need to do, you need to read the following to decide IF you want to do it.


This connection is not the safest due to the manufacturer's design, which has the ISP Header connected to a "floating ground" in the charger. For absolute greatest safety, it would be best to only use this connection to a laptop running on battery power.

Internally, this connection is DIRECT to the CPU of your charger. If you're using some homebrew DC power supply with floating GND, or your PC is plugged into an improperly grounded outlet or for any reason there's a voltage differential between your charger and your PC, connecting this way could in theory blow the processor clean off the board.

The GND of this header and the GND of the TEMP sensor header and CPU GND are connected to a common GND plane, but it is NOT connected to the Main Power GND. I'm CERTAIN this is why the iCharger "Custom USB Cable" has the Shield & GND disconnected.

BE FOREWARNED - If you do this mod and your Reaktor reaches Critical Mass and has a meltdown, YOU are responsible.

Okay... lets see how many more there are still with us. *Counts* Hmmm... lost a few. Okay...

You intrepid readers who are still interested, READ ON.

I'm not going to carelessly post a dangerous Mod out here for folks to toast their PC and their charger; I have at least a minimum sense of responsibility. We're going to build this serial adapter cable with some buffer resistors which should prevent any errant voltage differential from being able to harm either your PC or your charger.

In my experimentation before writing up this How-To, I checked with a multimeter for any voltage differential between the GND on the breakout cable I made and the GND pin of the FTDI BEFORE I connected to the FTDI plugged into my PC; I found none so I proceeded. I'm using an HP Server power supply at 13.5V for my Reaktor. It IS properly grounded, as is my desktop PC.

After finding that it worked, I tried & tested several values of resistor til I made it stop working, then went with the next lower value of 10KΩ. This limits the maximum current flow through any circuit and GND to 12ma at 240V line voltage; half that at 120V for those of us here in the States. As most common processor I/O channels are safe to 20mA, this leaves a fair amount of leeway.

This is by no means proof against a sparky, smoky doom for your Reaktor & PC if there is something grievously wrong with the power you are using; I still recommend you check with a DMM before you connect. But we've done all we can to eliminate the risk. So, now that the warnings are out of the way, lets proceed.

We're going to use two of these for each charger channel; one as an extension header to get the connection out of the charger, and another with the socket cut off to make the adapter pigtail for our FTDI.

The first thing we need to do is cut this little ridge off of the socket end connector housing; it's just a hair too wide with it on there.

Next, we need to take the plug end off of the cable; to do this, slip the point of a needle or X-Acto knife under the little finger and pull the wire out of the housing.

Next we pull the cables through one of the cooling slots...

...and now we have a nice, unobtrusive port to connect to for our data. I LIKE IT!

Since we already have the plug apart to pull the cable through, we're going to swap the locations of the ORANGE & BROWN wires; this way the GND circuit stays on the BROWN wire like we're all used to.

Here's that pinout again; in my build I placed the socket at the other end so the GND/BROWN was at the top; if you prefer, you can flip it around so GND/BROWN is at the bottom before you glue them in. Just try and be consistent for your own peace of mind. The only place you want to actually move connectors in the socket is at the plug end inside the charger; leave all other connections as they come so the colors of the wires all match.

Okay; first off, we're going to twist the legs of 3 10KΩ 1/8W resistors loosely together on one side, then cut the leads on the other side off, leaving about 2-3mm of bare lead like so.

This makes it easy to clip them in your helping hands and tin them all at once, then you can easily solder your pin header wires to the resistors.

Once you have that done, clip the other leads on the resistors short like before and clip them in your helping hands. Don't forget to slip some 3-4mm heat-shrink tubing over the wires like I did.

Now it's time to solder the leads of the Molex 1.25 Micro-Servo connector to the resistors. BLACK pin header wire needs to go to the BROWN wire of the servo lead; colors chosen for the TX & RX were pretty arbitrary. Meaning, I had a blue one and a white one with one end cut off already lying around.

If you moved the pins in the plug end inside the charger around like I suggested earlier, then Micro Servo ORANGE wire gets connected to FTDI TX, while Micro Servo RED wire gets connected to FTDI RX.

And here is my finished adapter. I opted to make a jumper-wire set, since I use my FTDI for other things. That's what the other wires you see under the BLACK, WHITE, & BLUE pin header wires are. I have another FTDI on the way; I intend to use it ONLY for this, so I'll be soldering the 3 resistors direct to the FTDI, then the Micro-servo wires directly to them for a super-compact adapter I know will be convenient to use. I'll post pix of it when it's done.

Okay; now it's time to get started on the TEMP Sensor circuit. First off we need to get room to work; take the entire left (fan) side of the case off and flop it carefully over to the right like so. You DID remember to unplug your charger from power before you started, didn't you?

Grip the pins about 2mm inside of the bend with a pair of smooth-jawed pliers; by bending from here, we make it much less likely that we're going to break the pin off from metal fatigue when we bend it back up.

When you're done, the pins should look like this. A little further than straight up is okay; the wire will be plugging in towards the right.

Here's the pinout at the board. The iCharger uses an LM35DZ precision Temperature Probe IC; it takes 5V from the board and sends back signal to the center pin at 10mV per Degree Celsius. You'll need to make or buy 2 150mm long Female --> Female standard servo cables.

I first tried a Male --> Female servo extension; I really didn't like the way it looked hanging out like that. A JR-style Female servo end JUST squeezes into one of the cooling slots for a snug fit; if you have Futaba or Airtronics or generic Molex, you may need to sand them a little to get them to fit.

Here is our completed Port End of the charger; I've taken the panel off for convenience. And because I was out of Epoxy, so I needed room to use the hot glue gun.

Be careful applying the glue; don't put any on the open side where the "fingers" are in the connector. It will get in the connectors and you won't be able to plug into them.

And here's the inside of the charger all put back together. At this point, I'm sure you're wondering how we're going to plug your Temp sensor in; if you have a stock iCharger sensor, it's female too!

We're going to MAKE some adapters out of 3-row right angle 0.100" header. While they DO make straight single-row 0.100" that's long enough to get you the 6-7mm on each side you need to make a pin adapter, most of us only have the kind with 6-7mm on one side and 2mm on the other. Too short, unless you want to solder together 2 pieces to make your adapter.
First, cut off 1 3-pin segment with a sharp X-Acto knife.

You should now have a segment that looks like this.

Again, using pliers with smooth, non-serrated jaws, squeeze the pins right at the angle to straighten them out. The compression of the jaws makes it less likely that you'll break the pins from metal fatigue; but it still does sometimes. If it does break, cut off another segment and try again.

Now, using a sharp flush cutter, cut the two longer pins to the same length as the shortest pin... and you're done!

Here's what it looks like with the straightened 3-Pin header segment...

...and with an adapter made by soldering 2 3-pin segments of straight header together. Really, not that bad.

And here it is with a JR-style servo wire plugged in; some sensors use this, while others use the white JST-XH connector. Either will plug into this; both are the same pin size & 0.100" spacing.

Alternately, you can make your own using scraps of leftover Servo wire and a 3-pin section of pin header; this is what I have in mind.

Nice & neat! Just add an LM35DZ IC at the other end; there are oodles of vendors on eBay selling them cheap. I found one US vendor selling lots of 5 pieces for $8 shipped; when they get here, I'll post a mini How-To on building the sensor from scratch.

The circuit is simple; we can simulate it with a 10KΩ potentiometer. I've adjusted it so the center tap outputs 200mV; as you can see, the charger reads 20 Celsius.

And here's the side view of the completed work. Nice & neat; only YOU will know it didn't come that way!


The Serial Data Out we're building isn't a lot of help without software; fortunately, the iCharger line doesn't use proprietary software, but rather outputs data in a format recognized by LogView, a DonationWare Log data analyzer/ graphing utility created by Dominik Schmidt & Holger Hemmecke.

What; you thought Junsi, a China-Direct manufacturer of Hobby Electronics, was going to PAY someone to write their software? Imagine THAT!

LogView Studio is their latest version; it does 3D charts and appears to have some statistical analysis functionality built-in as well.

Documentation is here:

While clearly very powerful, I found LogView Studio a bit over-complex for my needs (OK, I messed around with it for half an hour and couldn't figure out how to get it to connect to my Serial Data) , so I went with LogView V 2.1. That allowed me to select my Com Port manually, and I was up and running in 90 seconds.

Sometimes simpler is a welcome change.

Okay... now you have pretty much everything you need to know to get connected to your Reaktor and start logging data just like a regular iCharger.

Good luck!


The Silabs FT232-based FTDI now has signed drivers in Windows Update; Windows 7 and Windows 8 will automatically install the FTDI and ask you if you want to Search Windows Update for drivers. Click YES. Be patient; it DOES take it a while but I successfully installed on a Win7 and Win8 machine with no issues.

Make SURE you note which Com Port Windows assigns to your FTDI!

Connectivity issues:

If you can't get it to connect, even in LogView V2, try troubleshooting a few things.

First, verify continuity of GND with a multimeter to the GND pin of the TEMP sensor plug and to the resistor in the GND wire.

Also verify continuity of GND from the FTDI to the resistor in the GND wire.

Check the wires in your pigtail; each should measure 10KΩ.

If those test OK, try swapping the RX & TX wires at the FTDI; it's easy to get them mixed up.

I'll update as I have news and more mods.

Cheers, and Happy Modding!

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May 19, 2015, 11:33 AM
Intensely Calm
write2dgray's Avatar
Very slick sir - nice work! I did this years ago to an iCharger 106B (before the 106B+).

One thing to note, HobbyKing did not hookup with Junsi - the design was stolen and copied in their factories. It is not authorized by the iCharger folks in any way.
Jun 09, 2015, 09:29 PM
AMA 1033652
mnemennth's Avatar
Thread OP
Hmmm.... That's interesting, as it has the Junsi firmware as well.

I know I saw one of their people posting in one of the threads I researched in before digging into this; I suppose I should follow up on that.

As if I don't have enough projects going as it is...
Jul 04, 2015, 07:23 AM
I have read this controversy about HK stealing junsi's desighn I consider this not correct. This argument has good points on both sides but I myself find it hard to believe that HK stole this desighn and has not only not been sued but still carries the full line of junsi's products. Even if they did cut some kind of deal junsi surely don't want to just openly tell everyone that they can buy there exact product at a much cheaper price.
So even though I do not know all the facts I choose not to believe this was stolen.
To me obviously some kind of agreement has been made otherwise we would be seeing and hearing this in court. I think HK was able to put up a huge amount of cash for a very large order at a very sweet price and then put it in a case for us to buy at a nice deal. Plus there are other chargers such as the one from hobbypartz that's also the same copy of the icharger in another different case. Just my 2 cents is all.
Oh great thread by the way.
Jul 07, 2015, 05:16 PM
AMA 1033652
mnemennth's Avatar
Thread OP
Yeah, I kindof felt the same way myself. It seems ridiculous that Junsi would STILL be doing business with HK if they'd stolen their designs.

Under any circumstances, I'm tickled pink to be able to Chart and Temp-charge with mine now. It was an AWESOME bit of fun reverse-engineering this thing.

Nov 12, 2015, 06:05 PM
Registered User
JulianGoesPro's Avatar
uh I have a REAKTOR that may need some love... I should give that a shot :-P can't get worse^^

300W 20A Reaktor Charger Dead? (0 min 16 sec)


LOL mnem, why did't you tell me :-P totally miss read your thread^^ I thought it would somehow relate to FW updating.. upsi^^
Last edited by JulianGoesPro; Nov 12, 2015 at 06:44 PM.
Dec 04, 2015, 12:28 PM
Registered User
xsergo's Avatar
For FW updating read that thread:

Its about the Reaktor 250W, but could help you.

You will be fine with the German language
Sep 13, 2016, 02:52 PM
No Hangar Queens!
Willsonman's Avatar
I understand I'm resurrecting an older thread but MUCHAS GRACIAS! Yup, I reversed the Rx and Tx by mistake but I get it sorted and everything is great.

So... how do I organize all the data? Compile it? Trend charges? A point toward a discussion on this would be great! Totally geeking out and satisfying my OCD.
Oct 16, 2016, 02:31 PM
Registered User
Tried to connect this way to my single 300w because junsi firmware flasher won't connect over USB. Didn't get to connect this way either, think the firmware is royally pooched. Put a x2 300w on order so this will be helpful, just wish the photos weren't gone

Oh yay the photos are back, thanks!

I am debating moving one of the PCBs from the dual back into the case of the single. Tee dual is just so huge for my tiny charging case.
Last edited by Mugenski; Oct 19, 2016 at 05:23 PM.
Nov 22, 2016, 11:34 AM
Registered User
Crady's Avatar
I have the 300W 20A x 1 Reaktor (with USB and temp ports) - does anyone know if there is a way to detect when a charge cycle is complete - either via a pin that changes state or via the USB port?

Jan 05, 2017, 02:41 AM
Registered User
Im looking at getting a turnigy reaktor 300w version of these.

Will it support logging over USB or is it a random bit of luck as to whether the FTDI chip is present?
Jan 10, 2017, 08:48 AM
Registered User
Hi There, back again

I tried this with mine, using an FTDI 232 clone. I get no communication. All I get is <NUL> when powering the charger up.

My reaktor 2x300 w is firmware version 3.14. I wonder if they removed the comms part of the firmware to make way for other functions (such as motor test and hot wire mode)?
Nov 10, 2017, 04:15 AM
Registered User

upgrate FW

I would like to know if it is possible with the above configuration to circumvent the charger's FW
Nov 23, 2017, 04:46 AM
Registered User
hello hello i would like to mess up my reactor 300x2 but i do not know where to go to take the firmware program
does anyone know where to go?

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