Cycle Analysts are great tools for measuring all the important parameters on your ebike. If you don’t already know why a wattmeter like the Cycle Analyst can be so helpful, check out this article.
There are actually two main types of Cycle Analysts available, one for controllers with a Cycle Analyst connector (called the direct plug-in Cycle Analyst, or CA-DP) and one for controllers without a Cycle Analyst connector (called the standalone Cycle Analyst, or CA-SA). You can read about them both here.
Many controllers are available with Cycle Analysts connectors already installed. This makes it easy to simply plug in your direct plug-in Cycle Analyst and start enjoying all of its benefits. If your controller didn’t come with a Cycle Analyst connector though, you’re left with only two options: use a standalone Cycle Analyst or add a cycle analyst connector to your controller. The standalone Cycle Analyst works fine, but the only downside is that you don’t get any of the limiting features such as speed or current limiting, and you need to add a speedometer attachment if you want to measure things like speed and distance.
Here I’ll show you how to add your own Cycle Analyst connector to your controller so that you can make use of all the features available on your Cycle Analyst while using any controller you want.
Tools of the trade
Before we begin, make sure you have everything required for this project. The tools you need include:
- Soldering iron
- Solder (I use 60/40 rosin core solder)
- Screwdriver to open your controller
- Crimping tool or needle nose pliers (I use pliers)
- 6 different colored wires, 28 awg or larger (here’s what I used)
- JST-SM female plug (I bought 10 pairs for $7.50 on ebay)
- One 1,000 Ohm resistor (only required for version 2.3 and lower Cycle Analysts)
Step 1: Open the controller
SAFETY WARNING: Be sure that your controller is not connected to a power source at any time during this project. If powered up, you can easily short it by touching contacts on the bottom of the board. Remove your controller from its power source before undertaking any steps in this tutorial. Open up your controller and slide out the board.
Ok, now let’s get back to it. Open your controller on the end with the wires. You’ll likely have four screws, one in each corner. You’ll also likely have a number of bolts along the side of the controller connected to the heatsink. Unscrew all of those bolts. Make sure you put all the little screws, bolts and washers somewhere so they don’t get lost.
Next, slide the controller’s board out of the case. The wires and cover plate will stay connected, that’s just fine.
Now that we’ve got the board out, we can start locating the six points where we’ll be soldering our wires.
Step 2: Hunt around for the pin locations
There are six locations we need to find on the board. Each one will be soldered to its own wire and fed outside the controller. The six locations which correspond to the six pins in the Cycle Analyst connector are:
- Battery positive (or ignition wire if your controller has one)
- Battery negative (ground)
- Shunt negative
- Shunt positive
- Hall sensor signal
- Throttle signal wire
To find these locations, see the photos below of my controller. Your controller will be similar looking, though the individual locations of each component will be slightly different.
The battery positive and negative locations should be easy to find by following the thick red and black wires from the discharge connector outside of the controller. In my controller there are two empty solder through holes next to each point on the board. This will make it easy for us to add our wires.
Next we are going to look for our shunt. The shunt should look like one or more bars of solder that stretch across the board. Sometimes they are short, sometimes they are tall. Sometimes it’s just one bar, sometimes it’s three or more. In my controller I see the shunt is two bars right near the end of the board.
Looking carefully, you can determine which end of the shunt is positive and which is negative. The negative end will share a connection with the negative side of the battery (the thick black wire). On my board this is very easy to see because they are located right next to each other. That means the far end has to be the positive side of the shunt.
Next we need to find our hall sensor wires. The Cycle Analyst has to tap into one of the hall sensor wires in order to measure the speed of the motor and thus calculate the speed of the ebike. It doesn’t matter which of the three hall sensor wires you end up using, blue, green or yellow will work all the same.
On my controller the hall sensor wires are a bit congested, but I can find them by following the wires back from the hall sensor connector on the outside of the controller. When in doubt, lightly tug on one wire outside the controller’s front plate and watch which wire moves near the board. Double check to make sure you’re working in the right location. You should have five wires all in a row: red, black, blue, green and yellow (though not necessarily in that order.)
The last location we need to find is the throttle signal wire. The Chinese still haven’t agree on a standard for this, so it could be white, green, yellow, blue or pretty much any color. The easiest way to find it is to follow the wires from your throttle back to the board.
As you can tell, the throttle wires are pretty hard to see. The black and green wires are visible, and the red wire is hiding in back. They’re surrounded by all the other wires in this corner of the board and are really hard to get to. Let’s take a look at the other side of the board to make things a bit clearer.
Now we can see things much better. The three throttle wire pads are clearly visible at the edge of the board. The top pad is the positive line which delivers 4.3V to the throttle, the middle pad is the signal line and the lower pad is the ground line. The signal pad in the middle is the one we want.
Now we’ve located all six pads on the board that will be important to us. Let’s move on to the next step.
Step 3: Run your wires
This can technically be done after you’ve soldered everything up, but I prefer to do it first. This allows me to be sure that my wires will fit and that I won’t stress the solder connections by poking around too much after I’m done.
On my controller I was lucky enough to have a few extra holes in the silicone water barrier. I was abled to easily slide my wires through these holes and pull enough wire to reach each pad. If your controller doesn’t have enough space for your 6 wires, you might need to poke a few more holes in the silicone or drill a hole in the plate. Be very careful drilling holes, and of course only do this with the plate removed from the controller.
Step 4: Solder your connections
Now it’s time to make your connections to each of the 6 locations we found in step 2. Remember which color wire you are using for each connection. It’s best to write it down so you don’t make any mistakes afterwards.
We’ll go in order and start with the battery connections. You’ll remember that on my controller’s board I was lucky enough to have extra holes for additional components at each of the battery lead terminations. I’ll use one of these holes for each the first two pins, one for the battery positive and one for the battery negative.
One thing to note on this step is that things change if your controller has an ignition wire. An ignition wire is usually a thin red or orange wire that is included with the larger red battery positive wire, and must be connected to the larger red wire to turn on the controller. If you have one of these ignition wires, you’ll need to wire your first wire (battery positive) to this ignition wire and not to the larger red wire. This is because when you turn your controller off by whatever means you have for separating the two wires (handlebar switch, throttle button, etc) then your Cycle Analyst would still remain powered. If you connect your Cycle Analyst connector’s battery positive wire to the ignition wire pad though, each time you turn your ebike off by separating the ignition wire from the main battery positive wire, your Cycle Analyst will turn off too.
Find your ignition wire pad by following the ignition wire back from outside the controller. Mine controller had a couple extra holes in this location too, which made soldering straight through the board easy.
After soldering the battery wires onto the board, next you’ll do the shunt wires. You want to avoid adding too much additional solder to the shunt as this can change the performance of your ebike. In my case, I actually soldered the wires to the base of the shunt so that I had more room to work with. This also kept me from adding additional solder onto the shunt bars themselves.
Technically you can add the negative shunt wire to the negative battery pad, though you won’t get the most accurate readings that way. I’m going to add it directly to the shunt base on the underside of the board.
And a view from the top…
Next we’ll add in the speed sensor wire, which we can add to any of the three hall sensor signal wires, either blue, green or yellow. I’m going to add my wire to the pad with the largest solder gap compared to the other two. Also, I’ll make use of a convenient hole in the board right next to the hall wires to feed the wire down under the board.
The last wire to add is the throttle signal wire, which overrides the throttle for limiting features of the Cycle Analyst such as speed and current limiting. If you have a version 2.3 Cycle Analyst, you’ll need to also solder a 1,000 ohm resistor in line with the wire you connect to the throttle signal pad. If you have a Version 3.0 or high Cycle Analyst, you simply solder your wire straight to the throttle signal pad.
I actually didn’t include this wire in my controller here because I didn’t intend on using any of the limiting features of the Cycle Analyst. Assuming you do want to include this though, you’ll solder it just like in the diagram below.
Step 5: Add the connectors
The female connectors are really tiny so you’ll want to be careful when crimping them. There’s a special crimping tool you can buy, but of course I don’t have that tool, so I just used needle nose pliers.
Start by stripping the wires about 1/8 to 1/4 inch back from the end of the wires. Break the connectors off the strip they come connected with and crimp each one onto the end of a wire.
Go slow and make sure you have a strong crimp job.
Once you’ve got each of the individual connectors crimped to the wire, you can start placing them into the plastic housing. Use a small flathead screwdriver or toothpick to push the connector in until you hear a click. The order to connect the pins is:
- Battery positive
- Battery negative (ground)
- Shunt negative
- Shunt positive
- Hall sensor signal
- Throttle signal wire
…And that’s it, you’re done! Enjoy the satisfying feeling of having modified your own controller to work with a direct plug-in Cycle Analyst!