Cycle Analyst V2

Page Last Modified On: May 6, 2022

cycle analyst

2021 Discontinuation

After 11 years of manufacturing and supplying the V2 generation of large screen Cycle Analyst to tens of thousands of customers all over the world, we decided at the end of 2021 to put this particular product to rest. Most of our sales and interest has shifted fully over to the V3 model which has a lot more functionality. For those who want just a basic display and don't need control features, you can still use the CA3 for that and customize the display screens to only show electrical and speed data just like the CA2.

Original Intro

The Cycle Analyst (formerly called DrainBrain) is the first digital dashboard and battery monitor originally designed around the specific needs of electric bicycles. However, the flexible setup configurations, wide feature range, and affordable price have led it to widespread appeal in a range of other EV applications. From the dashboards of MIT's solar car, to record breaking electric motorbikes, to small trains, powered wheelchairs, and even sailboats and airplanes, the Cycle Analyst has become the e-meter of choice for keeping track of the vehicle's battery usage and performance characteristics.

What it Does

Once connected to the vehicle's power bus, the Cycle Analyst calculates and shows the following information:
  • Volts, Watts, Amps: The instantaneous electric power being drawn from the battery.
  • Amp-Hours, Watt Hours: The net energy that has been pulled from the pack since the meter was reset. The accumulated amp-hours let you know the remaining energy in the battery pack with far greater accuracy than a voltage or LED indicator.
  • Speed, Distance, Time: All of the basic features of a bicycle computer, including the average and maximum trip speeds, plus a total distance odometer.
  • Regen, Wh/km: There are several quantities this meter will calculate that you don't get with other instrumentation, such as the % extra range that was gained from regenerative braking, as well as the vehicle's average energy use in Watt-hours per kilometer or mile.
  • Peak Currents and Voltage Sag: Records the maximum forwards and regenerative currents as well as the minimum voltage on the battery pack.
  • Total Battery Cycles and Amp-Hours: Retains life cycle information on the vehicle's battery pack, such as how many charge and discharge cycles the pack has experienced and the total amp-hours that were delivered over its entire life.
Furthermore, the Cycle Analyst has the ability to over-ride the user's throttle and regulate the power delivered to the motor, turning an otherwise dumb ebike into an intelligent device with a user programmable speed limit, current limit, and low voltage cutout.
  • Speed Limit: This has the utility of providing legal compliance to the speed cap imposed on ebikes in most jurisdictions. When used with a full throttle, it serves as a cruise control on the electric bicycle. It can also be beneficial to riders who want to increase their torque and power by using a higher voltage battery, without simultaneously increasing their top-end speed.
  • Current Limit: An adjustable amps limit is useful to prevent damage to the batteries from excessive current draw, to increase the range that you'll get on a charge, and to protect the motor controller and motor in setups that draws too many amps.
  • Voltage Cutout: A low voltage cutout is used to protect a battery pack from being discharged too deeply, which can cause cell reversals in NiMH/NiCad packs, permanent cell damage in Lithium packs, and sulfation in Lead Acid batteries. The programmable low voltage rollback allows you to set an appropriate low voltage point tailored to your pack.

Additional Features

  • Remote Shunt: Unlike the watt-meters and amp-hour meters designed for RC hobbyists, the Cycle Analyst uses a remote shunt for sensing current rather than running wire through the meter, so you do not need to route heavy gauge battery cables up to the handlebar and back.
  • Backlit LCD: The display readout is well illuminated for night riding.
  • Water Resistant: The circuitry is fully enclosed in a sealed box enabling it to withstand exposure to wet and rainy conditions.
  • Handlebar Mounting: Easily attaches to handlebar tubes from 7/8" to 1 ΒΌ" diameter with included hardware. 
  • Save on Power Down: Trip data such as amp-hours and distance are saved when the meter is shut off, and are restored when power is re-applied.
  • Fwd and Negative Amps: Both positive and negative amp-hours are displayed separately, so you can calculate accurate regenerative braking statistics or use it to monitor charging currents as well.
  • Wide Voltage Range: Operates from 10V to 150V, accommodating the vast majority of all small electric vehicles. A high voltage option for use up to 350V is available on special request.
  • Flexible Speed Input: Detects vehicle speed either with a magnet and sensor cable or through the hall effect signal on brushless motor controllers.
  • Data Logging: Devices have a serial output stream that can be used for real-time recording the vehicle statistics to a computer or laptop.

Cycle Analyst Types

There are currently 4 standard versions of the Cycle Analyst being produced to accommodate different vehicle setups. All models have the same circuitry and code, and all of them have speedometer functionality. However, additional wiring is required by the end user to take advantage of the speed and current limiting features on the Stand Alone and High Current models.
cycle analyst cycle analyst connector cycle analyst speedo
Stand Alone Model: Stand Alone Model (CA-SA): The stand-alone Cycle Analyst comes pre-calibrated to a molded shunt resistor capable of handling 45 amps continuous and up to 100 amps peak. It is designed to be compatible with virtually all types of Personal Electric Vehicles (PEVs). A pair of pigtail leads on either side of the shunt simply connect between the vehicle's battery pack and motor controller. Speed is detected via a spoke magnet and sensor cable. Direct Plug-in Model (CA-DP): This unit is designed to plug directly into a motor controller to get the appropriate signals, resulting in a tidy installation with minimal wiring. Most motor controllers have an internal current sensing shunt resistor that can be used for measuring current, as well as a hall sensor signal that can be used to detect the wheel speed in direct drive hub motors. The CA-DP is terminated with a 6-pin plug that connects directly to the modified Crystalyte, Infineon, and eZee Controllers that we have at Direct Plug-in with Speedo (CA-DPS): This is a variation of the CA-DP device for ebike setups that can't use the hall signals in the motor controller for the speed sensing. This would include DC motor systems which don't have hall sensors, geared motor setups like the eZee kits where the motor RPM does not match the wheel RPM, and mid-drive arrangements where the motor powers through the bicycle drive chain. It uses a separate speedometer sensor and spoke magnet like the Stand Alone device to pick the speed from your wheel.
High Current Model (CA-HC): For larger vehicles that draw in the 100's of amps, a high current model is available that can be connected to a user-supplied shunt in the 0.1 to 1 mOhm range. The two sense leads that go across the shunt are terminated with a ring connector. The vehicle speed is detected with a spoke magnet and sensor as with the Stand Alone model.

Power from Cycle Analyst

The included 5.5x2.1mm DC Power cable can be wired directly from the Cycle Analyst by opening the CA and soldering the red and black wires to the CA's V+ and Ground pads. Since the CA and Lumenator are usually both located on the front handlebars, this saves running the cable down to the battery pack. If you don't have a Cycle Analyst, you can make an Anderson Powerpole tap for use with Powerpole systems, or wire in to whatever connectors or terminals you have available on your battery.

Firmware and Programming

The CA firmware is updated via the communications port using a TTL->USB adapter cable and the same firmware update tool as the V3 CA devices:

Download CA V3 Update Tool, V1.2

You will need the programming cable to be recognized as a COM port on your computer. Windows XP and Windows 7 will both find the correct driver automatically if you enable it to search windows update, otherwise you can download and install the VCP (virtual com port) drivers from FTDI:

In order for the bootloader to work the Cycle Analyst must be externally powered up, it won't get power just from the programming cable alone. So either bring a laptop nearby to your ebike, or have a battery or other source at hand to turn on the CA. The TTL->USB programming cables that we offer are a full 3m long which can help with the reach. 

To update the firmware, select the .hex file you want to load, select the serial COM port on your machine that is connected to the CA, and then hit the button "Update Firmware".

cycle analyst firmware uploader tool

At that point, the program will detect the CA automatically and start programming, or it will say "Please cycle power to the device" and it is waiting for the Cycle Analyst to be turned on. You have 30 seconds in which to turn on the device, and once that happens the Cycle Analyst will be detected and you will see a message showing the firmware upload progress, followed by a verify process, and finally an "Upload Complete!".


CA V2.4 Prelim Hex File May 2015, Try this one for battery gauge icon

CA Marine V1.03 Apr 2015, Special Marine firmware for applications that don't require speedometer
CA V2.3 June 2012, The Original V2.3 CA firmware 


User Manuals

The quick start guide for the current V2.4 CA Firmware is available here.

The V2.3 manual contains more details on display screens and setup parameters, and is available here.

Old versions of the user manual going right back to the Drain Brain devices are available from our documents listing.


As well, we supply the following accessories to use with the Cycle Analyst:
cycle analyst high current shunt
High Amperage Shunt: We offer a large 0.25 and 0.5 mOhm shunt resistor to use with the High Current Cycle Analyst devices for those who do not already have a suitable shunt in their system. The 0.5 mOhm device will work for recording up to 150-200A continuous currents, and 400A peak, while the 0.25mOhm shunt is good for up to 250-300A continuous and 800A peak.
TTL -> USB Converter: We also offer a TTL-> USB cable that converts the serial data stream from the CA into a USB format. When plugged into a computer, the cable is recognized as a virtual COM port, and data from the CA can then be viewed or logged with a program like Hyperterminal. Most computers will automatically install the necessary driver, but if not it can be downloaded here. Data saved and recorded via the TTL->USB cable or with the Analogger device can be conveniently uploaded and viewed on our Trip Analyzer web application.

CA-DP Extension Cable:
We have a 2 foot extension cable that is terminated with a 6 pin male connector at one end and a mating female connector on the other. This can be useful for some recumbent or stretched vehicles with the stock 5 foot cable lenth is insufficient for reaching between the display and the controller. 
The Cycle Analogger is our data logging solution that stores the information stream from the Cycle Analyst (and optional GPS unit) directly to a small solid state memory card. Then you can simply plug the card into a computer afterwards to study the data, rather than having to have a small laptop with the vehicle while riding. Complete user manual is available here

Frequently Asked Questions:

How do I purchase a Cycle Analyst?
We currently have over 50 vendors and dealers that carry the Cycle Analyst all over North America, Europe, and Australia, so if you have a local or favorite ebikes supplier you should be able to order directly from them. Alternatively, you can purchase Cycle Analysts straight from our online store which will ship from Vancouver, Canada.
For anything else, such as OEM boards, volume orders, or other custom requests, please contact us directly.
How can I use the data logging output, does it just plug into my computer?
No, the data output in Version 2.1 and 2.2 Cycle Analyst devices is a 0-5V serial data stream transmitted at 9600 baud. In order to read this information to a PC or laptop, it is necessary to either make or purchase a small RS232 level shifting circuit to interface with the computer serial port. Basic instructions on how to do this are included in the user manual. We also offer a TTL->USB converter cable that can solder to the Tx and Gnd pads and allows you to read the data through a USB port. Alternately, the data can be saved to a flash memory device for future analysis using the Cycle Analogger, or the Logomatic from SparkFun.
How do I turn off the backlight?
The backlight can be turned off by shorting the two pins leading to the backlighting LED. It would be possible to insert a switch across these leads so that you could have ON/OFF control of the light if desired.
As well, the backlight can be dimmed by putting a resistor or potentiometer in parallel with the backlighting LED. A range of 0-1000 ohms will provide a good adjustment span.
I need to extend the cables, is this OK?
Yes, the Stand Alone unit uses a 5' cable between the shunt and the display box. If a longer span is required, then an additional length of 4-conductor cable can be spliced inline. The Direct Plug-in version needs a 6-conductor extension.
If the speedometer sensor cable is also insufficiently long to reach the wheel, then that can be extended with a simple 2-conductor wire.
Is it possible to install a quick disconnect between the Shunt and Display?
Yes. You can install an inline connector if you wish for these two items to separate.
Can I use the 5V supply on the Circuit?
If an external device draws current from the 5V bus, then the data will not save properly on power down. If only a few (2-3) mA of current are required, then it would be possible to tap into the controlled 5V supply which goes to the LCD screen, through the pad labeled 5V*
How can I show RPM?
Set the wheel circumference to 1666 mm, and the display units in Km. Then the speed indicator will display in 10's of RPMs, so for instance 34.5 kph would be 345 RPM.
Oops, I ordered the wrong model, can I convert my CA-DP/CA-HC/CA-SA to a CA-HC/CA-SA/CA-DP etc?
In principle yes, all of the Cycle Analyst devices are internally identical, and it is only the wiring and some setup parameters that are changed between the various units. So you could take a CA-DP device, snip off the 6-pin connector, and then wire it up to a large shunt to make a CA-HC. Similarly, if you have a CA-SA but want DP functionality, then you could in principle replace the shunt with a 6 conductor cable terminated with the right connector.
I just got a Direct Plug-in Cycle Analyst, but how do I know the RShunt value of my controller?
Ideally, you will have some other current reference and then you can compare the readings on the CA with the known readings of another amp or amp-hour meter. So if the Cycle Analyst says 27 amps while a reference shows 19 amps, then the CA's RShunt value needs to be increased by 27/19 = 42% higher. 
By default it is set to 1.000 mOhm, in which case the correct value for RShunt would be 1.42 mOhm. If you don't have another current reference, then you can get a decent calibration value based on the current limit of the controller. Look at your continuous amperage draw (second screen) while riding low speeds at full throttle. If the CA says 53 amps while your motor controller is limited to 20 amps, then your best guess for RShunt is 53/20 = 2.65 mOhm.
The exact value of RShunt can vary quite a bit from controller to controller even from the same manufacturer and batch. The 6 mosfet Infineon controllers are typically between 5-6 mOhm, the 12 mosfet controllers are more often between 2.5-3.5 mOhm. Crystalyte controllers can range from 1.1 mOhm to about 2.6 mOhm. The eZee controllers are usually between 1.3 - 1.6 mOhm. For businesses or power users, we also manufacturing a precision RShunt measuring device that plugs in quickly to the battery and CA plugs of the controller to give an instant read out. 
I love my CA but I'm worried about theft, how do I protect it from getting stolen?
We get asked this a lot, but as far as we know no one is going around ripping Cycle Analysts off the handlebars of parked ebikes. Trust us on this. It's a specialty device that is hard wired to the bicycle (someone would need to gut the cables to get it off), with no black market value at all since no one would have a clue what to do with it.
That's a great device, I have an ebike resale business and would like to sell the unit re-branded with my name and logo, can you do that?
That's a great device, I am a designer / manufacturer of a quality electric vehicle and would like to incorporate the Cycle Analyst and all its functionality into the product. Can you supply an OEM board and possibly make the following customizations to the code?
Yes, in general we are open to OEM sales of this unit and love to work with entrepreneurs who are advancing the state of personal EVs. However, bear in mind that this is an accessory that is manufactured by hand in North America. It is not available in the 10000 piece lot for a few dollars apiece to throw on imported Chinese scooters.
Can you customize it for me to do X and Y, and display Z but not Q?
For OEM customers purchasing in volume, there is a limited amount of customization that can be done to the firmware and display screens to more ideally suit the application. For instance we have done this for both the Stokemonkey and the M55 ebike. The cost for customizations to the firmware starts at $1000.

Where to Order