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"Thinking Outside the Four-Wheeled Box" ebikes.ca |
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"Thinking Outside the Four-Wheeled Box" ebikes.ca |
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.
Once connected to the vehicle's power bus, the Cycle Analyst calculates and shows the following information:
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.
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.
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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. |
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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 controllers that we have at www.ebikes.ca. |
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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 kits 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 front wheel. |
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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. |
The Stand Alone device comes already calibrated to its own shunt resistor and is ready to go out of the box. The CA-DP and CA-DPS devices need to be calibrated to the shunt inside the particular controller to which they are attached. If they are purchased together with a controller from us, then we will be able to supply them pre-calibrated to each other. If you purchase the CA-DP(s) separately from your controller, then it will be supplied with a default value of 1mOhm for the shunt resistance, and you will have to change this to match your controller shunt resistance for the readings to be accurate. The High Current model needs to be mated to an external shunt, such as the one that can be purchased from our online store's
Accessories Page.
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Large Screen High Current Model (CA-HC-LS) We also have for sale an OEM version of the Cycle Analyst designed for use in larger electric vehicles such as scooters, motorcycles, and cars. This model has a display screen that is twice the size as our regular version so that it is easily readable at a glance. It's designed primarily to mount behind existing dashboards, and as such is not supplied with any enclosure, just the bare LCD and circuitboard. These are all high voltage units (up to 200V input) and are wired to use a user supplied shunt. They also feature the Version 2.1 firmware which enables a serial datalogging output, larger current and speed ranges, current and speed control via an external input and several other features which you can read about here and here. |
The regular Cycle Analyst units are available from JVBike in Vancouver, EVTech in Texas, BobTech in Germany, Electro Ride LLC in California, Power In Motion in Calgary, and several other outfits around the globe, such as OnBike in the UK, EMTB in Australia, and BinBike in Belgium. Thunderstruck-EV and Electric Motorsport both have the high current and 200V models in stock coupled with an appropriate shunt for larger vehicle applications.
Alternatively, you can buy Cycle Analysts directly from our online store.
For anything else, such as 200V units, OEM boards, volume orders, or other custom requests, please contact us directly.
Current V2.1 User's Guide Applies to CA devices with V2.1 or V2.11 splash screen, since May 2009.
Manuel Utilisateur, en Français, traduit par C. Bayard, merci beaucoup!
Cycle Analyst V2.0 User's Guide Applies to devices sold between June 2007 to April 2009
Original DrainBrain User's Guide For the original "DrainBrain" from way back in the day (2005-2007).
The installation of the Stand Alone unit is straightforward. The molded shunt is attached inline with the battery pack's discharge leads. The easiest way to accomplish this is by terminating the shunt leads with the same style of connector that joins the battery pack to the controller, and then the CA unit can be inserted and removed from the system at will. If there is an ON/OFF switch in the system, it should be connected on the battery side of the shunt so that the CA powers down when vehicle is turned off.
The speedometer sensor is attached to the fork of the vehicle with a pair of zip-ties, and a small magnet screws on a wheel spoke to detect rotation.
For the Direct Plug-in Cycle Analyst, installation is as simple as plugging it into the motor controller if it already has the 6-lead CA connector. All the controllers at our shop have this attachment. If your controller doesn't, you can attempt to wire a Cycle Analyst connector into the controller on the vehicle yourself. The tap points for the 20A and 35/40A crystalyte controllers are shown below. For other controllers, it is generally not that difficult to identify the correct soldering locations, however this is an at-your-own-risk pursuit, and incorrect wiring can cause permanent damage to the CA board.
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Cycle Analyst tap points for 20A Crystalyte controllers |
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Cycle Analyst tap points for old style 35 and 40A Controllers |
When the CA-DP is purchased from us along with a motor controller, it is pre-calibrated to the particular shunt resistance of that controller. If the unit is purchased alone, it is set by default for a 1.000 mOhm shunt, and you will need to calibrate it to the shunt resistance within your controller for the amps and watts readings to be accurate. As well, if you are using the hall signals for speed detection, then the #Poles variable in the advanced setup menu needs to be set to the number of hall effect transitions per wheel. The Crystalyte 400 series have 8 poles, the 500 series have 12 poles.
The High Current model is like the Stand Alone version but without a molded shunt, so that you can attach it to high amperage sense resistors. The blue wires with a ring terminal go to the (-) side of the sense resistor, while the white/orange striped wire goes to the (+) side of the shunt. The remaining orange wire is connected to the positive leads of the battery pack.
By default, this unit is supplied in the High Range mode (resolution of 0.1 A instead of 0.01A, and display readings in kW instead of watts) and the shunt is set to 0.500 mOhm.
In order to take advantage of the speed limit, current limit, and low voltage cutout, the Cycle Analyst needs to be wired in such a way that the Throttle Over-Ride output is able to take charge of the motor controller when one of the limits is surpassed. This is already accomplished in our CA-DP and DPS models when connected to any motor controllers which have the 6-pin Cycle Analyst connector, so no additional wiring is required beyond plugging the two devices together. If you are connecting it to a 3rd party controller then it will be useful to understand the following details.
The over-ride output is an analog voltage that can range from 5V down to 0V. When it detects that a limit is exceeded, the voltage begins to ramp down from its resting point (set by ItermMax), until power to the motor is reduced and the limit (speed, current, or voltage) is no longer exceeded.
The actual output is derived from an op-amp on the circuit board, and it is capable of both sinking and sourcing current. In the original Cycle Analyst boards (identified by a lack of label on the PCB) this output was wired directly from the op-amp, so it was quite stiff, but also made the board vulnerable to damage if the Throttle Over-Ride was accidentally wired incorrectly to a voltage source. In PCB revision 7 (labelled DB2 Rev7b), the output line was modified to include a 1k resistor (R6) to protect the silicone. This however means that the Over-Ride line can only source or sink small currents, and if more than a mA needs to be drawn from the output, then resistor R6 should either be reduced in value to a couple hundred ohms, or possibly shorted out entirely.
In most setups, the user typically has a throttle signal that varies from close to 0 or 1V when it is off, up to 4-5 V when the throttle is fully engaged. For proper operation of the Cycle Analyst limitting features, the signal for the motor controller should be the lower of these two voltages. An easy way to achieve this is with a diode and current limiting resistor on the throttle line as shown in the following schematic:
In cases where the controller circuitboard is readily accessible, then you will often find that there is a series resistor already on the PCB and the throttle over-ride should ideally tap in just after this point, and then an additional resistor is not required.
With the Stand Alone and High Current versions, you will need to drill a hole through the enclosure and feed a wire to the Th pad on the CA circuit in order to access the over-ride signal.
The response time and stability of the limiting features can be adjusted by changing the gain values in the advanced setup menu. Each one is implemented as a Proportional / Integral (PI) controller. Gain settings that are too high will lead to oscillations about the set point, while gain settings that are too low may cause large overshoots and time lags before the values have stabilized.
| Voltage: | 15-100V standard. 20-200V for CA-HC-LS, and by custom order |
| Quiescent Current: | 7mA |
| Current Range: | + - 200 mV/Rshunt. So for instance, with a 2mOhm sense resistor, the maximum current is 100 amps. With a 0.5 mOhm sense resistor, up to 400 amps, and so forth |
| Current Resolution: | 0.01 A in low range mode, 0.1A in high range mode |
| Current Accuracy: | Temperature coefficient and accuracy depend on the shunt and calibration. With the pre-calibrated Stand-Alone model, it is within 2% +- 0.04A. |
| Speed Range: | Up to 600 kph or mph. There is an upper limit of about 1kHz for the speed sensor input, which correlates to a very fast moving vehicle indeed. |
| Wheel Size: | There are no restrictions on the allowable wheel circumference within the range of 0 to 9999 mm. |
| Distance: | Trip distance is capped at 1999 km or miles. Odometer distance rolls over after 99,999 km or mi. |
| Amp-Hours and Watt Hours: | Both forwards and negative amp-hours are limited to 1999 Ah per trip, while the watt-hours can go up to 19999 Wh. |
The data output in Version 2.1 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 V2.1 user manual. We also make 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.
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.
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.
Yes. You can install an inline connector if you wish for these two items to separate.
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*
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.
No
Yes, in general I am open to OEM sales of this unit and love to work with entrepreneurs who are advancing the state of personal EV's. 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.
Unfortunately, the inrush current at these high voltages the moment that the Cycle Analyst was powered on can sometimes damage a resistor (R9) on the LCD circuitboard that is in series with the backlighting LED. The nominal 270 ohm resistor then ends up becoming in the 10's of kOhm. If this has happened, simply soldering a 1/4 watt replacement resistor that is between 300-600 ohms across the pads of R9 will solve the problem and restore full functionality up to the rated 100V.
Since Sept 2008, all CA boards have been modified to have a softer startup which reduces the inrush current so that this is no longer a potential issue.
In extremely noisy electrical environments, it is possible for noise pickup along the button wires to cause the microchip to reset. Since Apr. 2007, all units shipped have a small capacitor across the button pads that has all but eliminated this occurrence. A capacitor in the 1nF range is generally adequate.
With Stand Alone CA units shipped prior to June 2007, the capacitor used to filter the signal from the speedometer pickup was not always adequate at eliminating switch bounce from the magnet sensor. This could cause brief periodic speed glitches in the +100 km/hr range. Simply repositioning the magnet would generally cause the problem to go away, but if it continues then capacitor C6 on the back of the circuitboard should be increased from 1nF up to 30-100 nF.
If the speed is always showing 0, then there are a few things to check. First is to make sure that the magnet is passing adequately close to the sensor. An extra rare-earth magnet is included with the kits so that a decently large gap can be accommodated; otherwise the stock magnet needs to pass within less than 1mm from the pickup.
If this is not the source of the problem, then it is possible that the speedometer sensor cable has been torn. The cables are pretty thin and we have seen numerous instances where cable ties have been overzealously tightened to the point that the copper wire was sheared. When the wiring is sound, you should measure an open circuit across the speedometer pickup pads when there is no magnet present and a short circuit when the magnet is nearby.
The handlebar mounting bracket is made of nylon, and so there are not many adhesives that make for a solid bond to re-attach the display. Double-sided tape and super-glue are both adequate. As of Oct 2007, the mounting brackets are supported with mechanical fasteners in addition to glue, and so these pieces should stay together even in the worst wipe-outs.
With Direct Plug-in units, right after letting go of the throttle you may see an initial current which gradually settles to zero over the course of a few seconds or even tens of seconds. This is due to thermoelectric voltages produced by the interface between the material of the shunt resistor and the copper/solder PCB traces, and cannot be avoided.
If there is a steady offset current that persists, it is possible to reset the zero offset by performing the "zero amps" operation in the advanced setup menu.
The minimum allowable shunt resistance in the Low Range mode is 0.728 mOhm. If you have a lower shunt resistance than this, set the unit in High Range mode for operation down to 0.0728 mOhm.
Check to see if the Ground, (-) Shunt, or (+) Shunt lines or solder joints are broken. If any of these lines are open circuited and not connected to the shunt resistor, then the indicated current can swing wildly to one extreme or the other.