ePure Race Wiring

EM RACE schematic with revisions.pdf

Wiring Diagram

I can't take credit for the wiring diagram.  It was drawn by a friend and fellow ePure owner.  But I did sign off on it, so blame me if you find an error. 

A wiring diagram is a basic necessity that should have been provided by Electric Motion.

Note that I sometimes refer to ground” in various parts of this website.  Understand that to mean the negative side of the battery which is also sometimes called “return.” 

Nothing in the bike's circuitry is electrically connected to the chassis.

Resistors in Wiring Harness

There are two resistors in the main wiring harness (loom) associated with the LED/lanyard (listed as the deadman magnet switch on the wiring diagram).  See the adjacent photo.

A 2400-ohm resistor (color code: red, yellow, red) is in series with the blue (common/signal return) wire.

A 5600-ohm resistor (color code: green, blue, red) is in series with the red/black (battery positive) wire.

Location of resistors in wiring harness by  controller

Location of unfused connections.

Fix This!

Under the heading of questionable design choices, are unfused connections directly to the battery (see the Wiring Diagram input to the 300A fuse).  The input to the 300A fuse has 4 wires:

I removed the DC-DC lighting converter, but the wiring to the SoC meter is still a problem.  If the wiring itself were to short out, it could cause a fire.

The 2021 and 2022 ePure Race (and possibly others) have this issue.

I installed a small pigtail fuse for the SoC meter's source directly after the ring terminal. 

Small Connectors

The small connectors distributed around the bike and shown below are the ones originally introduced by JST.  I recently discovered the correct crimping pliers are made by a Japanese company called Engineer.  Their PA-20 is a good fit and is available inexpensively via Amazon.  This works much better than the Chinese ratcheting style that always required me to hand re-work each pin with tiny pliers.

JWPF connectors and sticky labels (ugh!)

Engineer PA-20 crimper & Chinese JWPF assortment pack

JWPF Tips

These next photos show useful techniques when working with JWPF connectors.  

In order to separate the connectors, it's necessary to apply pressure as shown to release the plastic catch.  Of course, it's much easier on the bench with new clean connectors.  There is very little clearance and once dirt gets under the plastic catch, it becomes much more difficult to release.      

The other photo shows a homemade pickoff connector used to measure signal levels.  Note there is a small segment of insulation removed from each wire.  This should be done in different locations along the length of the wires to prevent accidental shorting.   I prefer this method to back probing whenever possible. 

JWPF Connector Separation: Apply pressure as shown.

JWPF Pickoff Connector

Connector Tags

The little tags on each wire bundle indicating their purpose are most annoying!  It's a foregone conclusion that some will eventually fall off.  The writing on mine is already wearing away.  What's more, EM did not provide any type of legend.  Below is a start at one.

Large Connectors

Battery discharge connector: Anderson SB 120 

Motor sensors connector: AMP Superseal 1.5 series

Motor phase wires: Crimped lug, screw

Controller power: Crimped lug, bolt, nut

Miscellaneous ground (negative return): Bullet style

Throttle Handle

The early throttle handle (twistgrip) is made by Magura in Germany.  It is the same as that used on the 5.7.  

I understand the Magura throttle has been replaced by a Domino unit starting with the 2022 model year.  My friend who owns both a 2021 and 2022 says the Magura throttle exhibits about 72 degrees of rotation whereas the Domino is only about 60 degrees.

With the throttle released, the voltage into the controller is 0.65 - 0.73V (depending on how the throttle snaps shut).  It takes about 1.1 volts for the rear wheel to begin to turn (unloaded).  It will continue to turn down to about 1.0 volts (again unloaded).

See the 5.7 section on Deadband for the adjustment procedure that mimics the free-play adjustment of a throttle cable.

DC-DC Lighting Converter

The DC-DC converter takes in battery voltage to make 12 volts for the lights.  I removed it and all the associated wiring.  This system is mostly unremarkable, with the exception that the standard LED trials headlight is mounted in a 3D-printed plastic piece.  I wonder if this is the first use of 3D-printed plastic on a production motorcycle.

Battery Capacity Indicator / State of Charge Meter

A battery capacity indicator (State of Charge meter) is integrated into the handlebar impact pad.  It is a standard part manufactured by DROK (model number LY7) and available via Amazon for $14 (albeit without the foam padding EM added).  I'm not impressed with its capabilities.  It is programmed for 14 cells.

If you remove the OE unit from its foam padding, it is possible to access two programming buttons on the back.  You can enter programming mode by pressing the rear [K-] button while the unit is being power-on.  The number of cells is selectable, as is the parameter displayed (percent capacity remaining or pack voltage).  

DROK Battery Capacity Indicator.pdf

DROK Battery Capacity Indicator / State of Charge meter

SoC Meter.ods

I used a precision power supply to correlate the DROK Battery Capacity Indicator's percent remaining reading with applied voltage.  Results are shown in the adjacent spreadsheet.    The unit has a time constant of several seconds (i.e., a change in voltage is not displayed instantly).  This helps to prevent rapid fluctuations in the reading during surges in battery drain.

EM Security Magnet (with red LED)

A typical dirt bike kill-switch circuit is closed-to-kill / open-to-run.  This methodology dates back to the days when a magneto winding was shorted to ground to stop the spark.  The 5.7's kill switch operates in this conventional manner.

The ePure is the opposite – you close the switch to enable the motor controller and open the switch to kill the bike.

CPD's parts diagram calls the ePure's tether killswitch a “Security Magnet (with red LED).”  This is part number TL01N-60101-00-00 and it retails for $113 USD.  The unit has 3 wires which connect to the wiring harness (loom) as follows:

Red/Black goes to the positive side of the battery.  This signal is current-limited via a 5.6k resistor in the wiring harness.

Blue connects to the negative (cathode) side of the LEDs.   This signal is current-limited via a 2.4k resistor in the wiring harness.

Yellow/Black enables the motor controller.  The lanyard switch connects this wire to the battery positive to run.  Removing the lanyard opens the circuit to kill the bike.

This LED is illuminated whenever the battery switch is in the ON position.  The LEDs consume about 0.35 watts (assuming a nominal 50 V battery times a measured 7 mA.)

This device may have been designed specifically for EM as it does not appear in Leonelli's 2022 catalog.  According to trialworld.es, the Leonelli part number is M078072C00.  

It may be a fluke, but my security magnet switch failed just sitting in a box over winter.  It was stored with the magnet on.   I noticed the switch would no longer interrupt with the magnet removed.  After hitting it on a table sharply, it worked again but only for a few more cycles.  After hitting it several more times, the switch would no longer close to enable the controller.   

 I'm not sure which failure mode is worse - not interrupting when you expect it to, or leaving you stranded with no way to enable the controller. 

The circuit diagram is shown below.

Inside TL01N-60101-00-00

My initial guess as to what's inside was functionally correct, but after opening it I see there's a little more to it.  

The internal magnet is a torus measuring 8mm OD x 3mm ID x 3.5mm thick.  (You can see mine in the adjacent photo has fractured and that's what caused the failure.)  This magnet is located on the underside of a flexible conductor that forms part of the switch.  The assembly is heat-staked in place by deforming the plastic stalk that runs through the center.

When the lanyard magnet is bought near the handlebar switch, the flexible conductor contacts the underside of the PCB and closes the circuit.  The switch assembly is radially symmetric and provides a redundant pair of contacts.  Partly, I suppose this is to accommodate a slight misalignment. 

A clear-ish silicone rubber ring is visible under the PCB.  It provides some mechanical compliance to the assembly.

For future reference, I measured the tether magnet's field at about 3500 gauss near the perimeter.

If you don't have a spare lanyard switch, fabricating a failed lanyard bypass by connecting pins 1 and 3 in a spare female JWPF connector might be prudent.

Inside view of  EM's Security Magnet (with red LED)

Lanyard Delete

Call me stupid, but I hate lanyard (tether) kill switches.  They are not required by my club and I don't compete in national events.  Reach up to wipe your face, and the bike dies.  I replaced the costly OE unit with an inexpensive Chinese illuminated push button switch.  It is intended to switch an external load like a fog lamp but seems to work in this application.  The correct wiring is:

The switch is illuminated by an LED which has an internal current-limiting resistor.  Although it is intended for a 12-volt electrical system, it is compatible with the ePure Race's battery power of about 54 volts due to the current-limiting resistors present in the EM's wiring harness.  

The new switch's LED seems to have a reasonable brightness but is a bit dim outside in the sunlight. 

Credit: DERI Automo Store

Lanyard replacement

Illuminated Push Button

This illuminated push button is the same style as that used on the battery itself, but it's slightly smaller.

It can be installed above or below the handlebars. 

I have used this for a dozen rides and like it.  My only negative comment is that the blue ring often looks illuminated in sunlight even when it's switched off.