MPe and FAQ

MPe AND FAQ

- frequently asked questions and answers

In this article you will find the answers to the most frequently asked questions that arise:

  • when purchasing the MPe kit
  • when installing the MPe system in the vehicle
  • and also during its use.

We have collected them all in one place, so as to satisfy your curiosity, broaden your knowledge of the product and, above all, help you solve the problem you have encountered.

To make it easier for you to find the topic you are looking for, we have divided the questions into several sections (clicking on a given section will take you directly to it).

Column with questions for MPe computer

Will the MPe fit my vehicle?

The MPe computer is designed mainly to vehicles built from scratch and fits all controllers that have a thumb throttle input, and their supply voltage is less than 100V. If you are in doubt as to whether the MPe will fit your vehicle, you can contact us using the contact details. We always try to help our clients.

Unfortunately not. MPe is not designed to closed systems and central drives, which are found in factory e-bikes. MPe is not used to unlock the drive from the factory limits.

Connection to the vehicle and first run

Very important thing: if this is your first e-bike and you are just connecting components to the vehicle, first start and check if the vehicle is fully functional (battery, controller, motor) before connecting the MPe. Then refer to the sections the user manual, „Before Connecting”, „Connecting to the Vehicle” and „First run of the device”. Only in the next step, you can connect the MPe to the vehicle (then it is simply easier to eliminate the possible source of error).

Yes. You can use the ignition switch output with battery voltage and connect this battery voltage from after the ignition switch both to the controller and to MPe on connector No. 1. Then nothing is connected to connector No. 2 in MPe.

It is only important not to confuse the battery poles – positive and negative. It does not matter in which direction of the current flow we connect the current sensor, as it is bidirectional. If, after connecting, it turns out that the current read from MPe has a negative sign, it is enough to reverse the direction of the current reading in the configuration (parameter 6 – measurement direction). The current indicated by MPe while driving while the battery power is being drawn must have a positive value.

Connect the cable that comes out of the motor from the temperature sensor to connector No. 32. At the same time, we must set the „D” switch (on the main board) to the ON position, ie turned on. At this point, in the configuration, we can choose the type of sensor, depending on what is installed. The type of sensor T1 is selected in parameter No. 41.

Yes, of course. Normally we connect three wires of the thumb throttle to the controller, because the controller supplies power to the throttle. Two of the three wires are for power and the third is for the signal. When we use MPe, the throttle is powered from the MPe motherboard, and only a signal is sent to the controller, so the power cables are not used.

Unfortunately, this is not possible. MPe works with dedicated current sensors, operating on the Hall effect principle, where the output is by default half of the supply voltage (with increasing current consumption, the voltage increases, and with a decrease or negative value, the voltage decreases linearly with a given resolution).

Unfortunately, you cannot connect the bike’s lighting, as this 12V output is provided to power the MaxiColor 850C display. It also has a very low current efficiency, so it cannot bear the load generated by the bicycle’s lighting.

Most likely, the first run procedure was not completed in accordance with the operating manual. Such symptoms occur when, for example, the current reading generates a negative current, i.e. the direction of the current sensor operation is incorrect (parameter 6). Also, similar symptoms are the result of incorrectly set throttle voltages (parameters 13-18), incorrect low voltage cut-off threshold for discharged battery (parameter No. 3) or incorrect temperature reading that goes beyond the cut-off range of the motor. Follow the instructions in the „First run” section of this user manual.

The Charge Indicator bases its operation on the settings we have introduced, which are the battery capacity in ampere hours [Ah] and watt hours [Wh], low voltage cut-off setting and full battery voltage setting. These are the first four configuration parameters that must be properly set. During the first installation, even after these parameters are set, there may be a discrepancy between the battery charge level indication and the actual battery charge level. This is normal and it will self-adjust when we first charge the battery to 100% and the MPe detects it.
We can also refresh it manually.
For the MiniOled display: on screen 4, where we have labels such as IM, WU, WK and AU, hold the bottom button for 2 seconds, then the AU and WU values ​​will update to approximately the current battery level.
For MaxiColor 850C display: enter the statistics screen, holding the plus and minus simultaneously, and then, when we are on this statistics screen, hold the power on switch and plus simoultaneusly for 2 seconds, the battery discharge values ​​will refresh.

PAS sensor operation

Yes, the MPe computer allows you to add a PAS sensor for all controllers available on the market that have an input for the thumb throttle. Even for those drivers that do not allow adding PAS sensor by default.

The cadence sensor (PAS sensor) can be any, three-wire, 5V power supply. We recommend using a sensor with at least 12 magnets or more. Fewer magnets will result, for example, in a slower activation of the PAS or a later deactivation of the PAS when you stop pedaling.
We recommend that you only use sensors that do not work when cranking backwards. Sensors that also work when turning the cranks backwards are dangerous (when we pull reverse the bike, the cranks turn and the MPe can detect this movement as an impulse to activate the PAS assist system and the bike will move forward). Whether the sensor works while turning the cranks backwards depends only on the type of sensor used – please ask your dealer.

It has to do with improperly set input voltage of the thumb throttle TIN MIN. Most likely, it is set too low and the MPe believes that the thumb throttle is minimally twisted all the time and therefore does not activate PAS assist. This is set in parameter No. 15, which defaults to 90. This value should be rounded up to the nearest ten and greater than the minimum thumb throttle incoming voltage to MPe that can be read on the display.

For example: if the minimum thumb throttle voltage input to the MPe (read on the MPe display) is 91, then parameter No. 14 should be set to 100 (rounded up to the nearest ten).

This is due to an incorrectly (too high) set speed limit option for PAS BOOST activation (pedaling assistance, parameters No. 115-119). This speed must be set so as to be below continuous speed which can be maintained in steady normal driving. Usually it is about 8-10 km/h less than the general speed limit for a given assist level (parameters 80-84).

For example: When we have a general speed limit of 30 km/h for the assist level 4, the bike will accelerate with a steady ride to approx. 27 km/h, because from 25 km/h MPe starts to reduce the power so as not to exceed the set 30 km/h. Then we drive steadily about 27 km/h. This speed is maintained because the power-speed balance has been reached. Therefore, the speed limit of the PAS BOOST gain must be set below this value, e.g. up to 22 k /h (So 8 km / h less than the general speed limit for this assist level). The point is that this value should be below the speed that we are able to maintain during normal, steady and long driving.

In the locked mode, the power and speed of a given level of assistance does not change if is lower than that set for the locked mode (default 25km/h 250W). If the unlocked level of assistance is set above the locked values, then after activating the locked mode, the power and speed values of the given level of assistance will be overwritten / reduced with those for the locked mode. Therefore, if we have several levels of assistance set above the value of the locked mode, then after activating the locked mode, these levels will have the same limits (such as for the locked mode). Then, in locked mode, the change of assist level will not translate into a change in the amount of assistance power.

The default MPe settings should fit most vehicles. There may be times that the settings will have to be tuned to your vehicle. The most common cause of power fluctuations during support are incorrectly set PID coefficients (parameters No. 50 to 61). The parameters of the speed of power ramp up (parameters No. 100 to 104) also have a large influence on the unwanted power waving.

Thumb throttle

First of all, follow all the instructions in the “First run of the device” section and configure the list of basic parameters the user manual. The MPe computer must be in unlocked mode to use the thumb throttle operation. By default, the MPe starts in locked mode, in which the thumb throttle is inoperative and power is limited to that set for locked mode.

If this happens with the wheel in the air it is normal. The current sensor protection works, which does not measure the current high enough for the currently twist of thumb throttle. This functionality can be turned off in parameter 8.
If this situation also occurs during normal driving, most likely the thumb throttle voltage is wrongly set (configuration parameters 13 to 18). First, set the input parameters of the thumb throttle correctly (parameters 15 and 16). To do this properly, follow the recommendations in the section “Description of MPeV6 computer functions and their configuration” – “Throttle operation settings” the user manual. Next, set parameters 13 and 14. Parameter No. 14 (TOT_MAX) should be set as high as possible, before the point in which controller cuts off the drive.

For example: we set the value to 350, we twist the thumb throttle to 100% and the controller does not cut off the drive, it is ok. We give the value to 400, we twist the thumb throttle to 100% and the controller cuts it off, which means that there is too much voltage at the output to the controller. In this case, this value should be reduced.

The voltage of the thumb throttle output from the MPe is set as most controllers on the market expect, ie up to 3.5V. For some controllers, eg Sabvoton, this value can be changed, because these controllers also have their voltage regulation in the setup program. 

The reference voltage is not always equal to the actual voltage coming from MPe.

For example: not always TOT MAX voltage set to 350 wil result in 3.5V at output. It depends on the type of controller and installation. The TOT MAX parameters should be set as high as possible, just until the controller is still working normally. When we set TOT MAX too high, the controller will read it as a damaged thumb throttle and cut off the drive.

There is no such possibility and it is a deliberate procedure. The throttle lever works only for the unlocked mode.

Regenerative braking

MPe does not interfere with the operation of the regenerative braking which is controlled by the controller. In order to activate regenerative braking, the controller must be informed that the brake is applied. Therefore, we connect the brake sensor located in the brake handle to both the MPe and the controller. At this point, when we press the brake handle, the controller and MPe will cut off the drive, and the controller will activate regenerative braking (if it has such a function and it is correctly set).

Yes, the MPe computer does not interfere with the operation of regenerative braking managed by the controller. Of course, you can connect a regenerative brake thumb throttle to the controller.

There is, however, an inconvenience. Due to the fact that the brake thumb throttle is not connected to the MPe, the MPe will not see that the brake thumb throttle is applied and that we want to brake when using the regenerative brake thumb throttle.
This situation may occur: the rider pedals all the time, uses the regenerative brake thumb throttle, the controller cuts off the drive. MPe will read this as a drop in power, and because we are pedaling all the time, MPe will want to increase this power to get to what is possible and should be given. This increases the throttle signal sent to the controller. When the driver releases the regenerative brake thumb throttle, there may be a jerk (for a split second), felt by the driver. The only way to prevent this is to add a magnetic sensor that will react to the twist of the brake thumb throttle. There is a magnet in the thumb throttle, which will activate the brake sensor. The sensor should be placed near the regenerative braking throttle. When we twist the thumb throttle, the magnet will move and activate the brake sensor attached to the throttle and will give a signal to MPe that the brake is active. The position of the brake sensor glued to the brake throttle should be selected experimentally so that the sensor is activated at the minimum twist of the brake thumb throttle.

This delay is due to the fact that the current reading during regenerative braking becomes negative. MPe has a protection against throttle output when the current is negative. This is to prevent malfunction of the PAS assist system. This value of negative current, at which the drive is cut off, can be defined with parameter No. 9. By default, it is set to -2A. When we have a correctly configured MPe and only this functionality annoys us, we can increase the value from these -2A, to e.g. 10A or 15A. Then, the thumb throttle after braking will not be delayed.

MiniOled display

Enter the statistics screen (by pressing two buttons at a time) and on the screen 2 (where we have the TR value – this is the parameter) hold the bottom button on the display for 2 seconds. Together with the daily distance, all other memorized values will be reset, e.g. maximum speed, average speed, running time, maximum power, maximum current.

Yes, both the display and the buttons on it are waterproof.

MaxiColor 850C display

Enter the statistics screen (on the remote control, hold 2 buttons at once plus (+) and minus (-) for one second), and then hold 2 buttons at once for 2 seconds: minus (-) and switch (o). Together with the daily distance, all other memorized values ​​will be reset, e.g. maximum speed, average speed, running time, maximum power, maximum current.

Unfortunately, this is not possible. The MaxiColor 850C display turns on only with the remote control on the handlebar, which is dedicated to this display.

Yes, both the display and the buttons on it are waterproof.
Degree of protection: IP65 – the first digit of the text means protection against access to hazardous parts by a wire and full dustproof protection, the second digit – protection against a stream of water with an intensity of 12.5 l/min poured on the housing from each side.

Other questions

There is actually the same current sensor in each PowerPCB module that can measure up to 200A. These modules differ from each other in terms of connectors and wires that go to MPe.

In the 90A version we have XT90 connectors. The name itself indicates that they can handle a maximum of 90A. Due to the fact that in this version of the 90A we use both paths of the XT90 connector as a positive and negative poles separately, we can thus transfer the battery supply voltage to the motherboard module.

However, in the 180A version we also have XT90 connectors, but here it is connected differently, because both plug paths are used as a positive pole, i.e. the negative pole of the battery does not go through the PowerPCB 180A module. Therefore, at the output wires, there are no positive and negative poles for the battery on thin wires. Both poles of the battery need to be connected to the motherboard on their own, creating a separate installation for them.

On the PowerPCB 200A, the wires are soldered directly to the outputs of the current sensor. They are led out and have no connectors. Here, the user himself decides which connectors to use and how to solder them to the wires. Due to the fact that here, as in the PowerPCB 90A, we have both the positive and negative poles of the battery soldered, also at the output of this module, on the thin wires that go to the motherboard contain the positive and negative poles of the battery to power the motherboard.

To sum up: PowerPCB 90A, 180A and 200A have the same current sensor. They differ in terms of connectors and the fact that there is battery voltage (positive and negative pole) on thin wires at the output of PowerPCB 90A and 200A, and there is no battery voltage at the output of PowerPCB 180A on thin wires.

There is no negative pole in the 180A module, as both plug paths are used for the battery positive pole. Due to the fact that both paths of the XT90 connector are used as a positive pole, the current carrying capacity of the 90A plug becomes 180A, i.e. we double the load capacity of the connector, but lose one pole of the battery. Due to the fact that we do not connect the negative pole to the Power PCB 180A, there is no battery voltage on the output, on the thin wires, which is connected to the MPe motherboard. Accordingly, the installer has to ensure that the positive and negative poles of the battery are connected to the motherboard to power it.

If you are at the purchasing stage, see the previous question: what are the differences between 90A 180A and 200A. You will notice that they aren’t really that much different. First of all, you need to decide which version to buy for the installation you intend to build, the cables and plugs you will have in your installation. If you plan to modify your e-bike in the future, it is best if you choose the 200A option and make the connectors as you need.

If, however, you already own a PowerPCB 90A and you want to increase the power of the vehicle, it is enough to change the PowerPCB 90A module to a more powerful one, e.g. 180A or 200A. If you also have great manual skills, you can solder thick wires to the currently owned board. This way you will increase its current carrying capacity, because the only limitation here is the connector, which has the current carrying capacity of 90A.

For the MPe system, the PAS assist functions and cruise control base their operation on reading the current drawn from the battery. When the wheel is raised, the power consumption is negligible compared to normal driving. Therefore, it is impossible for the PAS and cruise control to function properly in service conditions with the drive wheel raised. These functions should be tested and fine-tuned during normal driving.

In order for MPe to correctly show the remaining distance to be ridden, it must have actual driving data. If it is a fresh installation or just after resetting the counter, this value is perfectly normal. It will update as the vehicle begins to move under normal road conditions.

Yes you can, but in MPe there is no output for two separate controllers. This means that we will not be able to define a different power for motor 1 and a different one for motor 2. However, you can connect two motors in parallel, simultaneously controlled by one thumb throttle with one signal. This solution can be done and there will be no problem with it. You then need two motor controllers for each motor individually. Both will be connected after the MPe measuring module, and the MPe will show the total power drawn from the battery by both controllers. This solution is possible.

You can use two different. Just one will take more energy than the other and give different power. Alternatively, you can use the wiring from the controllers and install various switches of their operating modes, or turn one off completely.

Technical support

If you have not found any information on your doubts in this article, please contact us directly via the contact form. You can also leave a comment at the bottom of this article. Perhaps you will help other people who already have an MPe computer or are planning to buy one. We will certainly try to help and advise you.

We also encourage you to follow us on social media and join our e-BIKEL group on Facebook. Here you can also find a lot of interesting information about electric vehicles and the MPe wattmeter itself.

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