Nube questions about MP5 vector

[Churnmaster]

I finally got around to building out my tandem with Magic Pie 5 vector.... bike is basically assembled but  throttle has sticker that says 36volt I'm running 52volt and its getting pretty warm.... the horn button doesn't appear to work. Do I  need to do any programming ? What are the factory settings ? What does the red button do ? what does the button on the throttle do ? I don't have a display. bike is running , just road tested it seems fine but still want to understand the controls  rides fines with about 400lb rider weight
 sorry for being such a nube !

[Bikemad]

Hi andto the forum.

The LED Battery Gauge will get quite warm if you are using a 36V throttle with a 48V (52V) battery.

It will not affect the operation of the throttle itself, but the LED Battery Gauge will not be able to indicate the state of the battery, as all three LEDs will remain lit, until the battery is completely empty and the battery's BMS shuts of the power altogether.
When a 36V throttle unit is used with a 48V battery, the three LEDs simply provide a visual warning that the system is powered up. 

I don't know how long the 36V battery gauge will run on 48V+ before it stops working altogether, but if it does eventually die, it is unlikely to have any negative effect on the operation of the throttle, motor and controller etc.

The horn button will only work if you connect a suitable external horn to the unterminated Blue and Yellow Horn wires on the front harness:



The button on the throttle is used to turn on/off suitable LED light connected to the unterminated Black and Red Lighting wires shown in the above picture.

The factory default settings for my Magic Pie are as shown below:



The Red button next to the Green Horn button is used to engage the cruise control, simply hold the throttle at the desired amount and then momentarily press the Red button, this will maintain the same throttle setting. You can then release the throttle completely and continue to run in Cruise mode until you apply either of the brakes or you press the Red button again to disengage the cruise control.

Alan
 

[Churnmaster]

Thanks for the response! Where do I get a 48v throttle

[Bikemad]

Your GM dealer should be able to supply a 48V throttle, but I wouldn't bother to replace it. There is very little to be gained from fitting a 48V throttle as the gauge will still be just as unusable with a 52V battery, although the throttle unit should feel slightly cooler when touched.

This basic LED battery gauge was originally designed for lead acid type batteries which have a more pronounced voltage drop throughout their discharge, but the LiFePO₄ batteries in use today have a higher voltage which drops very little in comparison as they discharge, and the LEDs would probably remain fully lit for 90-95% of the battery's use.



Take a look at this post to find out how a resistor can be used to adjust the gauge operation to better suit the battery type being used. As your cable has already been chopped it should be relatively easy to solder a variable resistor into the battery gauge power supply wire.

I have tested three different throttles using a variable voltage power supply to try and determine the working voltages of the three LEDs on the battery gauge and here are the actual results:

LED	24V throttle	36V throttle	48V throttle
Green	24.1V and over	36.2V and over	48.2V and over
Yellow	21.7V and over	31.6V and over	42.5V and over
Red	12V and over	21V and over	30V and over

(The above measured voltage readings were taken at the battery end of the thick Red and Black power cables on the motor harness.)

According to the above empirical results, the yellow LED on your 48V throttle should only go off if the voltage drops below ~42.5V.

As the Yellow LED would not start to go off until the pack voltage was below 42.5V, with a 14 cell 51.8V lithium battery (58.8V fully charged) it would need to be over 95% discharged before this would occur, and on a sunny day, I suspect that the battery would probably run out completely before you even noticed that the yellow LED had gone off.   

It would be a bit like a fuel warning light coming on in your car's dashboard, but not having enough fuel left in the tank to make it to the nearest filling station. 

Alan