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[Doctorbass]

For those who dont have any motor problem and that would like to push a little higher the power of your 2010 and 2011 zero S and DS, this might interest you.

A few month ago i talked about a mod to bypass the power limiting  feature of the MBB at low speed.

Bypassing this limiting feature does not mean 1000A+ in the agni but would mean that the motor current limit would be determined by the alltrax only and not by the MBB and the alltrax. so if the motor current is set to 400A i the Alltrax wich is the max recommanded, you would get 400A to push your zero from a dead stop instead of 50-100A like the actual MBB is doing.

After few hours of research and test i have discovered the right wires that connect to the controller, MBB and the magura throttle grip. Actually both controller and magura wires pair goes directly to the MBB.

The mod i'm talking about was done by  installing a DPDT relay that simply bypass the MBB and that jump the wires directly from the magura to the controller.

Once i put 12V to the coil of the relay The normally close contact that connect the alltrax wires to the MBB output just open and the normally open contact become close and jump the in and out  throttle signal  of the MBB, allowing the signal to pass directly from the magura to the alltrax.

I use a double pole relay to also switch the ground and the signal wires.

Since the full throttle is obtained with a high resistance, the throttle goes high only diring the relay contact are floating for few ms wich does not damage anything.


Ok now my impresions:

I can say IT WORK YES !! but i have something else to bypass to allow it to fully work. But from now the motor start very quickly and seem to have gained power ALOT!!  but i will confirm once i make a road test with the fully completed mod

The blue motor current sensor  is detecting a higher current too and i have not bypassed it yet.

The way i thought  and tried to do it is to just add a resistor divider to cut by 2 the motor current signal that the MBB is receiving but  once i push the throttle a little too fast, i still get the error light indicating that the motor current sensor is having problem... so i see that the resistor divider is not working.. On that current sensor, there is 4 wires. one GND, one 5V and 2 for the output voltage proportional to the measured current.

Next thing i will try is to use an OP amp that will keep the output impedense of the current sensor as is and wshould not be seen by the MBB so that mod should succed to fake a half current signal and allow full throttle and power to the motor.

Here is the thread i made on E-S about that:  http://www.endless-sphere.com/forums/viewtopic.php?f=10&t=39228&hilit=pimping+zero

 stay tuned!

Doc

[protomech]

How's the improvement in initial acceleration? And 0-60 time estimates?

[Doctorbass]

I will know when it will work 100%. From now i'm still getting the error code of the motor current sensor... probably the motor current measured is higher than the max allowable by the MBB.

My second option would be to split the cable that pass in the current sensor in half, let say two gauge 4 instead of one gauge 2 and have half the current not being measured by the current sensor so it will allow twice current.

But the motor accelerate really faster just with the relay mod.. but if i try to accelerate too fast  with  no load on the wheel,  the max current limit and error code  is reached just by twisting the throttle grip WOT. Look like the inertia of the motor is enough to kick the max allowable current by the MBB.

I WOULD REALLY LOVE TO HAVE THAT DEVICE THAT CONNECT TO THE ZERO MBB TO CHANGE AND READ THE PARAMETERS !!! just like the OBDII of cars !

i'm 100% confident that the current sensor bypass will work so the complete mod will too.

My guess is that the speed limit will also be bypassed

actually i think that the main relay is cutting suddenly  when i get the current sensor error code.... probably a protection from the MBB

Doc