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Discussion Starter #1
Hello all! I know this is going to be a stupid question but I'm hoping someone can help me understand the logistics of swapping out motors in a factory built EV.

I'm wondering if swapping out the original motor/controller (2011 Th!nk City) for a used BMW i3 motor/controller will provide me an increase in power. The Th!nk City battery pack is rated at 400v and the i3 is 360v. My concern is that the Th!nk battery module may not put out enough amps to the i3 controller to make it worthwhile.

My plan was to keep the existing 24kw Th!nk battery pack in situ and just replace the motor/controller for an increase in power. The Th!nk only made 47hp and 66tq while the i3 was around 170hp and 180tq. It seems the i3 motor would be compact enough to fit as well.

How dumb is this idea and what am I overlooking?
 

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Discussion Starter #2
65 views and no input from anyone?

Surely someone here has replaced a weak 10yr old motor with a newer unit.

It seems as though it's only a matter of wiring inputs to the controller from things like the ignition switch, TPS, etc. HV wiring from the battery to the controller should be fairly universal. It's really just mating the motor to the factory gear reduction and then wiring to the controller.

What am I overlooking?
 

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Hi
Your new controller may not like the voltage difference

As far as power is concerned I don't think that will be a problem - unless you are towing or on a steep hill you can't draw a lot of power for very long before you have to brake for the next corner

I have a Volt battery - the Volt is just over 100 kW - I'm drawing 400 kW (for a short period)
 

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Is there actually a voltage difference? Pretty sure they are both 96 cells in series and that the "360" is nominal (official specs say 352 which strongly suggests 96S) and the "400" is fully charged.

Edit: Found some info on the think packs. As expected they are also 96S. So voltage won't be an issue at all.

Edit 2: The official specs for the Think batteries are 3C peak (10s) and 2C continuous. So they can definitely do better than the stock Think motor, but definitely not as good as the i3. You could probably push them a little harder if you are willing to sacrifice some life, but keep in mind that there is no real cooling in the Think pack. Might still be worth doing...if you doubled your power it would go from sluggish to peppy.
 

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Discussion Starter #5
Is there actually a voltage difference? Pretty sure they are both 96 cells in series and that the "360" is nominal (official specs say 352 which strongly suggests 96S) and the "400" is fully charged.

Edit: Found some info on the think packs. As expected they are also 96S. So voltage won't be an issue at all.

Edit 2: The official specs for the Think batteries are 3C peak (10s) and 2C continuous. So they can definitely do better than the stock Think motor, but definitely not as good as the i3. You could probably push them a little harder if you are willing to sacrifice some life, but keep in mind that there is no real cooling in the Think pack. Might still be worth doing...if you doubled your power it would go from sluggish to peppy.
Thanks for the input. I would be happy with the investment of I could safely double my power.

If I wouldn't be able to take full advantage of the i3 motor I wonder what other motor I could use. Nissan leaf motors are very cheap and much more powerful. I can't really think of any other readily available AC motors that operate in this voltage range.

Do you have any insight into how complex it would be to swap out the controller? In my limited understanding it would simply be a matter of splicing the new controller to the old wiring harness using a pinout guide and then hooking up the cooling properly. How far off base am I?
 

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i haven't looked into the Think or i3 operating systems, but most of the OEMs use a dedicated motor controller aka inverter for commutation of the motor.

This inverter gets commanded over a CAN buss from some higher-level master control box like an EV-ECU. Every OEM has their own unique set of CAN parameters, data and commands based upon their operating system.

So the difficult part will be figure out what data and commands need to be sent over the CAN buss, and how or what box will be sending those in your swapped configuration.
 

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Discussion Starter #7
i haven't looked into the Think or i3 operating systems, but most of the OEMs use a dedicated motor controller aka inverter for commutation of the motor.

This inverter gets commanded over a CAN buss from some higher-level master control box like an EV-ECU. Every OEM has their own unique set of CAN parameters, data and commands based upon their operating system.

So the difficult part will be figure out what data and commands need to be sent over the CAN buss, and how or what box will be sending those in your swapped configuration.
I understand what you're saying. I'm a big fan of the K.I.S.S. method of engineering. Would it be easier just to remove any other sort of ecu controller and just stick with a basic motor/controller combo that would be used in any other conversion?

A basic system like an HPEVS kit doesn't require anything ancillary to operate. I'm also a huge fan of removing dead weight and features I won't use. If I can remove essentially everything aside from the original battery shouldn't I be able to just wire in a generic controller? The less stuff under the hood the less there is to go wrong!
 

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There has to be some way of controlling the controller, I.e tell it how much torque you are commanding. Something like the HPEVS system will have a logic board with a rudimentary state machine and some inputs for some switches and an analog throttle.

An OEM controller won't have any of that. In almost all cases, the OEM car has a VCU that runs the state machine, manages I/O and communicates with other devices over CAN. The throttle may be CAN or it may be analog but either way it talks to the VCU which uses it as one but not necessarily the only input for how much torque it wants to request. It will then request that torque by sending a command to the controller over CAN.

So...short of a new logic board for the inverter, you really have to do it that way. And a logic board is probably a bigger job than a VCU.
 

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Discussion Starter #9
There has to be some way of controlling the controller, I.e tell it how much torque you are commanding. Something like the HPEVS system will have a logic board with a rudimentary state machine and some inputs for some switches and an analog throttle.

An OEM controller won't have any of that. In almost all cases, the OEM car has a VCU that runs the state machine, manages I/O and communicates with other devices over CAN. The throttle may be CAN or it may be analog but either way it talks to the VCU which uses it as one but not necessarily the only input for how much torque it wants to request. It will then request that torque by sending a command to the controller over CAN.

So...short of a new logic board for the inverter, you really have to do it that way. And a logic board is probably a bigger job than a VCU.
If I understand you correctly, Even replacing the aftermarket/ HPEVS controllers require a logic board to interpret signals to feed to the controller? I was under the impression the controller collected the signals itself and I could simply just simply tap the Th!nk wiring harness for those signals and run directly to the new controller.

I just find it hard to believe that there isn't a simple solution to upgrading AC motors to something better than 44hp and 66tq. Even the 144v HyPer9 makes a continuous 51hp and over 170tq.

I just wish there were a few decent 360-400v motor options out there that didn't require anything so complex.


Let me ask you this, If you kept the stock controller but upgraded the motor you wouldn't see any performance gain would you? Because the controller is dictating that amount of power the motor can generate. Is that correct?
 

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Discussion Starter #11
Can anyone weigh-in on this motor/controller package? It seems to be everything I would need to replace the factory drive unit and electronics.

From what i understand this is the drive unit from a new, undelivered, Coda car.
 
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