MIMA for CVT

[nayrhyno]

I have been thinking a lot about a MIMA system for my CVT. I like the way JoeCVT has his MIMA-L set up with the pedal. I thought about simply PM'ing him about this, but I think a thread would provide useful info for other CVT owners looking to maximize MPG with a MIMA, and I can't find many CVT specific MIMA threads. Maybe I am just bad with the search.


I have come to the conclusion that I want to make a CVT specific MIMA system.

Goals:
In a CVT, I think the most useful thing to have would be an analog assist/charge throttle. From what I have read about Joe's install, he has a pedal to control assist. I think the pedal is a great design, perhaps a pedal with a two mode operation would be best. Flip a switch one way and the MIMA is on and the pedal is assist control, flip it to the middle and the system is stock, flip it the other way and the MIMA is on and the pedal is regen control. I can't think of any other really necessary control to have, since FAS is not as simple for the CVT. The main goal is to use the battery more intelligently than the computer can. Increased assist up hills and less regen when a downhill is approaching.

Questions I have before I pursue this:

Is it possible to have the IMA system totally disengaged, ie no assist and absolutely no charge, even trickle charge?

Would this type of operation be possible with the MIMA_L circuit?

Is it practical (assuming I have the necessary skills and motivation to undertake the project) to try and design this myself with the MIMA_L if I don't need the increased functionality of the full MIMA system?

Joe, did you ever add to your system the ability to cut the regen/recharge?

[joecvt]

Originally Posted by nayrhyno

I have been thinking a lot about a MIMA system for my CVT. I like the way JoeCVT has his MIMA-L set up with the pedal. I thought about simply PM'ing him about this, but I think a thread would provide useful info for other CVT owners looking to maximize MPG with a MIMA, and I can't find many CVT specific MIMA threads. Maybe I am just bad with the search.

I have come to the conclusion that I want to make a CVT specific MIMA system.

Goals:
In a CVT, I think the most useful thing to have would be an analog assist/charge throttle. From what I have read about Joe's install, he has a pedal to control assist. I think the pedal is a great design, perhaps a pedal with a two mode operation would be best. Flip a switch one way and the MIMA is on and the pedal is assist control, flip it to the middle and the system is stock, flip it the other way and the MIMA is on and the pedal is regen control. I can't think of any other really necessary control to have, since FAS is not as simple for the CVT. The main goal is to use the battery more intelligently than the computer can. Increased assist up hills and less regen when a downhill is approaching.

Questions I have before I pursue this:

Is it possible to have the IMA system totally disengaged, ie no assist and absolutely no charge, even trickle charge?

Would this type of operation be possible with the MIMA_L circuit?

Is it practical (assuming I have the necessary skills and motivation to undertake the project) to try and design this myself with the MIMA_L if I don't need the increased functionality of the full MIMA system?

Joe, did you ever add to your system the ability to cut the regen/recharge?

I still have my original MIMA_L board installed and it is still working with the pedal. In the current design, the pedal serves two functions. The MIMA is in the off state when the pedal is not pressed at all so the car behaves normally. As you start to press on the pedal, the increased voltage in the pot allows a transitor to apply power to the MIMA_L then add assist as you press down on the pedal further. On this current board, I do not disable IMA and have no regen control.

There have been a few times when I wish I had built-in IMA disable or a light regen when I want it to (and not the ECM) but the assist mode seems to be the most important function for how I used MIMA at the time

However, last winter, I did design a new board layout that would allow for multiple modes:

IMA disable
Pedal assist
Pedal regen
non-pedal preset assist
non-pedal preset regen

This new board layout would give me what I already have with normal mode to MIMA mode assist plus have assist / regen presets, IMA disable and pedal controlled regen.

I did not get a chance to build it this last summer but it is still on my mind.

Your idea of having a dual action pedal is right in line with my thinking except that I many use a dual pot due to auto activation.

I also designed another non-MIMA board layout that would replace two mode switches with a single momentary switch and two LED indicators (or one bi-color). Until then, two mode swtiches would have to be used until that other board gets built. The new MIMA_L board would be built first.

The pedal would get an upgrade to have a dual pot installed, one for regen and one for assist.

Also for temp setup.....Switch A and Switch B both connected to ground

Here is the idea of modes of operation:

Normal mode (no MIMA) - do nothing

Pedal assist - press down on pedal (turns on MIMA as pot voltage exceeds a set point being low pedal pressure) then provides from min to full assist levels as you press down further on the pedal.

(The two modes mentioned above are what I already have)

Pedal regen - flip a switch (switch A) - a relay activates to swap voltage input from pedal pots to MIMA board. This relay will also keep power applied to MIMA board even if you don't touch the pedal. At this point, the default duty cycle is set to 50% so assist and regen are disabled (not called for). Then, as you press down on the pedal....regen with level based on pedal pressure.

IMA disable - flip the same switch A for pedal regen but don't press down on the pedal as described above.

Preset regen - flip the same switch A for regen, then flip switch B. Since switch A is in regen mode all we do with switch B is activate another relay to cutoff the pedal input and replace it with a preset voltage for regen amount desired. This could be used to charge the battery with very light regen without having to keep your foot on the pedal.

Preset assist - do not flip switch A to ground so we are still in assist mode. Flip switch B to ground and this will again cut off the input from the pedal and use another preset voltage for assist. This mode can be used for very slight but long inclines to keep a constant assist level. There are two separate presets on the MIMA board so you can have a different level of preset assist and regen.

The new MIMA_L wil have two more DPDT relays (for a total of 4)

The future enhancement board to replace the switches with one momentary switch will act as follows:

Switch A and switch B modes will be determined by the length of time you keep the momentary pushed in (called short and long push). Much like the power button on your PC performs two different actions based on if you press it in quickly or keep it held in for a few seconds. Switch A will be a short push and switch B a long push. On / Off for both switches will be a toggle mode. Default mode with ignition first turned on will be both switches in off mode (normal mode then auto MIMA on and assist with pedal push).

Also, switch B mode will have a five or ten minute timeout (then turn off) so you don't forget you are using preset assist or regen since you are not using the pedal in these two modes. A bi-color LED will indicate if both A & B switches, one or neither are currently grounded.

Neither board design has been put on bread board yet but I believe the new MIMA_L has a pretty good chance of working correctly from the initial redesign.

JoeCVT = Just your average CVT owner

[Mike Dabrowski 2000]

The PIMA function can be tuned to provide assist and regen with your regular throttle as a controller, and can be set up with separate activation setpoints for the regen and assist, as well as having the ability to set the assist activation slope. Any analog output foot control like JoeCVT's can be added that would be in parallel with the stock MIMA joystick, so you could use one or the other.

[nayrhyno]

I sorta like the idea of doing it myself. I like projects of this nature.

Mike, do you sell the software for the MIMA_L anymore?

Joe, I like the idea of your proposed setup. Let me see if I have this straight. You would have a single pedal with two pots. When a switch is flipped one way, it works like your current assist pedal. Activates assist when pressed, then pedal pressure controls the amount. When a switch is flipped the other way, the other pot is activated, controlling regen. Doesn't matter too much, but why would you need the dual pot for your auto activation? Would the regen mode pedal be auto activate too?

I also like the preset charge/assist amounts. Especially the preset assist. You could set it for 4 bars for light hill climbing so you don't have to feather the pedal. You are saying a second switch (maybe a three way) would control this preset mode. One position for off, one for assist, one for regen.

Sounds like just what I am looking for, with added features I didn't even think of. Did you make a schematic for that board?

[joecvt]

Originally Posted by nayrhyno

I sorta like the idea of doing it myself. I like projects of this nature.

Mike, do you sell the software for the MIMA_L anymore?

Joe, I like the idea of your proposed setup. Let me see if I have this straight. You would have a single pedal with two pots. When a switch is flipped one way, it works like your current assist pedal. Activates assist when pressed, then pedal pressure controls the amount. When a switch is flipped the other way, the other pot is activated, controlling regen. Doesn't matter too much, but why would you need the dual pot for your auto activation? Would the regen mode pedal be auto activate too?

I also like the preset charge/assist amounts. Especially the preset assist. You could set it for 4 bars for light hill climbing so you don't have to feather the pedal. You are saying a second switch (maybe a three way) would control this preset mode. One position for off, one for assist, one for regen.

Sounds like just what I am looking for, with added features I didn't even think of. Did you make a schematic for that board?

MIMA_L does not require any software / firmware....

You have most of the idea straight I don't have much time tonight to type for now but with neither switch grounded, the MIMA circuit is mostly powered down and the the DPDT relay loops the signals by default to normal mode. I use a 12v to 9V to have stable power sent to the pedal pots since the Inisight's 12V DC fluctuates greatly and that would change the pedal voltages during that time if I did not have a 12 to 9 regulator (I bought that part from Radio Shack). One of the pedal pots will allow a transistor to apply ground to the LM7805 to power up the MIMA board as pedal voltage increases. Due to the pedal only being able to turn the pot approx 90 degrees, I don't think you can find 2.5v center AND have full range of 0-5V needed for assist and regen coming from the same POT. So I figure two pots with separate adjustments on the MIMA board to have the voltage in range for the current mode.

I am using the regen mode (switch A grounded) for two modes. With only the switch grounded and no pedal pressure = IMA disable. In order for this to work, the regen pot must = 2.5v without pedal pressure. Then as you press on the pedal and voltage changes, regen will occur based on voltage level.

The other two presets use the other switch (switch B) and have their own adjustments.

I do not have a schematic but I did create a part and trace layout based on a small Radio Shack board. It is very tightly compacted but if you look at the traces and Mike's MIMA_L schematic, you will figure out what I'm trying to do in this design. I just took some time earlier to label some of the parts, inputs and outputs to match my description last night. Sorry I don't have a real schematic but I typically use this method to design the circuit and board layout at the same time.

Besides the pedal circuitry, some added presets and relays for switching modes, this is still basically Mike's original MIMA_L design with a few more add-ons.

JoeCVT = Just your average CVT owner

Here is the board layout design with labels:

[nayrhyno]

Thanks for all that. I thought there was still a logic chip or something that Mike sold for MIMA_L. My mistake.

[nayrhyno]

I have been thinking over my design, and had a little revelation when using my PC joystick. The throttle control on it is articulated (it clicks from position to position and holds in place where you leave it). I could imagine using something like this instead of the pedal to control a single pot from 0-5v. If I understand correctly, your foot pedal rests at 2.5V and above that the system is engaged, variably until 5V. It seems like you suggest that the regen control is between 0 and 2.5V. With the throttle I have in mind, it could rest at 2.5V and go up to go 2.5-5 and down to go 0-2.5. This would also accomplish the preset goal with some simple marks on the throttle corresponding to the appropriate voltages. I assume this is similar to the standard joystick setup.

I am still not sure if I want to have a foot pedal or hand control. Maybe both.

[joecvt]

Originally Posted by nayrhyno

If I understand correctly, your foot pedal rests at 2.5V and above that the system is engaged, variably until 5V. It seems like you suggest that the regen control is between 0 and 2.5V. With the throttle I have in mind, it could rest at 2.5V and go up to go 2.5-5 and down to go 0-2.5.

Yes, my pedal rest near 2.5V and actually just a bit lower because it takes a bit of pedal pressure to power up the MIMA_L board then continue onward with assist so it is probably approx 2.0v at rest.

At 2.5V with MIMA_L activated (powered on) you would be sending 50% duty cycle basically disabling IMA control (telling the IMA you do not want assist or regen). Yes, regen is 1/2 of the 0-5V and assist is the other half. Parked at 2.5v is 50% duty cycle. Assist is 55% - 90% (90 = max assist) and Regen is 45% - 10% (10 = max regen). If you exceed the upper or lower duty cycle percentage, you will get an IMA light. I adjusted mine not to exceed 85% due to electronic temp variations in normal usage in all seasons.

JoeCVT = Just your average CVT owner

[3-Wheeler]

Hi Joe,

I noticed here...

DIY MIMA L - MIMA Honda Insight Modified Integrated Motor Assist

... that you have several pictures showing the location of your MIMA-L board mounted close to the shifter, in the passenger cabin.

Did you have to run wires from the board, to the back of the car in order to hook between the MCM and ECM? If so, where did you located them?

Thanks, Jim.

[joecvt]

Originally Posted by 3-Wheeler

Hi Joe,

I noticed here...

DIY MIMA L - MIMA Honda Insight Modified Integrated Motor Assist

... that you have several pictures showing the location of your MIMA-L board mounted close to the shifter, in the passenger cabin.

Did you have to run wires from the board, to the back of the car in order to hook between the MCM and ECM? If so, where did you located them?

Thanks, Jim.

Hi Jim,

All of the wires going from the ECM to the IMA stuff in the back go through a cable bundle that you can open up and tap into under the center console plastic. When you remove the four screws and lift out the console, you will see a large bundle of wires running along the bottom of the console (near passenger seat). You would have to undo the bundle (remove tape and plastic sleeve) to expose the wires that you need to use but they are all there. So basically, besides the pedal wires, all other wires are connected under the center console so it is a nice place to put the board. This was usually the location were early MIMAs were installed and connected to the IMA wires until Mike made an easier method of sort of a Plug-in MIMA.

JoeCVT = Just your average CVT owner