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Discussion Starter · #1 ·
After having a barely-to-non-functional IMA for the last several years, and reading so many great discussions here about the relative ease, stability, and affordability of LTO conversions using Honda Fit EV cells, I took the plunge. It's functional now as I write this post, but still a work in progress!

I bought 3 modules from Greentec Auto for $874.50 shipped, and got to work.

I removed the IMA battery module from the car and replaced it with the simple bypass (Making a simple IMA bypass connector from an old pack relay board - MIMA Honda Insight Modified Integrated Motor Assist) to keep the DCDC converter happy while working on my conversion.

After that I started working on a mounting solution. I liked the idea of keeping everything contained in the IPU, and the general layout suggested here: LTO Layout #2 seemed to be the direction to go to achieve that. First modification I made was flipping the hard plastic duct piece upside down (Mod to MPI Duct to Facilitate LTO Installations) for more clearance at the rear.

The duct has a mounting tab which I had to cut off to make it fit:


I then cut out part of the lower shield to accomodate the bulge in the hard plastic duct. I have some cheap "super scissors" in my tool collection, and though I've never had to cut a penny in half with them, they work quite well for stuff like this.


After that's done, it looks like this:
 
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Discussion Starter · #2 ·
Having a bunch of 1x2 scrap (3/4" x 1-1/2") already handy, I started working and found that it would probably make a very good frame. Two vertical pieces, bolted directly to the old battery module mounting points, with a piece of 1/2 inch plywood on top, would be perfectly level with the newly modified ductwork:


Then two LTO modules sit comfortably side-by-side. They're sitting directly on top of the duct, but all the weight is held by the plywood.

I don't plan to get the OEM junction board to fit exactly in its stock location, and there's just barely enough room for it to the left of these batteries.

Another 1x2 board behind these modules is exactly the right height for the LTO mounting tabs to screw onto:


Here's the birds-eye view:
 

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Discussion Starter · #3 · (Edited)
Outside the car, and screwed in:


The third and last LTO module will sit down lower, leaving room for the BCM and MCM on top. To make the bottom of the module flush with the bottom of my main mounting rails, I made cutouts for the four lower mounting tabs. The upper two tabs were already perfectly in line:


The forward module will also be supported underneath by a piece of 1x4 (plywood might be a better choice if I re-do this), and a 1x1 on top of that will be where the inboard tabs screw down:


And here's the entire mounting apparatus in the car:


I don't have any photos of the bottom, but note that the plywood is actually supported by 1x2s on all four sides. The rearmost one is solidly resting on the existing aluminum crosspiece.
 

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Discussion Starter · #4 ·
For ventilation, I have four 60mmx15mm 12V fans, zip-tied and wired together, then installed snugly in place with strips of adhesive foam insulation:


I decided to make my own battery cables by sacrificing an old set of 6ga jumper cables. I bought some 6ga battery lugs (excellent clearance price here: PK 25). I made my own crimper from this nut splitter I had lying around, by just removing the blade and replacing it with a 1/4-20 bolt to act as the anvil:


It worked extremely well:
You can actually feel it bottoming out when you've reached maximum compression - I think this is one of the best cheap tool hacks I've ever done.
 
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Discussion Starter · #5 · (Edited)
Somehow I don't have any pictures of the installation at this point :/ But once you have the batteries mounted and wired into the junction board, the only other modification necessary to have a minimally functioning IMA is the BCM fooler and VPIN voltage hack as Peter talks about in his thread and videos: UK/EU LTO Lithium Bulk Purchase and Installation Thread.

Assembled a basic 10x10k fooler like so:


The fooler then needs to be modified according to this basic schematic:


I went old-school with the modification, drilling holes and wiring point-to-point style, adding JST disconnects for the battery and ignition inputs because they're convenient and that's what I have around:


This shows the circuit underneath:


Or, more explicitly:
 
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Discussion Starter · #6 ·
To hook the fooler up, of course you need to sacrifice your old battery end-piece:


And solder it in:


The VPIN mod is a little bit tricky. Open up your MCM, cut the VPIN line, and insert a 4.7k resistor. Rather than soldering it in place, I crimped female dupont connectors onto the resistor and plugged it onto each side of the cut VPIN lines, so it will be easy to change values should that be necessary in the future (also this is not a particularly easy place to be soldering). The VPIN line is pin 16 of MCM connector B:


Also on the MCM I added a 5V output to use to switch the fooler's opto-isolator on and off with the rest of the system. This is simply done by soldering leads to VCC1 (pin 1 of MCM connector D) and SG10 (pin 5 of MCM connector D) and running it out through a newly drilled hole:


I don't have any panel mount DC connectors handy at the moment, but I do have a handful of these inline ones I acquired, so that's what I'm using for now:
 
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Discussion Starter · #7 · (Edited)
Here are the remaining connections on the BCM Fooler:


VCC1 and SG10 is the external output from the MCM that we just created, and
battery voltage is from the junction board, here:
 
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Discussion Starter · #8 ·
Yes, I know that one resistor has had the hell burned out of it - I hand matched all of them to be within .1% of each other, so it'll be a bit of work to replace it, and it's still actually good 😝
 

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I highly recommend having a look at the way I did the junction board for a nearby Insight owner. I added a quick disconnect from it to a socket on the IPU case, along with a grid charger harness. There are pins for IMA + and - and there are pins for 12V fan + and - so you get your grid charger functionality and the IMA leads for the BCM Fooler all sorted out in a really tidy fashion.

The link above is in my build thread, but the photos in question aren't my car; I haven't gotten to re-do my junction board yet.

Also, in addition to the grid charger hookups, you can see the mega fuse, and the removal of some of the bus bars, which allows for safer and easier cable installation.
 

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Discussion Starter · #12 ·
WoW! what a thoughtful, professional job. Well done.
I tend to overthink everything and spend way more time pondering than doing. I'm glad it comes off as professional, haha.

I highly recommend having a look at the way I did the junction board for a nearby Insight owner. I added a quick disconnect from it to a socket on the IPU case, along with a grid charger harness. There are pins for IMA + and - and there are pins for 12V fan + and - so you get your grid charger functionality and the IMA leads for the BCM Fooler all sorted out in a really tidy fashion.

The link above is in my build thread, but the photos in question aren't my car; I haven't gotten to re-do my junction board yet.

Also, in addition to the grid charger hookups, you can see the mega fuse, and the removal of some of the bus bars, which allows for safer and easier cable installation.
I do have a grid charger harness installed in the normal way. The fan wires on yours just pass through the junction board without connecting to it? From the wiring diagrams it seems to me that the necessary fan lines are already present on the junction board so perhaps one could just have all four grid charger wires terminate there and not splice into the fan itself, but I haven't verified that with a meter yet.

Right now my battery cables are connected to the original four points on junction board with little bolts and nuts, like I presume most have done? They're also zip-tied firmly in place, and the whole underside of the junction board is insulated with a sheet of corrugated plastic (e.g. political yard sign material) so it's pretty safe, but simplifying in that way does seem quite nice.
 

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Discussion Starter · #13 · (Edited)
For my first optional upgrade, I added the 2019 Current Hack PCB for 40% more assist and regen. It's incredibly easy to install. You open up the "bottom" (actually top as it sits in the car normally) side of the MCM:


And solder it in place. There's only one possible spot to put it:


After setting the jumpers on this PCB for the level you choose, you also need to add a corresponding resistor to the other module, the BCM. Open up the bottom of the BCM:


And find these solder points:


To solder a resistor across. For 20% boost, 560 Ohms. For 40% boost, 240 Ohms. For Maximum boost, 100 Ohms.


The higher current requires a higher amperage main IMA fuse. The stock fuse is 100A. For 20% boost, use 125A or higher. For 40% boost, use 150A or higher. For maximum boost, use 200A. I found a Littelfuse L50S 200A fuse for a good price, so that's what I bought. It's larger than the stock fuse, so you have to trim the housing a bit. I just used some pliers to tear it away a bit at a time:


And that's where my car stands right now. It's really nice to drive now that there is some actual power behind it. So far the gas mileage is really great and the battery appears to be staying at a quite high state of charge without any extra effort from me.

More mods coming soon, and I'll be sure to get some more pics to fill in the gaps with what I did above.
 

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May be safer to use 150A fuse instead of 200A.
 

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Discussion Starter · #15 ·
I finished adding CAN support to my OBDIIC&C gauge (OBDIIC&C LTO BMS CAN INTERFACE), so since I need to open up the IPU and identify all the CAN IDs of my batteries, I can show you what it looks like in there.

Here's how the switch now sits:
87164



Abundance of political signs means plenty of sturdy insulating material is always at hand:
87165


Here's how my batteries sit, and how they're currently routed:
87166
 

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Discussion Starter · #16 ·
Here's my modified OBDIIC&C gauge. Just four wires on it right now: Power, Ground, CANH, CANL. Power and GND go to a couple of bare wires, as well as to a pair of dupont connector pins. CANH and CANL go to another pair. Then I have a terminating 120 Ohm resistor wired to a third pair:
87167


These three plugs now go into one of the six-pin female-connector pigtails off my LTO batteries, like this:
87168


Now with an available 12V (I'm using the battery fan line) and chassis ground, I can power it up:
87169


And get all my battery IDs, and see all the cell voltages while I'm at it.
Electrical wiring Wire Cable management Electrical supply Electronics Electrical wiring Cable management Electronics Wire Computer hardware Electrical wiring Electronics Wire Technology Electronic device Electronics Electrical wiring Technology Electronic device Wire Electrical wiring Cable management Electronics Electrical supply Wire Electrical wiring Cable management Wire Electronics Electrical supply

I'm disappointed to see that the voltages of the last module (pair) is clearly not well matched with the rest of them, hopefully that can be resolved with balancing, and isn't reflective of degraded capacity.

Excellent job with the latest mods and software @retepsnikrep! It is quite a joy to see it all in action.
 

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Discussion Starter · #17 ·
Trying to track down this problem with my OBD port: OBDIIC&C Gauge Volume 2

I pulled all the connectors that are connected to the H-Line of the DLC, that is C452 (goes to EPS), C403 (goes to ABS), and C502 (goes to SRS and MCM) (Circuit F54)
As one would expect, there is now no voltage on that pin with the key on.

Reconnecting one at a time, C452 and C403, I get 5 volts. So the problem is with SRS, or somewhere in the wiring between C502, SRS, and MCM.
 

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Discussion Starter · #18 ·
Reconnected C502, disconnected C506, and still bad voltage, so problem is apparently with my SRS unit or with the harness between the SRS, C502, and C506. Don’t know how the hell I could have damaged any of that.
 

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Discussion Starter · #19 ·
Yep, SRS unit is the one bringing it down. Everything plugged in except SRS connector B, and my OBDIIC&C gauge is working again. Throwing about a million codes right now though
 

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Discussion Starter · #20 ·
Finally can test my new battery fans, using the OBDIIC&C gauge, and they are working great (y)
 
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