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Discussion Starter #1
I'm just toying with an idea at this point: thinking about the feasibility and all that, but does anyone have advice on removing the IMA battey with minimal hassle? Or information on the BCM / MCM communication scheme? Is it a standard communication protocol, or Honda-proprietary? Or I'd like info on what each module does, technical details, etc.

I searched the forum archives and was surprised not to find anything. So if you can direct me to the forum post that I missed that answers these questions, I'd appreciate that, too!

Thanks,

Karen
 

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You searched correctly. There is not any extensive information...AFAIK anywhere :!: :(

The IC encyclopedia is about as comprehensive as the Honda factory service manual and the electrical troubleshooting manual in this regard too. The "communication" in regard to what is related to the MIMA hack was an elementary analog signal. However, there are interconnections labeled in the ETM as serial data. The format is probably Honda propritary. The gist of what each module does is well outlined. The inputs that these controllers utilize could be "easily" skewed to favor a desired change in their output.

Removal of the IMA "system" will require installation and design of a 12v charging system. Obviously installing an alternator would be the "simplist" electronically. If you've got AC installed its the space available under the hood that makes this problematic. However, a close look at a DC-DC converter hack may allow using the existing IMA "motor" as the alternator. Although from my understanding it currently simply reduces the 144v to 12v. And since the IMA motors output will vary in the mid 100s and at a variable frequency there will be some challanges in designing the circuitry to do this job.

HTH! :)
 

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Discussion Starter #3
Thanks for the reply.

As far as removing the IMA battery goes, I am only interested in taking it out temporarily, and not in running the car with it out. That's quite a different proposition!

Props to the folks who managed MIMA without access to the computer's serial data ... I put that kit on my wishlist this morning.
 

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I've done the job. Had a rear ender that required floorpan replacement. The body shop was "afraid" of the IMA pack so we worked out a deal. :)

The service manual sufficiently describes the operation. You don't really need the special lifting tool. Just a helper and an awareness of what _NOT_ to touch. :shock: FYI there are a couple of points on the junction board that are still "hot" even with the IMA breaker off.

If you flip up the carpet that covers the IMA case you'll see the varoius sizes of wrenches needed. One is a torx. Allow about 4 hours of diligent work for an R&R.

HTH! :)
 

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Discussion Starter #6
Thanks for the advice! I got it out last night successfully, and, yes, without the special lifting tool. Disturbingly, there was some dark brown goo under the battery case. My "assistant" touched it & reported that it was sticky, then read the warnings on the side of the battery about alkaline substances and reported that his finger was burning. So, others who have pulled the pack:

- did you see any benign brown goo, maybe a kind of glue (I'm hoping)

- have you heard anything about batteries leaking? I didn't see an obvious point of leakage in the pack. I haven't had my IMA light come on, but have thought that the batteries don't hold charge well. The car has 96k miles, is a 2000 manual, and the battery pack voltage is ~156V when the car is off.

I just took the battery out for curiosity's sake, but perhaps I have discovered a real problem. Pooh.

Mike, I just took a look at your site, and I just have to say: you've done a lot of awesome work on that car.

Also ... anyone know about the charge scheme Honda uses?

Thx
Karen
 

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Thanks Karen
No goo under my pack. it was clean and dry.
A few things :
Did you look at the bottom of the pack to see if the goo came from there?
Did you try to smell the goo to see if it had any odor?A litimus strip would identify if it was alkali or acidic.
depemding on the SOC 156V is in the correct range. 169V seems to be the max volts with no charging taking place with a full SOC.
 

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No goop in or around my IMA pack either.

Geez Karen your full of tough questions lately. :)

The charging "scheme" is based in NiMH chemistry. Lots of highly technical information on the web for this. The voltage is almost flat from 0-100% SoC. One thing that makes using this type of battery more difficult. So you have to monitor and calculate the amount of charge going and coming. And also watch out for overheating or frozen cells (too hot-cold). Then limit the range of usage to a middle percentage segment as further life extending battery management.

HTH! :)
 

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Discussion Starter #9
Hi,

Yep, I am familiar with Coulomb-counting (which you describe) and have heard some notion about checking for a weird voltage rise at the end of the charging (or maybe that was NiCad). I also figure that if they're smart, Honda monitors the temp. I was wondering if there's any info (I haven't found any in the manuals, unsurprisingly) on what in particular Honda does.

If not, I'll have to see whether I'm up to Mike D.'s standard (or even close) , and see what I can figure out! So: any tips on taking apart the BCM and MCM without destroying anything? I took off the tops once before, but from what I recall that showed me only the back-side of the circuit boards.

Karen
 

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Karen
Not much to see inside the bcm or mcm except for some Ic's, you wont learn much from looking in there.
I have a couple of photos of the pack insides and the subpacks at:
http://99mpg.com/batterypacksexpose/
I have more photos of the BCM with the cover off as well if you want to see them.
You will want to download this document that came from a repair tec manual for the Insight. It explains the SOC system pretty well.
http://99mpg.com/Data/downloads/related ... nation.jpg
Have fun.
Since the SOC is kept between 20 and 80% SOC, we don't get into that voltage dip range at the end of charge. I believe that after a rercal, it may charge to that point, but I have no direct proof of that.
;)
 
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