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Discussion Starter · #1 ·
This thread will document conversion of my 2011 MT CRZ from a Nimh pack to a Lithium one.

88091


My object is not to put a late model CRZ OEM Lithium pack in a non Lithium early CRZ.
They are not the same voltage. Nimh 100V versus Lithium 144V approx.
You would have to transfer the entire brains/modules of the Lithium car into the NIMH one if you wanted OEM functionality etc. If you just wanted to use some of the cells from a CRZ OEM Lithium pack in a sort of Frankenstein half breed then that might be doable.

I'm interested in putting a homemade lithium setup into the early production Nimh CRZ.
There are loads around, all with weak ageing battery packs.
Two LTO blocks in a 48 cell setup with BCM fooler seems like a first test candidate..

Some notes and comments I have moved here from the other thread.

I won't be taking the CRZ IMA motor out to examine it physically. There are plenty of pics of it on the internet.
I'll just be upping the voltage/current and fooling the electronics at the back in various ways to up the output.

I've had 30kw out of a standard Insight motor, there is no reason to suppose this isn't capable of something similar.
One of the official OEM Honda tuning companies runs theirs at 144V IIRC.

My first purchase will be a second complete NIMH battery/ima unit so I can see how it all goes together.
Work out how to access the various points we need, like the current sensors etc.

Then I will put together a simple 48 Cell LTO setup and see if the car will accept that using just a BCM fooler.
I can talk to the CRZ with my Honda OBD tool so can monitor a load of stuff as needed.

I'll also install one of those remote wireless voltage/current sensor things to get some independent data.
Of course looking at the CAN is also on the list but I have other stuff to do first.

Fooling the current sensors by actually manipulating the outputs might be tricky.
It's likely a very compact inverter integrated design if the HCH2 on my bench is anything to go by.

But we can also physically bypass the sensors with a wire designed and calculated to pass a certain % of current around it. We basically solder a thick bridging wire around it.
Pass a known current through it, measure the sensor output and work out how much is being diverted and adjust the bypass wire thickness or the current sensor bus thickness with a file until we get the % reduction we want. :devilish:

Start off with 20% and then work up in 5% increments until it stops working!

I'll look at a straight 48 Cell LTO Swap first.
(Let's assume perfect cell balance for the below rambling)

48 x 2.4V LTO Nominal = 115V
84 x 1.2V OEM Nimh Nominal = 101V

I'll assume for now the CRZ assist control allows a cell to sag to 1.0V under load like the Insight.

120 cells in the G1 gives a minimum 120V under load.
84 Cells in the CRZ gives a minimum 84V under load.

48 x 2.7V LTO Max V = 130V
84 x 1.6V Nimh Max V = 134V

Minimal differences in practical terms.

How the car will react to the seeming endless capacity of the LTO 20ah versus it's own 4ah will be interesting.
Maybe like the G1 it will eventually say time to recalibrate.
This is when I had to use the SOC reset feature in previous conversions before the BCM Interceptor was developed.

Just digesting some CRZ info from the workshop manuals.

It has a 125A main battery fuse. 100V x 100A = 10kw
Because of the lower pack voltage it will use quite a bit more current than the G1 to reach the 10kw nominal maximum IMA power.

There appear to be only 4 current sensors. (1 x Battery) (3 x Phase) (One less than the G1 Insight)
The phase sensors look to have simple analog outputs so can possibly be changed with resistors as in the G1.

The battery sensor has an extra wire so will need a little investigating.
It looks like it has a normal and fine range output.

The Voltage tap inputs look standard albeit there are only 7 of course.

The IPU (IGBT) has a non CAN serial line between it and the MCM, so is probably sending voltage and temperature info to the MCM in a very similar way to the HCH1 IPU did. ;) That's very good for hacking.

The DC-DC converter looks similar to the HCH2 variant and has two non CAN serial lines between it and the MCM
The MCM will be sending power/voltage requirements to it, and it will be sending back temperature data etc.

Hopefully I'm picking up a full ipu assembly and battery today. :)
 

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Very interesting. I almost bought one of these while having a child like temper tantrum over something on my Insight. They are a nice motor, had there been a tad more room in the back I would probably have gone for it, but the rear seats are absolutely pointless if your over 6 foot! I wonder if the motors are the same and the Lithium version is just overdriving the NiMh motor or they have different windings? certainly makes a higher voltage pack a more potent option!
 

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Very interesting. I almost bought one of these while having a child like temper tantrum over something on my Insight. They are a nice motor, had there been a tad more room in the back I would probably have gone for it, but the rear seats are absolutely pointless if your over 6 foot! I wonder if the motors are the same and the Lithium version is just overdriving the NiMh motor or they have different windings? certainly makes a higher voltage pack a more potent option!
Same part number according to CRZ forum, thats how it gets its extra horses. I am watching this with interest as my CRZ has a good and strong battery, although its low mileage is probably the reason for that. it also charges its battery very fast when its depleted if I have been playing
 

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Discussion Starter · #6 ·
£220. It's all in bits now, photos/videos taken and mods underway.

Nimh sticks removed and will be making the BCM Fooler and high current wires later today.
Should be very simple to reassemble it and swap it over for the unit in my new car.
The LTO lithium packs will just be sitting in some sort of tray in the boot for now.

Couple of disassembly videos and pics. All looks fairly straightforward.



CRZ 125A Fuse versus G1 Insight 100A fuse.

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Inside the BCM/MCM Combo unit.
Note the HV isolated section on the right.

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Vacant space after batteries removed.
88095


You might be able to get 2 LTO blocks in here but need to look at the actual space in the car.

88096
 

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Discussion Starter · #7 · (Edited)
Modifying the CRZ switchboard for Lithium and adding a BCM Fooler.
Note this fooler is made from 7 x 10k 0.1% tolerance resistors.
I have also allowed for potential higher voltage hacking with a pre-resistor.


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Tomorrow I will be looking at the temperature sensors, IPU serial comms and battery current sensor.
 

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Discussion Starter · #8 · (Edited)
Todays tweaking and research..

Reattached modified switchboard to pack.
Installed 3 x 9.1k battery temperature fooling resistors.
Measured voltages of current sensors etc and input circuitry on pcb.
Checked removal of battery and voltage tap board etc would not adversely affect airflow.
Fan draws air through the IPU section before venting it so all seems good.

Powered up some modules on the bench to gather data for analysis.

 

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Discussion Starter · #9 ·
Testing the IPU (Intelligent power unit) with my HV supply whilst gathering data and I took it up to 200V without issue.
(I wasn't expecting any to be fair as the IMA motor will stress it far beyond that if the main fuse blows at any time and the engine is at high rpm.)
Over 250V output is not uncommon for the unloaded IMA motor at high rpm.

Early research is indicating that simply substituting a higher voltage pack 3 LTO blocks (172V Nominal) instead of 2 (115V Nominal) will be worth attempting later.
Initially if the 48 cell works ok I will add another half block (12 cells) for 144V Nominal.
Obviously some mods are required for the car to accept this configuration, you will see these as we go along.

A few pics of some bits today.

9.1k Temperature sensor resistors. (Should get us around 25C)
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Underside of MCM pcb.
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Battery current sensor inputs. 82k resistor to ground then 15k resistor into nether regions of board.
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Phase Currents sensor inputs. 10k resistor to ground, then 2k resistor into nether regions of pcb and beyond!
88122
 

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So you must be an engineer of sorts Mr. Perkins, or an electrical technician at the very least? Great project you're doing, would be interesting to see what it turns into. These little sporty cars are so tempting, I was almost about to get myself one. If only Honda continued the Insight's/CRZ's original legacy to this day, instead of making another boring hybrid sedan, sigh...
 

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On another point how do you rate the car? I really like our Z and unlike yours the battery isnt weak it provides plenty of push when required and charges back very quickly, we town drive in eco which uses more battery than normal mixed driving is in normal and when Jayne isnt in the car I use sport :devilish: which is fairly quick to say the least
 

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Discussion Starter · #13 ·
Seems very nice but the battery is feeble it discharges in what feels like a very short time.

I use ECO but have tried the other options. ;)

It should be quicker still once the hacked Lithium is installed.
 

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Discussion Starter · #14 ·
Busy day today working on the voltage hacks and adding accessible test /interface points.
Also weight and size comparisons of the LTO versus Nimh packs.

 

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Discussion Starter · #15 ·
I am using ex Honda FIT EV LTO 20ah cells for my prototype Nimh to Lithium CRZ conversion.
You of course can use whatever Lithium cells you want as long as they meet a few critical criteria.


These are a few guidelines and recommendations based on my long experience with Lithium, EV's and IMA conversions.

1) Use a safe Lithium chemistry. Not all Lithium batteries are naturally safe or rugged.
Don't be tempted to use LiPo. Yes they are powerful and light, but unless managed with a very good BMS they are flaky.
We have all seen pictures/videos of cheap scooters and the odd phone in flames.
Choose wisely and choose once. IMO Lifepo4 and Lto are good conversion candidates.

2) Don't underestimate the punishment and stress the car will inflict on cells.
The OEM Nimh cells are incredibly rugged and robust with a +100A assist and +50A charge capability.
It's remarkable they work as well as they do, but Panasonic really knew how to make them.

Any Lithium cells you choose must be at least on par if not better than the OEM cells as far as electrical properties are concerned.
Don't always believe exaggerated data sheet performance claims and numbers. Find some cells with real world hard data to back claims up.
If the cells you choose are at all marginal the car will punish you by killing them in a short time and possibly burning it down.

3) A BMS (Battery management system) is a tricky problem.
The LTO blocks luckily don't seem to need much managing/balancing, but other chemistries may need a lot.
I use my own systems to manage the LTO packs, you will have to research options very carefully.

Do not get any sort of BMS that has built in mosfets to cut power etc. This is common with cheap bike packs and the like.
They are fine for your scooter, but if any BMS cuts power in the car you will get an immediate IMA fault and possibly damage the inverter.
Any BMS you get has to communicate with the car properly and allow the car to shut things down in it's own controlled way.

4) Don't underestimate the time, effort, skills and money it will take to do a conversion to Lithium.
Unless you have all the skills and parts already you will need fairly deep pockets to get everything required and then pay someone to do it.
Messing around with high voltage isn't cheap or easy, and a lithium conversion will never likely save you money in puerly mpg terms.
Of course you will be able to follow my video guides and posts, but you still need all the other stuff above.

I bought a second pack so I could do the mods and research on the bench in advance of the actual fitting.
On my conversion day itself the process should be as quick as pulling out the old pack and putting in the new. Half a day maybe.
Once one conversion has been done and any bugs ironed out, then doing others will be much quicker.
Some enterprising people might offer a swap out service based on my work/ideas. ;)

5) Mods and OEM warranties do not go hand in hand. Honda are not going to fix your blown $3000 IMA if you mess up or it all goes wrong.
Do not undertake or get involved in any IMA modding except under the express understanding that you could break the car and lose your money.

6) Why do it then? Well if you like performance, the CRZ certainly does look sporty, and goes reasonably well.
But a lot of us crave a bit more oomph, or at least would like to be on par with our lucky OEM Lithium CRZ brethren.

IMA modding will give you significant bhp/torque performance gain and possibly some increase in mpg when the car is driven sensibly!
The OEM 10kw motor is easily capable of much higher outputs for short periods, 15, 20, even 30kw is doable with sufficient ingenuity and $$
30kw = 40bhp, that's a considerable leap, but the extra low down torque and acceleration is the real bonus.
Combined with some of the other popular CRZ mods like turbos and superchargers you will have a real beast on your hands.
The IMA will get you off the line and spinning up then the dino fuel can take over.

If I think of anything else i'll add it later/edit this post.
Thanks for your interest and feedback.

Peter UK
 

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Discussion Starter · #16 ·
Please keep upto date with this project on the CRZ forum from now on.

Converting my Nimh CRZ to Lithium...

It makes more sense to document it on there...
Sorry not enough time to keep posting in multiple places.
 

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No muss. No fuss. Where's the fun in that? ;]
 

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Discussion Starter · #19 ·
This has now been swapped again after various developments for a neat 80 x 2200F Supercapacitor pack in 40S2P configuration. Giving a working voltage range of 88 to 152V........

This post onwards gives you the details..

 

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Discussion Starter · #20 ·
I am the IMA Master now and you are my Slave! Muwahhhhhhhhhaaaa.....

CR-Z IMA Manual Control


Well it's very early days but it is in and working. No IMA errors so far. (y)

I have two magic buttons (Yellow Max Assist) (Green Max Regen)

If you press them at any time it does exactly what is says on the tin.
It overrides the car and launches into whichever you pressed and keeps it there until you release the button!
If the battery gets exhausted or too full that BCM protection will still kickin to prevent damage, but other than that the world is your oyster.

I am currently sending packet substitutes which equate to high levels of assist or regen whenever the appropriate button is pressed.
Lots of fine tuning is now required to establish the full range of numerical values available for assist and regen. :unsure:
Then a full variable control system can be implemented.

I also pre-computed checksums etc for the packet series required, this will have to be done on the fly with variable control.
With the max assist I also need to bring in the 85V voltage hack at the same time as the max assist packet substitution for ultimate current and power.

All exciting stuff and significant step forward which will probably be applicable to all the Honda IMA CAN cars. ;)
 
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