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Tuning the Lithium cars for more IMA power.

10334 Views 101 Replies 10 Participants Last post by  PeterPerkins
Tuning the Lithium cars for more IMA power.

You will have seen my long thread on tuning the Nimh system for more IMA power.

In that I hacked the current and the voltage to double the motor Kw output. It was very lively. :p

It involved swapping in a Lithium car inverter and dc-dc converter and using the cars original Nimh BCM/MCM module along with an up-rated 200A fuse.

So what can we do with the Lithium cars?

Well we can hack the current in exactly the same was as we did for the Nimh setup.
This will likely get us another 5-7kw or so. Taking us to ~20kw+...

The voltage is more tricky in the Lithium cars especially if we want to keep the Lithium control modules.

The Lithium MCM/BCM gets it's voltage data from three places.

1) The four BMS CAN boards on the pack.
2) A HV input into the BCM. (We can fake this as per Nimh with a very low current HV supply)
3) Serial data from the IPU IGBT module. (We can fake this as per Nimh)

So to tackle 1)

Can we make an interceptor type device that will send out perfect 75% SOC equivalent cell voltages on the CAN bus?
I'm saying 75% as at that voltage equivalent about 3.8V per cell the car will allow full assist and regen.

Yes I think we probably can fool the voltages, but this only gets us to around 190V which is where the OEM Lithium DC-DC and IGBT module max out.

To go higher we might need to use the HCH2 DC-DC which goes to 220V and possibly the HCH2 IGBT module which probably goes to a similar voltage.

That should get us firmly in the 30kw+ camp with a suitable battery pack.

Now to go even higher we need more voltage.. :eek:

So what IMA cars have higher voltage packs?
Do these dc-dc converters and inverters use the same data stream for control as the CR-Z etc? I bet they are similar.

So would a CRV 2019 or Jazz dc-dc and inverter work in a CR-Z????? Only one way to find out..

But before I start buying expensive parts.........

I'm going to need access to the Honda workshop manuals for these later models to check specs and wiring for compatibility.
Does anyone have current Honda subscription access to this data? Can you message me please.
If people want to support this research in some other way then feel free to message me.

Have a good Christmas and Thanksgiving etc. Peter UK
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Well I took another look at the HCH2 BCM pcb and it also has an isolated dumb HV section which measures the 11 battery tap voltages.
This is sent via 25 bytes of serial data 31250,9,O,1 via and opto to the battery monitoring chip. Blue zone.
Passive circuit component Circuit component Green Hardware programmer Electronic engineering

So we could use exactly the same technique as in the inverter and intercept the data and modify/reduce it as we want.

So with the HCH2 BCM we have the external voltage divider option or the internal serial data interception or do both for maximum flexibility.

Circuit component Passive circuit component Electronic engineering Electronic component Hardware programmer

So I will make up another little board to send modified data and install it inside the BCM.

We might be able to do quite a few nefarious things with a voltage divider and/or serial interceptor.

Resistor Voltage Divider.

Fake perfectly balanced tap voltages.
Reduce battery pack voltage sensed with a pre-resistor.

Serial Data Interceptor.

Fake perfectly balanced tap voltages.
Reduce battery pack voltage sensed by a set %.
Extend the life and performance of an older OEM pack by reducing it's sensitivity to minor voltage variations.

We will have to be careful as it looks like some voltage data is also passing between the HV/LV sections elsewhere on the board.
It may just be a simple voltage present check or part of the HV leak detection we shall see. Red Zone.
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So I modified yet another one of my OBDIIC&C devices to receive the internal BCM serial tap voltage data stream from the LV side of the isolation OPTO.

Passive circuit component Circuit component Green Electronic component Electronic engineering

This could be the basis of a handy gadget for HCH2 owners with standard cars wanting to find out which sticks are bad etc.

It's basically 25 bytes 31250,9,O,1 format. Weird baud rate but that's what the shortest bits says.
We have a two byte rotating header $80,$52 or $C0,$52 and then 22 bytes of voltage data and a final checksum.

In this example packet below the header is $80,$52. The checksum is $43.
The two bytes that make up each tap voltage have the high byte and the bottom nibble of the low byte combined to form 12bits of data.

If we take (Voltage Tap 1) VHB0 the first part high byte $5E and low byte $05 low nibble $5 we get $5E5 = DEC 1509 = 15.09V
This is the voltage between VHB1 (negative) and VHB0 (positive)
VHB0 is the positive high end of the pack. VHB12 is the negative low end of the pack.

POS ------ VHB0 --- VHB1 ---- VHB2 --- VHB3 --- VHB4 --- VHB5 -- VHB6 & 7 -- VHB8 --- VHB9 --- VHB10 -- VHB11 - NEGATIVE VHB12
$80,$52,-- ($5E,$05),($5E,$0D),($5E,$06),($5E,$0E),($5E,$03),($5E,$0D),($5E,$05),($5E,$0D),($5E,$05),($5E,$0E),($5E,$06),$43

Note VHB6 and VHB7 are directly connected internally via the battery main switch when it is on.
So in effect they are the same connection but provide continuity for voltage sensing on the taps either side of the switch when it is off.

The operating sensing range of each voltage tap is about 0.5V to 20.15V
Resolution is to two decimal places with accuracy of about +/-10mv or so.

There is a full 25byte serial data packet sent every 15ms.
That is about a 66hz refresh rate if you wanted maximum speed for logging/processing the tap data etc.

In the video I also show the 11 x 10k 0.1% tolerance resistor matrix divider (BCM Fooler) for simulating perfectly balanced battery taps.

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With a pre-resistor (inserted where the screw terminal jumper wire is) the voltage the BCM sees can be turned down to whatever we like...
i.e A 250V Battery can become 200V as far as the BCM is concerned.

Now to build and install the little serial fooling gadget into the BCM itself.
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Testing the BCM 'Gadget' on a live HCH2 battery pack..

Oh dear! Bit of a basket case with a nearly 1.9V deviation between the taps!!

Need to do some more testing and cycling of my spare HCH2 packs to find the best one.
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Video showing the TAP monitor more sorted and plugged into an Insight G1 pack using a simple wiring adapter.
It would be trivial to make an HCH1 adapter as well but I don't have need for one at the moment.
I will make a harness adapter for the Insight G2 and CR-Z Nimh cars as they use a 7 tap system and it would be handy to have for bench work. .

Need to tweak the software now to make the number of taps being monitored selectable.

I also recompiled the firmware for the cheap early PIC16F886 chip which I had loads of kicking around.
If you remember 15 years or so ago this was the first PIC I used in the OBDIIC&C gauge.
No point using a CAN enabled expensive 32mhz part for this simple job.
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Interestingly the Nimh CR-Z MCM/BCM module has exactly the same sort of HV detection and opto isolated serial interface!
So you could power up a module like the one in the pic and read/display the voltages in the same way as I'm doing with the HCH2 BCM.

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I don't have a spare voltage tap input socket so I would have to canabilise a dead MCM to get one and
hack off the bit in green to make an adapter. Not a lot of point in ruining a good MCM.

I might as well just reverse engineer the serial data in this module and add a 3.5mm jack socket so I can plug into it with the HCH2 gizmo!!
That's tomorrow mornings project then!!

Unless anyone has a dead/spare Nimh MCM and they want to send me the PCB out of it to support this research. ;)
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Coming in late again. So does this look like we can actually use the hch2 igbt and possibly mcm/bcm in the lithium crz to be able to put in a big high viltage pack? Im itching to be able to put in my spare 72 or 84 cell lto pack in my 13 crz and turn it up.
Just finished the Nimh CR-Z/Insight G2 voltage tap monitor device. (y)

This basically sniffs the serial data from the LV side of the Nimh MCM board and it is then displayed using one of my modified OBDIIC&C gadgets.

Now we can already get stick voltage data in a car from an HDS or from my earlier OBDIIC&C device.
This new method is basically a stepping stone towards future tuning where we can manipulate the voltages the MCM sees.

It's also useful for bench work where you can't use an HDS or my other in car device.
The Nimh battery in the video is a very well balanced (cycled) pack that has been in storage at least six months!

So we now have a plug in voltage tap gizmo for the G1 Insight, G2 Insight, CR-Z, Jazz and HCH2 Civic.

hello friend, please tell me where the circuit power +batt and -GND
What voltages do you want? +12V and +5V are available at the connector pins..
I now have the HCH2 Civic complete IMA system on the bench with a good OEM Nimh IMA battery.
The plan is check out the harness connections versus the Lithium CR-Z and if all OK plug it in and see what happens.
I'm expecting it to work a bit like the earlier CR-Z Nimh to Lithium transplant, but with non fatal error codes re the HCH2 aircon inverter etc.
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I tried the HCH2 IMA setup in my Lithium CR-Z today after slightly reconfiguring the harness connector.

Unfortunately they do not speak a similar enough language to be able to work as is.
The IMA error stated the ECM had lost comms with the IMA so that's then end of that avenue for now.
IMA and charging were disabled.

I need to finish off my Lithium buddy pack project and the CR-Z IMA Manual control so back to work on those shortly.

I might revisit the HCH2 setup in due course.
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