Help Please With 2009 i-MiEV: P1A33, P1A30, P1A39, P1A76 & P1A52

[martinwinlow]

My poor old (SSE liveried) 2009 i-MiEV has developed a fault again having been my daily driver since I fixed its CMU LTC chip failure back in 2024 when I first bought it as a non-runner.

It won't go to 'Ready' and nor will it charge AC charge. If I try to start it, the HV battery fan comes on and sys on for about 5 minutes before turning off. Likewise, if I turn off the ignition, the fan continues for a similar time and then turns off. 12V battery is fine...

I have to say that the range has become pretty poor of late (30-40 miles?) and I suspect a dud cell. I can't get Canion to connect despite using it only 6 months back on another iOn fix... The MUT3 reports low voltages on 3 cells in CMUID01: Cell D and F are at 2.100V Cell E is at 3.300V and all the others are around 3.8/9xxV. Beginning to wonder if I left the car on overnight...

Going only from the error codes and voltages of the error cells, has anyone anything useful to suggest? I'll have another go with both MUT3 and Canion asap.

MW

 

[MickeyS70]

My poor old (SSE liveried) 2009 i-MiEV has developed a fault again having been my daily driver since I fixed its CMU LTC chip

Going only from the error codes and voltages of the error cells, has anyone anything useful to suggest? I'll have another go with both MUT3 and Canion asap.

MW

Problem with low reported cell voltage is that the chances are 50:50 between a dud cell and faulty CMU, but a reported voltage of 2.1V means the CMU actually reports zero (if remember correctly) and that’s usually a tell tale sign of a faulty CMU.

Apart from the obvious and remove the pack to measure the actual cells, you could put a CAN bridge between the CMU/BMU to mask the low cells and start charging it, then remove the bridge and see if the values have changed..

 

[martinwinlow]

Thank you.

The fact that the car (which is a very early 'pre-production' version - one of its quirks is that its AC charging is 'dumb' ie it does not conform to the 62196 standard) has had a previous incidence of a failed chip on one of the HV battery module BMS PCBs (the CMU LTC chip I mentioned earlier) could suggest another one has failed. Unfortunately, I can't get my Canion to connect. If it did I might get the same quite distinctive readings which would pinpoint things a bit.

I gather there is an alternative to Canion these days but I can't remember what it's called - my Android devices are getting pretty ancient anyway...

A CAN bridge is a bit outside my experience. Is this a straight-forward process and where would I get a suitable bridge? Programming it? Where, physically does it go?

 

[martinwinlow]

Is the overall HV battery voltage just summed from the individual cell readings or measured separately? Just wondering if I were to add up all the cell voltages and it does not equal the pack voltage that that might suggest one sort of fault rather than another...

I tried it again this morning having had the 12V battery on charge overnight - just in case - and it very briefly went to 'Ready' before stopping and getting the yellow wrench again.

 

[kiev]

The MUT3 reports low voltages on 3 cells in CMUID01: Cell D and F are at 2.100V Cell E is at 3.300V

If you have a MUT3, then you have a much better tool than any phone app.

The MUT can drill down to read internal error codes of ECUs such as the MCU, OBC, BMU etc. Plus it can scan all the CMUs to read the cell voltages. Might be worth a look.

A weak 12V battery can masquerade as a "good" one--i've seen this hundreds of times on this and other EV forums.

The CMUs read the cell voltages and report to the BMU. The total pack voltage is the sum of the individuals, except in 2 places (that i have traced) related to Starting and Charging .

In the MCU where it is measured directly at START across the big black capacitor by the hybrid board in the bottom plenum. And in the OBC during Charging with a little op amp circuit on the bottom of the power board in the HVDC Output section.

 

[kennypats]

Thank you.

The fact that the car (which is a very early 'pre-production' version - one of its quirks is that its AC charging is 'dumb' ie it does not conform to the 62196 standard) has had a previous incidence of a failed chip on one of the HV battery module BMS PCBs (the CMU LTC chip I mentioned earlier) could suggest another one has failed. Unfortunately, I can't get my Canion to connect. If it did I might get the same quite distinctive readings which would pinpoint things a bit.

I gather there is an alternative to Canion these days but I can't remember what it's called - my Android devices are getting pretty ancient anyway...

A CAN bridge is a bit outside my experience. Is this a straight-forward process and where would I get a suitable bridge? Programming it? Where, physically does it go?

I have the same happing with a 2010 i-Miev and would be asking the same about CAN bridge

 

[MickeyS70]

I gather there is an alternative to Canion these days but I can't remember what it's called - my Android devices are getting pretty ancient anyway...

Hobdrive (paid version) seems to work well with almost any dongle

A CAN bridge is a bit outside my experience. Is this a straight-forward process and where would I get a suitable bridge? Programming it? Where, physically does it go?

I’ve done this myself and it’s surprisingly simple as others have already done the hard bit:

https://myimiev.com/threads/cmu-can-‘spoofing’.5505/

I used an Arduino Due and two SN65HVD230 CAN bus transceivers. The bridge is put under the back seats and connects in-line with the CAN High/Low wires going from the BMU to the CMUs in the battery pack.

A word of caution: masking a truly low cell can potentially fool the car’s low voltage safety shut off and create a fire hazard.

 

[martinwinlow]

If you have a MUT3, then you have a much better tool than any phone app.

The MUT can drill down to read internal error codes of ECUs such as the MCU, OBC, BMU etc. Plus it can scan all the CMUs to read the cell voltages. Might be worth a look.

A weak 12V battery can masquerade as a "good" one--i've seen this hundreds of times on this and other EV forums.

The CMUs read the cell voltages and report to the BMU. The total pack voltage is the sum of the individuals, except in 2 places (that i have traced) related to Starting and Charging .

In the MCU where it is measured directly at START across the big black capacitor by the hybrid board in the bottom plenum. And in the OBC during Charging with a little op amp circuit on the bottom of the power board in the HVDC Output section.

Thanks, Kiev.

I'll try a new 12V battery next.

Do you know how Canion calculates the total HV battery voltage (same question ie by adding all the individual cells or reading it as you suggest from somewhere else)?

I agree about the MUT3 but it is *really* tedious to use and all the data is spread over dozens of 'windows'-worth of data. The huge advantage of Canion is that it displays all the relevant data on one window... Also, if it is another failed LTC chip, the way the Canion displays the data may make it clear that the same fault has occurred to a different module...

 

[martinwinlow]

Hobdrive (paid version) seems to work well with almost any dongle

I’ve done this myself and it’s surprisingly simple as others have already done the hard bit:

https://myimiev.com/threads/cmu-can-‘spoofing’.5505/

I used an Arduino Due and two SN65HVD230 CAN bus transceivers. The bridge is put under the back seats and connects in-line with the CAN High/Low wires going from the BMU to the CMUs in the battery pack.

A word of caution: masking a truly low cell can potentially fool the car’s low voltage safety shut off and create a fire hazard.

Excellent, thanks for the link.

Is this the same technique that others have used to get much bigger HV packs (using new cells) to supply their full capacity to converted cars?

 

[MickeyS70]

Excellent, thanks for the link.

Is this the same technique that others have used to get much bigger HV packs (using new cells) to supply their full capacity to converted cars?

Yes, same principle: you intercept data, modify values of interest and send it on.

Main difference to pack upgrades is that in this case the CAN bridge connects to the ‘other’ side of the BMU and corrects ‘bad’ data coming from the CMUs.

 

[Gary12345]

Wowsers we are making this complicated - ok so its either the cell or the monitoring - if you take the pack out and check the cells directly you'll know if its a cell or not. If it needs a cell then put one in, if its needs a cmu then swap or repair that.

 

[MickeyS70]

Wowsers we are making this complicated - ok so it’s either the cell or the monitoring - if you take the pack out and check the cells directly you'll know if it’s a cell or not. If it needs a cell then put one in, if its needs a cmu then swap or repair that

Up until recently I would have agreed with you 100%, but there is now a real potential to ‘fix’ a faulty CMU without taking the pack out.