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

[kiev]

Lots of videos on the utubes of guys doing surface mount soldering for instrument clusters, speedometers, car electronics, etc. Search for them, find one close to your area, then send a note and ask. they know how to solder and would likely be glad to help make the repair.

 

[coulomb]

Does anyone have any other recommendations for replacing the surface-mount LTC IC on my i-MiEV's BMS PCB?

Yes, check the SMD fuses first, as per this post.

Edit: You could also do some easy sanity checks on the LTC chip:



You will need to power up the board for the voltage test, obviously. But checking for around 10kΩ in the two places indicated will often tell you if the chip is melted or not. V+ at the bottom comes from power on the connector, via an isolating DC-DC if I remember correctly. Dang, that's with respect to an earth I haven't marked above; sorry for the lack of info. I have notes somewhere that I can dig up if you are interested.

Sn are the sense pins, Cn are the cell voltage pins. C8-12 are not used.

 

[martinwinlow]

- try a PC/laptop repair store, they usually have the necessary tools required.
- get yourself a hot air solder station and DIY (might want to practice a bit beforehand)

Thanks. If t were a 'regular' BMS PCB I'd give it a go but having watched a few youtube vids and given it s an odd 'pre-production' PCB that'll be very difficult to replace, I think I'll leave it to a pro...

 

[martinwinlow]

Yes, check the SMD fuses first, as per this post.

Edit: You could also do some easy sanity checks on the LTC chip:

Thanks but I didn't make myself clear - I'm looking for a recommended alternative to the PhoneReco repair business I used the last time I needed a new LTC chip replaced... Given that the symptoms are identical, I don't doubt that the LTC chip is defective... Your suggestions are a *wee* bit beyond my skill set, anyway... "power up the board'... How?!
The 10k measurements... looking for 10k going from where to where (with the PCB powered up or not/doesn't matter)?
Actually, I *am* interested but, like I say, I think you are assuming I have knowledge that I don't have (yet)!

 

[MickeyS70]

Thanks. If t were a 'regular' BMS PCB I'd give it a go but having watched a few youtube vids and given it s an odd 'pre-production' PCB that'll be very difficult to replace, I think I'll leave it to a pro...

Try PM @alviseven, he has left over ‘red’ CMUs from his battery swap

 

[coulomb]

Given that the symptoms are identical, I don't doubt that the LTC chip is defective...

Oh, OK.

"power up the board'... How?!

I don't even remember how I did it on the bench. My notes, when I find them, will tell me . But you could put 12 V power on the main battery shell; I'll agree that's not ideal. From memory, the CMUs draw some or all of their power from the auxiliary (12 V) battery.

The 10k measurements... looking for 10k going from where to where (with the PCB powered up or not/doesn't matter)?

Resistance measurements are always when powered down. Where to where is indicated by the thin read lines. Those pad locations were hard won after weeks of research.

 

[MickeyS70]

But you could put 12 V power on the main battery shell; I'll agree that's not ideal. From memory, the CMUs draw some or all of their power from the auxiliary (12 V) battery

Yes, as soon as you apply 12V aux to a CMU, it starts transmitting cell voltage/temperature, this CAN data stream can (easily) be read/checked with an Arduino or similar.

Important: you need to have all cells connected to a CMU board before you apply 12V (SMD fuses may blow otherwise)

For a pinout see schematics in thread below:
https://myimiev.com/threads/cmu-board-notes-eprom-cell-re-numbering-can-messages.4302/

 

[Gary12345]

I've used these guys several times for LTC swaps, very high success rate.

https://www.mrtechuk.co.uk/

 

[martinwinlow]

I have sent the PCB and new LTC chip (I have several more spares, now) off to RADIOWAVES, in Stenhousemuir, Stirlingshire who quoted £20 + return P&P for replacing the IC. I'll update in due couse.

 

[BlindMoose]

So did you get an answer to your " you could put a CAN bridge between the CMU/BMU to mask the low cells and start charging it, " request, that doesn't involve removing the traction battery pack. Is it just a simple case of temporarily wiring out the sensors, or what. ?

 

[MickeyS70]

So did you get an answer to your " you could put a CAN bridge between the CMU/BMU to mask the low cells and start charging it, " request, that doesn't involve removing the traction battery pack. Is it just a simple case of temporarily wiring out the sensors, or what. ?

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

If you know the issue is caused by a faulty CMU one can ‘intercept and change’ the CAN data before it reaches the BMU.

Beware, masking a bad cell with this method can potentially lead to disastrous consequences..

 

[BlindMoose]

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

If you know the issue is caused by a faulty CMU one can ‘intercept and change’ the CAN data before it reaches the BMU.

Beware, masking a bad cell with this method can potentially lead to disastrous consequences..

Ok, thanks for your reply. I think this is going to be beyond my abilities. I was hoping for something a little simpler, like for instance temporarily wiring out some connections. I have already done the P1A15 resistor bodge in the MCU. Interestingly, I managed that without removing from the vehicle. Just needed to unbolt from the frame, and lift & twist the box, to get access to the bottom plate.

 

[kiev]

I have already done the P1A15 resistor bodge in the MCU. Interestingly, I managed that without removing from the vehicle. Just needed to unbolt from the frame, and lift & twist the box, to get access to the bottom plate.

That's good to know, thanks for sharing the tip.