Minicab MiEV support with charger/blown capacitors

[walkingthedog]

Hey everyone,

It's a bit of a long story but basically Keivan (car's name) died last week. I got a new 12V battery which allowed me to get it home to work on it. It still wouldn't charge. I have had some guidance and help from a mate (Rob) up in QLD and did a diagnostics scan to find error code PA14AD.

I watched this video https://www.youtube.com/watch?v=ynFKclo ... l=SydneyEV and did mostly what they said to do. Minus replacing the heat transfer paste.

I put the charger in and heard a pop and I think I found what the pop was. The capacitors on the top PCB seem to have cracks in them and when charging the charge light flashes on the dash or the charger ready light turns off. The initial attempt to charge short circuited the garage door. There was also a chemical smell coming from the dcdc converter box when I opened it back up again. Which could have potentially been the incorrect sealant I used but I don't think so.

If you haven't noticed already I'm a bit of noob when it comes to EV maintenance and knowledge of electronics. I am a dog walker and use my Minicab MiEV for work so I need to get it back on the road ASAP. I thought of taking it to an Auto Electrician who knows about EVs but Rob thinks that I couldn't find one who knows how to fix it. I'm going to take out the cracked capacitors on the top PCB and order new ones but still don't know what caused these things to break in the first place.

Could a poor soldering job on the capacitors on the PCB below have caused this? Do you know what the capacitor on the top PCB could be to? It's all chips and different coloured shapes to me haha

Any help/guidance would be really appreciated

- Liam
Walking the Dog Melbourne

[coulomb]

Hey everyone,

Welcome to the forum.

I have had some guidance and help from a mate (Rob) up in QLD and did a diagnostics scan to find error code PA14AD.

I suspect you mean trouble code P14AD (no 'A' after the 'P'). That's "EV-ECU control power supply voltage abnormal". It sounds like that may be left-over from whatever problem you had with the auxiliary battery. Can you clear that code now that you have a replacement battery?

Did you charge the new auxiliary battery? They often come with a fairly low charge. Your DC-DC may not be operating at present to charge it from the main pack.

I put the charger in and heard a pop and I think I found what the pop was.

I haven't watched the video; why was the charger removed at all?

The capacitors on the top PCB seem to have cracks in them...

This is a common failure mode. Have you checked the HV fuse in the motor controller, under the access panel? Usually, that fuse blows when those capacitors fail.

The initial attempt to charge short circuited the garage door.

Can you explain that a bit more? Was there a power brown-out when you started the charge, and now your garage door opener is faulty?

Is this when the capacitors are presumed to have cracked/failed?

There was also a chemical smell coming from the dcdc converter box when I opened it back up again.

The DC-DC converter is in the lower compartment of the unit that houses the DC-DC converter and charger. Are you saying it was specifically coming from that lower section, not the upper section with the charger?

I'm going to take out the cracked capacitors on the top PCB and order new ones but still don't know what caused these things to break in the first place.

The best resource I've found on iMiEV charger repair (I assume that the Minicab charger is the same or at least similar) is this:
Troubleshooting and repair for On-board Charger (OBC)

Could a poor soldering job on the capacitors on the PCB below have caused this?

It's probably not a soldering issue. The cause of the capacitor failing is not known, but Mitsubishi realises it's a design fault. So much so, that in the USA (but no other country, as far as I know), they extended the warranty on the charger to 8 years. So in the USA, if this happens, you just take it to a dealer and get the charger replaced for free.

Do you know what the capacitor on the top PCB could be to?

The purpose of the capacitors is also not clear. They are essentially across the output of the charger, which is more or less across the main battery pack when the charger is operating. They seem to be needed to suppress spikes, likely caused when some of the inductors suddenly lose current. Some speculate that the fuse in the motor control unit fatigues with time and opens under load, causing the current spike, and the capacitors are under-rated for the energy stored in the inductors.

In any case, you should replace the capacitors with more sturdy versions; there are suggestions in the troubleshooting and repair topic I linked to above.

[walkingthedog]

Thank you Coulomb, yeah typo with the extra A. I tested the new battery and its working fine. I plugged the charger into the MiEV to charge it but that was my issue so I opened up the DCDC to see the capacitors on the bottom PCB were blown. But I think you're talking about another charger. I followed the instructions in the video and when charging the car heard a pop sound and something has caused it to short circuit. I opened up the DCDC converter, it smelt chemically and bad but I'm not sure what has caused it. I can't see any blow things. There is a small amount of smoke/burn on the metal lid which is above the cords that plug in but they seem fine.. I'm at a bit of a loss

[walkingthedog]

The new capacitors I soldered in on the bottom PCB were larger than the original ones. I also changed the fuse in the case to the right of the DCDC converter

[walkingthedog]

Upon further inspection the surge absorbers look okay. I've taken the top PCB with me to work and it looks fine. Still not sure what has caused the issue

[coulomb]

Thank you Coulomb, yeah typo with the extra A.

Those typos can make it hard to search for information about the problem

I plugged the car into the MiEV to charge it but that was my issue so I opened up the DCDC to see the capacitors on the bottom PCB were blown.

Forgive me if I've got this all wrong, but it's sounding as if you think that the DC-DC is the lower of the two boards in the upper plenium. The DC-DC is actually in the lower plenium, towards the road. Is this the board you replaced the capacitors in? If so, which capacitors?

DC-DC board bLNOfTC.jpg (680.62 KiB) Viewed 94 times

[walkingthedog]

I'm very much new to all the terms and don't even know what a DCDC does exactly. I'll try share some photos

[walkingthedog]

The new capacitors

[walkingthedog]

Dug out the silicone on the lower PCB and replaced with the new yellow caps

[walkingthedog]

Then put it back into the metal casing it was stored in. Not sure if it's the DCDC converter

[coulomb]

Dug out the silicone on the lower PCB and replaced with the new yellow caps

[ Edit: that's the capacitors I thought you were talking about. But those are part of the charger, not the DC-DC converter. ]

Ok. So that's the lower PCB of the upper plenary. But there's a third PCB under all that, like a "basement" or a compartment under a "false floor" in the housing for the two converters. You possibly never even noticed that it's there.

The DC-DC converter converts DC from the main battery (360 V) and uses it to (DC) charge the auxiliary battery (12 V). It actually doesn't seem to fail nearly as much as the charger (which is an AC to DC converter; it converts 230 VAC to 360 V DC to charge the main battery).

[ Edit: added photo ]

Plenaries.jpg (150.77 KiB) Viewed 74 times

[nuggetgalore]

....
I also changed the fuse in the case to the right of the DCDC converter

Is it the 20 A fuse (Mitsubishi FUSE,MOTOR 9499A656) in the inverter you replaced?
Was it blown or did you just replace it to be sure?

[walkingthedog]

....
I also changed the fuse in the case to the right of the DCDC converter

Is it the 20 A fuse (Mitsubishi FUSE,MOTOR 9499A656) in the inverter you replaced?
Was it blown or did you just replace it to be sure?

Just to be sure

[walkingthedog]

Dug out the silicone on the lower PCB and replaced with the new yellow caps

[ Edit: that's the capacitors I thought you were talking about. But those are part of the charger, not the DC-DC converter. ]

Ok. So that's the lower PCB of the upper plenary. But there's a third PCB under all that, like a "basement" or a compartment under a "false floor" in the housing for the two converters. You possibly never even noticed that it's there.

The DC-DC converter converts DC from the main battery (360 V) and uses it to (DC) charge the auxiliary battery (12 V). It actually doesn't seem to fail nearly as much as the charger (which is an AC to DC converter; it converts 230 VAC to 360 V DC to charge the main battery).

[ Edit: added photo ]


Plenaries.jpg

Thank you so much, I'm learning heaps. Can I only access the third PCB by taking the whole casing out? Is there anything in the in the third PCB that I should be looking for? I'm definitely wanting to do an online electronics course after this.

Out of curiosity and probably a very silly question but, why would the machine need to have a converter? Couldn't it just send out 360V? Or does the converter keep the weight down and not take up as much space as something that puts out 360V?

[nuggetgalore]

Out of curiosity and probably a very silly question but, why would the machine need to have a converter? Couldn't it just send out 360V? Or does the converter keep the weight down and not take up as much space as something that puts out 360V?

The motor is three phase AC (alternating current) . The inverter (aka variable speed drive) makes alternating current with a frequency that is controlled by the accelerating pedal (well, sort off).
The traction battery is fully charged to 362 VDC, but the inverter can make the AC current from any voltage from 360 to less than 300 (very similar to a solar array,except a solar array makes AC at exactly the same frequency as the grid (50 H nominally) where as the iMiEV inverter starts at a very low frequency and as the car speeds up the frequent increases.

[walkingthedog]

thanks Nugget, good to know

[walkingthedog]

Could this be anything telling? Or just usual heat?

[walkingthedog]

I'm thinking I'll take the whole metal casing out and take it to someone who knows what they're looking at

[coulomb]

Can I only access the third PCB by taking the whole casing out?

I don't own an iMiEV, but I'd say yes, you need to take the whole casing out. I assumed you already did that for the charger, but perhaps it can be accessed with the case still in the car.

Is there anything in the in the third PCB that I should be looking for?

The DC-DC converter is usually pretty reliable, and it's easy to test: does the auxiliary battery voltage rise to over 14.0 V when the car goes to ready? If so it's working. If not, it's not working (or the fuse in the motor control unit is blown). If you don't have a multimeter, I suggest one of these: https://www.jaycar.com.au/in-car-batter ... y/p/QP2222 (or similar):



If the DC-DC converter appears to be working, I suggest don't attempt to open it, just leave it alone.

why would the machine need to have a converter? Couldn't it just send out 360V? Or does the converter keep the weight down and not take up as much space as something that puts out 360V?

If you connected 360 V from the main battery to the nominally 12 V auxiliary battery, the auxiliary battery would explode. Its voltage should not exceed about 14.4 V for long (the voltage at which the lead acid battery starts gassing hydrogen and oxygen); the converter is there to provide an appropriate voltage and control the current into the auxiliary battery.

[walkingthedog]

Ah I see, I do have a multimeter. The voltage from the 12V when off is 12.7 and when on 14.7

Yeah I can access the charger from the top and take the PCBs out. So if that's the case (pardon the pun) I should just take out the two PCBs in the charger and take them to someone who knows what they're looking at/for. Sorry I'm at a bit of loss right now and feel a bit in over my head.

Thanks for getting back to me folks

[coulomb]

Is there a trick to disconnecting these?

Yes, they can be a pain, even for seasoned car people. There is usually a tab that needs to be pressed, in such a way that it clears some piece of plastic. There may be a second tab on the other side, that has to be pressed at the same time. Nearly every connector is slightly different in the details of how to disconnect it. Over time, the connectors become tight, the plastic hard, and so on, so it sometimes take some patience.

Disconnecting automotive connectors.jpg (94.06 KiB) Viewed 28 times

[coulomb]

Could this be anything telling? Or just usual heat?

Disconcerting as it is, this is apparently normal, at least for this charger model. Hopefully the new model that replaces it handles the heat better.

[coulomb]

The voltage from the 12V when off is 12.7 and when on 14.7

Ok, so no need to worry about the DC-DC converter, and the MCU fuse is intact.

I should just take out the two PCBs in the charger and take them to someone who knows what they're looking at/for. Sorry I'm at a bit of loss right now and feel a bit in over my head.

So you're saying that after replacing the two blown blue capacitors with the yellow ones, the charger still doesn't work?

Finding someone who can fix your charger boards is going to be challenging. Do you think you'd be able to swap out the charger for one from a wreckers? You'd have to take the whole charger out, and after installing the new one, purge the air out of the coolant lines.

[walkingthedog]

Is there a trick to disconnecting these?

Yes, they can be a pain, even for seasoned car people. There is usually a tab that needs to be pressed, in such a way that it clears some piece of plastic. There may be a second tab on the other side, that has to be pressed at the same time. Nearly every connector is slightly different in the details of how to disconnect it. Over time, the connectors become tight, the plastic hard, and so on, so it sometimes take some patience.


Disconnecting automotive connectors.jpg

Awesome, that's good to hear

[walkingthedog]

The voltage from the 12V when off is 12.7 and when on 14.7

Ok, so no need to worry about the DC-DC converter, and the MCU fuse is intact.

I should just take out the two PCBs in the charger and take them to someone who knows what they're looking at/for. Sorry I'm at a bit of loss right now and feel a bit in over my head.

So you're saying that after replacing the two blown blue capacitors with the yellow ones, the charger still doesn't work?

Finding someone who can fix your charger boards is going to be challenging. Do you think you'd be able to swap out the charger for one from a wreckers? You'd have to take the whole charger out, and after installing the new one, purge the air out of the coolant lines.

Yeah, after replacing them the charging light is flashing, it wasn't doing this before when charging and it didn't short circuit some things in the garage. The problem is I have no idea what I'm looking at and can't see any issues that are standing out. I've been guided by someone up near Brisbane who had the same issue with theirs. They soldered in the new capacitors to the lower PCB in the charger casing and everything is back to normal for them. Would the wreckers even have the same charger? Are the chargers in the iMiev and MiEV exactly the same? Not sure how to purge the coolant lines..