skylogger
Posts: 76
Joined: Sun Dec 14, 2014 3:54 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Thu Sep 06, 2018 3:53 pm

Hi KIEV:
You can add this second Charrger that I am working on as #17 on your Index on this thread.
I've used Coulomb's suggestion, and I've replaced the 20 amp fuse in the MCU on the I-MIEV that I
am using as a test bed with a fuse holder and a 1000v rated 20 amp fuse that is commonly used
in the solar power industry. That way I don't have to worry about Arc problems. I've replaced the
vertical PCB in the doghouse with two 1000pf 3000v ceramic caps, I've visually inspected the
Charrger boards and the DC-DC Converter boards and could not spot any further damage.
I did all the basic tests that I did on the previous charrger and all supply voltaged looked good.
I installed the charger back into the test car and tried to check DTCs with MUT III.
In the beginning, the MUT III would not even communicate with the car and I received a message
that the 12v was low. I found that since the car had sit for a week, the 12v battery was sitting at 10v
It's a bit far away to connect an external charger, so I used jumper cables to connect a external battery
across the I-MIEV 12V, and managed to get 11.9v. I was then able to get the MUT III to communicate.
I could get car to go to "READY" and I could see that the DC-DC was working as the 12v battery was
now reading 14.3v. I did a scan for DTC, and got a POA09 error which was a left over error, so I cleared that
ran scan again and did not have any errors listed. I then tried charge car, connecting the charger cable.
I could hear the clunk of the contactors, The cooling fan came on, The charger light lit up on the dash, and all
looked good for a moment. While I was watching the charge light on the dash, I saw it blink off for a second but
came back on. The car seemed to continue charging for about another minute or so, then the charge light
went out. I disconnected the charge cable for a few minutes, then re-connected it but never saw the car try
and charge again (no charge light on Dash, no contactor clunk, no fan noise.) I checked the 20 amp fuse in
the MCU and that was still ok. I turned the car back to "READY" and ran a DTC Scan with the MUT III, and no
errors came up. I noticed that during the MUT III Scan, when it passes each section like BMU, CMUs etc it displays
a "OK" if there are no errors. When it got to the OBC scan, It displays "-" as if its not even scanning for errors on
that section, and no DTCs are reported. I pulled the charrger out of the car and put it back on bench. The two
1000pf caps in the dog house did not get blown are still ok. Later today, while it's on the Bench, I'll apply AC in
again and see what voltage appears across the 3x big electrolytics to see if the front end is still ok. I'll do a
basic diode check with multimeter across the IGBT section again to see if that still looks ok, and I'll check voltage
across all the electrolytics on the top pcb to see if any supply has died.

I've noticed this problem with My MUT III skipping over the OBC DTC scan on several other cars as well (all 2010 I-MIEV). I cannot read Hardware and Firmware revisions of the OBC like I can do with other ECUs in the car. The MUT III also says it cannot do canbus tests, so maybe the MUT III Cable to the car that I am using is incorrect, or there is some CANBUS difference in a 2010 I-MIEV that is preventing this. Maybe my MUT III is currently using LIN BUS for the other ECUs DTC Checked? I also noted that the CANBUS that is on the Chademo port is separate to the CANBUS that is on the under the dash OBD Connector, and I read somewhere that the EV-ECU connects to both CANBUS's and acts as a firewall between them. Do you know anything about this? During the MUT III Sofware installation, it installed BOTH MUT III AND MUT III SE (Second Edition). Only the SE will work with I-MIEV.
Last edited by skylogger on Thu Sep 06, 2018 4:08 pm, edited 1 time in total.

coulomb
Posts: 170
Joined: Sun Jun 10, 2018 8:32 pm
Location: Brisbane, Australia

Re: General failure thoughts

Thu Sep 06, 2018 4:01 pm

kiev wrote:Some more general theoreticals:

So if (during charging) the Aux battery hiccups for some reason, then the DC/DC senses a change in current or voltage such that it goes to the rails trying to maintain the 12V buss--resulting in a huge inrush thru the MCU fuse to the DC/DC.

I'm not sure what the DC-DC will do if the 12 V output disconnects for some reason. IF it behaves, it will suddenly draw very little current, not a lot of current. It will not have to supply much current (just some leakage) to maintain 14.0 V (or whatever its set-point is).

So I don't think it's the DC-DC that blows the MCU fuse.

However, I'm sure that if it's supplying 50-80 A and suddenly the 12 V battery goes open circuit, then even though it would try to pull back the current instantly, it won't be able to, and the nominally 12 V rail would overshoot. I have no idea what it would overshoot to; my guess is only 20 V or so. That would not trouble the charrger power supply at all. But maybe I'm wrong and it shoots up to say 60 V; that could be a problem.

kiev
Posts: 942
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Thu Sep 06, 2018 7:12 pm

skylogger wrote:Hi KIEV:
You can add this second Charrger that I am working on as #17 on your Index on this thread.


okay thanks, will do.

it sounds like you have done a great job of troubleshooting on that unit and may be close to getting it working. Thanks for sharing your notes and the detailed steps that you took.

i really believe it's necessary to have a good strong Aux battery before trying to drive or charrge these cars. If the main contactors let go under load they will be damaged. There are numerous small relays, the cooling fan and pump, etc that will be loading down the system. The CAN buss, instrument panel and all the processors in all the ECUs need power. The DCDC may be trying to hold these up, but it is a bootstrap situation with no fault tolerance.

The charrger wants to send current to the pack to charge the cells, but the DCDC wants to pull current from the pack in order to hold up the 14.3V buss. When the Aux is only reading 11.9 open circuit, it will be pulled to 11.5 or lower when going to READY. When trying to use the OBC to charrge the pack with a weak Aux--which way is the current going to flow?

i think an Aux battery below 12.5 OCV is worn out and not safe for use in an EV, maybe ok in an ICE car, but not in an EV.

The BMU has two CAN busses, the main one to the EV-ECU and another to the CMUs.

The EV-ECU also has two CAN busses coming in to IC5 and IC6 near connectors D and B in the picture i posted on the EV-ECU thread.
kiev = kenny's innovative electric vehicle

electronpusher
Posts: 45
Joined: Sun Jun 25, 2017 3:11 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Thu Sep 06, 2018 11:37 pm

Well, we finally got our iMiEV home today, so now I can start the work on the repair of the DC/DC Converter.

First thing we did was remove the cover from the Motor Controller to check the 450v fuse, got out the multimeter, set it to continuity, placed the probes either side of the fuse, hoping it was still in tact...... Damn, it's blown.

Called Mitsubishi to order the fuse, non in Australia apparently, well not in the warehouses anyway. I asked about possibility of some in SA, he checked and said the SA warehouse moved to Victoria, and there is none of that part there. He did say that he cannot check other dealers stock, yay for the dealership bullshit model, they don't talk to each other. Wishing we had money for a Tesla right now, since they do not have dealerships as such, but oh well. So I ordered the part, up to 4 weeks to deliver, sigh. I might try calling some SA dealers on Monday, skyloger any idea were in SA the stock may be?

So, the problem is the same as all the other iMiEV deaths.

Next up (probably tomorrow), we'll drain the coolant and remove the DC/DC converter and continue our investigation into it. Time to take our baby into surgery.

skylogger
Posts: 76
Joined: Sun Dec 14, 2014 3:54 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Thu Sep 06, 2018 11:54 pm

I've come across some faulty componens now. These have probably just blown up due to me jumping the gun and not taking Coulomb's advice and using a current limited powersupply during testing.
Since the charrger has now stopped detecting AC comming in, I decided to check the AC input part of the charger again.
When I measure from the AC Screw terminal Neutral on the top pcb to the Neutral pin on the white strip, I am now measuring a high value (This should be around 9.4 ohms. This means that one of the two 4.7R resistors in the dog house has gone open. I had to take the board down to a friend that has a rework station, because from the previous attempt to desolder all the pins on the white strips to remove the waffle board using solder braid was not working. Once the waffle was removed, I tested the two 4.7R resistors, and yup, one was open. The funny thing was that it was the one labeled 7K TAM 121 4.7R The other resistor was labeled P10K and I noticed that KIEV calls it P10KFUSE So maybe it has a built in fuse? These are in series with each other, but it looks like the one labeled 7k that does not have internal fuse is the one that blew open. It looks to be physically half way between a 5w and a 10w size. No one local has anything close to this. A 10 watt resistor that I can get my hands on is too long, so I am thinking of using two 5w resistors in series, side by side with one end of each going into the PCB, and the other end of each tied together. I was able to get 2x 2.7R 5w resistors at Altronics, so Instead of total series resistance of 9.4R I will end up with 10.1R So I hope this is not too far out of spec. should just mean it would take a bit longer on the soft start. I got to thinking that maybe the resistor blew because the relay never closed, so the resistor was left in circuit too long and over heated.
The relay that I have is marked a bit different to what KIEV drew on his schematic. There are 2 pins for coil, and 4 pins for contacts.
There are two sets of contacts, that on the PCB are wired in parallel, so I guess if one set fail, the other set of contacts will still work.
Each set of contacts is rated to 16 amps. The coil on this relay operates on 5v. The part number on the relay is K1AKOO5W-KW I soldered some wires to the coil pins and supplied 5v to the relay and could hear it click. I used ohm meter to check contact pins, but found that neither set of contacts would give me a 0R reading when the relay was activated, so it's looking like this relay has burnt contacts.
I had a look at Altronics and Element14 but neither of them have simular relays with 5v coil, 2 sets of contacts with 16amp contact rating.
I'll check if Digikey or RS might have something with same Pcb footprint. If anyone knows of an equivalent, let me know.

I

electronpusher
Posts: 45
Joined: Sun Jun 25, 2017 3:11 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Sep 07, 2018 12:07 am

kiev wrote:jray3's box that i have here failed like skylogger's [MCU fuse and snubber caps], but i haven't found a loose part that could have initiated the inductive spike yet.


Make that three, ours has failed exactly the same way, MCU Fuse and Snubber Caps blown.

electronpusher
Posts: 45
Joined: Sun Jun 25, 2017 3:11 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Sep 07, 2018 12:51 am

Interesting discussion regarding the Aux Battery possibly being to blame for the MCU Fuse/Snubber Caps issue. Taking that into consideration, we have a battery that is rather small compared to the size of the battery box, and hence I would like to swap it out before I put back in repaired components (when I have them repaired), just in case.

What is the biggest 12V battery we can fit in that battery box?

skylogger
Posts: 76
Joined: Sun Dec 14, 2014 3:54 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Sep 07, 2018 1:57 am

electronpusher:

I had same problem with fuse, I placed an order with Mitsubishi Dealership here in WA, But they said it would take a week to get the stock from SA. Maybe I grabbed the last one in stock in WA. So I did not want to wait for that to arrive to start testing, so in the meantime, I contacted one of the local Electrical Wholesalers that supplies to the solar industry, and bought one of their 20amp 1kv rated fuses and the fuse holder. The fuse holder is for a DIN rail, but I just made up wires with ring terminals that would connect to the mounting screws of the original fuse, and then ran the wires to this new fuse holder, which pushes down and fits next to original location. Here is what the fuse and holder look like:
Image

Here is the fuse:

Image

skylogger
Posts: 76
Joined: Sun Dec 14, 2014 3:54 am

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Sep 07, 2018 2:08 am

For the 4.7R resistor that I found blown in the doghouse, I found a DIGIKEY A102487-ND
This is rated at 7 watts, and has same axial 5mm pitch mounting and 14mm width so it looks
quite simular to the original part.

For the relay, I found a DIGIKEY Z6355-ND Which is an OMRON G2RL-1AE-ASI
I made the mistake when ordering this, as I got carried away with the -ASI Suffix that notes it can handle 51 amps in rush current.
The draw back, is that this one only has a single set of contacts, so only two of the four contact pins come out and go into the PCB.
The original relay was more like a G2RL-1A-E-DC5 Which has two sets of contacts, so if one pair fail, the other set that is parallel
would still work. Both of these have a 16 amp contact rating.

kiev
Posts: 942
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Sep 07, 2018 4:32 am

@ sky

it this in your latest repair unit(#2) Post 1, List 17., or the previous one(#1),Post 1, List 13? maybe we need to come up with a designator to identify and avoid confusion.

When are you thinking that the 4.7R ceramic and/or relay contacts were damaged--was it after your repair job or part of the initial failure?

Thanks for posting the part number, i thought it was a TAM 5K series, but the 7K is better, rated to handle 70W for 5 seconds but no internal fuse such as in the P10K.

7K datasheet

P10K datasheet

i haven't checked the contact resistance in jray's box yet, but that is a good idea and easy to do, thanks for the idea.


@electron

it may take some time for the fuse to come in, but it may also take some time to figure out why it blew--just replacing a blown fuse will usually result in needing to order another fuse unless the root cause has been discovered.
kiev = kenny's innovative electric vehicle

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