coulomb
Posts: 311
Joined: Sun Jun 10, 2018 8:32 pm
Location: Brisbane, Australia

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

Mon Oct 04, 2021 7:10 am

philsuth wrote:
coulomb wrote: Do you think it reasonable to assume that both capacitors (in parallel) were the same value?

Yes, though it's obviously not necessarily the case. 47 nF is the closest preferred value to half of 100 nF, which designers seem to like for bypass capacitors.

Also, why would you use two capacitors in parallel? Lower ESR?

Yes, I'm guessing lower ESR, and possibly it's hard to get 100 nF at 500 V in a single, reasonably sized SMD component that works with their pick and place machine.

philsuth
Posts: 26
Joined: Fri Apr 03, 2020 9:29 am
Location: Perth, Western Australia

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

Sat Oct 09, 2021 7:05 am

I'm making progress on the slow road to proper reassembly. I'd hoped to solder a chip capacitor in place of the original destroyed one, but a couple of hours of widening the pit in the waffle board and attempting the job convinced me that it wasn't going to work - at least at my soldering skill level. There is just too much heatsinking to make reasonable joins to a surface mount component in the confined space available.

Instead I have acquired a 630V (brown) greencap through hole capacitor, and connected it on one side to the pad where the chip capacitor was removed, and on the other side to the base of the connector to the boost inductor - electrically equivalent but easier to get to . I've made good solid solder joints on each side and the combined capacitance is as expected. Here's what it looks like:
Image

After talking the photo I filled the pit with a capful of the two part silicone potting compound I'm going to be using on the top board - Chemtools PCT7000 - and after gently oven baking the module at 65C for 2.5 hours to cure it looks like this:
Image

Tomorrow I solder the top board back in place again, do a retest to ensure I've not broken anything, then repot the top board, cure, and perform final reassembly and test. That's if all goes to plan....

philsuth
Posts: 26
Joined: Fri Apr 03, 2020 9:29 am
Location: Perth, Western Australia

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

Sun Oct 10, 2021 6:59 am

This morning I soldered the module back together again, then put it back in the vehicle. I ran a charging test for about 5 minutes, just long enough to feel comfortable that I hadn't broken anything else. I then pulled the module out again, put the plastic wall back in place on the top board and secured it with a few drops of super glue, then repotted with the rest of the compound from yesterday. I gently warmed the module for 2.5 hours at 65C, and peeled off the little splashes and overflows easily afterwards. It looks almost as good as new.
Image
Reassembled afterwards, went out for a much anticipated drive, then recharged again. All went well - after a little over two months I finally have my iMIEV back in action.

Huge thanks to all who followed along, commented and made suggestions, and especially to those who did all of the earlier reverse engineering work on the charrgers. While this particular unit was a little different in form, practically it was very similar, and the job would have been far harder without all of that work.

kiev
Posts: 1704
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

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

Sun Oct 10, 2021 7:08 am

Bravo! Great work on getting it repaired.

Is that potting compound something that could be easily removed if necessary?
kiev = kenny's innovative electric vehicle

philsuth
Posts: 26
Joined: Fri Apr 03, 2020 9:29 am
Location: Perth, Western Australia

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

Sun Oct 10, 2021 7:25 am

kiev wrote:Bravo! Great work on getting it repaired.

Is that potting compound something that could be easily removed if necessary?


Thank you.
The potting compound is very similar to the original one used for the upper board, other than the colour of course. It hardens into a silicone rubber which can be dug out fairly easily. I was surprised how well it worked.

iOnico
Posts: 24
Joined: Wed May 19, 2021 8:47 am
Location: Karlsruhe, Germany

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

Sun Nov 14, 2021 7:03 am

Some months have gone by since my last post. This post should be (hopefully) the final resume of my repair, as the car is charging again! The news isn’t that new as, after the repair had been done, I have observed the car for quite a while to see if everything works reliably. Having had two setbacks in situations where I thought that I had fixed the issue made me become careful with announcing victory too early...

First setback was when I thought that I had only the "classical" snubber caps issue and after replacing them the car still wouldn’t want to charge. The second one was after a long troubleshooting on the control board and the discovery of many damaged ICs I finally completely replaced the control board by another one. It was not 100% identical, some components were not in the same order, even if it was the same chips. So, at this point I can’t say if the failure of the repair was due to overseen damage on the power board (seems to be the more likely explanation) or if it was due to incompatibility of the replacement control board (seems to be the less likely explanation).

So, my repair finally ended as an easy “plug & play” repair. Due to a lack of knowledge, experience, good soldering and testing equipment and a complicated damage scenario with damage on many ICs of the control board and probably also one or more undiscovered damage(s) on the power board, this turned out to be the most implementable solution for me: getting an identical OBC box form a scrap yard as a donor and exchanging the two boards. That worked... :D

After the repair the car was announcing a much higher range expectation than before. I thought that this could be somehow due to the fact that the 12V battery was weak before and that it was providing a bad reference voltage, but actually this explanation didn’t satisfy me. I got the correct explanation after some days, when the little turtle icon went on and I had to call a neighbour to tow me the last 3 km home: obviously the calibration of range expectation and state of charge (SOC) aren’t correct any more. When the turtle icon went on, the car was announcing 15 km of remaining range and 2 remaining bars on the SOC. I assume that this wrong calibration is due to disconnection of the main and the 12V battery during longer periods while the car was waiting to be repaired and that it will correct itself with time and charging/discharging cycles.

That’s it. I want to thank all the people that have contributed to gather the knowledge in this forum and especially those who actively helped me by answering my questions during my repair journey.

shuma89
Posts: 4
Joined: Mon Nov 15, 2021 4:47 am

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

Mon Nov 15, 2021 5:10 am

haloo from georgia.
my country is near from the russia.
we have some nissan leaf in owre country.
I have problem with obc onboard charger on nissan leaf 2011 year.
problem is that my home charger not charges vehicle. i have other home charger, it do same.

we have not good repairmans, one of them says thet onboard charger that is back in the car is bad, i changed it myself. vehicle warks good. but i want repair old OBC block.
if anyone can tell me, from what i bigin repairings. whare i can search problems in onboard charger?
i allready open the cover off.
Top (Control) Board seems very well. there is not eny problems that i can see.
please halp me to search the problem in this OBC block.

my english is not so good as I want, excuse me for this.

Sorry for my poor English.

kiev
Posts: 1704
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

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

Mon Nov 15, 2021 6:10 am

The miev and leaf OBC do have many of the same components. i would recommend that you post some high quality pictures of your boards over in the leaf forum, for example over in this thread with other repair activities, and i will give you some help over there:

https://mynissanleaf.com/viewtopic.php? ... 9&p=590974
kiev = kenny's innovative electric vehicle

shuma89
Posts: 4
Joined: Mon Nov 15, 2021 4:47 am

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

Mon Nov 15, 2021 9:47 am

kiev wrote:The miev and leaf OBC do have many of the same components. i would recommend that you post some high quality pictures of your boards over in the leaf forum, for example over in this thread with other repair activities, and i will give you some help over there:

https://mynissanleaf.com/viewtopic.php? ... 9&p=590974




I have registrated today on this forum, also on thet forum you write me.
If you can give me advice, i will be happy.
Thenk you for your answers.

Lic
Posts: 104
Joined: Mon Dec 28, 2015 2:11 pm
Location: Canada

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

Mon Nov 15, 2021 12:48 pm

I still have same problem 4,7Om resistor died again. It worked from last repair around 1.5 months. As I see in smart plug history, car was charging around 3 hours and on one moment power of charging went from 1.32kwt to 180 wt and after few minutes charging stopped. So I believe something happened with relay, it did disconnected and charging continued through resistors and one of resistors died. I don't understand why relay did disconnected but charging continued. I checked relay again- it looks fine, connects and disconnects without delays, without any increased resistance. Should I change relay anyway? What could be else wrong here?

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