The Troubleshooting and Repair for On-board Charger (OBC) Thread

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Yes it will work, may require some routing of the coolant lines or twisting of the coolant fitting (swivel fitting).

$500 for a waffle plate does seem high when a complete unit is the same price. But It is a lot of work to desolder a waffle plate, and you have destroyed a OBC to get it.

That ebay seller is including my drawing of the waffle plate schematic with his auction...nice rip off the forum :LOL:
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Alas, he never answered your (kiev's) question about what magic chemicals or techniques were used.
I just saw my name drop above. The epoxy removal info is actually there in the following few posts. Alas no magic was found, so I had to fall back on elbow grease. I used a Dremel grinder initially, then switched to Kenny's suggestion of spot heating with a hot soldering iron and scraping - using the soldering bit itself along with some sharp dental probes. USe plenty of ventilation for all this work to keep breathing fumes to a minimum, The heating proved quite successful in making the epoxy easier to scrape away, but it was by no means easy.
Thanks Phil for your summary, and sorry for the false accusation 🤭.
It seems that the links from the index do work OK;
Sigh. I was wrong about that. However, the links can be repaired.

Consider a link like number 21: . This needs to be changed to . When you get there, the search bar will show, which presumably will be faster for the server to find, so use that address if you're posting a link. So just copy the last 5 digits of the link to the clipboard, paste in the constant "[/URL]" without the quotes, ^V to paste the post number, and you have an initial URL.

Kiev, it seems that 30 days of editability is all we're going to get from this forum, so we need a new forum that can be edited forever, to link into the various posts throughout this valuable thread. I think that the posts themselves belong here, no need to migrate the whole thing over. Might I suggest making a post in the AEVA; that way I can also make edits since I'm a moderator there. But maybe you hate that idea 🤢, and would prefer any other forum for that reason. Hopefully Google will learn to prefer the new URL over time (though it's notorious for remembering out-of-date URLs because they were the most commonly used). If you still have some editability, you could add a link to the new index to the existing old index, while you still have the power to edit.
Great idea, i have created an id over there and posted in your thread. Or did you want to start a new thread on AEVA?

i couldn't find the picture or post, but someone used some ?dental burrs? or ?carbide burrs? and was able to hog out the epoxy in a big way.

It seems that the epoxy gets hot in a hurry when drilling and seems to draw the carbon out of the steel and dulls the cutting edge.
Great idea, i have created an id over there and posted in your thread. Or did you want to start a new thread on AEVA?
I wanted a new thread, but that's OK, I used my moderator powers to make it so.

I've made a tentative start, but there are a lot of links to add and so on. We use PHPBB over at AEVA, the same as the old forum here, so you should find it familiar to use. You may care to reply to the thread with a few placeholders. I can shuffle posts around to make them the second and third (etc) posts, so that way you will be author of those posts and will be able to edit them.

The Troubleshooting and Repair for On Board Charger (OBC) Index.

For now, I'm just trying to replicate the existing index posts; we can chop out uninteresting ones, add more, move things around etc as desired later. Please don't edit anything for a while, as I intend to make a lot of edits tonight my time (GMT+10), and it will be easy to step on each other's toes and lose work. Later we can just edit whenever we feel like it and the chances of clashes should be very low.

Thanks for agreeing to this; hopefully it will be a good resource. You may wish to link to the new index from this thread's first post now; I don't know when your 30 days (?) will run out.

Edit: I've now done the first post; basically I just added all the links to posts and images. I'll wait for your placeholders (please add 4 or more) before I'll start on the next ones. That way you'll be able to edit them.

My latest way of fixing URLs: copy the link, paste into the address bar of a new tab. Check if the post number is correct. If not, edit the address (which has probably changed already but is not quite right yet) from /#p12345 at the end to /post-12345 . It should come good, and the address may have changed again. So take the address from the address bar, this is the URL to use for posts.
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If you ever get a repair where the auxiliary battery was wired in reverse polarity, apart from a lot of obvious fuses that need to be replaced, the DC-DC has a 125 A or 175 A (2019 model) fuse in the bottom plenium. This post has a photo. Reverse polarity lets the output diodes conduct with only the transformer secondary to minimise the current, enough to blow that fuse. These fuses are easy to find, although we had to grind one side of the replacement as the lug was too wide to fit properly. Remarkably, the dual 100 A Schottky diode survived the abuse! The 2019 model has a weird printed circuit board that made it look like the diode was faulty when in-circuit. It was a pest to remove the diode, so test in place with the connections removed before attempting to take it out. Maybe the earlier models will be easier to work with.

Here is the 2019 diode and nearby parts. The fuse is unfortunately not visible in the photo. The weird board with huge ceramic resistors is at the bottom of the photo. It's normally screwed in where it obscures the diode connections. The diode is under the four screws (the bottom right one is highlighted in red). Diode part number is STPS200170TV1Y: Schottky dual 170 V 100 A (average, each, so I think it could pass 200 A between the two diodes). I believe that the earlier models (with the 125 A fuse) have different dual diode.


Edit: The older models seem to use a P2H80QH20 part, 200 V 80 A.
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Kiev, I'm thinking that the index post as is now might be enough. I was going to pull in the part 2 and part 3, but they don't look like they'll need any editing in future. We can always copy them later, there are two placeholders waiting for them.

Feel free to edit it now, rearrange things, etc.
Which thermal paste do you guys recommend to put between the waffle plate and the charger enclosure? I purchased 8327GL6-25ML from MG Chemicals but it turns out it's very thick and difficult to spread out evenly. I think it would be best to use something that is a bit more runny
Would someone know the value of the shunt located between pins 15 and 16 in the waffle board? I'm measuring 2.94mOhm (26.5mV with 9A). 294 is a standard number/decade for 1% resistors, but I want to make sure. Thanks!
8327GL6-25ML from MG Chemicals but it turns out it's very thick and difficult to spread out evenly.
That would be as good as anything else if it could be spread thinly.

The base heatsink surface seems to be milled to an almost mirror finish, but the waffle is just a stamped plate.

The best thermal path is a metal-to-metal contact and the paste just fills in the microscopic grooves and gaps to displace all the air.

My approach would be to butter each surface separately and scrape off the excess with a straight-edge to fill the gaps and leave metal exposed.
i've never seen it since its buried in the epoxy, but i would guess it might be a 3mR resistor.

How accurate was your measurement of the 9 Amps (or how did you even measure the current in that circuit)?
To measure, I placed a 9 A (my meter goes to 10A, did not want to blow the fuse) constant current source between the N pins (above 15-16) and the emitter of one of the bottom IGBT (per the x-ray these are the two ends of the shunt), then measured the voltage between 15 and 16. Took three different measurements switching the meters and got same readings. Darn epoxy!
That's about 1/4 Watt thru the resistor--hope it is sized to handle that much power without damage, otherwise it will be some digging into the "darn epoxy"
A quick question: May the OBC from a 2014 be installed on a 2012? Possibly found one and might buy if yes
The seller shipped me an inverter instead of a charger ($400 US anyone?). Found a 2016 charger, which this time I will go check myself before I buy it. May a 2016 charger be installed in a 2012?
Thank you Kenny for confirming. I was unsure if the 2014 and 2016 were the same charger. Now I have a 2014 inverter for spare/sale.
Hello friends. Thanks to the thread and all of you, I figured out how to fix the charging problem that I had as well. I replaced capacitors C121 and C122, and fuse F102. I have the following questions. I couldn't find a fuse for DC 420V 20A anywhere, so I soldered for AC 500V 20A. Is this OK? Also, does the space around the capacitors need to be re-filled with some heat conducting material, e.g. silicone? Thanks a lot in advance for your answers.viber_изображение_2024-02-14_16-10-15-253.jpg
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Was that fuse F102 actually blown?

If so then that is very unusual as it is always the 20 A fuse in the MCU which gets blown, and this has been a puzzle to me.

i like to use liquid electrical tape product (sold at home depot) to fill in around those capacitors. The black rubber is more for vibration control than thermal.

It looks like your snubbers exploded quite energetically and flung molten metal, so clean up the residue on the bottom of the control board and inspect carefully for shorted pins and traces and any other damage that may have been created by hot molten metal.
Thanks again.
Yes, F102 was burnt. Yesterday I installed the board, everything is fine, the car started charging. Then I decided to check the fuse in the other box you mentioned and this is what I came across to my surprise. Someone had tried to "fix" the fuse by soldering a thick piece of wire to the sockets. I disassembled it, cut the plugs, and soldered them to the fuse I had available.
Otherwise, I filled the space around the capacitors with dental silicone for impressions.