Another charger failure

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Active member
Sep 23, 2015
Apparently there are 1000s of posts on this topic, so I will try to be brief and to the point. (And wow, I am HUGELY grateful to @kiev and all the rest who have been so helpful to others on this!)

First and foremost, what I seek is any ideas for problems that might look like a charger failure but aren't. Like the member who got the usual "plug in, click, whoosh, blinky-blinky on the EVSE, and then a few seconds later another click and charging stops." But after he re-did his stereo power connection and replaced a fuse with the proper type, all went back to normal.

The reason is that, while I'm an ME with electronics experience, I don't have the skill or knowledge to hunt down all the electrical gremlins I've seen described here. Worse, I haven't the time. There is zero bandwidth for another project. (And this comes just as I was planning on upgrading to a road-trip-worthy EV, so the timing couldn't be worse.) If I can't get this back on the road fairly expeditiously, it has to be scrapped, or sold to some electro-capable soul who can do a repair. It's a perfectly wonderful car otherwise. I'm in the suburbs of Philadelphia, PA.

I considered the possibility of asking for a "goodwill" warranty replacement, but I'm a year past even the extended warranty and the TSB-19-54-016 I looked up that covers that seems to require the dreaded P0A09 code, which I don't seem to have. (See more below.)

CAR: Build date 12/2011, Model SE (aluminum wheels, no nav/cruise/CHAdeMO), Mileage is 43.5k

COURSE OF EVENTS: Left for an appointment in a hurry yesterday, noticed I was two bars down even though I had charged the night before, but I needed to get moving. I could get to my appointment and back if needed but it would be tight. Stopped to charge on the way home, got the start-whoosh-blinky-stop that is now all-too-familiar to many. Hypermiled home, on turtle for the last mile. Plugged in, same sequence. Also worth mentioning, about a year ago there was an unexplained turtle event on the road, followed by an EMU light during charging, all of which appeared to sort itself out. That brief thread can be found here:

Interestingly, after going below 0 Range Remaining (RR) on turtle mode, after I disconnected/reconnected the 12V battery I showed 3 bars and 9 RR yesterday, 10 RR today. (Maybe my deep discharge triggered a recalibration of the Guess-O-Meter?)

There are no dashboard alarms or fault indications. Everything seems to work fine. Car drives as normal, just won't charge. (All charging attempts are AC, no DC capability.)

DIAGNOSTICS: 12V battery is 4(?) years old but seemingly fine. Disconnected:12.91V. Connected, ignition off: 12.89V. Ignition on (nothing switched on but interior lights): 12.4V. Ignition on (with interior lights, seat heater, cabin heat and fan running): 12.02V. "Ready": 14.55V. Connected an old industrial charger to the 12V battery, set it at ~14.1V and made another attempt at plugging in the EVSE. Ran back to the voltmeter and saw it go up to 14.55V (DC-DC converter voltage), and when charging stopped in a few seconds the 12V battery was back at the 14.1V of the external charger. Seems to me the 12V battery is OK and the DC-DC converter works fine.

I had to stop using Cani0n after a phone upgrade because it won't stay paired to the dongle. I'm using CarScanner, which reads a long list of DTC codes, though none has a label that specifically references the charger (DC-DC converter, MCU, EV and other likely candidates). I had it read everything, and it only came back with "Dashboard/Meter#2: U1116" and BCM/ETACS#2: U1111" which I believe are inconsequential. How likely is it that there are pertinent codes that phone apps are unable to read?

All the sensors looked OK. Cell min and max was 3.78V and 3.83V. Two versions of SoC at 25.5% and 27%.

All the fuses under the dash and hood were checked for continuity. Some were squarish and looked more like relays (breakers?). I didn't check those. Or any of the many relays, which I couldn't figure out how to remove.

If it helps, I've included below a photo of the MDC/charger pair with all labels.

I'm out of ideas. Anything I missed or other suggestions? With all the activity surrounding this one failure, I would have thought someone more skilled and enterprising than me would set up an informal repair service by now. If that was available and I could be reasonably confident a basic remove/replace would be uneventful, I might consider doing that. If my charger is well and truly toasted, I'd be interested in offers for my broken car. It's in fine shape in every other way and I've loved it for 8 years now. It's white with blue trim. It would be a real shame to scrap it.

Photo of MCU/charger here:
Sorry to hear this @ctromley, and am surprised that your car lacks CHAdeMO capability- I thought all the 2012 cars with blue trim were SE Premiums with DCFC. At this point I'd be certainly popping the OBC lid to eyeball the boards in preparation for a chargerr swap. I just sent my last spare OBC to an off-forum Canadian who was denied a goodwill repair, but I've got too many balls in the air to get into the component repair or battery upgrade business.
You might keep your eyes on OfferUp and EVen the CoPart/IAAI auctions, as the salvage yards don't seem to be interested in these low-volume orphans. My last parts car cost under $1k, and it had a good chargerr!

But if you do scrap it- I've got dibs on them rims! :roll:
Howdy ct, sorry to hear of your trouble,

Since you figured out the 12V and DCDC is okay, then the fuse in the MCU is okay. So from your reported symptoms the issue is likely on the AC Input side rather than the HV DC Output side, which is good for repair possibility.

There are a handful of components in the AC Input section that we have seen fail over the years, and it is usually obvious due to their damaged appearance. Many of these have been repaired involving the white ceramic resistors or the AC filter capacitor. The root cause seems to be related to a failure to actuate the AC relay.

i can't prove it yet, but i suspect that there are some electrolytic capacitors on the OBC control board that have reached their end of life (typically 10 years for electrolytics). This causes the same symptoms that you reported, but there is no visible damage found in the OBC. Not been able to repair one of those yet.

I know that there are no guarantees, but what I'm hearing is that my repair is likely to be more straightforward than many of those I've seen by skipping through the monster thread on this. A few questions:

1. I noticed I hadn't done all the 'easy things to check' in your post #2 of the big thread. I can re-do the 12V battery sag test per the manual (headlights for 15 seconds) just to make sure. I have not checked any relays, because I didn't see a way to remove them from the underhood fuse block. I pulled hard enough to risk breakage, so I backed off. What's the secret?

2. It appears different versions of charger have the AC input stuff on either the top control board or the lower HV board. If mine are on the lower board, can that stuff be replaced without de-soldering the waffle plate? Others seem to have struggled with that, and my board re-work skills are limited.

3. Is it safe to assume that removing the safety plug under the seat kills all HV power everywhere? Or is it easier/better/simpler to just separate at the fat connectors in the two orange harnesses to the box? How long should I wait for caps to bleed down?

4. In the unlikely event that I'm able to locate a replacement charger, do all the various versions bolt in and plug in the same? (No car harness or peripheral component changes needed?) Or do I need to find the right type?
There seems to be about 3 versions of OBC, 2010-2011 which have multiple small Waffle Plates (call it Gen 0); 2012 which have a single large WP (Gen 1); and the later models 2013 on, which have no WP (Gen 2).

Some Gen 1 units have an external EMI filter on the AC Input mounted on the lid which has a couple of fuses inside.

Inside the OBC, the AC input travels thru a fuse or two plus some lightning protection and transient surge suppressors on one edge of the upper control board completely isolated from the digital control stuff at the other end of that board toward the flat ribbon cable.

The AC input is routed to the lower power board into the fenced area with the black potting, the AC relay, ceramic resistors, choke and cap; latest version here after some additional reference designator digging by a forum friend coulomb: link to Mike's update

re #3. Take out the safety plug if you want to, after disconnecting the 12V battery. With no 12V then the main contactors should be open and no HV at the terminals under the access cover in the MCU (next to the OBC in the rear "engine" compartment)

re 4. All the Gen 1 units will work; swapping to a Gen 2 is possible but requires some plumbing and wiring connector changes.

re 1. Don't worry about the relays if the car runs and drives. May take a special tool to remove relays.

re 2. Most folks have made repairs without removing the WP. It is quite a chore to successfully desolder all 72 joints of the WP.
OK, got some time to open up my charger and found one visible failure. I can't seem to get photos to show here no matter what hosting service I use, so please excuse the use of links.

First photo shows lid open (still connected by the high voltage wires going to the doghouse on top of the lid, see photo in first post). There is some evidence of heat on the lid, but that seems to be just the (originally clear?) PVC sheaths over the large wires bundled in the enclosure. The only components there seem to be big transformers with no visible damage. Photo here:

Second photo shows close-up of the potted area on the top board where others have had blown caps. Everything looks fine here:

Third photo, bottom board wide view, good news and bad news:

Fourth photo, close-up of bottom board potted area. Good news, my blue M&M caps look fine, as does the component next to them (another cap? EDIT: AC input relay /EDIT). But the big 2.2 μF cap on the other side of the choke has puked all over the ceramic resistor next to it:


I assume at a minimum I need a new 2.2 μF cap, very likely the resistor next to it, and the other resistor next to that just to be safe while I'm in that area. Since this is such a well-established weakness, are there components that are more robust with the same footprint/pinout?

And since I've gone this far, is it prudent to replace the M&Ms, that bigger rectangular component [AC input relay] next to them, and the bigger caps potted on the top board? Perhaps with more robust components? (I'd rather not do all this again in another year or so.) I can dig through the main thread to get values for those components, but will it be abundantly clear to this noob that a) I'm looking at the right diagram for my charger, and b) peripheral-but-critical info like voltage capacity, temp ratings, etc?

Also, any links to tips and tricks for removing the existing potting, clean away any residue, and a recommendation for goo to re-pot it?

As a reminder, I'm a decent (though inexperienced) technician, but my background is as an ME with electronics packaging experience. I am an electrical dolt otherwise. Responses cannot be dumbed down too much. I appreciate everyone's indulgence in engaging me on this thread, because frankly the main charger repair thread is a forest far too deep for me to navigate intelligently.
The black potting is very soft and easily removed with a wooden spudger or bamboo chop stick wittled to a flat screwdriver blade. i don't use metal because there are traces underneath that could be damaged.

i couldn't access any of your pictures; they must be set as private and google won't let them be viewed without some sort of login.

If the ceramic resistors measure ok, then i wouldn't try to replace them. Those parts are hard to find.

Sometimes the 2.2uF blows; many folks have replaced it and soldered it in from above since it is so hard to remove the waffle plate. Some have reached in between and soldered in the cap, since it is located toward an edge (long skinny soldering iron).