coulomb
Posts: 134
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Leaf Number: 200445
Location: Brisbane, Australia

Re: Onboard charger capacitors failed

Tue Oct 06, 2020 4:31 pm

wxmatt wrote:
Tue Oct 06, 2020 3:52 pm
Upon further review, my piece looks exactly like a part of this "Waffle Plate."
Yes, as my crossed post indicated.
I'm guessing it's pretty likely that I'll be buying a new onboard charger.
The Mitsubishi people found that a brand new OBC cost of the order of US$4000, and that's for a 3.6 kW model. They found it far better value to find a wrecked OBC and install that. With the iMiEV, there is no VIN locking of the OBC; that may not be the case for Leafs.

There is a common fault with the Mitsubishi version of this charrger, where two small capacitors tend to blow up (literally shatter into pieces). If you do use an OBC from a wreck, it may be worth replacing the equivalent of those capacitors before installing. Use higher rated (e.g. 4 kV) parts. Mitsubishi USA actually extended the warranty on the OBC to something like 10 years, so several of them have been replaced under warranty. It may not be wise waiting for Nissan USA to follow suit :o
2012 Leaf with new battery May 2019. New to me June 2019.

nlspace
Posts: 323
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Delivery Date: 06 Jun 2017

Re: Onboard charger capacitors failed

Wed Oct 07, 2020 7:13 am

There are 5 metal standoffs made from hex stock--these are threaded on the end and used as hold-downs for the big board and go thru the mounting holes of the waffle plate. As coulomb mentioned they have a sequence of circled numbers, start at 1 and remove the screw or the standoff and follow the arrows (should be 11 fasteners to remove). The white plastic faston covers have a release mechanism for the locking fastons--slide the plastic up the wire to release the tab and they will easily come off, pulling on the wire and they will fight you.

This is only the second failure i have ever seen or heard about of some component in the plate and would be very interested to find out what failed. i spent a lot of time tracing the waffle plate circuits and have a schematic that can be used to check the diode drop voltages inside, but yours has definitely blown the epoxy right off.

The good thing about the Laef OBC board is that all the components for the PFC circuit and the secondary LV supplies are mounted on the top surface--nothing on the bottom side which is not reachable without desoldering the 72 joints to the waffle plate. Also no little blue snubber caps.

Good luck and let us know what you find,
kenny

wxmatt
Posts: 20
Joined: Sun Sep 27, 2020 3:34 pm
Delivery Date: 14 Nov 2014
Leaf Number: 023861

Re: Onboard charger capacitors failed

Wed Oct 07, 2020 10:20 am

Thank you, again to everyone who has responded and given their input. 🙏🏻

I wasn’t able to see much, because accurately de-soldering 72 pins is a little beyond what I have time for today (or beyond my expertise, if I'm honest), but I was able to detect the location of one component that failed.


Image
I found more pieces of epoxy that look to be part of components… Five total.


Image
I don’t know if it’s obvious on this picture but it’s a little more obvious when I look at it, but I think the component that’s in the lower left-hand corner is at least one of the componets that has been separated from the waffle plate.


Image
Relative to the board on top, it would be the lower left-hand quadrant, assuming you were looking at the charger as it would vertically be mounted in the car.


Image
Referencing this picture which was posted in a report from Oak Ridge national laboratory, I have circled the one componet I solidly can see the scar from. https://info.ornl.gov/sites/publicatio ... b46377.pdf


As far as repairing is concerned, I have located a used 2011 charger with the part number 296A0-3NA0A. I know that the 3NA8A has superceeded all previous models, including my current, failed 3NA5A. I don’t doubt that I could probably swap in this used charger, which believe it or not comes with a six month warranty from the shop who pulled the part, but long-term, if newer revisions have solved this sort of problem, or others, I would rather go with the new part at twice the cost. My wife and I currently live only 6 miles from our work, and within the year will be moving within 1 mile of work, so as long as the other components holdup, we could use this for a commuting vehicle for (pretty much) ever.

Thoughts?
2012 LEAF (White) - Purchased in 11/14
2010 Rogue (Black)
1987 BMW 325i (Red)

LeftieBiker
Moderator
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Re: Onboard charger capacitors failed

Wed Oct 07, 2020 2:05 pm

In the upper left corner is a component that appears to be the twin of the one I mentioned a few posts earlier. (It says L201A near it.) It appears to have three connections. Two of them have plastic insulation shaped onto them. The third is bare, in a way that suggests to me that it had plastic on it but it broke or melted off.

Image
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nlspace
Posts: 323
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Re: Onboard charger capacitors failed

Wed Oct 07, 2020 6:25 pm

Good job wxmatt, you have done an excellent job of sleuthing out the circuit board. Those 5 pieces that came off the waffle plate are from the PFC Boost section in the left lower quad, 3 FETs and 2 diodes. They are controlled by IC312.

i would guess that something caused the PFC to stop chopping and turn hard on, and the direct current thru the FETs just blew them off the board taking the diodes with them.

It takes a fairly powerful desoldering station to remove the plate. The part number is on a tag on the edge if you find one that you want to swap out, but i would guess the root cause is from a component on the board rather than the plate, so i wouldn't reuse it without finding the culprit.

wxmatt
Posts: 20
Joined: Sun Sep 27, 2020 3:34 pm
Delivery Date: 14 Nov 2014
Leaf Number: 023861

Re: Onboard charger capacitors failed

Wed Oct 07, 2020 9:18 pm

LeftieBiker wrote:
Wed Oct 07, 2020 2:05 pm
In the upper left corner is a component that appears to be the twin of the one I mentioned a few posts earlier. (It says L201A near it.) It appears to have three connections. Two of them have plastic insulation shaped onto them. The third is bare, in a way that suggests to me that it had plastic on it but it broke or melted off.
I hadn’t noticed it until you pointed it out, but on the side of that component, something looks to be fractured, and it almost looks like where you see R108, there is a little soot, as though it burst out that direction.
Image
2012 LEAF (White) - Purchased in 11/14
2010 Rogue (Black)
1987 BMW 325i (Red)

Lothsahn
Posts: 658
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Leaf Number: 007797

Re: Onboard charger capacitors failed

Thu Oct 08, 2020 6:35 am

nlspace wrote:
Wed Oct 07, 2020 6:25 pm
Good job wxmatt, you have done an excellent job of sleuthing out the circuit board. Those 5 pieces that came off the waffle plate are from the PFC Boost section in the left lower quad, 3 FETs and 2 diodes. They are controlled by IC312.

i would guess that something caused the PFC to stop chopping and turn hard on, and the direct current thru the FETs just blew them off the board taking the diodes with them.

It takes a fairly powerful desoldering station to remove the plate. The part number is on a tag on the edge if you find one that you want to swap out, but i would guess the root cause is from a component on the board rather than the plate, so i wouldn't reuse it without finding the culprit.
Also keep in mind that GE Wattstation EVSE's can fry the OBC due to high inrush current. If you have a GE Wattstation, throw it in the trash and get an EVSE before you blow your next charger. More info:
viewtopic.php?t=7996&start=10
2011 Silver SV, purchased 2018, lives in Missouri (previously in CA)
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Battery swap 2019/04/24 (87% SOH, 12 bar)

nlspace
Posts: 323
Joined: Mon Jun 05, 2017 10:21 pm
Delivery Date: 06 Jun 2017

wxmatt's OBC failure [blown PFC Boost section]

Thu Oct 08, 2020 7:22 am

Good catch to find that blown diode next to the capacitor. That gray material is an RTV staking compound to hold the cap to the board and reduce vibration.

The diode is inline on the HV(+) side to bypass the big PFC inductor coil (orange wires that attach to the board at the L201A and L201B faston tabs) and attach to the (+) of the big black 2700 uF capacitor that attaches to the Red and Black faston tabs.

The four 100k resistors in series comprise a bleed-down circuit for the big cap.

Does your big L201 inductor have continuity or might it be blown also?

Is the big 2700uF capacitor okay or might it be shorted?

Image

wxmatt
Posts: 20
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Re: wxmatt's OBC failure [blown PFC Boost section]

Thu Oct 08, 2020 10:09 am

nlspace wrote:
Thu Oct 08, 2020 7:22 am

(1) Does your big L201 inductor have continuity or might it be blown also?

(2) Is the big 2700uF capacitor okay or might it be shorted?
1) I believe that the L201 inductor could be blown because I got a continuity reading of infinity when measuring it from the pins below the board.

2) I got a reading of near zero ohms on the large black capacitor, so (the non-electrical engineer in me believes that) it looks to be shorted.


I just purchased a used charger from an early 2011 LEAF off of eBay that I plan to put in the car, but I’m still very interested to see what all blew up in this one so that I can feel confident that there wasn’t something else on my end that caused the issue.

Lothsahn wrote:
Thu Oct 08, 2020 6:35 am
Also keep in mind that GE Wattstation EVSE's can fry the OBC due to high inrush current.
My EVSE is an early model JuiceBox (15kw/60A circa 2014). Dumbly, my power cord ran under my garage door and for a number of years I didn’t have a block to protect it until about a year ago. I do have some concern that this could’ve contributed to the problem, but that’s purely speculation.
2012 LEAF (White) - Purchased in 11/14
2010 Rogue (Black)
1987 BMW 325i (Red)

nlspace
Posts: 323
Joined: Mon Jun 05, 2017 10:21 pm
Delivery Date: 06 Jun 2017

Re: wxmatt's OBC failure [blown PFC Boost section]

Thu Oct 08, 2020 10:39 am

wxmatt wrote:
Thu Oct 08, 2020 10:09 am

1) I believe that the L201 inductor could be blown because I got a continuity reading of infinity when measuring it from the pins below the board.

2) I got a reading of near zero ohms on the large black capacitor, so (the non-electrical engineer in me believes that) it looks to be shorted.


I just purchased a used charger from an early 2011 LEAF off of eBay that I plan to put in the car, but I’m still very interested to see what all blew up in this one so that I can feel confident that there wasn’t something else on my end that caused the issue.

My EVSE is an early model JuiceBox (15kw/60A circa 2014). Dumbly, my power cord ran under my garage door and for a number of years I didn’t have a block to protect it until about a year ago. I do have some concern that this could’ve contributed to the problem, but that’s purely speculation.
Measure for continuity between the two orange wires leading to the inductor. It should read a very low, close to zero Ohms if okay.

Measure the capacitor between the red and black wires. If it reads close to zero ohms then it is shorted. A shorted capacitor could cause the damage you have found so far. i would expect to see some evidence such as the vent plug would be blown out or bulging if it failed over time. For a sudden overvoltage punch-thru it might look normal externally, but would be shorted internally.

It seems that if the EVSE voltage was too high then i would expect something upstream would have been taken out. A lightning strike or sudden loss of power during charging could cause damage in the OBC, there are protection circuits but everything has limits.

There are 3 fuses on that board that need to be checked for continuity also. F101, 102, 103.

Measure for resistance between the solder junctions labelled "8" and "7" on the seventh row down on the left hand side.

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