kiev
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Under the Cover--an Inside Look at a 2018 On-Board Charger (OBC2)

Fri Sep 20, 2019 6:40 pm

i just got kiev back today with the new style On-Board Chargger, calling it OBC2. It has a date code of 2018.05.17 and is quite different from the 2012 version.

Overview
Image

Top Board
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AC Input (no more doghouse)
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Boost Transformer
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HV Output
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Current Sense Resistor and Fat Blue Caps (snubbers?)
Image

These will be much easier to repair-- no Waffle Plate™, all the high power diodes and transistors can be seen along the bottom board edges.
kiev = kenny's innovative electric vehicle

coulomb
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Re: Under the Cover--an Inside Look at a 2018 On-Board Charger (OBC2)

Sat Sep 21, 2019 6:18 am

kiev wrote:i just got kiev back today with the new style On-Board Chargger

So naturally, the first thing you did was to rip the covers off :D

These will be much easier to repair-- no Waffle Plate™, all the high power diodes and transistors can be seen along the bottom board edges.

This is indeed great news. Still made by Nichicon; I wonder what prompted the change of design.

Thanks for the photos.

JoeS
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Re: Under the Cover--an Inside Look at a 2018 On-Board Charger (OBC2)

Sat Sep 21, 2019 7:49 am

kiev, thank you very much for the photos of the new OBC/dc-dc innards. Any comments whether this new design has improved the component thermal management? I was always disturbed that the case of this module becomes hot despite the the liquid cooling system.
coulomb wrote:This is indeed great news. Still made by Nichicon; I wonder what prompted the change of design.
What's interesting is that they went to all the trouble to make this new design fully interchangeable with our 'older' 2012 configuration. As evidenced by the number of failures on this forum, Nichicon/Mitsubishi must be experiencing an unusually-high failure rate, prompting them to redesign this unit rather than continue producing the original configuration - this is very good news, IMO. Nice of Mitsu to (rather belatedly) step up to the bar and extend the warranty.
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
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Don
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Re: Under the Cover--an Inside Look at a 2018 On-Board Charger (OBC2)

Sat Sep 21, 2019 4:42 pm

My concern is . . . . if your original doesn't fail in the first 10 years, you're out of luck. If it fails later, I'll bet this new one is $4K if you have to BUY one from Mitsu . . . . and that would likely mean trashing your 11 or 12 year old car, regardless of the low miles you might have on it

Don
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kiev
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Location: The Heart o' Dixie
Contact: Website

Re: Under the Cover--an Inside Look at a 2018 On-Board Charger (OBC2)

Sat Sep 21, 2019 6:56 pm

i think if you were to proactively replace the 20A MCU fuse as a maintenance item, then your old OBC would work just fine for a good long time.

i'm still doing research on the failure modes. i'm struggling to understand how the MCU fuse could experience an over-current condition and blow, without taking out the little 20A fuses on the input of the DCDC or the output of the OBC.

Also i don't understand how shorting by the snubbers caps would cause the MCU fuse to experience an over-current. If the snubber caps were to fail shorted, then the rectifier diodes in the waffle plate would likely fail and repairs would not be possible. Yet several have been repaired by replacing just the caps and fuse.

But i can see how an interruption of the OBC output current outside of the OBC, such as a mechanical break in the MCU fuse, could create an inductive over-voltage condition on the output side of the boost transformers that could cause the snubber caps to split.


Another weak link might be the AC input relay contacts; but i see that they have the same relay in the new box, so there will likely be a few failures on the AC side such as we have seen on the old box.
kiev = kenny's innovative electric vehicle

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