MCU 20A 450VDC fuse investigation

[jray3]

I was wrong when I initially thought the LEAF ignored the J1772 plug's push-button. It does indeed immediately and electronically (i.e. safely) ramp the charge current down to zero when the button is pressed. It's just that there is absolutely no indication that anything has changed; the blue LEDs stay the same, there is no beep or anything else to suggest that the current has stopped. As soon as you let go of the button, the current ramps back up to normal.

Hi Coulomb, I'm finding that the proximity switch does indeed do nothing on early LEAFs. On both of the 2011's that I've worked on with multiple EVSE, they never respond to the button push, and only break current when the shorter proximity pin comes out. Pull the plug very slowly, and you'll hear the EVSE contactor open up, but yank it fast, and there will be a little arc as you unplug. The i-MiEV responds quite nicely to the proximity switch.

 

[coulomb]

On both of the 2011's that I've worked on with multiple EVSE, they never respond to the button push, and only break current when the shorter proximity pin comes out. Pull the plug very slowly, and you'll hear the EVSE contactor open up, but yank it fast, and there will be a little arc as you unplug. The i-MiEV responds quite nicely to the proximity switch.

The EVSE contactor coming off is different to ramping the charge current down to zero quickly. I actually prefer the Leaf's method which somehow doesn't cause the EVSE contactor to disconnect. It means I can use the button on my adjustable current EVSE to change the current; when changing to lower currents, I have to cycle all the way through 16 A, wrap back to 6 A, then continue up to the desired current. I prefer not to yank 16 A out of my home energy system unless the sun is really strong.

However, that doesn't explain the arc that you observe; maybe the behaviour is different between 2011 and 2012 Leaf models (they are otherwise very similar). Or maybe the fast yank doesn't allow enough time for the charge current to ramp all the way to zero before the AC power pins disconnect.

Can you test with the EVSE plugged in via a power meter, or use LeafSpy to check the charge current?

 

[Adoepner]

Seeing as my 2012 is now out of warranty, I ordered a 0HEV030.ZXISO from mouser.ca to replace my MCU fuse immediately. Interestingly, the 0HEV020.ZXISO now has a minimum order quantity of 1, however the item remains non-stocked. I ordered a 0HEV020.ZXISO as well, and should get it in a few months and will swap it for the 0HEV030.ZXISO when it arrives.

Thanks all for the research posted here on this subject.

Andrew

 

[JoeS]

Seeing as my 2012 is now out of warranty, I ordered a 0HEV030.ZXISO from mouser.ca to replace my MCU fuse immediately...

Good for you! I had planned on doing the same but forgot and my OBC failed six weeks after the warranty expired. Hope the fuse replacement does indeed preclude the OBC failure - situation whereby "it can't hurt, might help". Ordering a fuse myself, belatedly ...

 

[Phximiev]

Any updates on the dissection of older fuses?

 

[Adoepner]

I will happily volunteer my 10-year old unblown OEM fuse for dissection.

Andrew

 

[Phximiev]

From one whom is considering the replacement of the fuse, how did the replacement fuses work out?

Have you looked at the replacements to see if there is less or no vibration damage?

Why a 40 amp fuse or 25 or 30 when 20 is used originally?

Thanks.