Quixotix wrote: I"m struggling with the terminology in this thread -- vertical pcb (I don't see one),
Your charrger doesn't have one. Some (roughly half?) of the chargers have a vertical PCB with surface mount capcitors on it instead of the two through-hole capacitors.
That's just the potted area walled off with plastic. Your burned capacitor is inside one, but there are others on other PCBs.
Anyway, I'm attaching 2 pictures (I hope).
I can only see the first one, and only on my phone. If it's hosted on something like Google Drive, you need to change the sharing settings so that everyone can see it. [ Edit: I can see them both now, thanks! ]
I think that's a capacitor that's completely burned up. Am I right?
Yes, that's badly burned (based on the first photo only).
Assuming it is, does someone know what size it is? Maybe it's the same size as the one next to it, but with the potting I can't read that one either.
The two are the same. They are 1 nF (1000 pF) 3150 V capacitors, as specified in this post
: Murata DEHR33F102Kppp . [ Edit: the "ppp" might actually be three special characters that aren't rendering well, but in my PDF reader, these characters show up as empty boxes but match "ppp" in a search. ]
Whether they should be replaced with something "stronger" is debatable, but you are unlikely to find a higher DC voltage rating.
I'm thinking I will: 1) carefully mill out a pocket where the burnt part is (milling is easy), 2) desolder and remove the heat sink assembly (what I pain) so I can get to the pins for the capacitor, 3) solder a new capacitor into the original position, 4) re-solder the heat sink assembly on.
I would be careful with milling. You don't want to touch the PCB tracks. Others don't seem to have had much trouble removing the potting material with simple tools (perhaps a screwdriver or wooden chopstick).
If you're very lucky, you might be able to leave some pigtail exposed, and solder quickly to the pigtail, so you don't have to desolder the many connections to the Waffle Plate™. You really need a proper desoldering station to remove that plate. Be quick, so that you don't melt the solder under the board. However, it might also be possible to completely remove the capacitors from above, and re-solder them all from above as well, again avoiding removing the Waffle Plate.
Should I replace the other capacitor next to it?
I think that would be a good idea. It is in parallel with the other one, so it has seen exactly the same voltage spikes as the burned one.
(or any other components)
We still haven't found the Root Cause. So it's possible that eventually we'll know what else to replace. But unfortunately, we're not there yet. One thing we're suspicious of is a too-small or too-old auxiliary battery. There are also suspicions about the pre-charge relay. But the relay definitely can't be replaced without taking off the Waffle Plate.
Are there likely any small components under the potting that are within a mm or so of the burnt capacitor? I'd like to avoid cutting off any components with my mill other than the burnt one.
I don't believe that there are.
Should I re-pot the new component?
That would be a good idea. Cars are a high vibration environment, so the leaded capacitors could use some mechanical constraining. But it's also good to keep dust and grime away from the high voltage DC elements like those capacitors. It doesn't have to be the exact same material; I'd use neutral cure silicone. Neutral cure is definitely required, as acid-cure silicone will conduct electricity. Silicone has excellent insulating qualities. If you use some other material, make sure it is designed for electrical work (silicone generally is not), or is known to be a good insulator. I find it hard to source suitable potting material.