electronpusher
Posts: 11
Joined: Sun Jun 25, 2017 3:11 am

Re: Car not charging,..DC/DC converter failure. not what we expected.

Tue Jun 12, 2018 2:03 am

Kiev: Does your car have DC quick charge, level 3 charge port?


Yes, it does have DC quick charge, and we are considering borrowing a CTEC CHAdeMO charger from someone here in Sydney, and seeing if we can put charge in that way. We will however still need to charge the 12V battery separately since it currently does not charge from the battery or 240V. This will give us plenty of electrons to get the car out to our new home.

We will probably import a DC/DC Converter from a wrecked car in Japan, and swap out the top board to see if that fixes it. If not, then we will probably sell parts or the whole car as is.

coulomb
Posts: 2
Joined: Sun Jun 10, 2018 8:32 pm

Re: Car not charging,..DC/DC converter failure. not what we expected.

Tue Jun 12, 2018 5:33 am

kiev wrote: Howdy Mike, welcome to the miev forum.

Hi. I may be starting an interest in iMievs, for a colleague.

I was thinking those blue caps were like the 2 Y caps of an EMI filter such as this: ... and it read: HR R 102k

Yes, that clinches it. Now I'm thinking that electronpusher's "resistors" may have been surface mount versions of those Y capacitors. They all look much the same when burned. Is this possible, @electronpusher ?

With the chargers seemingly so voltage agile, I can't see any reason for resistors in one model and capacitors in another. Maybe they changed the circuit, perhaps for reliability problems. So I agree that swapping the bottom board should be ok. Weird that the mains conditioning is on the DC-DC board though. I guess it's just where it fitted.

Edit: some more thoughts. It looks to me now that both the charger and the DC-DC are on the bottom board. That's why the mains goes there. The mains comes in on two orange wires (with active marked as black, the US convention, and strange to we Aussies where black usually means neutral), and the charger output (to the battery) goes out on the other two orange wires at the bottom of kiev's photos. There is a green there too (hopefully with a yellow stripe) that goes to ground/earth/chassis.

So the top board seems to be all control logic, plus half the mains conditioning: fuse, surge arrestor, X capacitor and bleed resistor (which doesn't seem to be visible under the potting, but you can see its symbol under the PCB), and three movistors (MOVs, Metal Oxide Varistors, which are voltage dependent resistors, basically more surge protection). The surge arrestor appears to be in series with two of the MOVs, one each to active and neutral. So actually, electronpusher, there is a fair bit of protection on the mains side. I'm moderately impressed. The potting seems to be to keep dust and grime (even though this box is probably sealed) from making paths for the higher voltage, and to keep high voltage parts and tracks away from fingers. It also has the effect of mildly frustrating repairers, but safety and longevity are obviously more important. Electronpusher, does your surge arrestor (designated "SA" on the top board) look as-new as does Kiev's?

Another thought: perhaps "soot from resistor" is actually arc flash from inside. I've seen this with Elcon chargers. Is that possible?
Last edited by coulomb on Tue Jun 12, 2018 6:42 am, edited 1 time in total.

kiev
Posts: 594
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: Car not charging,..DC/DC converter failure. not what we expected.

Tue Jun 12, 2018 6:18 am

It's a dual function box--it does both the dc/dc for the 12V, and the ac/dc for the pack charging.

Here's what i think we are looking at: the 3 big electrolytic caps and coil at the rear of the box (bottom edge of picture) are the rectified dc buss , the diode bridge and FETs for PFC are mounted to the water-cooled heatsink underneath the board, as are the PWM boost FETs, and the output cap and coils are toward the front (top edge of photo).

In the scorch picture, the fat shiny orange cable harness runs from this box to the pack terminals inside the motor inverter located to the right. So there is HV when the pack contactors are closed, either for charging or in READY drive mode.

i've posted some notes of my findings about these cars on my fat stacks and morning wood blogsite: http://fsamw.myevblog.com/i-miev-technical-stuff/
kiev = kenny's innovative electric vehicle

electronpusher
Posts: 11
Joined: Sun Jun 25, 2017 3:11 am

Re: Car not charging,..DC/DC converter failure. not what we expected.

Tue Jun 12, 2018 6:53 pm

coulomb: I was thinking those blue caps were like the 2 Y caps of an EMI filter such as this: ... and it read: HR R 102k

Yes, that clinches it. Now I'm thinking that electronpusher's "resistors" may have been surface mount versions of those Y capacitors. They all look much the same when burned. Is this possible, @electronpusher ?[/quote]

Quite possibly, won't be able to check that for a while though as it is all back together now so we can drive it out to our new home. Out there we intend to remove it again, and we'll clean up the soot from that area, and see if I can make out any markings on the remaining component.

I also agree that there would be no reason for them to be resistors, if other models have caps, so my assumption now is that they are resistors. It may be repairable yet.

The concern I have with protection on the mains side is that it is all contained in this one $4000AUD box, which if a surge does occur, they want to replace the whole thing. With an EVSE the cost is cheaper for replacement.

As with the soot, I guess it could be HV discharge, but the only thing it would have discharge to was the relay next to is, as there is not burn marks anywhere else. Kinda hard to say.

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