kiev
Posts: 759
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Location: The Heart o' Dixie
Contact: Website

Re: And now my I will not charge!!

Tue Jul 10, 2018 6:55 pm

There may be other damage also, so check the capacitors while the board is out.

i don't recognize the connector, there may be a clamshell cover. Jay (jray3) just recently swapped one out so he will likely know how.
kiev = kenny's innovative electric vehicle

jray3
Posts: 1541
Joined: Tue Dec 06, 2011 1:05 am
Location: Tacoma area, WA
Contact: Website

Re: And now my I will not charge!!

Wed Jul 11, 2018 3:33 pm

1pk wrote:I’ve found someone in my local area who can replace the resistor so I’m removing the inverter at the moment.

Can someone tell me the secret to this connector? Where is the release mechanism?

https://imgur.com/a/P9mZyxe

Thanks

Yes, I wrestled with that one too, but there is a release tab on the skinny side of the female connector.
2012 i-SE "MR BEAN" 91,000 miles
2000 Mazda Miata EV, 78 kW, 17 kWh
1983 Grumman Kurbwatt EV,170 kW, 32 kWh
1983 Mazda RX-7 EV 43 kW 10 kWh
1971 "Karmann Eclectric" EV 240 kW 19 kWh
1965 Karmann Ghia Cabriolet

1pk
Posts: 68
Joined: Thu Jul 10, 2014 7:34 am
Location: Chemainus, BC

Re: And now my I will not charge!!

Wed Jul 11, 2018 10:46 pm

I did figure it out eventually and the inverter is now at a local shop for repair. The owner didn’t seem too confident about removing the bottom board from the box. I’ve sent him a link to this thread for reference so if anyone has any additional info that could be helpful please post it here.

Kiev, have you had a look at Jrays inverter yet? Curious to see if the board is soldered or just screwed down.

I spent money on gas today. I didn’t like that much

jray3
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Joined: Tue Dec 06, 2011 1:05 am
Location: Tacoma area, WA
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Re: And now my I will not charge!!

Wed Jul 11, 2018 11:02 pm

1pk wrote:Kiev, have you had a look at Jrays inverter yet?

I finally shipped the the old unit yesterday, so Kiev is at least a week out from rendering any verdicts. IIRC, the lower board was screwed in place. Those Phillips screws are quite soft, btw- had me wanting a small impact driver.
2012 i-SE "MR BEAN" 91,000 miles
2000 Mazda Miata EV, 78 kW, 17 kWh
1983 Grumman Kurbwatt EV,170 kW, 32 kWh
1983 Mazda RX-7 EV 43 kW 10 kWh
1971 "Karmann Eclectric" EV 240 kW 19 kWh
1965 Karmann Ghia Cabriolet

1pk
Posts: 68
Joined: Thu Jul 10, 2014 7:34 am
Location: Chemainus, BC

Re: And now my I will not charge!!

Thu Jul 12, 2018 7:13 am

So did you remove the bottom board? If it is held only with screws then any repair job will be much simpler.

kiev
Posts: 759
Joined: Sun May 03, 2015 7:15 am
Location: The Heart o' Dixie
Contact: Website

Re: And now my I will not charge!!

Sun Jul 15, 2018 5:52 am

@1pk,

i was wrong about the solder joints. Skylogger over in Western Australia has removed the board and the power devices came out with it--no need to desolder to remove the board.
kiev = kenny's innovative electric vehicle

1pk
Posts: 68
Joined: Thu Jul 10, 2014 7:34 am
Location: Chemainus, BC

Re: And now my I will not charge!!

Tue Jul 17, 2018 4:50 pm

I just heard from the electronic repair guy who is working on my inverter

Here is the body of his email:

Have managed to remove the top Printed Circuit Board. Closer inspection indicates that both Resistors are Cracked and the one that is discoloured has been overheated by excessive current. I have little hope that just replacing it will correct the problem. Something else must be Shorted. The resistor still needs to be removed in order to determine its value.

There is a massive heat sink on the underside of the board. It has 56 points of soldered connections thru the board.
This must be removed to gain access to the Resistor solder joints.

I have researched all part numbers that are on the board to see if it is available = no results.
Next step is to unsolder all 56 points & remove the heatsink/circuit module.

I’ve asked him to keep going.

Is it possible that the resistors were damaged by overheating or is it possible to tell if overcurrent was the cause as he said?

Aerowhatt
Gold Member
Posts: 426
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Re: And now my I will not charge!!

Tue Jul 17, 2018 5:06 pm

1pk wrote:Is it possible that the resistors were damaged by overheating or is it possible to tell if overcurrent was the cause as he said?


Yes over current is caused by over voltage with a resistor (or less common, resistance value drifting out of spec). Over current results in overheating which damages the resistor. So overheating without over current will achieve the same cracked ceramic resistor.

Aerowhatt
2014 cool silver ES, acquired new 4/2015 (42.7ah at ~26K miles)
2014 Labrador Black Pearl ES, acquired new 3/2016 (41.5ah at ~15k miles)

coulomb
Posts: 81
Joined: Sun Jun 10, 2018 8:32 pm
Location: Brisbane, Australia

Re: And now my I will not charge!!

Tue Jul 17, 2018 5:42 pm

1pk wrote: ... Closer inspection indicates that both Resistors are Cracked and the one that is discoloured has been overheated by excessive current. I have little hope that just replacing it will correct the problem. Something else must be Shorted.
...
Is it possible that the resistors were damaged by overheating or is it possible to tell if overcurrent was the cause as he said?

The schematic for these chargers hasn't been traced yet, so we don't know anything for certain. However, it's reasonably likely that we can learn from experience with other EV chargers. We strongly suspect that at least one of these resistors, probably the one that was cracked, in a pre-charge resistor. In normal operation, it will be shorted by the input relay about a second after mains is applied. This resistor has a hard life, pulsing a lot of power over a short period of time. (Then it does nothing for 99.9% of the charge time). But to crack, it likely seen this high power for longer than the usual one second or less. This can happen if the input relay doesn't come on, or if its contacts are burned. In Elcon/TC chargers, a common failure mode is that a pair of the MOSFETs short out, putting a short on the DC bus, which causes the power supply to drop out, which then causes the input relay to drop out. Now the pre-charge resistor is supplying 120 V or 240 V into more or less a short circuit. It will see possibly 10x or 100x its nominal power rating, which causes it to overheat. It appears to be a wire-wound type, which will often act as a fuse, going open circuit. There are other fuses there, but the pre-charge resistor often prevents the current from reaching a level where the actual fuses will blow. 200 watts will blow a 5 W resistor to pieces, but it's well short of the current normally passed by the charger (up to 3.3 kW).

So the short answer is, unfortunately, that I agree with the repairer: something else has likely shorted. Hopefully Kenny will be able to trace at least the pre-charge part of the schematic soon, so we know more about what's going on. For example, we don't know why there are two large white resistors. My guess is that one of them is a bleed resistor, so it will have a high value (hundreds of kilo ohms), and the other will be the pre-charge resistor (tens of ohms).

It's not uncommon for high power ceramic resistors like these to discolor with age, so the other resistor could well be fine. But of course cracking is not normal.

1pk
Posts: 68
Joined: Thu Jul 10, 2014 7:34 am
Location: Chemainus, BC

Re: And now my I will not charge!!

Thu Jul 19, 2018 6:41 am

Here is the latest from my inverter repair

IMIEV. Took two hours to remove the 56 pin heat-sink circuit.
As careful as I was, I do not believe that all of the 56 thru the board 'eyelets' came out of it intact. These eyelets allow components to be soldered in place & also provide circuit continuity from one side of the board to the other. Because of the large heat sink, all de-soldering has to be done from only one side of the board.

Managed to get at the leads for the resistors & unsolder/remove them. There is a 5 Watt & a 10 Watt. These are Ceramic wire wound dual 'radial' leads. Both are labelled 4.7 ohm but BOTH measure OPEN. This is not encouraging as I have not read anywhere about this much damage being repaired successfully. There must be shorted components elsewhere that have caused these resistors to overheat like this.

There is overheating damage to two other surface mount component circuits but this is probably secondary damage.

My opinion is that this item is NOT Repairable.

So that doesn’t sound good. Im going to go talk to him this afternoon and I’ll post pictures of the board.



I’d he

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