Nuggetgalore's iMiEV charger failure

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nuggetgalore
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Re: Nuggetgalore's iMiEV charger failure

Post by nuggetgalore »

tonyw wrote: Thu, 03 Sep 2020, 14:57 Heh. I found the plug (opposite the inlet hose from the inverter) and tried to remove it with a 6 mm Allen key. Nothing doing. Having broken an Allen key many years ago in the same circumstances (and still wearing the scar), I abandoned the attempt.

The plug and the inlet hose are at the same level anyway, so there is little benefit to be gained (unless there is a baffle between them).

I refitted the charger into the car this afternoon. It's only waiting for the new caps and I can add them while the charger is in the car. Installing it now means I won't be in a hurry to get it going later, and make mistakes.

I had to recharge the auxiliary 12 V battery yesterday, it was down to ~11.9 V. Now back up at 13.6. Still need a trip to Bunnings for some neutral-cure silicone.

Come on, RS, where are my caps?
Come on, RS, where are my caps?
The few things I bought from RS were delivered pronto, very happy.
Bought a number of other stuff for the battery project, already a fortnight and still waiting.
Any way, good to have been able to get the fuses and good luck with soldeing the caps back in. I did all that onboard, was glad I did not take the charger out.
tonyw
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Re: Nuggetgalore's iMiEV charger failure

Post by tonyw »

Urgent need to get the car going again, so I installed the 2200 pF/4 kV caps instead of waiting any longer for the 1000 pF/3 kV.

Car now comes up Ready and the charger works, but the coolant motor won't run, so I daren't run it for more than a few seconds.

I remember at one stage when the OBC was removed, I turned on the "ignition" to observe indicators and the coolant pump ran then, even though there was no coolant in the reservoir or the pump itself. It only ran for a second or two before I switched it off again, so I'm sure it wasn't damaged in that time.

Do I have to clear fault conditions before it will run again? I don't have any means to do that. I have no fault indications on the dash.

The vacuum pump is running OK, but the coolant pump usually runs after the vacuum pump stops. Usually, but not now.
cheers

tony

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jonescg
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Re: Nuggetgalore's iMiEV charger failure

Post by jonescg »

Pretty sure those pumps are self-priming so nothing to worry about.
AEVA National Secretary, WA branch chair.
tonyw
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Re: Nuggetgalore's iMiEV charger failure

Post by tonyw »

I'm not worried about the pump, I'm worried that there could be large areas of the coolant circuit that are empty and I won't be confident until I see it circulating, sans bubbles. The Russian manual gives a thorough description of how to bleed the circuit, but it depends on using an "ASC" switch, which I don't have in my car.

Maybe I'll be brave and leave it charging for a while, see what happens...
cheers

tony

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Re: Nuggetgalore's iMiEV charger failure

Post by mark_hetho »

It's the traction control switch. I just had a look at my car and it's labelled "TCL OFF".
nuggetgalore
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Re: Nuggetgalore's iMiEV charger failure

Post by nuggetgalore »

tonyw wrote: Tue, 08 Sep 2020, 07:14
Car now comes up Ready and the charger works, but the coolant motor won't run, so I daren't run it for more than a few seconds.

I remember at one stage when the OBC was removed, I turned on the "ignition" to observe indicators and the coolant pump ran then, even though there was no coolant in the reservoir or the pump itself. It only ran for a second or two before I switched it off again, so I'm sure it wasn't damaged in that time.


The vacuum pump is running OK, but the coolant pump usually runs after the vacuum pump stops. Usually, but not now.
I just posted a reply but it disappeared!
Anyway , I was saying that the coolant pump on my car when charging runs for a few moments, then waits several minutes and runs again for a few moments....and so forth. I assume as the charger gets hotter the time intervals change . At the start of charging the car does a handshake
dance, the fan can be heard and probably the coolant pump but that I have no proof for.
tonyw
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Re: Nuggetgalore's iMiEV charger failure

Post by tonyw »

Well, the manual says "press the button at least ten times within the first seven seconds". It has no effect here, the pump does not run.

Chris said earlier "don't worry about it", so I bit the bullet and left it in charge mode, with more coolant and funnel ready. When the pump turned on some ten minutes later, I was only just in time to catch the level before it got so low that the pump started sucking air. But after a couple of normal "runs" of the pump, no more air bubbles and all is good.

I've taken lots of photos during the repair, in case someone wants me to write a "how-to" for Aussies. I haven't time to look at waveforms at the moment, that will have to wait a few days. Maybe my new 100:1 CRO probes will have arrived by then, too. At that time, I'll hit the caps with the silicone to prevent them breaking off.

Interesting that after about an hour of charging, the cover of the OBC was very warm (~50 C) but the coolant output was only barely above ambient.
cheers

tony

tonyw
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Re: Nuggetgalore's iMiEV charger failure

Post by tonyw »

Well, my high-voltage CRO probes finally arrived yesterday, so I was able to open up the OBC and measure the voltage across the capacitors. I can't measure across the capacitors directly, as I can't safely get a couple of CRO probes in there with the upper PCB in place, so I measured the voltage across the pins in the connector to the heat sink assembly (probably 1.5 - 2 cm from the caps).

While I was repairing the OBC, I soldered a couple of wire hooks across the terminals to allow easy and safe access to a CRO probe. With my new 100:1 probes, I was able to capture a (repetitive) spike in excess of 800 V across the connector pins. And that's with my 2200 pF caps, not the standard 1000 pF! The caps that I installed were rated at 4 kV, and there is no way that I would ever revert to 1 kV-rated caps. My mains voltage at the time was only 228 V, so the spike may be even more extreme at higher mains voltages.

I have a screen shot of the oscilloscope if anyone would like to see it. I don't have anywhere to host it, or I'd post it here.
cheers

tony

nuggetgalore
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Re: Nuggetgalore's iMiEV charger failure

Post by nuggetgalore »

tonyw wrote: Sun, 04 Oct 2020, 06:43

I have a screen shot of the oscilloscope if anyone would like to see it. I don't have anywhere to host it, or I'd post it here.
It is easy (if it was not I could not do it ,lol) with imgur to post pictures, thanks to coulomb's how to thread.
https://forums.aeva.asn.au/viewtopic.ph ... gur#p70959
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brendon_m
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Re: Nuggetgalore's iMiEV charger failure

Post by brendon_m »

You should be able to post it straight on the forum without hosting, use the attachment tab.
Last edited by brendon_m on Sun, 04 Oct 2020, 19:34, edited 1 time in total.
tonyw
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Re: Nuggetgalore's iMiEV charger failure

Post by tonyw »

OK, here goes. Pic from CRO screen, both traces 200 V/div, 0 V on centre line. Note yellow trace swinging down to -560 V while blue trace is flying up to +280. a difference of 840 V. The ringing is at a frequency of about 2.2 MHz. If that is the resonance of the 4400 pF caps and stray inductance, it suggests stray inductance of about 1.5 µH, which seems reasonable for that length of track.
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cheers

tony

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