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Author Topic: SR DC/DC Converter Internal Moisture Ingress  (Read 718 times)

UlsterZero

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SR DC/DC Converter Internal Moisture Ingress
« on: January 17, 2021, 11:35:13 PM »

Hi Guys,

As per the subject, I was wondering if anyone has experienced moisture ingress with the DC/DC Converter. I don't mean on the connector, which is a known weak point, but internally within the converter itself.

I have had a recurring error 20 issue for a while now, which I had initially put down to damp or dirt around the DC/DC converter connector, as the error doesn't occur when the converter is disconnected.  After drying/cleaning the connector, and re-applying di-electric grease, the error had continued to occur, and just before Christmas, Error 28 also started appearing.  Finally, the lights remained on, even with the key off, and after drying/cleaning the connector again (which didn't show any signs of corrosion, or washed out di-electric grease), the errors persisted.  On a test run, the lights began flashing and when I keyed off and on the bike, the converter stopped working completely.

I had ordered a replacement converter which is estimated to take 3-4 weeks to arrive, will probably be longer due to entering our third Coronavirus lockdown, and new EU rules delaying (or blocking) most goods entering Northern Ireland!  >:(.  In the meantime, I have been running the bike with the converter removed, and so far after just under 200 miles, there has been no recurrence of any isolation errors.

Since this I left the converter sitting on top of a radiator at home, to see if it would "dry out" any.  After a week, it started working again (tested off bike with an 80v supply and driving a 55w headlamp bulb), however it was showing a voltage leak of around 70v between both the input and output negative terminals and the base plate.  After another 2 weeks the leakage is now down to around 0.2v between the input and base plate, rising to 5v when enabled.  There is no longer any leakage between the output and the base plate.

I know the converter is supposed to be IP67 rated, and with it seemingly a solid block of potting compound (or similar material),  I cannot see how moisture would get inside it unless it is either making it's way past the connector pins which aren't sealed, or the screws on the base plate itself.

If it continues to improve, and the leakage to the base plate is eliminated, I may put it back in the bike to test, especially if the new one doesn't arrive soon!  ;)

If any of you guys have had similar experiences, I would like to hear of them.
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Crissa

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #1 on: January 18, 2021, 03:54:45 AM »

It's always possible you got a bum component.

-Crissa
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2014 Zero S ZF8.5

UlsterZero

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #2 on: January 18, 2021, 02:01:02 PM »

Thanks Crissa,

I had initially thought something had burnt out in it, but the fact that it seems to be gradually "repairing" itself is very strange.  The only explanation I can come up with so far is that moisture made it's way in and was shorting some components.  There may still be damage, and it might never be usable again, however, the replacement is ordered, and in the meantime, I have rigged up a small 12v battery to provide power to the lights etc. so the bike is still safe to use, and of course legal!  :)

UlsterZero
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Crissa

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #3 on: January 18, 2021, 03:09:33 PM »

Your moisture idea is probably close.  Waterproof coatings aren't always perfect.

-Crissa
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2014 Zero S ZF8.5

UlsterZero

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #4 on: January 19, 2021, 09:10:19 PM »

Time will tell if it works again, but if it does and I decide to put it back in, I think I will need to find a way of making it more waterproof.

It's usually pretty damp here a lot of the time, so I've been thinking of maybe making up a short extender for the dc converter cable so that the connection to the bike can be relocated to a more protected position.  That way I can make a permanent connection to the existing pins on the converter and seal them up fully with potting compound.

I might even change the connection on the bike itself to something IP67 rated, that way there should be no chance of moisture getting in.  Not sure if anyone has done something similar, but I'd be interested to know if they have.
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UlsterZero

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #5 on: February 02, 2021, 02:22:15 AM »

Hi All,

Thought I would give an update on my adventures with the DC/DC Converter.  While waiting for the replacement to arrive, and having seen that that original one seems to have "dried out" fully, I decided to re-fit it, just to see how it would work.  The results, I think, have been positive.  It seems to be working well, although I have only managed to cover around 100 miles since it was fitted, but all in wet, or very wet conditions (and salt covered roads).  So far I have not experienced any isolation errors, the converter cutting out, or indeed staying active when the bike is keyed off.  :)

It would seem that moisture/water can indeed make it's way into the converter, the most likely route being between the mating faces of the connector housings, and from there through the space for the connector pins.  It doesn't look to be getting it via the base plate securing bolts, as the threaded holes all appear to be blind.  The good news is that this ingress seems to be reversible, drying out appears to work, and without any damage, to this one at least.  Unfortunately, I can't be sure that corrosion hasn't started inside the converter, especially since it's possible road salt has also made it's way inside.  This may eventually lead to a complete failure, but for now it seems to be ok.

I believe the original application of dielectric grease in the Zero factory may have been insufficient, as it appeared to be only present on the terminals themselves.  To try and get a more waterproof installation, I also applied grease to the connector housing on the converter before inserting the plug.  The result was somewhat messy, but has, I believe, coated the mating surfaces, and created a better barrier to ingress.   The grease I used seems to be a thicker variety, and hopefully will resist wash off much better too.

I had hoped to run the Isolation test on the MBB console, but unfortunately it appears to need level 2 access, and I don't have the password for that.  The BMS Data is showing Isolation resistances of between 227 and 347 kOhms, with the least Isolated cell varying between 1 and 2.  I think these may be lower than normal, but don't seem to be low enough to trigger an error.  I may run it again with the DC/DC converter disconnected to see what, if any, difference this makes, or since the replacement converter has finally arrived, I may try it to see if it performs any better.

It seems, for the moment, the original converter is not quite ready for the junk yard, but when it does decide it's time to go, at least now I have a replacement ready!  I do wonder, though, how many converters were deemed to have failed in a similar fashion to this, but simply needed a bit of time in a warmer environment to rejuvenate them...

Ulster Zero
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Crissa

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #6 on: February 02, 2021, 02:40:13 AM »

It's always a 'yay' when you get it working again.

-Crissa
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2014 Zero S ZF8.5

centra12

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #7 on: February 02, 2021, 03:45:42 AM »

You should not drive with a Zero in the rain ;D
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Crissa

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #8 on: February 02, 2021, 01:36:56 PM »

I'm going to do it again tomorrow, centra!

-Crissa
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2014 Zero S ZF8.5

UlsterZero

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #9 on: February 02, 2021, 04:47:52 PM »

Centra, I don't see any reason not to ride in the rain, unless maybe you don't like getting wet...

This is Northern Ireland, wet weather riding here is a fact of life.  Even "dry" days will probably have a wee shower somewhere along the way.
If you won't venture out just because it might rain, then you'll hardly be out at all  ;)

Anyway, the Zero seems to be able to deal with the wet every bit as well as any previous Internal Combustion bike I have owned.  This issue
with the converter didn't cause the bike to stop, or leave me stranded, so I don't have any qualms with riding in the wet again...

I'm with you Crissa, come rain or shine, I'll be out...  ;D

Ulster Zero
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centra12

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Re: SR DC/DC Converter Internal Moisture Ingress
« Reply #10 on: February 02, 2021, 05:44:43 PM »

I'm going to do it again tomorrow, centra!

-Crissa

Please don't forget to play the "BeeGees" which fit best to the instrument cluster diso lighting   ;)
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