Author Topic: Venting my thoughts on CARC dashes  (Read 557 times)

Online Huzo

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Venting my thoughts on CARC dashes
« on: September 14, 2017, 02:01:49 AM »
I know someone has had a go at this bit if we'd could elaborate a bit, it'd be good.
I've had bugger all misting issues with my dash, but can't say it's never happened. I mentioned a while back about introducing a vent pipe to duct warm/cool air into the dash case and a small  hole to allow pressure equalisation.
I'd suggest not warm air as a preference since warm air can hold more water vapour than cooler air does. I thought to have the intake pipe somewhere near the oil cooler or such so as to take advantage of the inflow and a small bell mouth for initial trials.
Is it worth experimentation based on experience of these who've tried it? (If any)

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Offline ITSec

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Re: Venting my thoughts on CARC dashes
« Reply #3 on: September 14, 2017, 11:53:25 AM »
Another good source of dessicant packs that might be even better suited to this would be dive camera suppliers. I use these in my underwater camera, and they might be a good choice. They're small, don't swell much when absorbing moisture, and less likely for the container to break down over time. If not exposed to moisture, they remain ready to work for years.



http://www.sealife-cameras.com/accessories/moisture-muncher-capsules

BTW, I've never seen this problem - but then again, the Mojave doesn't have the climate of the northeast US or central Britain!
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Re: Venting my thoughts on CARC dashes
« Reply #4 on: September 14, 2017, 12:00:58 PM »
Zero experience, but if I did, I would try putting some Desiccants in there and then sealing it to keep any more moisture from coming in.

https://www.amazon.com/dp/B001O62T4O/ref=asc_df_B001O62T4O5169462/?tag=hyprod-20&creative=394997&creativeASIN=B001O62T4O&linkCode=df0&hvadid=198109564750&hvpos=1o1&hvnetw=g&hvrand=12053463151093765264&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9015261&hvtargid=pla-348581066070

But I thought you can't seal it completely because it houses the engine's atmospheric pressure sensor?
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Offline jlburgess

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Re: Venting my thoughts on CARC dashes
« Reply #5 on: September 14, 2017, 07:54:46 PM »
I've had a dessicant pack in mine for quite a while and it didn't seem to impact it.  I'm on my second dash after the first one went tits up over 5 years ago.  It's just a minor annoyance at this point.  There are lots of threads on this website about sealing them if you search.

Online Huzo

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Re: Venting my thoughts on CARC dashes
« Reply #6 on: September 15, 2017, 03:56:01 AM »
Yes, sealing dashes or attempting to, is frought with problems as I see it, 'cos there'll always be atmosphere in there which contains water vapour.
That vapour will condense or evaporate due to ambient conditions which warm or cool the case, even if it's sealed. My musings were not how to seal it, but to provide ventilation to purge the air continually.
Just a VERY light, but continual flow.
« Last Edit: September 15, 2017, 01:26:22 PM by Huzo »

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Re: Venting my thoughts on CARC dashes
« Reply #7 on: September 15, 2017, 12:18:01 PM »
If the goal is to eliminate misting and corrosion from condensation by ensuring that air flows through, then I'd probably start by looking for the point that is lowest on the cluster when installed, maybe when on the side stand. I'd then try to pick a point nearly opposite, and create vent holes at those two points. It would be important to check that neither of the selected locations results in too much exposure of the internals, and that neither is where wind-driven rain could directly enter.
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Re: Venting my thoughts on CARC dashes
« Reply #8 on: September 15, 2017, 01:25:46 PM »
If the goal is to eliminate misting and corrosion from condensation by ensuring that air flows through, then I'd probably start by looking for the point that is lowest on the cluster when installed, maybe when on the side stand. I'd then try to pick a point nearly opposite, and create vent holes at those two points. It would be important to check that neither of the selected locations results in too much exposure of the internals, and that neither is where wind-driven rain could directly enter.
Yes, that seems completely sound

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Re: Venting my thoughts on CARC dashes
« Reply #9 on: September 15, 2017, 02:08:48 PM »
Yes, sealing dashes or attempting to, is frought with problems as I see it, 'cos there'll always be atmosphere in there which contains water vapour.
That vapour will condense or evaporate due to ambient conditions which warm or cool the case, even if it's sealed. My musings were not how to seal it, but to provide ventilation to purge the air continually.
Just a VERY light, but continual flow.

I connected a container of desiccant and an aquarium pump to circulate air through the dash to dry it. In the end I decided to rely on a conformal coating.

I did learn quite a lot about water vapor and electronics during my project.

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Online Huzo

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Re: Venting my thoughts on CARC dashes
« Reply #10 on: September 17, 2017, 01:53:54 AM »
I connected a container of desiccant and an aquarium pump to circulate air through the dash to dry it. In the end I decided to rely on a conformal coating.

I did learn quite a lot about water vapor and electronics during my project.

Moto
Did it end up just a pointless exercise in reality, Moto?

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Re: Venting my thoughts on CARC dashes
« Reply #11 on: September 17, 2017, 06:11:04 AM »
Did it end up just a pointless exercise in reality, Moto?

Strange question. No, I think my dash is well protected now, which was the point. Learning was also very satisfying, and a worthwhile point on its own.
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Online jas67

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Re: Venting my thoughts on CARC dashes
« Reply #12 on: September 17, 2017, 06:17:29 AM »
I thought of a way the dash can be completely sealed, yet, still have the atmospheric pressure sensor work.
You'd could put a durable, yet flexible membrane or bellows over a hole.   This way, the pressure could normalize, but, no air or moisture would be exchanged.
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Online Huzo

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Re: Venting my thoughts on CARC dashes
« Reply #13 on: September 17, 2017, 06:26:12 AM »
Strange question. No, I think my dash is well protected now, which was the point. Learning was also very satisfying, and a worthwhile point on its own.
Sorry mate. My point was given that you have done some work on the topic, I just wondered if working out ways to provide venting, is a waste of time or not. Everything I said was just guesswork.

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Re: Venting my thoughts on CARC dashes
« Reply #14 on: September 17, 2017, 10:49:41 AM »
I thought of a way the dash can be completely sealed, yet, still have the atmospheric pressure sensor work.
You'd could put a durable, yet flexible membrane or bellows over a hole.   This way, the pressure could normalize, but, no air or moisture would be exchanged.

That was the first idea I pursued, but it turned out that water molecules are so tiny (one of the very smallest in nature) that they permeate, or pass through, most structural materials, including plastics and even metals(!). They do so until the partial pressure (loosely, concentration) of the water vapor gas is equalized on the inside and outside of a container. Published permeation index values guide engineers in predicting how long it will take for a certain amount of vapor to pass. I concluded it would be difficult, at least, to provide a membrane or bellows that would not allow passage of water vapor over time, equalizing the interior humidity with the longterm average in the environment. It would take extremely careful choice of materials and construction to preserve a dry interior in this kind of system for a period of years -- if it could be done at all.

It's a good idea in principle, except for the water vapor permeation problem, I believe.

Moto
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Re: Venting my thoughts on CARC dashes
« Reply #15 on: September 17, 2017, 12:12:16 PM »
Sorry mate. My point was given that you have done some work on the topic, I just wondered if working out ways to provide venting, is a waste of time or not. Everything I said was just guesswork.

Sorry on my part. I realized as I went to sleep that I probably
misunderstood you.

Yes, I think venting is probably not too useful. A main
consideration, I believe, is that most of the damage is being
done while the bike is stationary, in the garage (or somewhere
worse) overnight. Water vapor condenses out of the air inside the
dash as the temperature falls, forming droplets on the dash's
printed circuit board (PCB). The droplets pick up contaminants
from the board, and corrosion and another process that bridges
circuits begin.

In the garage, venting just serves to equilibrate the humidity
conditions inside and outside the dash. No useful evaporation
from air circulation would occur, I believe. When the bike is in
motion on the road a set of vents could be either helpful or not,
depending on the humidity, just like opening the windows in a
house is not always a good idea if the air is humid. I remind
myself that the outdoors, which is exceptionally well vented,
also exhibits dew drops in the morning.

Heated air could dry the dash out, but air entering again when
the bike is stationary and the heated air supply is presumably
turned off would continue to be a problem.

I now think of the dash as a little terrarium that I keep in the
garage. Inside it is air of unknown dampness. When I bring my
little terrarium out into the sunlight, especially on cool days,
the sun's rays pass through the transparent top, warm the
insides, and soon condensed water evaporates, rises as vapor, and
forms droplets that I see on the inside of the cooler, transparent
cover. I expect that many of us have seen this happen in our
dashes.

The problem is that the water forming those droplets has already
been doing its damage, working undisturbed in the little
terrarium over night, and over the winter, unseen and
unrelenting. Venting won't stop that, since the humidity of the
outside environment is not always low.

I believe the two solutions that I did implement on my bike can
both be effective. The first is a desiccant chamber that the air
entering the dash (for the use of the on-dash air pressure
sensor) has to pass through, and that is used to dehydrate the
air in the dash enclosure by flushing with an aquarium pump, the
whole setup taking advantage of some mysterious half-finished
tubing provisions in the dash mounting as it was delivered from
the factory. The second solution is a conformal coating I applied
to both sides of the PCB, carefully avoiding covering up the air
pressure sensor and other sensitive things like electrical
connectors.

The first solution has been only marginally effective, probably
because remembering to check the desiccant for the change in
color that indicates discharge, and to flush the system with the
pump, is something I'm not good at. To be really effective, I
believe I'd have to continue flushing and desiccant maintenance
through the winter. At any rate, I have seen moisture on the
inside of dash reappear on two sunny, cool days since I installed
the system.

I believe the second solution, the conformal coating, actually
works, even though moisture continues to enter and condense on
the coated board in spite of system number one. Its operation is
fascinating to me because it does not rely on stopping water
molecules from getting to the PCB. Being merely a plastic
coating, water molecules readily permeate it, moving though the
spaces between the molecular polymer strands. But, properly
applied, the coating adheres tightly to the surface of the PCB,
preventing water molecules from collecting together into
conductive droplets once they reach the board.

I expect I may get around to wiring the aquarium pump into the
motorcycle's harness so that it is always on when the bike is
running, but that really won't be enough because of the long
downtimes in the winter and overnight. If I were even more
obsessive than I am, I could wire the pump to run forever (just
like it is used to supply air to fish tanks), but it seems likely
that the conformal coating is a sufficient solution.

Moto

P.S. I saw that my lines of text were really long before they wrapped,
so I shortened them in an editor. I don't know why the problem happened.
Anyone know how to fix this?

P.P.S. Huzo, rereading your original posts, I see that you have thought
about some of the venting issues I just wrote about.
« Last Edit: September 17, 2017, 12:30:30 PM by Moto »
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