A/C condenser protection?

Post by **CometBoy** » Wed, 01 Jan 2014, 19:22

The little i-MiEV just had its first real wash and clean and one thing that has become obvious is the amount of bugs and road litter already collecting on the A/C condenser which is wide open and unscreened. Neither is there any protection from stone damage. The condenser is well back from the front of the vehicle and I guess this was the design philosophy to keep it safe from damage.

Not sure what others have done but here is one idea that seems simple to implement, will allow easy cleaning, will keeps stone away from the condenser and not change air flow to any degree. I also pull some of the front body panels off (behind the moulded bumper) to see if an easier more obvious mounting arrangement could be added but no such luck. But maybe someone else can see an easier solution?

So I’m open to suggestions.... Please note this is prototype 1 – it will have a small “U” section rubber edging fitted and will be secured with four small “L” brackets using ‘NutSerts’ (or whatever name you like to call them). This will allow the mesh to be removed easily. See the bottom photos for details of this.

Unmodified

The template – ‘A’ rests on the little lip and ‘B’ slots up behind neatly

The template fitted

316 SS mesh cut to template size

About 14 wires per inch - .6mm dia. wire used (ONLY because I have a roll) - nice mix of units here!

Sample fit

Small profile rubber 'U' shaped edging will be used to prevent scratching of the paint work and cutting fingers.

Will end up looking like this....

Mesh will be secured via 4 SS screws to 4 small satin black 'L' brackets using a NutSert tool for captive nut fastening. I think the mesh will be left unpainted in our case....

Anyway it sort of suits the front appearance of the i, I have some intercooler mesh from a modified WRX turbo frontend but it really looks out of place given the car is so small.

Now for the first i-MiEV question of 2014:

What is the little thingy for on the right side of the A/C condenser air intake channel??

Bruce

Post by **BigMouse** » Wed, 01 Jan 2014, 19:53

Nice mod!

The thing in the last photo appears to be an outside air temp sensor, but I'm no iMiEV expert.

Post by **acmotor** » Wed, 01 Jan 2014, 20:06

Left side of vehicle.
It is an ambient air temperature sensor.

Item 1 on the diagram.

Bruce, I'm not with you on this grill fit up.

At a guess, that grill will reduce the air flow by maybe 80%
40% by volume and 40% by turbulence.

The best grill material has low on edge volume and knife/fin like profile to air flow. Round material causes more vortex airflow disruption.

Forced air will flow with this restriction but the biggest difference will be to natural vehicle motion airflow.
Fitting this grill will make the electrical fan run more often.

Still, a good idea to have a grill. Mk2 perhaps ?

Post by **BigMouse** » Wed, 01 Jan 2014, 22:34

Good point acmotor. Something like this might be better?

You could probably find it aftermarket for some other car (the photo is a Ford Focus) and cut it to fit.

Here's some on eBay: 0.3sqm Honeycomb Grille

Or just search for "honeycomb grille"

Post by **CometBoy** » Thu, 02 Jan 2014, 02:38

Yep you win the prize BigMouse it’s the AAT (Ambient Air Temperature) sensor and very easy to get at like most things on these! Discovered it a couple of weeks ago when pulling the front bits off to have a look.

Lots written up on ecomodder.com on grill designs including mesh materials and lots of interesting armchair views. As per that forum, I think the best thing is to try a few concepts on the road and see how it effects the with and without w-h/km under fairly controlled test drives. So far 10km tests actually show an improvement if anything in using the mesh! Tests were only at 60kph on a hot afternoon with AC running at max. So very early times.

The other interest discussion on ecomodder.com is on the subject of ‘Grill Blocks’. Maybe a good future for auto grill blocks?

For the next version, I would like to use something easier to work with – SS mesh is not nice.

Have tried a piece of that large plastic honeycomb grill material but it looks all wrong for the small area we have. A nice small honeycomb would be good assuming it can follow the slight curve – still looking for a piece of that to suit.

The material used on this grill design (2013 Mustang) would be nice as well....

Any other ideas appreciated....

Have any others here actually fitted something??

Bruce

Post by **acmotor** » Thu, 02 Jan 2014, 04:52

CometBoy wrote: ... I think the best thing is to try a few concepts on the road and see how it effects the with and without w-h/km under fairly controlled test drives. So far 10km tests actually show an improvement if anything in using the mesh! Tests were only at 60kph on a hot afternoon with AC running at max. So very early times....

you're kidding of course.

That's like polishing the dipstick adding 10% to the engine power.

You right though, form and function of suitable grill would be a good mod.

Post by **offgridQLD** » Thu, 02 Jan 2014, 15:11

Isn't the cooling system radiator Behind the AC condenser? It would be nice to actually have readings of what the cooling system temps are (perhaps a good request for the canion developer to sniff out).

As it would be hard to know what effect the potential air flow restriction was having without any way to measure it.

It's a good modification though & nice documentation as usual Bruce. I was thinking the same thing when I first poked around the front end of the car, as you say its very exposed.

Bugs are not my main concern as a good vacuum attachment and a grill comb for the big destructive bugs gets the job done on my other cars and the Imiev has easy access for cleaning. Lots of open road 110kph country driving is when you usually collect them and wedge them tight in the fins. I don't do a lot of this kind of driving in the Imiev.

My main concern was the road we live on (single lane, tree lined dirt loggers trail) Lots of sticks on the track after a good storm and not much road width to avoid them.

Kurt

Post by **CometBoy** » Fri, 03 Jan 2014, 04:46

Interesting the more you look at things… Perhaps the idea of Active Grille Shutters should be look at for the i-MiEV? Seems to be integrated well into the Spark EV http://gm-volt.com/forum/showthread.php ... e-Shutters. The concept has been around for many years but seems only recently that car maker are embracing it to improve aerodynamics and maximize thermal efficiencies.

Even Hyundai seems to go with the concept now http://ecomodder.com/forum/showthread.p ... 14948.html claiming a decrease in the Sonata Hybrid's coefficient of drag by as much as 10 percent at highway speeds (Hard to believe! must have acmotors polished dipstick and silicone spray as well

).

Some interesting but mostly basic DIY projects around if you Google key words such as, automatically grill block or active grille or grille block etc and add in Arduino if you want to see how some are playing around controlling the opening/closing. Most are basic and not great designs (especially the Prius on Ecomodder with blocks of wood!), but the general idea is there. I see some of the i-MiEV owners in colder climates are playing with the idea now as well. Guess the most important part of a good DIY design would be to have the failsafe be in the max open position but that is stating the obvious… and not hard to do.

But the hypermiling guys on Ecomodder have one strange hobby!

Kurt not that hard to measure potential air flow restriction using external methods but would be nice to gain the reading from the AAT at least with caniOn – yes, good idea to ask Xavier if it could be included in the next wish list (you want to ask or shell I??)

Bruce

Post by **acmotor** » Fri, 03 Jan 2014, 16:51

good to see you laugh at the wild claims out there Bruce.

Post by **CometBoy** » Fri, 03 Jan 2014, 18:36

Hey great I can keep you amused!

The reason for posting some of this stuff is to try and get constructive feedback on improving in every way the first concept that comes into prototyping. It is never the final outcome and many versions are tried along the way. By posting here I am looking for other ideas and examples that might offer a better result in a number of ways.

Constructive help is very much appreciated and hopefully others will gain from a final simple solution we all contribute to (if achieved).

Bruce

Post by **acmotor** » Sat, 04 Jan 2014, 00:11

Totally.

On one hand, I do find that the advise telling you that you are on the wrong track is useful. It can save you heading off in the wrong direction, has been tried before or is part of the world of myth.

On the other hand, the online community has worked up some really great ideas and revealed all sorts of wonders on the EV scene. Especially when the poster does such a good job at doccumenting their explorations, like CB Bruce.

Post by **CometBoy** » Sat, 04 Jan 2014, 02:21

No, want to hear the ideas that challenge the concepts! That is great keep it happening....

Back to the issues....

Anyone used one of these?

http://www.jaycar.com.au/productView.asp?ID=QM1646

I can borrow one to do some grille tests but would need to make an extension lead to be useful. Not sure it is worth the effort?? Hopefully would be more useful then w-h/km comparisons. Have used more professional tools like GreyWolf but no longer have access to these monitors.

Any other clever ideas for testing comparative air flows in this situation? Guess the old hot wire thermistor trick could be used?

Bruce

Post by **BigMouse** » Sat, 04 Jan 2014, 04:16

CometBoy wrote:Any other clever ideas for testing comparative air flows in this situation? Guess the old hot wire thermistor trick could be used?

Bruce

A manometer? Measure the pressure drop across the screen. Can be made with a simple length of clear vinyl tubing from bunnings and some water. Measure the pressure difference by measureing the displacement of the water column.

Post by **acmotor** » Sat, 04 Jan 2014, 05:06

So physics concept is mesh grill reduces airflow. Challenge idea is ' no it doesn't '.

I'll pass on that one. Not a concept to challenge.

The more important question is does the grill change the drag co-efficient of the vehicle.
How to conclusively measure that ? A wind tunnel would be good.
If there is a small change it may be hard to quantify without very controlled testing.
That does open the whole question of the iMIEV aerodynamics.
Is there a list forming around the world of airflow mods for the i ?

Post by **CometBoy** » Sat, 04 Jan 2014, 15:44

No question about any grill or filter of any type affecting airflow to some degree. The challenge is to find the balance between a slight reduction (hopefully only a few %) and the benefits of adding some useful protection from foreign objects.

Re the drag co-efficient, sure it is going to change but given the dated vehicle design in general, I can’t see the grill being a major player. As I mentioned the only way I can see trying to measure this at home is doing repeated tests under hopefully the same conditions and measure w-h/km with caniOn. Even with that prototype 1, I cannot see any difference but it is most likely ridiculous to try and see any difference with this method. What I do know is I could measure a clear difference on MightBoyEV when adding the air block behind the little grill on it and a belly plate under the front (originally had an AC condenser in the lower area). The big open whole left after removing the ICE radiator etc was not good – obviously the block and plate served as a water shields as well. I used w-h/km in that situation and maybe incorrectly thought it would useful here. BTW used w-h/km comparison when playing with fat tyres and 14” ‘pretty’ show rims on it as well, that was very noticeable! So useful for some things.....

Maybe a new thread on iMIEV aerodynamics is needed? Be interesting to cover the front air intake, tape the front bonnet gap and remove the large wiper blade and see if anything changes! Maybe on a cool non-rainy day! I’m happy and still surprised at actually how good the i is in energy use. Hard to believe big improvements could be gained in airflow improvements on these anyway but certainly not an area I know much about.

Back to the original thread topic: So I’m looking at a better way of doing comparative tests on the various grills I have now. Easy to cut different styles once you have a good template. Have also come up with a better mounting arrangement that doesn’t involved any hole drilling and uses the standard 6mm Scrivet clips (as per the factory).

After thinking about the simple manometer idea I thought maybe a simple DIY anemometer might do it as I can run a lead up into the cabin and see the results (a bit hard with a manometer...) have lots of small DC motors and various small fan blades to play with. Maybe mounting a small DIY one centrally in that air flow channel and reading the output with a multimeter inside the cabin would be fine for a comparison?

Bruce

Post by **acmotor** » Sat, 04 Jan 2014, 16:26

Airflow reduction is a given and way more than a few %. I understand you need to prove this to yourself.

Granted the airflow info would help in choosing a grill material design though the info for that is already out there.

More useful than a measure of this airflow reduction alone would be log of coolant / condenser / ambient temperatures and coolant pump duty cycle / coolant fan duty cycle. All that data I expect streams around the CAN bus so digging in that direction would be the way to go. I.e. Ask the vehicle what it thinks of the grill. Failing that, fitting your own sensors would be the next best.

Post by **offgridQLD** » Sat, 04 Jan 2014, 16:39

That's it, wind drag defects. If you don't see any measurable difference when using 1 whr - km as your resolution. Measuring over say 80 - 100km distance then it's under 1%.

Like you said The Coefficient of Drag for the Imiev is terrible for a small car. my old 1997 opel had a CD of 0.26 vs 0.35 for the Imiev. The leaf is 0.28. Even the old Mitsubishi mirage and lancer were 0.30.

How much is a new AC condenser. As that's all we are protecting from potential damage with the modifications.

Temperature effects from air flow restrictions like AC motor said need to be measured as a temperature gain.

I think just putting a mesh that isn't to fine is the go. Small insects don't do much if any damage its only the big beetles that mess up the fins , bees, fly's and so on just get stick and need vacuuming out.(give them long enough they do just decompose and turn to dust and fall out)

Kurt

Post by **BigMouse** » Sat, 04 Jan 2014, 16:41

CometBoy wrote:After thinking about the simple manometer idea I thought maybe a simple DIY anemometer might do it as I can run a lead up into the cabin and see the results (a bit hard with a manometer...)

There's no reason the manometer can't be located inside the car, with the ends of the tubing installed at your sample points. The hard part would be measuring the water height in a moving car. The water would likely be moving around enough to make it difficult or impossible.

Maybe pick one of these up from Jaycar: Pressure Differential Sensor (0-10kPa).

It would be a very simple circuit, and just use a multimeter to read the pressure drop.

Post by **BigMouse** » Sat, 04 Jan 2014, 16:43

offgridQLD wrote: How much is a new AC condenser. As that's all we are protecting from potential damage with the modifications.

The cost of the condenser is likely only a small part of the cost to repair. The system would need to be evacuated and regassed as well. On a vehicle with an electric compressor, special high resistivity oil is used, so this is a dealer-only job.

Post by **offgridQLD** » Sat, 04 Jan 2014, 16:49

" On a vehicle with an electric compressor, special high resistivity oil is used, so this is a dealer-only job. "

I would think it would be any different to a modern spit system AC unit.
and would cost no more than having one of them re charged. (if you didn't go to the dealer)

Kurt

Post by **BigMouse** » Sat, 04 Jan 2014, 17:29

offgridQLD wrote: " On a vehicle with an electric compressor, special high resistivity oil is used, so this is a dealer-only job. "

I would think it would be any different to a modern spit system AC unit.
and would cost no more than having one of them re charged. (if you didn't go to the dealer)

Kurt

In the Prius, the electric A/C compressor requires special compressor oil due to the oil being used to cool the windings of the compressor. I'm not sure about the i-MiEV, though I expect it's the same.

There's some more details in this article.

Linked Article wrote: The motor’s insulated windings are immersed in the compressor’s lubricating oil. The oils used in these compressors have high dielectric (non-conductive) properties. DENSO has produced a chart showing that as little as 1% contamination by an improper oil can affect the dielectric properties. If a different type of oil somehow makes its way into one of these compressors, and if the insulation on the windings has become damaged or compromised, a variety of problems may occur.

Unfortunately, the oil is stored in the machine that is used to perform the re-gassing operation. You can't use a different oil for just one job. Dealerships that work on hybrids and EVs will have a machine dedicated to it, with the proper oil in it.

Post by **acmotor** » Sat, 04 Jan 2014, 17:47

1. Has any iMiEV around the world suffered condenser damage that would have been avoided by a grill ? That may help with priority. I agree there may be a requirement.

2. My kitchen fridge, as have probably all sealed units since year dot, runs the emoter windings in oil. I think someone is having you on if they suggest only the latest e-compressor needs non conductive oil.

Post by **CometBoy** » Sat, 04 Jan 2014, 23:12

Ok got the DIY anemometer working nicely with a reasonable voltage curve.

Too gusty here to get good data but did a return run and averaged it to get a reference curve (ie no grill) that corresponded to 500mv @ 60km/h.

Then I quickly did a worst case scenario run with the closed mesh (as shown in prototype 1) that corresponded to 320mv @ 60km/h once again averaged over a return run.

So about 65% gets trough.... not useable.

Will put up curves and better data once I get the car again and have a non-windy day.

And also check the other grills I have made – hoping to get to under 5% loss but the measurements will be the proof.

Bruce

Post by **CometBoy** » Wed, 08 Jan 2014, 20:45

Received a reply back from Martin re caniOn additions including AAT etc as follows:

“Hello Bruce!

We are also interested in these temperature data. But we do not have any documentation from the i-MiEV's can-bus-data. All data we found are explored on base of comparison with the peugeot garagetool and exploring raw data on the can bus.

Most common obd-tool i know is the android app torque. But this is only working with combustion engine cars.

Martin”

I have also tried using both Torque Professional and even my VAG-COM (VW – Audi) readers and both error out and will not communicate to the ECU. Maybe one day we will have more information from the CAN. Must be nice to play with the Prius and have access to all that information.

So 30 mins later and using anemometer mk1, I have Grill-o-Meter ready to test the samples sometime in the next few days. Yes acmotor I need to prove it to myself – I’m sure you are right and know the answer already. From an interest point of view I am also going to check the fibreglass fly screen material I have used for years to keep bugs out of the rad and AC condenser on various vehicles. Most likely not a good outcome as well...

So the simple Grill-o-Meter looks like this:

Ended up using a $2 Cheap as Chips battery operated fan - puts out 510mv @60km/h in free air. It fits neatly into the opening about half way back (will add a photo of the mounting position later when I have the car).

I’ve just used what I have around... So a standard old Arduino with a two line LCD display and a sketch reading into an array in a 100msec loop. That seems to give a good result and smooths out the data well. Using the multimeter, readings jumped around too much to be useful. Wanted to be smart and get that GPS module in there as well (to show speed vs output) but I have never succeeded in getting it to work on any project. Wasted enough time on something so basic anyway...

Results soon!

Bruce

Post by **Johny** » Wed, 08 Jan 2014, 21:20

I love the way you have written the calibration data on one blade.
Looking forward to the result and I don't even have an i!