Some nice cars there. I look forward to having a closer look in Melbourne.

Was anyone officially taking any scrutineering photos?

I have been trying to get hold of all the times from the event but haven't had any luck yet.

I still don't know how they managed to organise the national track for your event. It was still in Melbourne on Sunday and they would have had to set it up for you guys on Monday.

From what I've also been told, the Girrawheen car was super light and weighed only 260 grams or so.

miseli

Guys here are some images from the NSW event.

Sorry for the delays in getting the pics up, but I've been rather busy getting ready for exams recently.

The results were as follows:

1st - Scorpion, Syndal South Primary School
2nd - Killswitch, Box Hill High School Killswitch
3rd - Lean Green Speed Machine, Lean Green Speed Machine
4th - Skylite, Geelong College
Best Engineered - Nigresta, Box Hill High Schoo
Best poster - Cost-a-lota, Sandringham Secondary College
Best First Entry - Auto Kinito, Ashwood Secondary College

And now some pictures...






I'll upload more photos from other people later once I manage to get my hands on them.

Hello Hello

Mark nice forum. I reckon Girrawheen's cars are crap compared to other states.
I heard your demo car goes really fast. How about a race at the Nationals with Horizon 3 (Girrawheen Car)which was seeded 4th (after Burst Limit-Girrawheen seeded 3rd) at the W.A however if we were permitted we would have came second (maybe). Sorry to be quite harsh but the 2nd ,3rd , 4th place getter's in WA were not the top cars. Girrawheen Vs Belridge in the top 16, which knocked out the second seed. What was with that? All the fast cars vs all the fast cars. The slow with the slow. We had other versions of Fred Adlers designs vsing our 3 wheeled cars which almost beat us in the top 8. The formatting was totally off! However the seeding was quite correct!

Explora looked like if it was pulled together in the last minute. However it was designed in 2008 but never raced until 2009. So there has been quite a bit of preparing. Girrawheen cars! None of them had any testing before the WA competition and the only adjusts to the cars were the maximisers. Although I would make a comment how Winthrop BC 3rd adjusted theirs and never seemed to perform quite as well. A note which i made to heaps of schools! If your cars performing at its full potential, why adjust it. I.e. Hint Hint!!! "Grand Final - don't change your gear ratio if you don't know 100% if its going make a great difference - or when the shadow is not in your favour. Ie. Girrawheen's wildcard is called SHADOW

Explora won all its races with like 3-4meters to spare! Is it fast? I'll let you decide for yourselves. Hopefully this will be the car to beat in the Nationals. Although those Eastern state cars look light and have potential to go fast.

To make a note. The sunlight conditions in WA never reached 100% although it look like it was. There might have been brief intervals. Girrawheen has been given a Wildcard Enter however I can not state if this car will be faster than Explora, without testing it. Which will be the Nationals in Melbourne!
Time Trials - Explora clocked a time of 15.46sec for 86metres in 68.3% sunlight.
Calculated at 100% 13.5seconds.
However on the competition day, Explora set a time of 17.46 secs (full national track-94?)in around 80% sunlight. Not 100% sure about the sunlight but it was close to that!
The time to beat is 16.18second in 122%sunlight. So I reckon the time we achieved was acceptable!

Our designs are simple and light!
Should I post images, so can you guys wait for the competition?

Some nice pics there unussapiens. I can certainly see why your car won the best engineered award.

I actually received a CD yesterday from Ian Gardner with scrutineering photos of all the Victorian cars. I will try and load some up shortly. I am however currently smack bang in the middle of exams so it might take a week or so.

jhg, please do post up some images.

Yes, my 2009 demo car will be at the nationals, so anyone will be able to give it a race. I don't know how it performs in good sunlight, but I expect it will be similarly matched to last year's demo car if not faster with the better aerodynamics. I will bring both along.

I don't know why you had fast cars racing other fast cars earlier on in your competition, but that certainly won't be happening in Melbourne. I also find it quite strange that you ran your time trials over 86m and not the 95m which the races are over.

miseli

Hello everyone

unussapiens
Wow your car looks amazing. Can I ask why did your car weigh so much? How heavier was your car alone and the power wattage. I'm really curious. At the nationals, I'll be very interested to have a closer look. Don't worry, Girrawheen S.H.S. is very friendly! and anyone can have a closer look at our designs! There's nothing out of the extraordinary compared to Nigresta. It's the basics to build a winning car, although if you asked me, I still reckon a 3 wheeled car performs better. However I can't seem to get it working as good. Maybe one day!

Anyone that's interested our cars all ran a 1:6 gear ratio with a maximizer. There's no secret about that. I have attached an image of Horizon 3; my car which was seeded 4th that beat the 3rd seed Burst Limit from Girrawheen when we had to race off to see which of our three cars could represent our school in the top 4. However if we had the chance, all three cars may have been in the top four. However, as you can deduce, Horizon 3 lost against Explora which was clocking the fastest times for the competition. Explora was the only car to hit the 17second mark in W.A. for the full 95meters.
AND another thing about this Explora car; It was the car that was constantly breaking. If i counted correctly the front guide came off 4 times. Horizon 3 also lost its front wheel when one of our team members applied down pressure on the car to stop it. If you look at the image, its obvious why.

Marc, I'm really surprised that they brought the national track over too! I was so excited when i found out 3 days before the competition. As a result we adjusted our guides lower. Amazing no cars came of the track. Well all but one. Winthrop B.C. which I had my eyes fixed on. Their car was one too beat, however every time it seemed to take the last corner, it was quite unstable, although all three wheels were casting like the Tas cars. Best crash was when Belridge rammed into theirs(WBC) but didn't damage the drive system. Lets say the balsa shattered a little.

Overall the Western Power (WA) competition was a success. Maybe its because our school won! But with the average sunlight being close to 80% it was better than all the other states. It will be interesting to see which design wins because the winning car from Vic followed the winning design from the nationals from last year.

Does anyone have any details on the Vic cars?

Girrawheen is all about research and development! Hint Hint to new entries!!!=]

I've had a look at the Vic competition results. It's surprising!

I've done a few basic calculations!
First Place= Syndal South PS's Scorpion=516grams
Second Place= Boxhill HS's Killswitch=237grams
Third Place= Syndal South PS's LGSM=472grams
Fourth Place=Geelong Collage's Porche TGC 2000=392grams

These weighs are only the chassis and body of the car, not including egg, panel and ballast.
What is with Killswitch coming only second, while its car weight is half that of the number one car!
I've got to also make comment; the cars at the Vic competition are really ordinary weight wise!
If Killswitch makes a few adjustments, I'm sure it can win the nationals!
The design won last year!

Most of the weight of the car was from panel + ballast (About 2 of the 2.4kg). We were running with a 12W panel (mainly because the BHHS electronics require 12V or so to start properly) giving us a power to weight ratio of about 200g/W, which was about the same as top cars at the Vic competition. The car that I believe had the lowest power-weight ratio was Killswitch at around 190g/W, so we weren't too far off. Our car will be at the nationals whether or not we're racing, so feel free to come and have a look at it.

Admittedly, 3 wheeled cars do seem to perform better, but it wouldn't have been practical to build a 3 wheeler and keep our chassis/body (The two are the same thing) as it is. We decided to keep the extra wheel in exchange for better aerodynamics and stability, and the losses from cornering ought to be reduced greatly by the steering (We'll be doing some tests on that next weekend).

Our car ran with varying gear ratios, depending on the sun levels (the advantage is slight, but we'll take everything we can get). The ratios used range between 11:100 and 16:100. As I mentioned earlier, we were running with BHHS electronics (MPPT). Nigresta was measured with the 3rd fastest time in the round robins.

It really does prove that low weight isn't everything. Syndal South must of been doing a lot of the other stuff right. Reducing your losses is the key. If you haven't got your other losses minimised then even having the lightest car won't help. The first car I built in 2003 actually weighed less than 200g. That didn't mean that it won though.

Although the effects of added weight are clear and can easily be observed over a race using a simulator,I hope to run some actual on-track tests in Melbourne and getting some track times while incrementing the weight of the car from say 1 to 2 kg by 100g or so. I also have some aerodynamics and panel temperature testing in mind, just to try and show students what kind of differences and to what extent certain parameters will have on the performance of a car.

miseli

Hi Jhg,

Im quite confused by some of the comments that you have made in your original dialogue. You seemed to thing that the Adler designs were particularly fast, and i'm sorry but it appears you have been living in the past. The such designed cars completely failed to perform at this years event, with only one of the BSHS cars even making the top 16, and then being demolished by you. The cars being fast in the past completely failed this year. Also you are not the only school that has fallen victim to the strategic placing of the draw. All schools with multiple cars were subject to this to prevent monopolisation within the event. You cannot argue with the reasoning behind this, it is a schoolage competition for fun. Any problems should be directed to Thuy.

Now with respect to your critisism of the aquinas practices in the grand final i also fail to see where this concerns you. Possibly the fact that girrawheen won in the first round prompted the change - a repeat of the same setup would again have yielded a loss in that race. I would not jump to conclusions too quickly, there are many factors which influence a solarcar race, and the ideas behind it are constantly being developed.

C.C

Hello Conitsiotis

I'm not going to go off in an argument which will led nowhere. There's no point. If you guys went to the nationals last year (4th I know) then maybe you would understand a bit more about Fred Adler's designs! There's nothing fancy about their cars; it just works pretty well. Our car's follow a similar design although they are slightly lighter. However I have come to the conclusion weight doesn't effect your car as much as I originally thought. This is evident with Syndal South P.S. placing 1st and 3rd although their car were 2 times heavier than the Box Hill HS's Killswitch which came second because they were not allowed to come 1st and 2nd.

If you had a talk to Fred about his maximisers, then you would know why his cars perform really well in low sunlight and not 50%+. Last year Morley came first because it was Fred's daughter's car. We had to settle second, but I'll talk about that later. I reckon Belridge would have came second placed the year if they didn't stuff up the formatting (seeding was correct for the first day) because it was the most closest car to Explora. Last year at the nationals it was evident that Belridge and Morley performed extremely well in low sunlight but got thrashed when the sunlight come out. Belridge still came 3rd, although it lost one of the semi finals because the boys forgot to turn on there car! Idoits! One of the students entered the same car this year but with a different body ; still same chassis and panel. The other cars from Belridge don't seem to work as well because they don't have years of experience behind them. Stephan has around 5years of knowledge to draw upon with Fred Adlers designs! I won't forget to mention that he had the best Belridge panel, although Stephan did make the comment that the panel was getting old. HAHAHAAA thats not the case. I also noticed Stephan was changing gear ratios too, this is because the way there maximizers are set up. The other Belridge cars used DSE like explora but i don't think the student really knew what they were doing.

Last year in the WP finals, Morley and Girrawheen didn't change anything. We did panic because we lost the first round. We won the next and then lost the third. How do you explain that? If you have set you cars perfectly then you wouldn't have to change any gear ratios.(John Jeffery's Solar Model Designs for Dummies 2009). Your maximizer does all that! Even this year, Horizon 3 and Burst Limit our two other cars lost their first race in the competition during the second race in the top 16. After the school won the second race we didn't change anything, nor did they. They had their hopes up! But we hoped for luck/conditions (our cars perform exceptionally well in high sunlight conditions). Then during the 3rd race our cars won and knocked the cars out! Its almost impossible to change gear ratios to suit the conditions. It changes ever minute- second! It all comes down to luck I suppose. If the sunlight was low at Hobart, Morley or Belridge would have came first last year. Even if we raced you for the next hour or two, I reckon you would be trying very hard to get those gear ratios right. Especially because you had to caught up around 1second (4-5meters). Explora as I expressed earlier on, used a 1:6 throughout the competition. There was never the thought of changing it! The only thing we did was check our ballast were still in the right position and all the wheels including guides were freely spinning!

If you want Conitsiotis I will show you a thing or two at the nationals. I'm year 12 so I don't really care, although I wouldn't mind winning the national title like Marc which is a two time national Champion! May I say congratulations. Next year I will be offering my services to Western Power to help students and their schools! But you don't have to trust me if you wish not too. I'm just another azn boy! =] Ive got three years of experience behind me, although it feels like decades. If you get the chance to talk to Fred, John, Marc or even my schools science technician which built a really good car for a private school in 1994 or something then; I advise you to do so because knowledge will allow you to improve your car design! There's nothing stopping your cars to beat us in the nationals! Do a bit more research into your panels. Know it back to front along with your maximizer and gear ratio! Winthrop for example stuffed up there maximizer which effected their performance. According to John Jeffery's (whom I call father of Maximizers) you don't have to adjust it ever day because the difference is so less. Adjust it right the first time with the same panel and it should last for a life time. That is if the panel or maximizer doesn't breaks in the meantime. Horizon 2 had this problem at the nationals last year, where we had to borrow belridges spare, heavy panel! After that our car never seemed to perform as well. Why does it seem like all the scrutineers have a thing for Girrawheen! We're a public school from a low social eco background, it doesn't mean you have to push us to the limits. Fred made us move our panels behind the egg, Uncool although you are allowed to have the panel over the egg at the nationals. Last year John didn't allow us to have a small wattage for the spare panel and therefore we had to use Belridges and not Winthrop's which kindly offered! I'll ask John about this spare panel business because their is nothing in the regulations about the replacement panel having to have more power!

Conitsiotis are you guys changing anything to your design! Hope not, because last year when we made a new car, it never seemed to go as well as the state car! If it works, don't remake a new one unless it breaks. You guys have a track at your school, so try and test the gear ratio before Melbourne. I'm free after next week, so if you want and can organise with your teacher, I can come in and give you guys advise on how you can improve your car. I'll even allow you to have a closer look at Horizon 3 with its new improvements! After all it's all about bring the trophy back to W.A. which has won most of the national competitions! Sorry Marc, we had this thing going on with the W.A teams last year to win!

See you all there!

With regards to Killswitch at the Victorian event: We had a massive crash on the saturday, which broke our electronics, destroyed a wheel, shattered most of the body panels, and dislodged a guide roller. Considering we got it repaired on the saturday night, it did fairly well, and should have got first. We've got the videos of the final race at the Victorian state event, and they show that the Syndal South car would have lost by a bit in a one-lap race. They managed to accelerate almost constantly throughout the race, something which our car strangely didn't do.

Also note that there was a seeding stuff-up at the Victorian event, which will be rectified.

jhg: If you want fast, lean designs, look up the following BHHS cars:

• KillSwitch
• NFG
• Electrical Fault

All are optimised for power-to-weight. We've used the same chassis construction method for the past 4 years, with decent results. It's a bit complicated for starting schools without access to Carbon Fibre or a Mill Drill though.

Jhg,

I cant say i completely agree on your take on the event, with regards to the BSHS cars and such. However the fact still remains that you do have an extremely fast car. I would definatly like to see your take on some particular issues - the correct gearing being one of them. The thing with that however, is that we are using a maximiser that does not need to be manually set - if you have a look around on the site you will see there is some documentation for the Easymax series of optimesers, created by the site moderator TonyB. They use something like MPPT tracking softwear that searches for the panels maximum power output at the start gate (you may have seen my teammmate bend over the car before the start of the race doing this.

However there may be a problem with you coming to ac, as the techie is very secrative with the whole solar car scene - there have been incedences in the 90's where something akin to espionage has happened. Assuming you are staying with us in Melb I will definatly invite you to have a look at whats going on with our cars.

Cheers
C.C

PWK, may I ask how did your car crash? Sounds like one heck of a crash. We had accidents of our own, which were never too difficult to solve. Our cars never crashed but our stopping methods were to brittle for our cars to handle! It is obvious why this was so, if you have a look at Horizon 3. BALSA! Easy to work with, but be prepared to fix it if anything happens.
So for the nationals, we're going to cloak the panel with a towel like Velox did last year.

One of the front casters came off when one of my team members applied downward pressure onto the car when stopping it, which chipped the supporting balsa off. It only took two minutes to repair! Although I did panic because I wasn't sure if I could fix it. Also, the winning car in the W.A competition lost its front guides several times (4), until the boy repaired it properly! They were under serious pressure, especially because in the top 16 they vs. seeding 2. They won by 2-4meters still. After each race against Belridges car, they had to reattach the guides! I know what John Jeffery's would be saying right about now, "I TOLD YOU SO." The place not to save weight on is with your guides!
But hey, what’s the fun without experimenting and taking everything to the edge! Well that is if your prepared for the consequences!

It is understandable why Syndal South PS wouldn't have won the first lap. The main reason I will be suggesting is only one factor! It's weight! 500grams chassis and body alone. I wouldn't like to push start a car which is 2 times heavier than it needs to be! Although it picks up speed slower; a heck of force is required to stop it. Inertia! That’s why Scorpion performed better in the second lap.

I will have to say the most important part of the car is the maximizer! Everyone uses the similar things, design, motor, panels! Adjust your maximizer with the panel the first time correctly and you don't have to panic ever again. Unless it gets damaged of course. Our seeding in the W.P. competition was a bit off the first day, especially with heaps of car taking their cars home and adjusting parts! As you may know, our cars were seeded 1, 3, and 4. So I’m not chasing after speed but I am looking into the ways we can improve their efficiency. I hesitated to allow the boys with the best seeding to adjust their maximizer on the second day because what if something went wrong. I help adjust it and the car went even faster! In the meantime, our cars which were seeded 3rd and 4th seriously need adjusting to theirs. It was evidence that they weren't kicking in at the start for some reason as well as they should. On the second day when we developed a better method of adjusting the maximizers they worked 100% better than they did on the first day! The kicked in straight away, rather than rolling for a meter or two before it start to accelerate faster. If you have your maximizer adjust properly don't fall a victim to readjusting. A clear example is Winthrop B.C. Their car performed extremely well on the first day being 0.2seconds of our 3 and 4th seed. However I think when they saw us adjust our maximizers, they followed because for some reason our cars were all performing exceptionally well. We also made it quite public that we were adjusting our maximizer because we were so close to the track (Not intentional) if you have all this right, you should have a car travelling at a constant speed.

On the other hand, know your panel back to front. This determines the gear ratio; you probably should use. After that, you shouldn't have to change it; even if the sun changes from 100% to 40%. Well that’s from my observations with our cars. John will most probably agree with this as a decent maximizer will do the trick. All our cars use John's maximizer, maybe it’s because his our only source atm.

I have seen most of the Box Hill cars! They all have their advantages and disadvantages! Just use your basic knowledge of physics principals. The question is, which design do you pursue? The internet has many resources and past cars you can copy. So if you build it right then next year you will make it into the nationals. That is if the other cars don't follow the same concepts too. In theory and if properly built, a three wheeler driven by the back will be the most efficient. However if you have a design from four years ago, then keep the idea. In 2007 I had a design like Killswitch. Over the past 3 year which our school has been a part of this competition, we have explored a number of designs. Now we found one. Examine criticise and improve it! That’s what we have done.

Yes, it is a great achievement to get a good power: weight ratio (200). Last year Horizon 2 had 149 (no extra 20% for using a maximiser). However this year our power: weight ratio is still under 180 slightly. In the vic competition the lowest power: weight ratio for cars using maximizer was 185 by Allez - Box Hill (not in the top 8) However Killswitch which placed second had a 190 ratio. Most certainly the highlight is 175 ratio by Skylite by Geelong HS which didn’t us a maximizer but still places 4th. The winning car actually had a power: weight ratio of 213.

No that’s not true. Nothings complicated about this competition. Carbon Fibre can be bought at any hobby shop - if not they can be order it in for you. In 2007 we used materials lying around. However in 2008 we found art craft stress skin materials, balsa and bought foam to make our three designs. This year we did some extensive testing on materials with balsa coming up on top. So basically all of our cars used it. In 2007 we bought a carbon fibre rod which cost $6. We didn’t even end up using it so one of the students took it home. The fibres were starting to split. It wasn't until after the Western Australian Comp this year until I realised carbon fibre isn't bad ($2 increase in price), if you know how to work with it properly. If you save weight here and there it can be as light as balsa. Balsa 1cm*1cm per metre weighs 15grams, while a 6mm carbon fibre rod weighs 21grams per metre. Balsa is also easier to shape and attaches on to anything if you use super glue. Carbon fibre, nothing really glues on well. = [So you have to add nuts and bolts to be sure the bonds don't break. (With my new car I have simply gone with glue-although I do worry about the joints and the carbon fibre splitting). But I know I will not throw in the towel!

Mill Drill? Is that how you make your wheels? We use a lathe. However last year there was a school which used laser to cut their wheels and in fact the whole car. I think it was a Vic school. They entered a similar car this year. Girrawheen SHS is a public school and we do struggle to get our car parts accurate. If you work with balsa, you don't need a mill drill. In fact this year we didn't use it at all! All the materials were recycled. All the holes we needed on the balsa were slowly twisted out using a drill piece. You can use a normal hand drill, although it won't be accurate. For my new design, I do have around 50 holes drilled out to keep the weight down on my aluminium framing.

Many thanks to Marc, for the Vic data sheet of the Cars

P.S - As I said before, I would like to see all yours cars; however i would love it more if you had a look at ours too. We may learn a thing or two from each other! I might write an article in conjunction with John Jeffery later on this year called SMCC-Learning the hard way!

OMG, I hope no-one is getting annoyed with my extremely long posts. I can't help myself!

Conitsiotis... Maybe next year, I will be able to help you when I'm at Uni and not bias towards Girrawheen. They have all my knowledge which they can draw on. Our coordinator's daughter is entering the competition. She will ask for help! So I reckon if you ask early in the year for help, you will get all the advise you need. I will have a demo car ready and will take it to schools to show and tell i suppose. If they have a track they can see how it performs! I reckon there are only a few little details which you have missed out on your car. In practice our set up (4 wheeler - driven by the back) is the fastest! The winning car in NSW and Vic all follow this set up! With both KARO 3 (NSW champ) and Scorpion (VIC champ) having 4 wheels being fixed! Why isn't physic principals not showing its true form. Fixed wheels have so much drag! Conitsiotis keep what you've got. They only won because the quality of the other cars must have been not of sufficient quality as previous years. Sorry if that was mean, but you have to face the fact/ truth. Conitsiotis; I still stand with my opinion of Belridge. However if you can beat them, You will be in the top 8 of that national by far!

I have told Thuy that I'm making myself available next year and future years to come, so when they send out the packages, my contact should be attached also. Me Spy. Hahahaaa. I'm hopeless at that. What is there to spy on! I'm not competing next year and the Girrawheen SHS already knows what their designs going to be for next year. Just change the body and maybe a new chassis to satisfy and obey the regulations.

I was wondering why you guys were putting your cars down and adjusting something. It was a bit annoying. We don't own a easymax. But i think Marc is using one for his demo car. It works really well. However I still prefer the Max4 from John. If you guys have spare cash lying around, invest in one; as you have a track to test it on. Winthrop BC uses the Max4 also! I'll be talking to them also and will help adjust their maximizer if they trust me!

From what I have heard, your school is taking a lot of students? Right? I think were in the same hotel. As I have heard its IBIS (3/5stars) Anyway it should be better than the dorms we had in Hobart last year. We have the same flight bookings, so see you on the plane! If not, ill have a look on saturday and tell what i think about your design. Everything looked right to me. maybe the guides are not in a favorable position?

To be honest i didn't know much about gear ratio at the being. After talking to Marc and John after the WA comp, I realised I did something right without much thought. In 2008 we bought $200 worth of gears for three cars. Next year the school might buy a new set which have smaller teeth. Horizon 3 was using a 5:571 gear ratio instead of 1:6 because we didn't have anymore 12teeth pinion and we don't have a 13teeth (normally a 72 teeth gear but i used a 78:14). Uncool but I worked around it. In fact Horizon 3 could have gone down to a ratio of 1:5 and even at 3pm still perform really well. I suspect you may have changed your gear ratio the wrong way. Your solar panel sets the gear ratio you have to use(revolve around). What was the wattage read you got from Western Power and the max voltage? The maximizer should not effect the decision of the ratio as I have been discussing with John.

In fact Burst Limit may have performed better if the team actually went to a 1:5 gear ratio instead of the 1:6 used.

On another note are you guys ready? You guys have a box to carry it in right. We making a smaller one out of foam so we can take it as hand luggage. Last year I saw the guys throw the Belridge and Morley box around although they had stickers stating they were fragile. Hahahaaa

I'll do some research into the Easymax and post up what i think

jhg,

If you aren't aware, Boxhill are running their own maximisers. These track the max power point continuously on their own many times a second so the units never have to be set up....ever.

The two main other maximisers being used at the moment are the one that you are using, the Engelec, which requires manual setting with a voltmeter and the Easymax which sets up at the push of a button.

All three operate virtually the same if set up properly and this is somewhat where the challenge is.

For the two units that need to be set, once the max power voltage has been located, they can be more or less left alone after that. Below is a chart based on some measurements that Ian Gardner performed with regards to max power voltage vs sunlight %.



Basically, your panel's MPP will not change a great deal unless you start getting down to the lower sunlight percentages.

Where problems can occur is if you begin to fiddle around with your panel temperature. The extra power delivered by a cooler panel may in some cases be the difference between winning or losing a race, but the panel's MPP will change with panel temperature and as a result, the electronics may also need to be adjusted.

This is where, in my view, Boxhill have a real advantage at the moment as they can do whatever to their panels and not stuff anything up.

The MPP will not vary greatly over the course of a race so if the other 2 units can be set up moments before racing they should all, again, give more or less the same result. It's a matter of convenience really.

miseli

Just thought I'd load this up.



What it shows is the torque vs rpm output of both the Faulhaber 2232 6V and the Maxon RE 25 118740 at three sunlight percentages.

The main thing that Ian Gardner was testing here was the effect of the panel configuration on motor output if you are using electronics.

It shows that there is some measurable difference depending on your panel's output configuration. Apart from obviously having a smaller rpm range to work with, the parallel arrangement also appears to consistently have a lower output. From this, it might be concluded that a panel with a higher voltage and lower current may be a slightly better choice for your car.

A higher voltage panel will be also be more suitable for the electronics, as unit efficiency increases when a higher voltage is seen by the motor. For the the higher powered panels, the voltage is up there anyway so this is not really an issue, but for those with lower power panels it will be worth looking at. In other words, a 15V 500mA panel may give a better result than having say a 11V 700mA panel.

Since the above test is based on more extreme circumstances (parallel and series) their differences (if the voltage is high enough to more or less overcome the electronics issue) will potentially only be minor though. Just something else to consider.

At first glance you might also think that maxon's higher torque line will make it a better motor. This is however only really the case at low rpm or when starting a race. You will be at motor speeds higher than this for the majority of the race. Once you get to the higher rpm, they actually perform very similarly. The Faulhaber performs slightly better in lower sunlight conditions and the maxon in higher sunlight. The extra torque that can be seen at 92% is most likely to be all but wasted anyway in the form of wheel spin. Not to mention that the maxon is about a couple of hundred dollars more expensive and weighs an extra 70g or so.

miseli

Just to make things clearer, the black curves on that graph are the T vs RPM for the F2232.

The red and Blue curves are the T vs RPM for the Maxon 118740.
---- In this case, the red curve shows the output with your panel in series.
---- And the blue line shows the output for your panel in parallel

There are a total 9 tests at 3 different light settings. 16%, 50%, and 92%.

During the 16% test with panel in parallel, the easymax is operating with an input voltage of around 7-8 volts, which is outside of its spec. It still functions fine at this voltage, however, it wont store the MPP after power-off. So it needs to be re-set before the next race. We however dont need to worry about this as we are never operating the easymax under 8 volts.

As can be seen from the test results the maxon produces higher output for speeds up to around 7000RPM. The curves later match up, and the 2232 outperforms the maxon. During a typical race using a SX10 panel, a faulhaber 2232 usually reaches speeds near 17-18 KRPM.

If you look at the blue curves, you will notice the torque drops of considerably at around 10000RPM, this is because it the voltage of the motor has reached the panels open circuit voltage, and cant speed up any further.

In summary.....

As Tony mentioned, for starters your voltage needs to be within the operating range of the electronics.

Secondly, the lower your voltage the less rpm range you have to work with and the sooner your drop off will be.

Thirdly, the higher the voltage across the motor, the more efficient your electronics become. To achieve this you need a higher panel voltage. The efficiency starts to level out, so increases will only be minimal from a certain voltage onwards. I posted this plot in another topic a little while ago but here it is again.



If you have a panel made from modules or cells that are putting out high current and a low voltage, then I suggest you go either one of two ways to optimise the performance of your car:

1) Add extra cells to increase your voltage if required. This will mean that you will end up with a higher panel power. This is the reason why so many of the Vic cars have such high powered panels this year, as they are using scorpio cells which are putting out a rather high current.

2) On the other hand, if you want to keep a low power panel you must reduce your current. For this you will require a new set of cells with a smaller surface area.

The segments that Dicksmith used to sell are/were ideal. 10 of these would give you a max power voltage of around 14V and a current of around the 500mA. The new modules that John Jeffery is getting made and selling are basically the same as these but better. These have an improved Fill Factor. John is also looking to get some new ones made where the cell area is slightly smaller and there are 4 cells and not 3 per segment. This will get you around 2V per module with 400 to 450 mA and so then only 8 modules would be required per panel.

miseli

Marc so your suggesting to keep your current low, but increase your voltage?
In 2008 one of our cars got a reading of 5.98watts using 9 DSE cells. We still have this panel! In fact I added an additional module this year so it was our spare panel. So in fact the reading for this panel will be around 6.65watts however with a max voltage of 15volts now? Is this far superior than my other panel of 7.2watts and max of 11.5volts which had more current=less work for the maximizer to do(bumping up the current)? Most of the cars in the nationals 2008 had lower than 12v max voltage which most of their power reading being close to their max voltage but not above. Why did they perform so well? I'll take a crack at it. (The sunlight was close to 100% towards the end, therefore there maximizer were alright?)

There are ways to get around the loss of performance by the maximizer if your using the engelec maximizer with a high current and lower than ideal 12volts. This is why Belridge and Morley performed so well in low sun conditions. I'm sure if you had a look at the graph at the top by miseli, you could probably guess what they actually did!

Thanks Marc for posting up the information