Packcycle 2.5 (watercooling mods in progress)

[docnjoj]

Hey Link! Any chance your school has a Science Fair? Then maybe you could win a prize (money?) and get some serious recognition for college entrance? Just a passing thought from an old professor.
otherDoc

 

[Link]

Already out of high school.

And I haven't even seen a science fair in 6 or 7 years. None of the schools around here hold any. I don't even know if the high school I was gonna go to before I moved still has them. :?

 

[John in CR]

Already out of high school.

And I haven't even seen a science fair in 6 or 7 years. None of the schools around here hold any. I don't even know if the high school I was gonna go to before I moved still has them. :?

If that's a gauge of what is to come in the US, I'm so glad I got out.

John

 

[Link]

If that's a gauge of what is to come in the US, I'm so glad I got out.

John

Tell me about it. Those were my favorite times of the year. On par with the Monday holidays, even.

 

[TPA]

If I were you, I would do this event:
http://www.shell.us/home/content/usa/responsible_energy/ecomarathon_americas/eco_marathon_americas.html
Since it is near you in fontana california

in the solar category.

I did the gasoline prototype category as my Mechanical Engineering senior project, but since I live in texas it is too far to do every year. The subject of my avatar is the transmission for that vehicle.

 

[Link]

I'd get raaaaped by the teams who actually know WTF they're doing.

Anyway, the batteries from HobbyKing FINALLY showed up earlier this week. I've been busy (read: lazy) up until now, so I'd figure I'd put together my "oven".

After spending like $20 on tiles and springs, I ended up modifying the design so that only four springs and a wood frame were needed. So much for the other $14. :x it's not really an oven anymore, either.

I'm being conservative with the wire, because, as it is, it should be drawing something like 300W from a 12V battery. ABS is a pretty good insulator, so if I get it too hot, one side will char before the other's soft enough to stick on the vacuuform. As you can see, I can very easily add more nichrome in parallel with the existing wires to up the wattage.

I'll add the power wires and try it out tomorrow. I'm going to see if I can't make an attachment to put on the bottom of my table saw to replace the current bag, because, quite literally, more dust is flung out by the air around the blade than actually makes it into the sack.

Oh, and I'm working on getting a CNC router put together, so I may end up using that for something on the bike at some point. I already have some steppers and an almost complete plan in my head, so I just need to learn a bit more about how CAM programs output to the parallel port (or if they can be configured to do it a certain way) so I can put together a basic stepper driver.

 

[docnjoj]

"I'd get raaaaped by the teams who actually know WTF they're doing."

Hey Link! Surprise! There won't be that many teams who have someone who knows more than U do at your age level. Please don't sell yourself short. Also the key word to those "Science competitions" is "team"!
otherDoc

 

[swbluto]

Also the key word to those "Science competitions" is "team"!
otherDoc

Haha! Several of my single-handed victories beg to differ. (Although I'm sure it becomes more important as your peers began to approach comparable levels of reasoning and knowledge as far as is applicable.)

 

[TylerDurden]

Several of my single-handed victories beg to differ.

Self-reliance is a virtue, but not the most efficient one.

 

[swbluto]

Several of my single-handed victories beg to differ.

Self-reliance is a virtue, but not the most efficient one.

Depends on context. In most practical contexts in the real world, as opposed to science competitions, you're right but it seems scientific/mathematical thinking has an element that seems to be more associated with temporarily isolated concentration for breakthroughs, originality and generally deeper results although the works of others do help out.

 

[TPA]

"I'd get raaaaped by the teams who actually know WTF they're doing."

Hey Link! Surprise! There won't be that many teams who have someone who knows more than U do at your age level. Please don't sell yourself short. Also the key word to those "Science competitions" is "team"!
otherDoc

Or give other teams too much credit. There were about 30 teams that entered in 2008 when I went. Only about 2/3 posted a result. Some were not able to complete the course, some never passed the safety inspection.

It is very difficult to build a vehicle from the ground up while attending engineering classes and working 40 hours a week simultaneously. This is the reason for so many failures. My team finished 14th...everyone was too busy to work on the project.

My guess is that if you focused your attention you would do well.

Here are the results of the competition:

 

[Link]

WTF 2,800MPG?

Meh...maaaaybe if I end up with spare time and money, neither I think I'm going to have due to school and this one particular birthday present I'm going to get. :wink:

Anyway, the thing works, but it puts out a lot more wattage than I'd expected it to (well over 500W) and still doesn't even come close to getting the plastic hot enough to bend. I'm debating between adding more nichrome to it now, getting it up to about 1,000W, or redoing the element somehow so I can run it on 120V. I don't trust myself with 120V mains power (even though I'm fine with the 88V+ I'll be getting from the lipos...) despite the convenience of not having to deal with a battery to run it, so I'll probably add some more strands of nicrhome and two more power wires. The 12AWG wires I have now work fine, but they reach like 70°C+, which means they're wasting power and, out of OCD, I'd just rather not have them be that hot. If that STILL doesn't work, I'll probably see what I can do about insulating the thing better. Or mebbe just put it on the barbecue. :?

 

[John in CR]

2800mpg, yes wow, AND it was a high school entry with 2 of the top 3 places. If my high school, class of '78, was like that Mater Dei then the world would definitely be a better place...no oil related wars, etc.

John

 

[Link]

AND it was a high school entry with 2 of the top 3 places

That surprised me, too. MY high school scored the lowest in the district on every standardized test there was. -_-


Anyway, I added some more wires and it should now be drawing around 100A, and figuring both batteries hooked up were probably dropping to 10V, that's about 1,000W. It seemed like the plastic would have melted eventually, but the batteries ran out of juice just as it was starting to soften up. Dammit.

Looks like I'll be sticking to 1'x1' pieces heated in the cooking oven for now. Probably redo this as a more enclosed thing working on 120VAC later. I'd rather not spend any more time on this right now.

Anybody know what that stuff that they wind toaster elements around is made out of? That stuff would really come in handy right now...

 

[dogman dan]

Nichrome wire. Look for pottery supplies and replacement kiln elements can be bought.

 

[Link]

No, the stuff it's attached to. Looks kinda fibrou-*Googles it*

It's mica. At least, that's what it's called, even though it's not always actually mica. To eBay!

Come to think of it, why the HELL did I not think to look that up when I put together the strip heater? I mean, seriously. That took me all of like 5 seconds to find out. What possible excuse could I have had for not doing a search for "heating element insulation"? Seriously...I'm like..."WTF is my problem" right now? This is going to be one of those minor things that I can't quite forget about for years, I know it.

 

[TPA]

I think your typical hot plate runs on about 1000W, and the coverage area is smaller.

Another point is that a hot plate has a higher element density/area than you are using.

maybe more strips and a little more juice?


And yes the mileage is high. The record in the European event is somewhere around 12,000 mpg equivalent. The strategy is to use the engine to get up to a speed and then coast.

 

[Link]

I think your typical hot plate runs on about 1000W, and the coverage area is smaller.

Another point is that a hot plate has a higher element density/area than you are using.

maybe more strips and a little more juice?

For now, I'll stick to small pieces and the cooking oven.

Once I get that mica stuff in, I'll probably try it on around 1,300W. If that doesn't work, I'll reduce it to a 1'x2'.

12,000 mpg equivalent

wat

 

[aaronski]

Hey Link,

I'm new to the forum and found your backpack in this thread intriguing. how hot does the battery/controller get inside the backpack?

I read to the end and thought, perhaps a hotplate and a heat spreader like baking dish might spread out the heat and last long enough to soften the plastic.

Thanks,
Aaronski

 

[Link]

I'm new to the forum and found your backpack in this thread intriguing. how hot does the battery/controller get inside the backpack?

Batteries are stone cold. Controller's warm-ish, probably because the batteries are sinking a lot of heat out of it. Plus, even if it is an enclosed space, the mesh of the thing's weave isn't particularly fine, so there's at least a small amount of airflow through it.

I read to the end and thought, perhaps a hotplate and a heat spreader like baking dish might spread out the heat and last long enough to soften the plastic.

Possibly, but I'm thinking that's way too great of an effective surface area increase for any material to spread heat around evenly enough to avoid charring at the heat source, save for, perhaps, a flat heatpipe. And the problem is mostly that 2ft^2 of surface area just exposed like that is capable of convecting quite a bit of heat to air. Looks like I'm going to have to make it an actual box instead of just...uh...the sides of a box.

Oh, and my grandma basically ran over the thing. It's all bent now. Oh well, I was gonna take it apart, anyway. Deal with that whenever the mica gets here.


You know, now that I think about it, I wonder if the "HC" addendum on the plastic's title has something to do with it working at a slightly higher temperature than normal ABS, because I noticed that the beige plastic sheet was more difficult to bend on the heat strip (need to re-do that too, I think) than the black stuff...

Also I'm feeling semi-lazy because it's almost 6AM and I only slept from about 11:30 to 3 because it's too damn hot in here. I woke up sweaty and pissy, and am not really in a mood to go look for a DC/DC capable of turning wattage from a 44-88V battery back (yes, adding a relay system to the packs) into 12V and, say, 5A to power the fans, pump, and temperature monitor. Anyone care to do it for me? :wink:

 

[Link]

It took me like a half-hour of winding nichrome around a rod of aluminum before I figured I'd see if it'd fit in the chuck of my drill. It did, so half of it took 30 minutes, the other took 5 seconds. FFFUUUUUUUUUUU-

Oh well. That's two 20Ω wires in parallel (10Ω total), so it's a 1.2kW element on 120V. No time to enclose it in anything today, so I'll have to leave that for tomorrow. Need to find a switch and some metal screen, anyway, so no problem.

Now, what to do with that little 4Ω piece I have left...

 

[John in CR]

Now, what to do with that little 4Ω piece I have left...

Save it for a foam hot wire cutter tbu at a later date.

John

 

[Link]

Would, but I don't think I can straighten it out enough to use as a cutter. Not that I'd get rid of it anyway, pack rat that I am...

Lazy self got around to Home Depot and picked up a plug and some butt splices (easiest low-current connections ever <3). Loved how easy the plug was to use. Insert wire in insert. Insert insert in housing.

It heats plastic fine, but I couldn't get it soft enough to put on the vacuform because I couldn't pin its edges down hard enough with my hands to keep it from sagging into the oven. Well, I could, but then I'd have issues with getting it OUT and avoiding the very hot element with the 120V of potential across it. Forgot to get some steel screen to cover the thing with when I was at the store. >_<

The lighter-gauge cord that feeds it gets a little hot, but not very. Only about 110°F, I'd say. Same for the plug.


Regarding the actual BIKE, I think I'm going to ditch the idea of having everything on it. It would simply kill the stealth, which I kinda value. Plus, if I just put everything in a box in a backpack rigged up specifically to allow the radiator to vent out the side, that's WAY easier when it comes to figure out how to mount everything inside. But what about the tubing, you ask? Well, during my perusal of PC water cooling products, I happened across some special fittings that could be disconnected and reconnected without dumping everything out of the loop. They were expensive, but this bike's already cost me WAY more than I had initially planned, so WTFN.

Ah, here they are. Yeah, even for the cheap ones that spill 1-2ml per disconnect (the good ones supposedly leak 0.2ml), it'd be like $30 for a set. :? Blah...

http://www.koolance.com/water-cooling/default.php?cPath=103

 

[Link]

"Even heat" is not the proper word to describe this.

I suspect the problem could be solved with a piece of wood over the whole thing, but I don't have any 24"x24" pieces handy and can't afford to go get any until Friday.

 

[liveforphysics]

Have you thought of just tossing a heat gun or hair dryer into the box? You would get strong air movement to create more even heating, and easily 1500-2000w of heating.

Otherwise, I think sticking a fan in the box to blow across your heating elements is the way to provide the even air temps you are looking for.

Best Wishes,
-Luke