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My DIY Battery Powered Cooling Fan


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Well basically I got tired of how hot my bike got while riding in tight trails. I see some people recommended going to a different type of coolant, but I didn't feel that would really help things if the radiators simply can't get rid of the heat fast enough - because you're not traveling fast enough.

The idea here was to do things on a budget. The official Honda fan kit is around ~$350, but wouldn't fit my bike anyways as they are designed for the 250X/450X not a 2002 450R. I scrounged up what I had around the house and kept what I had to buy down to a minimum:

The fans I chose are 92MM Vantec Tornado computer cooling fans. Your average computer fan moves about 20CFM of air - these move 119CFM. They cost about $13 a piece not including shipping from newegg.com.

One thing I had to consider was how was I going to power them? A stator kit cost around $120, so that was far out of my budget. So I had to go with battery power. Alkalines were out of the question as these fans suck down a lot of power, and would kill them in no time. So I definitely was going to go with rechargeable. I decided to go with Lithium-Ion batteries, as I had a flashlight and charger that already used them and they store more power per given size and weight then NiCD or NiMH batteries.

I remembered that I had a few years old Dell Laptop battery pack lying around - its built in controller had failed rendering the pack useless to a laptop. However the battery cells inside of it were still good. I gutted the controller out, and re-wired the 6 4.2v cells inside the pack so that I had 3 batteries in series for 12.6 volts - in parallel with another set of 3 cells - to increase my total capacity. I also put a tap after two cells in a series so I could get 8.4v for a low speed. I soldered everything up to a standard computer 4 pin Molex connector to make things easy to connect.

Unfortunately I had bought two fans with the original intent of putting one on each radiator. Well putting one on the left er shifter side? radiator at least on an 02 is next to impossible. Honda chose to run every single piece of cooling system hose and T fittings right infront of that radiator.

But both wouldn't fit on the right side radiator either without seriously kinking the upper radiator hose(excuse the slightly bent radiator - got it that way)

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It does however look like if I have a radiator shop turn the upper radiator nipple to about a 40* angle, the hose will clear the second fan just fine:

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Decided to just run one for now, i'll see how it does and decide if the second is necessary.

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Here is a shot of the wiring. You can see the battery pack just zip-tied down for now. I haven't had time to "pretty up" the bracket I made for the switch yet however. You'll also notice a little extra white connector resting against the fork tube, this connector has battery voltage on it at all times. I may use it for some kind of lighting system, or whatever runs on 12 volts really. Don't ask about the skeleton guy, he came with the bike.

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Shot of the bars and switch: down is low, middle off, up is high. Like I said, the switch bracket still hasn't been prettied up, and I'm still trying to decide how I want to mount the battery pack.

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I haven't had time to take it for a ride yet to see if one fan is enough to keep it cool when going slow, or judge run time before the batteries go low. In theory though, I should be able to get around 3-4 hours of run time on High, and a little more on low.

I'll post up some videos of how loud it is, and how effective (at least at idle ) the fans are.

(on a side note: I noticed the fan blows hot air right towards your leg:bonk:, might be useful in the winter though:thumbsup:)

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There is a metal grille between the fan and the radiator. I've sat there idling and let my multimeter get upto 200*F before and the fans showed no signs of melting.

Remember that in computers, its not uncommon for processors and graphics cards to get in excess of 100*C/212*F

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Maybe you could use some of that 3M super tape stuff to hold the battery pack to the frame with. I forget what it's called but it's gray and kind of thick. After a couple days to flow that stuff holds on like a mother. That's what I use to hold my aftermarket coil on with that wouldn't fit the factory mounts. It has never even come close to loosening up. In fact during a recent rebuild it was quite a task to rework it but I eventually realized it comes off OK if you twist on it.

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That 3M stuff is what they put emblems on cars with. Not a bad idea. Id think about looking for a spot under the seat for the battery. If you really wanted to get tricky about it, you could put it inside the seat under the seat foam...

Get a tiny micro switch for the on/off. Or even a thermostatically controlled switch. On at 200, off at 180?

what you could do also is mount the fans to the shroud with a little plastic duct to the rads, then they'd blow out at an angle a bit and not right on ya.

Ya know, a lighting coil would run those things incessantly...that would be trick for Off Roaders and trail guys that like to plunk along at 2 mph over rocks and roots and shit.

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Ya know, a lighting coil would run those things incessantly...that would be trick for Off Roaders and trail guys that like to plunk along at 2 mph over rocks and roots and shit.

I've kinda wanted to try this forever. The right switch mode AC -> DC converter/regulator (similar to a computer power supply) might even do it's thing to power some 12VDC fans and lights with lighter weight components than a battery. Weight is always the sticking point for me converting to a DC setup and it's all because of the batteries. Although using a high power density/ weight ratio laptop battery is a clever idea. I always thought in terms of lead acid which are pretty heavy in the street bike sizes. If anyone knows a good regulator which could be uised without a battery they oughta post it up.

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You can get an off the shelf regulator and rectifier from TT. Its right in the catalog.

http://shop.thumpertalk.com/catalogs/Tucker_Rocky_Offroad_2009/default.asp?p=753

Its all right on this page. Including a NiMH batt pack. But 3700mAh aint much.

You could use a big capacitor to do the same thing though. Its just a damper really to absorb and deploy spikes.

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As for a toggle microswitch, didn't have one handy. I had that nice double throw single pole toggle though so I could run high/low. I had also considered getting thermostatic switch, but I had no place to really put it anywhere. These radiators don't have provisions for one like the X's do.

One thing about the battery though is that it needs to be easily removable for charging. I was thinking about making up some kind of bracket that uses thumbscrews for easy removal? If i ever do decide to get a lighting coil, I'll definitely be converting the fans over to that.

These 92mm Vantec Tornados do move a ton of air though.

In this video I'm just making sure the switch and my wiring actually works.

http://www.youtube.com/watch?v=Dv1nSH-OlEg

In this one I have the temperature probe of my multi meter stuck into the radiator about 3-4" above the fan itself. Temperature is in *F

EDIT: Guess the youtube tags don't work?

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Hmm there is nothing in the Trailtech instructions indicating that you cant't just run that regulator/rectifier external batteryless/capless. The schematics do show where to put it if you do have it but nothing says it's required. I'll have to emaill them and verify. If you just get an unstable but still DC voltage with no cap/battery it wouldn't matter much in my case as long as the fans always started up moving consistenly. The lights might be percieved as slightly dimmer and the fan would move a little slower if the voltage weren't a steady 12V but as long as it stays DC and they still consistently start up the fans wont mind. The dimmer light/slower fan effect could be compensated for with more powerful bulbs and faster fans if it turned out significant.

I might have to order one depending on what Trailtech says. Even if it does require a sufficiently small/lightweight aluminum electrolytic external cap it might still be worth it. I have enough power to run some fans along with my lights.

I guess I've just always assumed there would need to be some big bulky battery for a decent DC setup. Now I'm reconsidering. Some of those overclocker super turbo tornado computer fans would practically turn my crf into a camper special. haha.

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Lithium batteries are awesome. My pack weighs in at under a pound and in theory could provide 55 watts of power for an hour straight (the batteries aren't new so they don't have maximum capacity anymore).

If I were to add a lithium battery (or replace a lead acid battery with a lithium) to a system with lighting stator, I would try and find one that is designed for that application - one that has built in charge/overvoltage/overcharge/undercharge protection. Also try to put the battery in the safest most protected place you possibly can. The last thing you want is a punctured lithium cell.

Actually just found one: http://www.orientexpress.com/product_info.php?products_id=16833 Cost quite a bit though, but may be just the solution for people looking for light weight alternative to a lead acid battery.

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Oh so you're using lipo batteries? I used those so much in RC so I've got some laying around.

I'm using Sony 18650 Li-Ion cells. Li-Po cells would work too.

Street bikes coolant Sensors come on at 220f an turn off at 210f. IMO engine ice is a lot cheaper! Riding faster works wonders too.

Your bike may be running a little lean and hot?? Fix the problem, not the symptom.

I'm an average rider, some of the trails around here are very tight and you need to keep your speed down. Trying to get the bike unstuck from something, like mud or sand is also where the fans will come in handy. Another benefit now is that you can actually let the bike idle - as shown in my video the fan will easily keep idle stationary temperatures under control.

That is very useful for me as I often stop to wait up for riding buddies or stop to discuss where to ride next. It can be a hassle to start this thing if you have to kill it every time you come to a stop and your legs are a bit tired

As for cost, I have about $30 into this project total. Would have been only about $15 had I made sure both fans would have fit before I bought them - and I still have the option of making the second one fit if I feel its necessary.

@xxXXDeathXXxx; it looks like you can make your own for a fraction of the cost: http://www.r6-forum.com/forums/showthread.php?t=103556. Those cells go for about $8 a piece, and you'd only need 4 of them for just running lights and stuff on a 450r.

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nice idea, those are some powerful little fans! i could see it killing the battery fast though... but i could be wrong, let us know.

Are the rans sucking air through toward the back of the bike or blowing it forword? If blowing toward the front of the bike it posibly could have a uneffecient effect while moving vs having them suck air through and blow it out the back. also to mount that top fan, build a little frame around the hose to bump the fan out and still get good cfm's.

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I have been contemplating doing something like this, but I have a lighting stator that really doesn't power anything during the daytime. I usually just unhook the lights during the daytime and ride until dusk and stop (due to riding buddies that don't have any lighting....). I have seen some fans on ebay in the thirty dollar range and there are a couple of options that I have seen too. I am assuming and going with a fan that pulls air, but I am always up for suggestions due to the bike having an extended range and I just need some more cooling! I am running engine ice, bike is jetted good and I still overheat in the tight stuff. Sorry about the hi-jack!

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nice idea, those are some powerful little fans! i could see it killing the battery fast though... but i could be wrong, let us know.

Are the rans sucking air through toward the back of the bike or blowing it forword? If blowing toward the front of the bike it posibly could have a uneffecient effect while moving vs having them suck air through and blow it out the back. also to mount that top fan, build a little frame around the hose to bump the fan out and still get good cfm's.

The fans suck air through the radiator and blow it towards the rear of the bike. So any natural movement of air through the radiator gets assisted by the fans. Never thought about making some sort of shroud for the second fan. I'll have to see if I can make it fit.

As far as battery life goes, I should be able to squeak out at least 2-3 hours on high. More on low. The fans will only need to be running when I'm not going that fast anyways.

I have been contemplating doing something like this, but I have a lighting stator that really doesn't power anything during the daytime. I usually just unhook the lights during the daytime and ride until dusk and stop (due to riding buddies that don't have any lighting....). I have seen some fans on ebay in the thirty dollar range and there are a couple of options that I have seen too. I am assuming and going with a fan that pulls air, but I am always up for suggestions due to the bike having an extended range and I just need some more cooling! I am running engine ice, bike is jetted good and I still overheat in the tight stuff. Sorry about the hi-jack!

As long as you have a regulator that puts out 12-14 volts DC then the fans would run happily off that.

These 92MM vantec tornados are a good compromise for size, air flow and price. For about $12 a piece they are a good deal.

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