Arduino Fan Control Project

My RC buggy has a brushless LiPo system in it. It can get pretty hot when running bashing hard. The motor tops out at 190F and the battery should stay under 120F. The motor mount comes with 2 pre-drilled fan mounting places which is nice. However I didn't want to wire them in straight and have them run constantly because that would be inefficient and deplete the battery prematurely.

Charging the 6S battery pack on my HPI Vorza

So the solution (which also gives me another project) is to make a temperature control circuit for my Vorza. Having a background in electronics engineering this should be a fun and challenging project.

Here is the scope of the project:

• Temperature monitoring of the motor, battery, and inside the car body.
• Two high CFM fans. One mounted on the motor and one mounted on the car body. The fan on the car body will exhaust hot air created by the ESC and motor fans which gets trapped under the body.
• The fans will turn individually on when the motor and the interior of the RC body reach a TBD temp.
• The battery temp will be monitored and an alarm will sound with a specific series of beeps if it gets too close to over temp.
• The battery voltage will be monitored via the balance connector. A specific series of beeps will alert me of the charge level. 3 beeps for 75%, 2 beeps for 50$ 1 beep for 25%.
• There will be a 7 segment LED panel that will cycle through the temps and the battery voltage.

I plan to use an Arduino Mini Pro for the microprocessor, it's cheap and very small. It will fit into a socket on the circuit board so I can take it out easily for programming changes.

It has more I/O than the project requires, but like I said it's cheap (about $10). I'm designing a circuit board to mount the electronics necessary to switch the fans, measure the temps, and display the processed info. Here is what I have so far. It's a work in progress and I need to change out some of the components for SMD to make it more compact. 

Work In Progress

The circuit board hasn't had the traces routed yet, so disregard the rats nest of lines. I'm using Eagle CAD to design the circuit board. I'm using some fairly basic circuits. So far I have a voltage regulator circuit, 2 relay circuits to switch the fans and some sockets to plug the fans, TMP36 temp sensors and Arduino. 

I haven't figured out how to distribute the power yet. The sensors and Arduino are 5 volts, but the fans are 12 volts. If you have any experience with this please help me out with it.

I found some Sunon fans from Mouser that should be more than enough to keep the motor and interior cool.

The programming should be pretty straight forward, I already have the fan sensor/fan switching code written and working. The next trick is to add the beeps and LED panel code.  

HPI Vorza Update - Thoughts after some time behind the wheel

After having some time behind the wheel of my HPI Vorza Flux I have a few opinions. Some good, Some not so good. The only so far upgrades are 6S Turnigy, 19/46 gearing and a Spektrum DX3e Radio.

First off I think buying the Vorza was money well spent. It embodies my attitude engineered into a RC buggy. It's mean, fast, capable, engineered, durable, and a shit-ton of fun!

Having the D-8 genetics it has a lot of adjustments you would find in a racer. Being a tinkerer, I really like that. I like messing with different set ups that are true racing adjustments. Unlike most racers some key parts are beefed up, I assume to make it more durable, because after all it's considered a basher.

Being beefy also means being heavy. That translates into poorer than usual handling. I have tried many different setups using the stock suspension parts and although it goes like a stabbed rat, it still seems to have under and over steering issues. A lot of that I feel has to do with having lots of power and useless stock tires. I have completely trashed the stock tires and it's time to upgrade to a set of PL Badlands, which seem to be the ipso facto tire choice for the Vorza. I'm sure things will change drastically with a new set of tires.

My biggest complaint with the buggy is how sloppy the drivetrain, suspension, and steering is. I think it suffers from driving accuracy because of it. I'm not sure there is any way to fix these issues without spending lots of money on aftermarket parts. Upgrading the stock steering servo will likely go a long way to tighten up the steering slop.

All that said I love this buggy! I don't plan to race it, I only plan to make it the meanest, fastest, best tuned basher I can. Other than tires and more batteries, I think I'll leave it the way it is and save my money for a racer. I like the new TLR 22-4.

I wouldn't hesitate to buy it again if I had to do it all over. If you are considering getting one, check out all the YouTube videos and decide if it looks like something you would buy. The only advice I have is to buy some replacement parts right away. Drive shafts and suspension parts tend to parish under 6S power. Also a 6S pack tends to make the car heavy on the left side. So maybe do a 4 or 5 cell just to keep the weight even. That might balance the performance slightly.