Quick Tech Hobby

Newbie RC Project Part 2: ESC From Alcatraz

 

Why Won't it Run?

By Chris Sterling, Resident RC Rookie

Welcome to the second installment of the "Newbie RC Project." The focus of this segment is the installation of electronics onto a Team Losi XXX-T. The article also includes tips from myself and Bill Jeric, Horizon Hobby's Surface Brand Manager (and all-around car guru). We've also included some expertly produced, professsionally directed, and maticulously edited video for your enjoyment. Enjoy!

The leads have been soldered to the motor. They're never coming off.

The Good, The Bad, and The Ugly
Like every great Clint Eastwood movie, my attempts to make my newly constructed XXX-T move on its own were filled with drama, heartache, confusion, and finally, success. Once the construction is complete, installing the electronics is pretty much smooth sailing. You just have to know what you're doing. I didn't.

My "It's all good" attitude came to a screeching halt once I finished building the XXX-T. Proud, cocky, and clueless, I viewed installing the electronics as if I were putting batteries in a smoke detector. That was bad. Whenever I underestimate a project, I don't plan for speed bumps.

Although building the car was more time-consuming than difficult, actually getting the thing to run was a different story. It was kind of ugly. I was like a nameless Clint Eastwood character in a new town-something bad was bound to happen. My problems weren't due to any kit design flaws or faulty product; they were due to my ignorance.

The Rookie
I was back to square one with installing the electronics-I had no idea what I was doing. Clint is usually clueless about what's going on in his movies, but he always comes out shooting. Likewise, I was armed, dangerous, and perplexed. The Internet and a few co-workers were instrumental in helping me to figure out what I would need.

Here is what I used to make it go:

· 6-cell battery pack
· Electric motor
· Motor wires
· Battery charger
· Transmitter w/receiver and servos
· Electronic speed control
· Pinion gear
· 8 "AA" batteries (for the transmitter)

I went with a 2500mAh Ni-MH battery pack and a Trinity Green Machine. I figured if I'm going to do this, I want some power. But since, I had nothing to compare the driving experience to, I guess it didn't matter what I put in the car. Maybe I'm just a sucker for clever advertising.

As much as I've read about Ni-CDs and Ni-MHs, I still don't get the whole deal with charging. Checking the battery every so often to see if it's warm just doesn't seem scientific (or practical). To allay my fears, I got a Dynamite® Vision Peak™ Plus. It seems to work pretty well and stops charging before the battery gets too hot (I think).

Unbeknownst to me, battery packs are not charged at the time of purchase. Some of the knowledgeable people around here seemed to get a kick out of this. Again, this goes back to the whole smoke detector analogy. When you put the batteries in, smoke detectors work - at least you hope so. Upon plugging in the battery, nothing worked. I thought maybe the ESC was broken. After a short conversation with someone who knew what they were doing, I charged the battery and, like magic, everything turned on. It went something like this:

All necessary electronics have been installed. The next step would be to tie any loose wires together.

Me: I plugged in the battery and nothing works.
Them: Did you charge the battery?
Me: No, it's brand new.
Them: You need to charge the battery.
Me: But it's brand new.
Them: You need to charge the battery.
Me: Oh.

Everything was cool until two days later when I turned the car on again and nothing worked. Thinking I broke it somehow, I found myself in a very familiar conversation.

Me: I plugged in the battery and nothing works.
Them: Did you charge the battery?
Me: Yes. Two days ago.
Them: You need to charge the battery.
Me: What?!
Them: You need to charge the battery.
Me: #%@*!

Apparently, battery packs discharge whether or not you're using them, more so if you use them, of course.

After this ordeal, my other issues didn't seem as dire. The first pinion gear I used not only had the wrong number of teeth, it was also the wrong pitch. This didn't vex me as much as the battery issue and only required ordering the pinion gear I had originally intended to order. The battery lead must be getting to my brain.

 

Adjustment and Tips

The (finally) completed kit-- and it actually runs! Don't believe me? Watch this short video (2 MB, QuickTime) and see for yourself.

Every Which Way But Loose
R/C cars need a lot of tweaking. Everything from the chassis to the tires can be adjusted. The setup doesn't stop there. Electronic components are just as important. Consumers can choose different speed controllers, sizes and capacities of batteries, receivers, motors, and servos. Since I'm only slightly more advanced than a casual RTR driver, I just tried to get everything to work properly.

The motor did not come with wires so I scrounged some up from our R&D department. I had the choice to either use prongs that hold the leads in place or solder the leads onto the motor itself. I knew I wasn't going to be responsible with the XXX-T, so I chose soldering. It wasn't very hard to do, and now I don't have to worry about loose or disconnected wires.

When I first successfully turned the XXX-T on, the wheels faced to the left. I fiddled with my JR XR-3 for a minute and trimmed it out so the tires were straight. When I attempted to drive it, the car wouldn't turn left. This was my first lesson on digital trims. As nice as this function is, it doesn't compensate for poor servo installation (read: user error). After a few tries, I got the servo in the correct position and didn't need to trim it.

Unforgiven
I assume that some people, like the Matt Francises of the world, are born with an innate sense of how R/C cars work. They don't need instructions. They can build entire kits in 30 seconds by the light of a firefly using only one hand and a sharp stick. I'm not bitter, I'm just jealous. I still don't understand how one determines the size of pinion gear needed just by the type of engine used. And I'm still puzzled about how a battery can discharge without being used. I guess I should just chalk it up as another great mystery of the universe, right next to the extinction of the dinosaurs and "The Bridges of Madison County".

And as I drive off into the sunset, dusty and battered, I try to imagine what Clint Eastwood would say if he were in my shoes. The more I think, the more I realize that he wouldn't say anything. He'd just assess the damage and move on.

Chris's Tips for Installing Electronics:   Bill Jeric's Tips for Installing Electronics:
· Charge the battery pack before every use: somehow it dies on its own.

· Tape the electronic components down: loose wires tend to get pulled into moving wheels.

· Install the servo properly: a little trimming is okay; a lot of trimming makes the car go in circles.

· Use the correct sized pinion gear: your spur gear will thank you.

· When using the motor for the first time (and any other time), turn the transmitter on first: otherwise you risk damaging the ESC or the motor.

· Make sure you have lead wires for your motor: some, like the Trinity Green Machine, don't come with them.

· Solder your leads to the motor: bumps and jumps can loosen and/or disconnect non-soldered wires.

· Put protective coverings on the car before running: dirt and water are not friendly to the engine and gears.
 		  · Most of today's motors from Trinity, Reedy, Peak, etc. have internal capacitors installed at the factory. However, many RTR and entry level motors don't. Make sure to have 3 .1 microfarad caps soldered on your motor to prevent interference.

· Use good servo tape. Losi and Novak both make a super "spongy" servo tape that helps to isolate equipment from vibration. Use it for both the receiver and Speed Control.

· Always use good solder, 60/40 resin-core is recommended. NEVER use acid-core solder.

· When mounting your receiver, make certain that the antenna does not touch any graphite material. Use a piece of antenna tube or fuel tubing to keep the antenna off of any graphite surface.

· Never allow your electronics to get wet.

· Bundle all wires neatly using wire ties.