This is what will power the bot. These booster packs from Harbor Freight have a 17ah SLA deep cycle battery in the. And with the coupon, they were $37.99 each. That is about what I can buy just the batteries for online.

I cracked them open and took out the batteries. I may use some of the other components in this project.

The radio set also came in today. I mounted the receiver in the control box with double sided tape. The two antenna leads are supposed to stay 180 degrees apart.

The motor controller and wheels came in today. I started off by taking the wheels apart so I could clean and paint them.

As planned, I tapped the bottom side of the heatsink to mount the motor controller. Whatever this aluminum is, it is almost impossible to tap. I also mounted some switches to turn the unit on and off. One will control 24v power and the other will be a disconnect between the batteries so I can use a 12v charger on them.

Still waiting on parts, but I made a little progress this afternoon. For safety reasons, new mowers have a brake that stops the flywheel when you stop the engine. For my application, I decided to remove it. Inside the brake mechanism is the kill switch. I cut the wire and ran it out of the cover to control it remotely.

Here is the brake/kill switch mechanism. A cable normally runs from this to a lever on the push handle.

Here it is put back together without the brake; you can see the wire coming out that will run to a remote switch or relay. This wire kills the ignition when it is grounded:

I decided on a new mower instead of a used one. I wanted a clean working surface, and people around wanted new mower prices for junk. I found this one at Wal-Mart for $138. I know it isn't the best, but should last forever mowing my tiny yard. I really wanted an OHV motor, but settled for the flathead engine mostly because of price.

When I got it home, I started taking it apart. Another reason I chose this mower is because of the flat surfaces on the front and back of the deck. This made mounting the front swivel wheels pretty easy. The wheels are 4" solid rubber from Harbor Freight. I wanted the 5" version but they were out.

The wheel mounts are made from what used to be a 19" telco rack. I went with aluminum because I want to add as little weight as possible.

I am starting this blog to document the progress on my R/C lawn mower.

At this point, I have started collecting parts; from eBay and other sources. I started the project after finding a deal on two power wheelchair motors. The ones I found are from Invacare.

They didn't come with wheel/tires, so I found a set of 5/8" shaft wheels. I am not sure if these will end up on the final product, but these were cheap.

At this point, I started looking into the electronics. I noticed that a lot of the projects I found online used a Sabertooth 2x25 motor controller. My motors only draw 3.3a, so I decided on the 2x12 R/C version. It is a simplified motor controller that connects straight to an R/C receiver.
http://www.dimensionengineering.com/products/sabertooth2x12rc

Since this will be a zero turn style robot/mower, I wanted a tank style radio with two joysticks that return to center. Most of the ones I found had a lot of features and channels that I simply didn't need. After a little research, I found a budget friendly radio system that uses 2.4ghz. It is made by GWS; and since it is made for robotics, it has dual joysticks that auto center. And I like that it has the feel of a game controller.

I wanted a way to keep my electronics out of the elements, but also provide cooling for the motor controller. It has a metal bottom and is designed to be mounted to a heatsink. So I came up with this; I took a Pelican case I already had, cut a hole in the top, and mounted an old AMD CPU cooler to it. The motor controller will mount to the bottom side of it, and it should keep it nice and cool. All of my power connections, motor controller, and receiver will be inside this waterproof box.