The EV Grin
My second Electric Vehicle project drove out of the garage today, and proceeded to drive around the section, including up and down some real hills.
OK, so I didn't really build it - it is actually an old Ransom park mower which I picked up for $200 on Trademe. At one time it had three electric reel mower decks slung from it, but they are long gone. Also missing were the batteries and the electronics off the speed pedal. However, it did have the main travel motor and other running gear intact, along with all the wiring and controllers.
In good ghetto-tech fashion, I first connected it directly to my "Franken-welder" MIG welder (with full capacitor bank) since that thing is basically a big transformer and rectifier, and it puts out about 50 V. Amazingly, all the lights came up and the electric steering worked.
A little research and I found the electrical schematics for both the mower and the off-the-shelf Curtis motor controller it uses. With the help of these, I took an educated guess at the missing speed pedal module, and hacked one up with a knob, a switch and a 7805.
With hacked speed controller in place, the Franken-welder would now spin the (jacked up) wheels! Success, although I wasn't going far any further than my extension cord like that, and besides, I didn't want to put any load on it with only the welder to power it.
Today, I purchased 4 car batteries for $200 - they are new, but old stock (hence the low price). I also spent another 100 or so on battery terminal clamps, and wired it all up. And away it went - woo hoo!
So it's only a ride-on mower, and the top speed is not much more than a sedate jog. But I still gave me a smile to take it for a spin up and down the drive! It's also an interesting thing to drive on hills. The "gas pedal" (currently a knob) is actually a genuine speed control - the Curtis controller senses the motor speed, and adjusts the power to keep the speed constant. This even applies when you start going downhill, as it applies engine braking. It works so well that you can almost stop on a slope without using the mechanical brake (it always creeps a bit). The steering is pretty cool, too - it has a little motor and gearbox to swivel the back wheel, and the steering wheel operates it via some electronics. It's sensitive to how fast you spin it, like a computer mouse.
It's neither fast nor practical as it is, having no suspension, crazy rear-wheel steering, and a very heavy frame. However, I think I could build something fun with the parts. I think maybe a three-wheel ATV which could trundle around the forest here. It doesn't need to be fast or have a huge range for that sort of work - we use a Polaris ATV at the moment, but a typical trip is only 5-10 minutes.
If I add a solar panel to the shed roof to charge the batteries, it could be a self-contained, low maintenance utility vehicle!
OK, so I didn't really build it - it is actually an old Ransom park mower which I picked up for $200 on Trademe. At one time it had three electric reel mower decks slung from it, but they are long gone. Also missing were the batteries and the electronics off the speed pedal. However, it did have the main travel motor and other running gear intact, along with all the wiring and controllers.
In good ghetto-tech fashion, I first connected it directly to my "Franken-welder" MIG welder (with full capacitor bank) since that thing is basically a big transformer and rectifier, and it puts out about 50 V. Amazingly, all the lights came up and the electric steering worked.
A little research and I found the electrical schematics for both the mower and the off-the-shelf Curtis motor controller it uses. With the help of these, I took an educated guess at the missing speed pedal module, and hacked one up with a knob, a switch and a 7805.
With hacked speed controller in place, the Franken-welder would now spin the (jacked up) wheels! Success, although I wasn't going far any further than my extension cord like that, and besides, I didn't want to put any load on it with only the welder to power it.
Today, I purchased 4 car batteries for $200 - they are new, but old stock (hence the low price). I also spent another 100 or so on battery terminal clamps, and wired it all up. And away it went - woo hoo!
So it's only a ride-on mower, and the top speed is not much more than a sedate jog. But I still gave me a smile to take it for a spin up and down the drive! It's also an interesting thing to drive on hills. The "gas pedal" (currently a knob) is actually a genuine speed control - the Curtis controller senses the motor speed, and adjusts the power to keep the speed constant. This even applies when you start going downhill, as it applies engine braking. It works so well that you can almost stop on a slope without using the mechanical brake (it always creeps a bit). The steering is pretty cool, too - it has a little motor and gearbox to swivel the back wheel, and the steering wheel operates it via some electronics. It's sensitive to how fast you spin it, like a computer mouse.
It's neither fast nor practical as it is, having no suspension, crazy rear-wheel steering, and a very heavy frame. However, I think I could build something fun with the parts. I think maybe a three-wheel ATV which could trundle around the forest here. It doesn't need to be fast or have a huge range for that sort of work - we use a Polaris ATV at the moment, but a typical trip is only 5-10 minutes.
If I add a solar panel to the shed roof to charge the batteries, it could be a self-contained, low maintenance utility vehicle!