Friday, November 5, 2010
Here is your so what: It is responsible for disconnecting the battery pack from -- everything. With a car battery pack you have this big giant source of energy, Tsunami like energy, and if you don't have a way to disconnect it and a problem arises you will have a meltdown. Think Chernobyl on an automobile scale.
On a good day Bubba connects your battery pack to your car and is capable of carrying enormous amounts of energy. But in the event of a short circuit, which would be a bad day, it will disconnect itself and all will be well.
It's a safety device that will pay for itself again and again. One of these fellas retail for around $1200.
But sometimes you can get lucky and find one for around $800.
Once in a lifetime you can find one for $30.
Yes, Kids, he said, "$30."
Bow down to the Great Ebay.
Saturday, October 23, 2010
...with something fresh off the truck. Especially
<<--- this happy guy. Let's find out what this thingamajig is all about....
The Mechanic reports: "That is an electrically assisted power steering shaft. It connects directly to the steering to simulate hydraulic powersteering except we don't have to use a hydraulic power steering pump."
We'll use instead (yup, you guessed it) Electricity.
And yes, once again this is another treasure found on Ebay. The unit is brand new purchased from dealer stock where the dealer had gone out of business. They retail at $989.
But we got ours delivered for... (cue Hallelujah chorus here...) $27.18.
Monday, October 18, 2010
They look like the kind of batteries you might put in Nintendo DS, or a small flashlight, but they would be overkill for a low-powered device like that. I mean, way overkill.
Like using a firehose to water your lawn.
These were developed by a company in Massachusetts called A123. The product is now manufactured in Hong Kong for A123 (however, I have been told that they are building a factory in Michigan).
But to go back a bit, I found a listing for the batteries on Ebay about 2 years ago, then found out where they came from, which is A123, tried to get the people there to sell to me, but to no avail. They have a strict policy of only dealing with mass producers, so I had to find a creative way to get the batteries to my shop. Long story short I ended up contacting the manufacturer in China and had to show them that I had the experience to assemble the batteries and to protect them from overcharging. So to date, we've brought in several shipments and so far, so good maintaining a good relationship with them.
This type of battery is called a Lithium Iron Phosphate (LiFeP04). It's used primarily in rechargeable power tools like those made by DeWalt or Ryobi, and until recently weren't considered as an option for large scale projects because of cost. There are cheaper options, but the current battery choices they are finding can't be used on a large scale (for big EV projects) because they can't release large amounts of current, or, in worst cases, they go into thermal cascade. Common lithium batteries that are cheap don't last long either; meaning they don't hold a charge long, and they lose their capacity to be re-chargeable.
Okay, so here comes the LiFeP04 which has THOUSANDS of life cycles and maintain their current integrity and... well, make me sport wood.
Anyways, so, I started buying them to make battery packs for people who are doing smaller projects like electric bikes and motorcycles (hence the battery tab welder in the photo above which is holding the battery cells), in order to help pay for the cells that I will need for my project.
Which is to the tune of about 4000 cells (and a cost of about $4800).
(Note: The large car companies that are developing electric cars are using a battery technology called Lithium Manganese Dioxide. Very high energy density but still can't release the amount of current that A123's can safely. Mostly A123's are being used by DIY guys, but it's very cost prohibitive.)
Thursday, October 14, 2010
People make all kinds of stuff out of styrofoam now. It's basically just plastic with a lot of air inbetween. And people have actually been doing for years with other sources of transportation* the same thing that I am doing with the design of this car. Styrofoam covered with fiberglass is light and incredibly durable and it's 11% lighter than aluminum for the same size and dimension.
Durable and light is important to my project because we expend energy trying to move mass, so the lighter something is the less energy we use moving from a dead stop. If it requires less energy to get this car rolling, basically it'll take less energy from my battery pack. The less energy I use then the farther I can go on the limited amount of power that is stored in my batteries.
So where does one get a truckload full of sheets of blue styrofoam...? You can find it at the hardware or other supply stores... OR if you're on a shoestring like I am, once again to the rescue is the online auction where one just needs to search and find it on Ebay.
I purchased a full skid, about 150 9'x4'sheets of styrofoam, for a hundred bucks. I picked it up in Indiana with my wife's F150 and drove it home in a wind storm. The height of it in the bed extended to 12 feet high, and if you need some comic relief I was the guy all over the road that day coming down Rt 30 through Bucyrus tipping like a stack of Jenga blocks. Fun stuff.
PS. As an aside, we also used the styrofoam sheets for insulation in our home remodel (under the kitchen and bedroom walls that we replaced in the CrapShack), and we also put it up to keep the wind out of the shop insulating the bay doors with it. Get some styrofoam today you'll find good uses for it!
Wednesday, October 13, 2010
Assistant: Ok. So, what is it?
Assistant: Just kidding.
Assistant: So. What is it?
Mechanic: Well, it's a close ratio 6 speed transmission out of a 2004 Corvette. Manufactured by Tremec, not GM. (Note: GM is General Motors. This mechanic does not like GM).
Assistant: (typing) How do you spell that....
Mechanic: T-r-e-m-e-c. Tremec. Transmission masters, they are.
Assistant: Ok Yoda. Anything else?
Mechanic: I chose this transmission because there is no driveshaft between it and the rear differential. It allows me to mount this unit directly under the rear of the vehicle with the motor attached directly to it, keeping the center of gravity of the car low to the ground. With the weight of the transmission and the motor it allows me to balance them out with the weight of the battery pack which will run down the center of the vehicle. So basically it allows for good weight transfer between front and rear. Good handling capabilities.
Assistant: Is the battery bank as heavy?
Mechanic: It's a good balance between the battery bank and the drivetrain.
Assistant: Do you like that transmission?
Mechanic: I do. I like it a lot. That Tremec is rated to be able to handle, like, 606 foot pounds of *torque!
Assistant: Cool beans.
1. The moment of a force; the measure of a force's tendency to produce torsion and rotation about an axis, equal to the vector product of the radius vector from the axis of rotation to the point of application of the force and the force vector.
2. A turning or twisting force.