The Solectria Sunrise
The Sunrise EV2 Project Homepage
Welcome! We are a group of dedicated electric vehicle enthusiasts whose goal is to create an affordable, high performance electric kit car that anyone of modest skill can assemble. The Sunrise EV2 is a four-passenger pure electric sports sedan, designed to meet all the safety, performance, and comfort requirements of a modern state-of-the-art automobile.
The original Sunrise was designed by Solectria Corp. using the Hypercar principles of Amory Lovins. It achieved remarkable efficiency and range, through the use of lightweight construction, innovative design, and superb aerodynamics. Unfortunately, only a handful were produced.
We bought the last unfinished Sunrise from Solectria CEO James Worden. It is being redesigned as a kit car, along the lines followed by manufacturers of light plane kits for the EAA (Experimental Aircraft Association). The steps are:
Our goal is to make the Sunrise EV2 as modular and open source as possible; like a PC clone, where many different parts can be used, from many different vendors. We'll provide the basic "box". Builders can then use any motor, controller, batteries, charger, interior, and instrumentation they like. Depending on your budget and performance requirements, your Sunrise can be AC or DC, lead-acid or lithium batteries, etc.
We look forward to having a community of Sunrise EV2 builders, where members can exchange ideas, buy/sell/trade parts, and assist others in building their cars. Check this website out occasionally to see how we're doing.
October 6, 2013: A Lincoln Mark 8 parts car has been stripped and
flipped. We removed the parts that will be used in the Sunrise
(front and rear subframes, brakes, steering, doors, etc.). It was
then cut in half, shortened 9" (to the Sunrise wheelbase), and
welded back together. It was then flipped on its roof to make
working on it easier. It will now be used to make molds of the
suspension mounting points and wheel wells. This mold will be used
to make production composite Sunrise EV2 chassis.
Other recent updates:
In this section, I'll be regularly posting EV tips and techniques to save you money, find parts, measure performance, and improve your EV. As new ones appear, the old ones will move to the Lee's EVs page. Purchases contribute to the Sunrise EV2 Project. If you like what you see and want me to write more of them, please click the "donate" button below. :-)
High Voltage DC Relays and Contactors
You may have noticed that when you open a circuit (with a switch, relay, contactor, connector, or whatever), you get a spark. A little arcing is inevitable. But if it is not limited, it will shorten the life of the switching device, or even destroy it and leave the load still powered!
Switches, relays and contactors have voltage and current ratings, either printed on them, or listed in their data sheets. They can be pretty confusing! For example, here are the ratings printed on a Potter and Brumfield T92S7D22-12 relay:
Even more ratings are provided on the data sheet. But you don't need to be a contact engineer to understand all of this. It's sufficient to learn the basics, so you can pick a suitable contact for what you want to switch.
UL, CSA, and VDE are safety regulatory agencies. These codes tell you that someone other than the manufacturer has tested this part, and certifies that the ratings are honest. To get agency ratings, the part has to be able to switch the specified loads for 100,000 cycles. If you don't see any agency markings, the manufacturer is free to make up anything he likes. You'll often find absurdly high ratings on parts with no agency testing or confirmation. For example, automotive grade relays have no agency listings, and can only switch their rated loads for 10,000 cycles (or less)!
Let's look at the AC ratings. The higher the voltage, the lower the current it can carry. The first two values assume a resistive load. HP is "horsepower", i.e. an inductive load. Each horsepower is about 1000 watts; so 1HP is 1000w / 120v = 8.3 amps, and 3HP is 3000w / 240v = 12.5 amps. Inductive loads arc a lot more, so the current rating is roughly half as much when switching an inductive load.
Now look at the DC rating. Once you have more than about 30 volts across a contact, it will arc. Thus this relay only has a DC contact rating of 28 vdc at 20 amps. So why is the AC voltage rating so much higher? It's because AC voltages automatically go through zero 120 times a second at 60 Hz (or 100 times a second at 50 Hz). This automatically extinguishes the arc, so it won't last any longer than 8-10 milliseconds.
But on high voltage DC, once an arc starts it WON'T STOP until the contact spacing is very large, the current is very low, or some other mechanism stops it. The arc lets current keep flowing to the load, and also quickly destroys the contact. This particular relay has no provisions for switching high voltage DC; thus the low DC voltage rating.
The voltage rating of contacts in series add, because they increase the total open contact spacing. This is a double-pole relay, so you can wire both 28vdc contacts in series to switch 56vdc. Likewise, you can use a relay with four 30vdc contacts to switch 4 x 30vdc = 120vdc. Just make sure that ALL the contacts open and close at once (i.e. they are all part of the same switch or relay).
It also pays to look at the data sheet. Some switches and relays have higher DC voltage ratings at reduced currents. Schrack relays (now owned by Tyco) often have this data. For example, the Schrack PT570012 (Digikey PB912-ND) is a 4PDT relay with four 6 amp 120vac or 30vdc contacts that the data sheet also rates at 300vdc at 1 amp.
You can also get relays and contactors specially designed to switch high voltage DC. Several methods are used. First, much larger spacing between the open contacts. Second, putting more than one contact in series. Third, blowout magnets.
The Potter and Brumfield PRD-series is a common example. It is often used to switch EV chargers, heaters, and other DC loads up to 20 amps. It has two contacts, each rated at 125vdc that can be used in series to switch 250vdc. To get this rating, it has a blowout magnet, and extra-large contact spacings (see photo). It is available from multiple sources (Tyco, Deltrol, Magnecraft, etc.). The AC versions are far more common, so be sure to get one with the blowout magnet (such as the PRD-7DH0-12).
The smaller Potter and Brumfield KUEP-series is similar, but rated for 10 amps at 150vdc. It is useful for DC/DC converters and other smaller loads. It also has a blowout magnet (see photo), and two contacts pre-wired in series. Again, AC versions are much more common, so look for one with the magnet, like the KUEP-3D55-12.
I normally have these relays in stock for EV projects. If you need one, email me for details.
In our next installment, I'll cover "snubbers". These are inexpensive RC and RCD circuits that can be added to greatly increase the contact ratings of switches, relays, and contactors.
Electric Vehicles in the News
Donations for the
Sunrise EV2 Project
Interested? Want to get involved? There are several ways you can help.
Contact us: Questions or comments? Corrections or problems with this web site? Contact Lee A. Hart by phone at (320) 656-9574, by email, or by mail at 814 8th Ave N, Sartell MN 56377-2240.
Design: Producing the best possible EV requires the best possible minds. The Sunrise EV2 development team has over 100 years of combined EV experience, but we are still learning and improving as we go. If you have ideas for improvements, can help with vehicle design, construction, or testing; or have skills you think we can use, please contact us!
Labor: The Sunrise EV2 prototype is being assembled at our shop in Rice MN. At present, we are building our prototype composite body and the molds to produce it. It's very labor intensive, so if you're in the area and have some time, please contact us about a visit. See and help build the prototype, and in the process learn how to build your own Sunrise EV2.
Components: Most of the parts and materials to build the Sunrise are being donated by our development team or interested individuals. Our motor, controller, and innumerable tools and shop time have been provided, but there is alway more. Do you have any EV related parts that could be of use? Contact us and see!
Donations: Developing a car is an expensive project. The project is entirely funded by our development team and donations from interested individuals and businesses. Donations will be credited toward future purchases of Sunrise EV2 products. Contributors are also given special attention by members of the EV2 team! Send donations to the Sunrise EV2 Project c/o Lee A. Hart at the above address. To contribute using Mastercard Visa or Paypal, use the "Donate" button below. Every penny helps!
The Sunrise EV2 Project, copyright 2007-2013 by Lee A. Hart.
Website created 2/4/2008 by admin. Last update 12/5/2013 by Lee
Go to TOP of this page ................ Questions? Comments? Want to help? CONTACT US!
Web hosting provided by Turtlehut Internet Marketing http://www.turtlehut.com