On 26 Sep 2014 at 18:08, Cor van de Water via EV wrote: > BTW, which car has a flat 90 sqft straight roof surface and is > aerodynamic?
This is what Lawrence is talking about : http://www.evdl.org/archive/index.html#nabble-td4671714 http://www.greenoptimistic.com/2014/09/24/stella-500-mile-solar-powered- electric-vehicle/ http://tinyurl.com/qh2f6ox http://www.dailymail.co.uk/sciencetech/article-2385976/Stella-solar-powered- family-car-travels-420-miles-sunny-energy-positive.html http://tinyurl.com/lyq3n6o Estimating from the size of a person's hand near the PV panels in one photo, I'd estimate that the car has somewhat less than 90 sq ft of PV. I'd guess closer to 60, but I could be wrong. In any case, the ENTIRE top of the vehicle is covered, literally nose to tail. This PV array is claimed to produce either 1.2kW or 1.5kW, depending on the source. Presumably that's under ideal conditions - fine if you're driving in San Diego, maybe not so fine here in cloudy Ohio. Supposedly they got the car to run on 50 watts (!). I haven't found that claim elsewhere, but that's what Lawrence says the "day time running system including lights" uses. I find this impossible to believe. My e-bike cruses at 15mph, typically using between 150 and 250 watts (depending on terrain and how much I pedal). My bike weighs 50lb. Their car weighs around 900lb. You do the math, and tell me how they manage 50 watts. All that aside, the principle here reminds me of the solar racers, highly optimized engineering-challenge vehicles where cost is no object. Most solar racers are developed in academic settings with hundreds of thousands of dollars in (largely donated) components and materials. Tens of thousands of labor hours go into them, made possible in part by teams of students who volunteer their time. The tools and workshops are provided by the university, or are donated. The result is a super-efficient vehicle suited only to one purpose, winning the prize in a solar race. Solar racers by and large are not practical for everyday use. They're notoriously uncomfortable, and frankly most of them would be pulverized in a low speed road accident. The folks who built Stella, from a university in The Netherlands, claim they've made their solar racer more practical and comfortable. Unlike the other racers it does indeed carry more than one person. It does not seem to have doors, however. (No word on the safety issues.) The builders claim the PV cost them only UKP 2600 (about US$4200), but I'm skeptical. (Of course $4200 also buys a fair amount of batteries.) The drive system for an EV like this would have to be highly optimized. Every compromise you make so that it's buildable in your garage instead of a university machine shop is going to cost efficiency. If the typical home EV converter built an EV like this, he might end up with something interesting. Would it manage to be, as these students claim, a "car you never have to plug in" (100% self-solar powered)? That I'm not so sure about. The other problem I see with this is that you're building a high-precision complex machine from scratch. Look at how many kit cars never get finished, and this would be even more work than those! You'd have to be really, really serious about building it, truly dedicated. If that's you, my hat's off to you. Personally, I wouldn't try building something like this because (1) I don't want to devote all my time to it; and (2) I'd be afraid that I wouldn't have it done in time to drive it before I was too old (or dead). But hey, I'm kinda old already. ;-) I think this would be a great project for someone who's dedicated to the EV cause, and fairly wealthy. Duplicating this prototype could work, if you could afford to hire out most or all of the labor and fabrication (sort of like what Neil Young did with his LincVolt). I can see someone like Ed Begley Jr commissioning something like this, for example. David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)