Solar-Electric Beetle project on crowdfunding

Hello there,
years of motivation and information through this forum, drove me to build several electric bikes, a moped, convert a gwiz to lifepo bldc and now i am starting a new project for a solar Beetle.
This time i thought to look for funding via Indiegogo!
I did not publish any technical information trying to make it easy to understand, i would like to tell me your thoughts about the idea and the whole concept and if possible forward the campaign.
I am not looking for funding in here, just spread the idea if you like it guys!
Thank you!!

Nick

I'm not sure how we can help, without details one way or the other.

If you're looking for help with funding your thread needs to go in the Online Market section, in the Items Wanted section (unless you're selling something in exchange for the funds, in which case it goes in one of the Items for Sale sections).

If you want help with the project itself, you'd have to post details about it here.

I have no problem moving the post if necessary!I dont know how though

The details are the usual calculations and parts available on the market that are discussed all over the forum,nothing strange or new i just figured that it is possible at the moment to make a light ev-bug and every 8 hours of sun have enough battery to move it around town for 40-50km.

Using maxeon cells and a light bldc motor with sine wave controller are my thoughts.
I have a sepex motor/controller set from my g-wiz but the motor itself is around 35kg and 4.8kw continuous.

6-7 sq meters of cells covering the body panels of the bug is the key idea. These cells are 30% flexible, it is very tricky but it can be done,i broke some b grades training but i am about to cover my scooter body panels with cells and post some pics.

I am experimenting with dc boost converters capable of cc/cv output to eliminate the solar charger from the equation.
After purchasing a fake mppt 48v solar charger (wellsee is the brand) i figured going this route for the small scooter application.
A boost converter capable of 4.5-40v input and a regulated 40-52 cc/cv output works kind like a (cheap)charger.Using 2 i can get cheap 95v solar charging for the 28s pack of the scooter.
It will arrive next week and i will see what i can get from it.

And here's the link!

http://igg.me/at/solar-beetle/x/9090328

nick2earth said:

I have no problem moving the post if necessary!I dont know how though

Click to expand...

Any moderator/admin can move the post if you need to.

The details are the usual calculations and parts available on the market that are discussed all over the forum,nothing strange or new i just figured that it is possible at the moment to make a light ev-bug and every 8 hours of sun have enough battery to move it around town for 40-50km.

Click to expand...

At what speed, and what acceleration rate do you expect?

Both of those will decide a lot of how much power you'll eat up, and thus how much it'll take to recharge it.

Car-sized vehicles for the most part take quite a lot of power, much more the faster you go, and much more the faster you intend to accelerate. Accelerating fast enough to not be run over by cars behind you at a stop will usually take up to several times more power than if you just gently get started over a long distance, and the heavier it is the worse the problem, especially on any upward slope/hill.

I personally doubt you can put enough panels directly on a vehicle to get enough capacity back into the batteries in 8 hours to go that far at typical car speeds. At slower 20-25mph speeds, maybe, but probably not even that.

Remember that
-- panels that are not perpendicular to the sun are not going to get nearly the amount of power output that they could, and
-- most panels are not even 30% efficient to start with before they get hot, and that
-- most places even under perfect conditions you won't get more than 500w/square meter worth of sunlight anyway, probably less than that on average given angles of sun to panel change thru the day, and
-- anything fixed to the vehicle surface won't be able to stay pointed at the sun, and will get less and less power as the angles change away from perpendicular.


Using maxeon cells and a light bldc motor with sine wave controller are my thoughts.
I have a sepex motor/controller set from my g-wiz but the motor itself is around 35kg and 4.8kw continuous.

6-7 sq meters of cells covering the body panels of the bug is the key idea.
Let's be optimistic, and say you get 7. Then say there's 50% of the possible power of 1kW always falling on them, for a total of 3500W input to the panels.

So let's say the panels are superefficient and, so you get 50% of the input power out of them...that's 1750W.

Let's say your converters are 80% efficient at the output point of the panels, so you get 1400W out, constantly.

That, over 8 hours, would net you 11.2Kwh of energy into the battery.

Let's say it only takes 300wh/mile for your vehicle including all it's controller/motor conversion efficiencies, then you could actually get up to 37miles / 60km or so, whcih would more than meet your goal.

But I suspect all those numbers are much more optimistic than you'd actually get--you'd have to do the experiments, math and calculations first to see what you'd actually get out of the panels thru a whole day, what the efficiency is of your conversion processes, what the vehicle would take for power consumption, etc.

I'd be interested to know what all those numbers really are for your project.

Thank you for your interest i appreciate your opinion and agree with the numbers.
The bet is weight.
I've found a number of lightweight (like an mx5)conversions that give real numbers of 200-250wh/mile
I assume that a vehicle that weighs 500kg will be under 200wh/mile worst case in low speed city driving.
The gwiz weighs 650kg and has a range of 50min-80km max ,with lead acid batteries that (my calculations) after the peukert effect give less than 5kwh usable energy(t125 trojans at 48v,195ah 5hr rate, i calculate 100ah usable at 1hr discharge 80% soc)
I agree that 50km "solar" range is a long shot but it's the target.i will be very happy with 30-35.
But at some point my calculations let me believe that its possible.
Maybe it has to be slow to achieve that range but its a good start and a nice hobby for my time!
I suspect that crowdfunding will be a total fail but one way or another i will get into making it even if i have to use the sepex compo and bgrade cells

Sine wave controllers are a pretty good idea only if you can get one with great regen settings. Adaptto is one but its also very under used as you would want to be charging the car while driving if its sunny out. I would use John from CRs hub motor 93% efficient, the mid sized one, 2x adaptto minis to run it. Get a chain drive diff and mount it side onto that. That should be able to keep the weight down and still allow a usable performance.

I applaud the desire to build a lightweight car, but I think some of your expectations are a little optimistic.

First, the 500kg build. I researched lightweight vehicles for years before selecting the donor for my lightweight build, pickings get mightly slim below 1,600lb. I saw a VW Bug in your link, that's 1600lb-1800lb vehicle that you can expect to be heavier after the conversion, even if you use a lightweight 170lb battery like I did. If you completely remove the bug body you will be at 1,100-1,300lbs before conversion, not sure how much your "exotic materials" body plus solar panels will add. Also keep in mind that if you cover the car with solar cells, at any given point maybe 1/3rd of them will be pointed at the sun such that they get enough light to produce power.

The drivetrain looks intended for an NEV. IMO 20kw is great on an ebike but not a enough power for a 500kg build - especially with VW aerodynamics. It might be enough to get up to 35mph if you have enough road and a tailwind, but golf carts will be passing you along the way. Maybe that is not a factor of your design criteria, however.

You mention 98% efficient motor/controller combos in your crowdfunding, I am not aware of anything that efficient, but if it exists I'd expect to reach that efficiency in 1% of the duty cycle, the rest of the time it will be at an rpm/load where it runs less efficiently.

The best way to learn is build, so I'd encourage you to give it a try and get a sense of what the limitations are.

-JD