The Sunfoil Project - Save car fuel using solar panels
Damien P
3.5% of the battery's capacity, can save about 20% of your fuel burn,
due to inefficiencies in the engine, the alternator, and the belt
connecting the two.
It's interesting stuff - he's done plenty of calculations on it (of
course whether they're right is another thing), and he's a true
outback inventor.
Check it out:
http://www.youtube.com/watch?v=Ott85qsDz4E
Robert Hart
hybrid car.
One of the thought was to take a conventional car
* remove the alternator and starter motor
* swap all the lights for LEDs
* Make a mount for a Three phase motor with a toothed belt, Modify the
Crank pulley and Aircon pulley for a toothed belt and link them all together
* Install some Lithium Batteries in the boot and variable speed
controller for the three phase.
Use the three phase motor to start and assist the petrol motor to
provide more power and efficiency over the friction in the engin.
Then plug it in to charge each night, as main/solar power is cheaper
than petrol all the petrol motor has to do is provide toque power.
The thought also occurred to me that for those who are hoons could get
an extra boost from there conventional engine with parallel electric
assistance.
With a bank of super capacitors maybe the equivalent of nitrous-oxide boost.
Just a day Friday afternoon dream
Kylie Willison
It needs a new engine though. It's available for any HackerSpace project.
Kylie :-)
Paul Shirren
> Then plug it in to charge each night, as main/solar power is cheaper
> than petrol all the petrol motor has to do is provide toque power.
I always thought a low tech diesel electric car would be cool.
Especially if the electric part could be made as tough and low
maintenance as the diesel bit for reliable country use.
Run it of mains charged low capacity cheap-as-shit batteries for a run
down to the shops or pick the kids up. Ninja silent, no smell, no gears,
no fuss, torque on demand - all your basic electric benefits.
Then fire up a loud smelly fuck-the-greens country-style diesel spewing
out sulphur and soot on the big open road running 1000+km/tank like a
big old locomotive with the possibility of biodiesel when it all goes
post-apocalyptic.
Apart from it weighing as much as a train and me having no skills to
implement it I wonder what the difficulties would be?
Damien P
the 20% saving is right, this setup would probably pay for itself in
about 10 months. I'm a bit surprised that the charging circuit uses
so much fuel.
It would be interesting to put an ammeter on the car, to see how long
it takes to charge each trip.
Ken
Ken.
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alphie
points. Firstly the coupling of the electric motor to the drive
system. From what you describe it sounds like you want to be able to
run each motor independently of each other. The problem would be
separating the coupling of each motor when you are driving the other
motor, otherwise you would be creating unnecessary drag.
Terry Baume
accurate.
The claims in the video are based on a few incorrect calculations and
assumptions:
* Reduction gear vs power - one of the key points in this video is
that by using a 2:1 step-up gear to drive an alternator, twice the
input power is required - ie 2hp input power for 1hp arriving at
the alternator's pulley (then of course less inefficiencies in the
alternator resulting in even less power output). This is *not*
correct - while the step-up increases the RPM delivered the the
alternator's shaft, it decreases the torque delivered - overall
power in the system remains the same (less inefficiencies).
* Belt efficiency - the video claims that drive belts are horribly
inefficient. This is not the case - in fact belts are usually
considered quite efficient, with typical efficiencies in the
ballpark of 95%.
* Charging current & engine loading by the alternator - the author
makes the assumption that because the battery is not fully
charged, it's placing a heavy load on the alternator (& hence the
engine) at all times whilst the engine is running. Charge current
for a lead acid battery drops off as the battery charges - a
battery that's 'mostly' charged (ie most cars on the road) will
have a very low charge current. Just because the alternator is
running at its rotational speed of maximum efficiency does not
mean that it's placing a heavy load on the engine.
If you want a good demonstration of the last point, go and jump on the
electric generator bike in the UofA Innova building - by pedaling the
bike you drive a generator, and you're able to switch on and off light
bulbs of varying wattages connected to the generator. What you'll find
is that the load on the engine (ie your legs) depends on the bulbs you
have switched into the circuit - with a low current draw (a small bulb)
you'll find pedaling much easier than with the large bulbs switched on
(with a greater current draw).
Certainly his solar panels would help charge float charge the battery
when the car is parked, but they're not going to net him a 20% fuel
saving. A totally discharged car battery might draw 20A off the
alternator (~500W engine load assuming 50% alternator efficiency), but a
'mostly' charged battery is really only going to be drawing a couple of
amps or so (perhaps 50W engine load or less). 50W might sound
significant, but when you consider that with a fuel pump & fuel
injectors the standing load on the alternator could be 20A+ (500W engine
load or more), it's not very much. When you throw things like
headlights, air conditioning & other axillary loads into the mix, an
alternator can easily be loaded with 50A (1300W engine load) - saving a
few watts by having the battery fully charged when you start the car
isn't much in the scheme of things, and the power provided by the panels
as your drive is pretty negligible (20-30W).
I can't say much for his claims with regards to drag, but I would be
very surprised if his modifications decreased drag at all. Car
manufacturers do test their cars & optimize designs in wind tunnels
after all, and he doesn't mention how he arrives at his figures for drag
reduction.
If anything I my guess would be that increased drag would result in a
reduction in fuel economy (even roof racks are said to heave a
measurable impact on fuel economy). Any savings found are likely
attributed to changes in driving style or other factors that haven't
been accounted for - unfortunately like many car fuel saving stories,
this seems simply too good to be true.
Terry.
Geordie Millar
On 17/03/2011, at 3:43 PM, Terry Baume wrote:
> * Belt efficiency - the video claims that drive belts are horribly
> inefficient. This is not the case - in fact belts are usually
> considered quite efficient, with typical efficiencies in the
> ballpark of 95%.
Let's look at it this way: the energy goes *somewhere*. What doesn't get transferred from input to output comes out as light, heat, noise etc etc. Drive belts aren't particularly noisy - so the only way energy could be lost is to heat. And if you put a significant amount of heat through a drive belt... it's going to catch fire.