Solar Panel for Car
John
battery. So far the ones I've seen have been too long and thin, and
they would block up my air vents or speakers.
Can anyone recommend any sites in the USA or UK that sell small panels
that are about 12x8 inches in size? Was only looking for a panel of
around 2-3w maybe 150ma at 15v give or take.
I think size around 12x8, 11x7, 12x7, 10x8 would be the best types of
size as this wont block my airbags, speakers or air vents up and it
would be able to sit nicely on the dash and connect to the battery.
Thanks for any links,
John
Eeyore
John wrote:
> I'm looking to get a small Solar Panel to trickle charge my car
> battery.
Forget it. All of them are worthless scams. Unless you ger a REALLY big
panel that might fit on the rear shelf of a hatchback type car.
Graham
Eeyore
John wrote:
> I'm looking to get a small Solar Panel to trickle charge my car
> battery. So far the ones I've seen have been too long and thin, and
> they would block up my air vents or speakers.
>
> Can anyone recommend any sites in the USA or UK that sell small panels
> that are about 12x8 inches in size? Was only looking for a panel of
> around 2-3w maybe 150ma at 15v give or take.
For how many hours a day ?
It's not going to help your battery any but will relieve your wallet of
some money.
Graham
John
Thanks for the input. You reckon its not worth it and they don't make
much of a difference?
At the moment I have just bought a new car battery its a special
sealed gel type that's for my car and cost £165. Unfortunately I have
a lot of electronics on my car that drain the battery while I'm not
driving. I have alarm and also the cardkey autosensors amongst other
things.
I often don't use my car over the weekend and it takes a few attempts
to get started on Monday morning. Even within the week when I am
driving each day to work it often doesn't start first time.
At the moment we're going into Winter here in Britain so we wont have
as much daylight, maybe 5 to 7 hours max over the next 6 months. In
summer a lot more. I think if I only get a small amount of juice to my
battery from a small panel it may be the difference between my car
starting first time and not starting, and the difference between
keeping the battery maintained in top condition and not having to
spend more money in another four years to replace the battery, it
could last a few years longer than that still.
A small solar panel of maybe 2 or 3 watts may only cost £30 or £35, I
guess around $50 USD give or take, and may last 10 years and more. I
think if that is something that would work then it would be cheaper
for my wallet than the cost of having to replace the battery sooner
than I should especially with the type for my car?
What do you think? Still not worth it? Are you generally against
anything that is renewable? Because I am not some sort of eco-freak
I'm just interested in this to save money not spend it. Are you saying
that a small 2 or 3w panel won't help my battery and that I would
really need a bigger one? 5w? I guess I could have two small panels on
the front dash that connect to my battery, its just the reason I can't
have one big one is there's nowhere to put it where it will get a lot
of sunlight and wont block up other important stuff.
BTW, I have a small hatchback but it wouldn't be a good idea to put a
bigger panel on the parcel shelf because it wouldn't get much sunlight
there because my rear window is very small and pretty much vertical.
Thanks for your input,
John
Slick
"John" <ma...@carta.com> wrote in message
news:v0che45vh58a1g42l...@4ax.com...
The reason everyone is saying it is a waste of time and money is because the
size of panel you are talking about might be able to keep an iPod or your
security system LED flashing , the rate of charge recommended for Gel / AGM
batteries is 10% of the battery's AH capacity .
Being a late model car you could expect that your battery will be at least
80AH , so you need 8 amps to charge it.
If the things you have running are drawing it down enough to effect the
starting , then it means it must be dropping by around 40% of it's capacity
and this is only over the weekend !So around 32AH ,
Over the weekend the charging you are talking about if there was 8 hours of
perfect sunlight everyday would replace 2.4AH in 2 days.
I have standard AA touch batteries rated at 1100ma , your panel suggestion
would be lucky to even charge one of them on a good day let alone have any
noticeable impact on car battery..
If you were considering something around the 25w mark you might see a more
noticeable effect , but then for the cost you would be better off saving
that money until you batteries dies and replacing it with a brand new one
and still have money left over.
You might even want to consider a dual battery system , this would better
cater to your concerns.
spaco
that, if the UK is anything like western Wisconsin in the USA, December
and January are alomost TOTAL washouts as far as solar energy goes.
This would mean that you'd have at least 2 months where it would be of
no value at all.
I am not making this up! I have been recording solar input daily
here for almost a year now. See: http://www.spaco.org/PV/PVSolar.htm
I have a cheap 1 meter square panel and it stores a maxumum of about
150 watt hours on a totally sunny day in summer, facing due south and at
the correct vertical angle. On a typical cloudy day, (like this very
day so far), I am getting 2 watts at 12.51 volts into a "car battery".
Since I left a small (10 watt) load on that battery all day yesterday,
the terminal voltage was 12.2 at midnight last night when I removed that
load. The terminal voltage will improve during the day today, up to
maybe 12.89, by day's end.
Remember, this is a 1 meter square panel, capable of supplying up to
30 watts in DIRECT sun.
Why not fix the car so it starts the first time? Are you certain that
the car's alternator is working properly?
Or, at least one mfr on this side of the pond makes a "Dual battery" If
the main section goes dead, you throw a switch that is built into the
battery, and the other section starts your car.
Pete Stanaitis
------------------------------
nicks...@ece.villanova.edu
>... the rate of charge recommended for Gel / AGM batteries is 10% of
>the battery's AH capacity .
That sounds more like a max than a min.
>Being a late model car you could expect that your battery will be at least
>80AH , so you need 8 amps to charge it.
If a battery takes 3 weeks to self-discharge, we might keep it charged
with 80AH/(3x168H) = 160 mA, ie 1.9 watts, on a continuous basis.
Nick
danny burstein
[ snip ]
>Why not fix the car so it starts the first time? Are you certain that
>the car's alternator is working properly?
>Or, at least one mfr on this side of the pond makes a "Dual battery" If
>the main section goes dead, you throw a switch that is built into the
>battery, and the other section starts your car.
I had one of those two decades ago under the Sears Diehard
brand name. It worked fine, and saved my ass when I left the
headlights on one time.
BUT, one day, when I turned on the ignition, it went "kaboom".
Small explosion, fortunately, with no damage.
I headed to Sears and they swapped in a regular Diehard.
A bit later I checked and found that they had stopped selling
them, and there were some indications this was because of
some similar events. (This was before the day of easy internet
access, so I didn't see any stories).
One of the big battery manufacturers whose name escapes
me for the moment had a similar unit, and kept offerring
it for a while (but I could never find a store that actually
had it or was able to order it with a reasonable delivery
time), leading me to suspect they were the supplier and
had stopped making it.
If there's anyone selling this product these days, and
they've got good quality control, it could be worth it.
Oh, another two suggestions for the original poster:
a: if your battery drain is one of those unwanted things
(i.e. a short somewhere) you could hook up a fairly
cheap and easy "kill" switch at the battery. These are
commonly used for a theft protection device, but would
help here as well. On the other hand, this might mean
losing all your radio, etc., settings.
b: One of the best $30 investments I made was a "jumper
battery". This is a self contained unit ,about half the
size of a tissue box, which contains a small rechargable
battery and jumper cables. You simply lift it up and
hook it to the main bettery, and you've got plenty of
power to start up.
In the USofA these range from $20 to $50 or so and are
available at automotive supply stores and mass marketers.
Any model above the el-cheapo-basement unit would be fine.
--
_____________________________________________________
Knowledge may be power, but communications is the key
dan...@panix.com
[to foil spammers, my address has been double rot-13 encoded]
Eeyore
John wrote:
> Eeyore wrote:
> >John wrote:
> >
> >> I'm looking to get a small Solar Panel to trickle charge my car
> >> battery. So far the ones I've seen have been too long and thin, and
> >> they would block up my air vents or speakers.
> >>
> >> Can anyone recommend any sites in the USA or UK that sell small panels
> >> that are about 12x8 inches in size? Was only looking for a panel of
> >> around 2-3w maybe 150ma at 15v give or take.
> >
> >For how many hours a day ?
> >
> >It's not going to help your battery any but will relieve your wallet of
> >some money.
>
> Thanks for the input. You reckon its not worth it and they don't make
> much of a difference?
Absolutely 100% worthless. I know someone who tried one and the battery still
went flat from all the electronic loads (like an alarm) on it when not in
use.
> At the moment I have just bought a new car battery its a special
> sealed gel type that's for my car and cost £165. Unfortunately I have
> a lot of electronics on my car that drain the battery while I'm not
> driving. I have alarm and also the cardkey autosensors amongst other
> things.
Yes, and a solar cell has NO HOPE of powering those. it'll provide a few tens
of Watt-hours a day but it's pathetic.
Graham
Eeyore
spaco wrote:
> One other reason that a small solar panel won't serve YOUR purpose is
> that, if the UK is anything like western Wisconsin in the USA, December
> and January are alomost TOTAL washouts as far as solar energy goes.
> This would mean that you'd have at least 2 months where it would be of
> no value at all.
Precisely true.
Graham
Eeyore
nicks...@ece.villanova.edu wrote:
Which is ~ 45Wh per day. With maybe 2 hours eqivalent peak sunlight in winter
that would require a 25W panel (allowing some margin).
@ a typical 15% efficiency a 1 metre square panel only provides 150W so you'd
need a 0.17 m^2 panel. Say 1 foot by 2 feet and it must be in direct sunlight !
No guarantee of that so maybe a 2 foot sq panel would do.
BUT, with heavy loads on it, I bet his battery won't last 3 weeks either.
Increase the numbers accordingly.
Graham
Mauried
Ive got essentially the OPs problem.
A car thats only used on weekends and sits idle in the garage
for the rest of the week.
Battery goes flat over the week.
Simple cheap fix is a small mains operated battery charger
available from any car parts shop, mine cost me $15.
Put a cigarette lighter plug on the charger and just leave it pluuged
into the car socket when not using the car.
Batterys always fully charged when needed.
Much cheaper than a solar panel.
John
>The reason everyone is saying it is a waste of time and money is because the
>size of panel you are talking about might be able to keep an iPod or your
>security system LED flashing , the rate of charge recommended for Gel / AGM
>batteries is 10% of the battery's AH capacity .
>Being a late model car you could expect that your battery will be at least
>80AH , so you need 8 amps to charge it.
Apologies but I've not had time to read all the responses yet, but
just to quickly confirm my battery is only an 48amp 12v gel type
battery in my car. It is just for a small 1.6 litre engine petrol
hatch.
Thanks for all the help and advice,
John
John
>The reason everyone is saying it is a waste of time and money is because the
>size of panel you are talking about might be able to keep an iPod or your
>security system LED flashing , the rate of charge recommended for Gel / AGM
>batteries is 10% of the battery's AH capacity .
>Being a late model car you could expect that your battery will be at least
>80AH , so you need 8 amps to charge it.
So 48 amp battery 4.8 amps to charge.
>If the things you have running are drawing it down enough to effect the
>starting , then it means it must be dropping by around 40% of it's capacity
>and this is only over the weekend !So around 32AH ,
If it lost 32 amps I don't think it would start at all ;) it would
only have 16left.
>Over the weekend the charging you are talking about if there was 8 hours of
>perfect sunlight everyday would replace 2.4AH in 2 days.
>
>I have standard AA touch batteries rated at 1100ma , your panel suggestion
>would be lucky to even charge one of them on a good day let alone have any
>noticeable impact on car battery..
okay, taken onboard.
>If you were considering something around the 25w mark you might see a more
Would 15w do for 48 amp battery? I am guessing the 25w was for 80amp?
John
John
>Yes, and a solar cell has NO HOPE of powering those. it'll provide a few tens
>of Watt-hours a day but it's pathetic.
>
>Graham
Thanks for the advice! That saves me wasting money on something that
isn't going to work then ;)
John
wrote:
>One other reason that a small solar panel won't serve YOUR purpose is
>that, if the UK is anything like western Wisconsin in the USA, December
>and January are alomost TOTAL washouts as far as solar energy goes.
>This would mean that you'd have at least 2 months where it would be of
>no value at all.
> I am not making this up! I have been recording solar input daily
>here for almost a year now. See: http://www.spaco.org/PV/PVSolar.htm
> I have a cheap 1 meter square panel and it stores a maxumum of about
>150 watt hours on a totally sunny day in summer, facing due south and at
>the correct vertical angle. On a typical cloudy day, (like this very
>day so far), I am getting 2 watts at 12.51 volts into a "car battery".
> Since I left a small (10 watt) load on that battery all day yesterday,
>the terminal voltage was 12.2 at midnight last night when I removed that
>load. The terminal voltage will improve during the day today, up to
>maybe 12.89, by day's end.
> Remember, this is a 1 meter square panel, capable of supplying up to
>30 watts in DIRECT sun.
>
>Why not fix the car so it starts the first time? Are you certain that
>the car's alternator is working properly?
Yep. It's just the battery it gets drained by all the electronics plus
I don't travel that many miles in the week. I only do upto 200 miles
in the week and it usually most weekends sits on the drive unless I am
away somewhere.
John
John
Unfortunately I can't have a kill switch on the battery because it
would reset all the sensors etc and my keycard would no longer work
with it. I'd have to get it recovered to the main dealer who I'd have
to pay ŁŁŁ to have it reprogrammed.
John
John
>Ive got essentially the OPs problem.
>A car thats only used on weekends and sits idle in the garage
>for the rest of the week.
Its just used in the week mate and usually sits idle at weekends.
Monday mornings sometimes takes three attempts to start. In the week
after work or in the morning sometimes I get lucky and only one
attempt but usually two attempts before it starts.
>Battery goes flat over the week.
>Simple cheap fix is a small mains operated battery charger
>available from any car parts shop, mine cost me $15.
>Put a cigarette lighter plug on the charger and just leave it pluuged
>into the car socket when not using the car.
>Batterys always fully charged when needed.
>Much cheaper than a solar panel.
That is a very good idea. I don't think I would be able to leave such
a device plugged in though because my cigarette lighter is cut off
from the battery when the car is switched off.
Would such a device give enough juice though if in this socket when I
am starting up the car? Because I'm sure the socket will become active
when I hit the start button and try start the car up.
Thanks,
John
danny burstein
>Would such a device give enough juice though if in this socket when I
>am starting up the car? Because I'm sure the socket will become active
>when I hit the start button and try start the car up.
Not enough to start the car right then and there, but
if you could leave it hooked up for 10 minutes or so
you'd probably be pleasantly suprised.
Trygve Lillefosse
>I'm looking to get a small Solar Panel to trickle charge my car
>battery. So far the ones I've seen have been too long and thin, and
>they would block up my air vents or speakers.
http://www.dealextreme.com/products.dx/category.410~search.solar
--
SEE YA !!!
Trygve Lillefosse
AKA - Malawi, The Fisher King
Eeyore
Mauried wrote:
Now, there you go. The good old-fashioned ways work best.
Graham
Eeyore
John wrote:
> Would 15w do for 48 amp battery?
Not a hope in hell.
Graham
Eeyore
John wrote:
> Yep. It's just the battery it gets drained by all the electronics plus
> I don't travel that many miles in the week. I only do upto 200 miles
> in the week and it usually most weekends sits on the drive unless I am
> away somewhere.
That shouldn't flatten your battery. You have a serious fault drain current
somewhere.
Graham
Eeyore
John wrote:
> Unfortunately I can't have a kill switch on the battery because it
> would reset all the sensors etc and my keycard would no longer work
> with it. I'd have to get it recovered to the main dealer who I'd have
> to pay ŁŁŁ to have it reprogrammed.
Damn car manufacturers ! How old is it ? Under guarantee ? Get THEM to fix it.
Graham
Eeyore
John wrote:
> mau...@tpg.com.au (Mauried) wrote:
>
> >Ive got essentially the OPs problem.
> >A car thats only used on weekends and sits idle in the garage
> >for the rest of the week.
>
> Its just used in the week mate and usually sits idle at weekends.
> Monday mornings sometimes takes three attempts to start. In the week
> after work or in the morning sometimes I get lucky and only one
> attempt but usually two attempts before it starts.
Your battery could be totally fucked.
Graham
David Turner, islandco.com
electronics
I have a little BMW 1999 that is used maybe 10 times per year
We're in Savannah GA where it gets v hot and quite nippy in the winter
I have had to charge the battery once in a year - with anti-theft running
etc.
You'll be better off to attach a conditioner/charger that you plug into your
mains outlet - halfords?
Alternatively for my boat I purchased one at www.northerntools.com
It was $99 and works v well in bright sunlight (we get 10-11 hours in the
Summer of unobstructed light)
--
David B Turner
=============================================
Island Computers US Corp
PO Box 86
Tybee GA 31328
Toll Free: 1-877 636 4332 x201, Mobile x251
Email: dtu...@islandco.com
International & Local: (001)- 404-806-7749
Fax: 912 786 8505
Web: www.islandco.com
=============================================
"Trygve Lillefosse" <ne...@lillefosse.NOSPAM.org> wrote in message
news:9ntke45hndp8acdd2...@4ax.com...
David Turner, islandco.com
if so that would explain everything.
I understand Solar panels don't work in the UK anyway...
One needs the Sun to power the Solar panel - my 22 years of living there
proved that there ain't much of that.
Shame there isn't some kind of Environmentally friendly generator that works
with RAIN.
Now that would work...
;0)
--
David B Turner
=============================================
Island Computers US Corp
PO Box 86
Tybee GA 31328
Toll Free: 1-877 636 4332 x201, Mobile x251
Email: dtu...@islandco.com
International & Local: (001)- 404-806-7749
Fax: 912 786 8505
Web: www.islandco.com
=============================================
"Trygve Lillefosse" <ne...@lillefosse.NOSPAM.org> wrote in message
news:9ntke45hndp8acdd2...@4ax.com...
David Williams
-> with RAIN.
Well, let's imagine a vertical pipe 100 metres tall. At the top is a
funnel with a cross-section of one square metre that sends water into
the pipe. At the bottom of the pipe is a tiny turbine and generator.
If 1 centimetre of rain falls, which would be common during a day in
the UK, 10 litres or 10 kg of water would go down the pipe. The energy
available would be (m.g.h) 10 x 10 x 100 joules or 10 kJ. That's about
3 watt.hours. That might be enough, if supplied every day, to keep a
car battery from going flat.
dow
David Turner, islandco.com
pole???
They gotta take some power
;0)
--
David B Turner
=============================================
Island Computers US Corp
PO Box 86
Tybee GA 31328
Toll Free: 1-877 636 4332 x201, Mobile x251
Email: dtu...@islandco.com
International & Local: (001)- 404-806-7749
Fax: 912 786 8505
Web: www.islandco.com
=============================================
"David Williams" <david.w...@bayman.org> wrote in message
news:1224792431.9...@bayman.org...
David Williams
-> pole???
-> They gotta take some power
Make the whole thing as a thin, inflated structure, like the pylons
they use in air races. They're so light and insubstantial that a plane
can collide with them without being damaged. Then no lights would be
needed.
Actually, I'm not sure how high a structure requires lights. There are
plenty of buildings more than 100 metres high here in Toronto. The
tallest ones have lights, but I don't think they all do.
dow
Eeyore
David Williams wrote:
> If 1 centimetre of rain falls, which would be common during a day in
> the UK,
No it wouldn't. More like one fifth of that.
Graham
Eeyore
David Williams wrote:
> -> What about running the Aviation warning lights on top of the 100M (330Ft)
> -> pole???
> -> They gotta take some power
>
> Make the whole thing as a thin, inflated structure, like the pylons
> they use in air races. They're so light and insubstantial that a plane
> can collide with them without being damaged. Then no lights would be
> needed.
How do you think they land at night ?
Graham
Eeyore
David Williams wrote:
> Actually, I'm not sure how high a structure requires lights. There are
> plenty of buildings more than 100 metres high here in Toronto. The
> tallest ones have lights, but I don't think they all do.
Probably because they're not on a flight path.
Graham
David Williams
-> > If 1 centimetre of rain falls, which would be common during a day in
-> > the UK,
-> No it wouldn't. More like one fifth of that.
-> Graham
You're near London. My family's from Wales.
"Common" does not mean "average".
dow
David Williams
-> > -> pole???
-> > -> They gotta take some power
-> >
-> > Make the whole thing as a thin, inflated structure, like the pylons
-> > they use in air races. They're so light and insubstantial that a plane
-> > can collide with them without being damaged. Then no lights would be
-> > needed.
-> How do you think they land at night ?
-> Graham
What are you babbling about? We're talking about lights on a 100-metre
high structure. It's already attached to the ground.
dow
David Williams
-> > Actually, I'm not sure how high a structure requires lights. There are
-> > plenty of buildings more than 100 metres high here in Toronto. The
-> > tallest ones have lights, but I don't think they all do.
-> Probably because they're not on a flight path.
-> Graham
There's an airport within a couple of kilometres of downtown Toronto.
dow
Eeyore
David Williams wrote:
You should have said "in Wales" in that case.
Graham
Eeyore
David Williams wrote:
The lights are on high structures to warn pilots.
What are you babbling about?
Graham
Eeyore
David Williams wrote:
And ? Do you know what a glideslope or an approach pattern is ?
Graham
David Williams
-> > high structure. It's already attached to the ground.
-> The lights are on high structures to warn pilots.
-> What are you babbling about?
-> Graham
Have you ever seen an air race? I know one was held near London quite
recently. It was shown on TV here. Small planes zoom around a course
that is marked by pylons that stand up from the ground. The planes have
to fly below the level of the tops of the pylons, and must pass
extremely close to them in order to get the best time. Collisions are
inevitable, but they don't cause the planes to crash. That's because
the pylons are inflated structures made of very thin fabric. When a
plane hits one, it just tears without damaging the aircraft. If an
airliner hit one, the same would happen. So there is no need to put
warning lights on them.
dow
David Williams
-> Graham
Yes. And I also know that planes stray off course.
dow
David Williams
-> >
-> > -> > the UK,
-> >
-> > -> No it wouldn't. More like one fifth of that.
-> >
-> > -> Graham
-> >
-> > You're near London. My family's from Wales.
-> >
-> > "Common" does not mean "average".
-> You should have said "in Wales" in that case.
-> Graham
I said "in the UK". As far as I know, Wales is still part of it.
Some major English cities, e.g. Birmingham, get their piped water from
Welsh rain.
dow
Eeyore
David Williams wrote:
> -> You should have said "in Wales" in that case.
>
> -> Graham
>
> I said "in the UK". As far as I know, Wales is still part of it.
You're not typical of the UK thank God.
Graham
Eeyore
David Williams wrote:
> -> > What are you babbling about? We're talking about lights on a 100-metre
> -> > high structure. It's already attached to the ground.
>
> -> The lights are on high structures to warn pilots.
>
> -> What are you babbling about?
>
> -> Graham
>
> Have you ever seen an air race?
Yes.
What's that got to do with lighting on fixed erections ?
Graham
Eeyore
David Williams wrote:
Tell us more. Never heard of ILS ?
Graham
David Williams
-> Graham
Probably not. I'm five time-zones to the west.
dow
David Williams
I suggested that the "rain battery" could be made as a thin, inflated
structure like the pylons in air races. Then it wouldn' pose a hazard
to aviation, and wouldn't need warning lights.
Lights can be hazardous in themselves. North of Toronto, there's a
stretch of highway (Hwy 400, near Barrie) which is straight for several
kilometres. Than it makes a turn to avoid a hill. On the top of the
hill was a TV transmitting mast carrying red warning lights. Some years
ago, a plane flew directly into the mast. The pilot was killed so he
couldn't be asked what happened, but it appeared that he was flying
VFR, using the highway as a guide. It was dark, so he would have been
following the lights of vehicles on the road. Apparently, he mistook
the lights on the tower for tail lights of vehicles, and thought he was
safely following the highway...
dow
David Williams
Ever heard of small, light planes, and of pilots who are not instrument
qualified?
Bob F
"John" <ma...@carta.com> wrote in message
news:6k0ge4peg8e2ckn7h...@4ax.com...
> I'm looking to get a small Solar Panel to trickle charge my car
> battery. So far the ones I've seen have been too long and thin, and
> they would block up my air vents or speakers.
>
> that are about 12x8 inches in size? Was only looking for a panel of
> around 2-3w maybe 150ma at 15v give or take.
>
> I think size around 12x8, 11x7, 12x7, 10x8 would be the best types of
> size as this wont block my airbags, speakers or air vents up and it
> would be able to sit nicely on the dash and connect to the battery.
>
Add a second battery for the accessories, with a battery isolator to keep it
charged while you drive while protecting the starting battery when you are
parked.
http://www.hellroaring.com/bic75150.php is one example.
FallintoColors
http://www.financialpost.com/reports/story.html?id=638173
Eeyore
John wrote:
> I'm looking to get a small Solar Panel to trickle charge my car
> battery. So far the ones I've seen have been too long and thin, and
> they would block up my air vents or speakers.
>
> Can anyone recommend any sites in the USA or UK that sell small panels
> that are about 12x8 inches in size? Was only looking for a panel of
> around 2-3w maybe 150ma at 15v give or take.
Won't do the job, your car's electronics take more than that even when the
key's out.
Forget it. I once calculated you'd need about 4 sq ft to do any good.
Graham