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NY_Dutch

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Facts are facts regardless of who says otherwise. The numbers do not add up and that is a fact. That's all I am saying.

Or have we recently invented perpetual motion machines? Or discovered Ohms Law isn't true?

-Don- Reno, NV
So you're convinced driving a specially built light weight vehicle 1800 miles using solar for power and charging is not possible. Please advise the folks of that at the Bridgestone competition and Eindhoven University, as they're obviously not aware that they're doing the impossible.
 

DonTom

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So you're convinced driving a specially built light weight vehicle 1800 miles using solar for power and charging is not possible.
Sure it's possible. I already said so. All that is needed is countless hours of direct bright sunlight to charge up your battery when the EV is not being used.

Otherwise the 1.2KW solar is negligible to even a very small EV. I would rather have an extra 1.2 KWH in the battery and remove the solar. Makes more sense. At least I can draw 4.8 KW from that 1200 WH battery for 15 minutes, unlike you can do with the 1200W of solar.

Solar can make sense if you have a few days of sunlight to charge up before your drive.

But let's work with some real numbers. What speed is the EV driving at and how many KHW does it take to go a certain distance at that speed? After we have how many miles per KWH then we can figure how many feet get added with extra 1.2 KW. It's all very simple math once we have the numbers to work with.

-Don- Reno, NV
 

NY_Dutch

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Sure it's possible. I already said so. All that is needed is countless hours of direct bright sunlight to charge up your battery when the EV is not being used.

Otherwise the 1.2KW solar is negligible to even a very small EV. I would rather have an extra 1.2 KWH in the battery and remove the solar. Makes more sense. At least I can draw 4.8 KW from that 1200 WH battery for 15 minutes, unlike you can do with the 1200W of solar.

Solar can make sense if you have a few days of sunlight to charge up before your drive.

But let's work with some real numbers. What speed is the EV driving at and how many KHW does it take to go a certain distance at that speed? After we have how many miles per KWH then we can figure how many feet get added with extra 1.2 KW. It's all very simple math once we have the numbers to work with.

-Don- Reno, NV
There are number of factors involved that neither one us is aware of. The fact remains that the Bridgestone competition has been around for a number of years, and each year the vehicles reach new heights of performance. You're making a number of assumptions with no knowledge of the reality the vehicle designers are working with. Students have also made huge strides in ICE performance with MPG's in the 3,000+ range. Try doing some research before just ruling out what these young people are doing to advance vehicle performance.
 

DonTom

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BTW, how come the most important piece of info. is left out in the OP?

How many KWH is the battery? It's not saying. And that is what determines the real range. Remove the solar and you're unlikely to even notice the difference in total range.

However, the solar is good when parked for many hours in sunlight. A 1.2 KW charge when parked is better than nothing, but not a lot better, unless you have a lot of time.

Bus since we don't have the numbers there, let's compare to Tesla where we do have numbers. 70 KWH battery, ~325 mile range

A Tesla Supercharger will charge at 150KW. Say that is ~30 minutes for a full charge. The 1.2 KW of solar will take 125 times as long to charge up. 125 times 30=3,750 minutes to charge. 62.5 hours. 2.6 twenty-four hour days of sunlight. Say we have 12 hours of sunlight a day. 5.2 bright sunny days to get the same charge at 1200W with solar.

Again, simple math. But above clearly shows how negligible it is to add solar to an EV. And it makes no difference who does it. A watt is a watt.

It's usefulness is limited to when parked for a long time in the sun, not so much when being driven.

-Don- Reno, NV
 

NY_Dutch

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BTW, how come the most important piece of info. is left out in the OP?

How many KWH is the battery? It's not saying. And that is what determines the real range. Remove the solar and you're unlikely to even notice the difference in total range.

However, the solar is good when parked for many hours in sunlight. A 1.2 KW charge when parked is better than nothing, but not a lot better, unless you have a lot of time.

Bus since we don't have the numbers there, let's compare to Tesla where we do have numbers. 70 KWH battery, ~325 mile range

A Tesla Supercharger will charge at 150KW. Say that is ~30 minutes for a full charge. The 1.2 KW of solar will take 125 times as long to charge up. 125 times 30=3,750 minutes to charge. 62.5 hours. 2.6 twenty-four hour days of sunlight. Say we have 12 hours of sunlight a day. 5.2 bright sunny days to get the same charge at 1200W with solar.

Again, simple math. But above clearly shows how negligible it is to add solar to an EV. And it makes no difference who does it. A watt is a watt.

It's usefulness is limited to when parked for a long time in the sun, not so much when being driven.

-Don- Reno, NV
Are things like solar charging while underway and regenerative braking worthless then? As I said, there are a lot of factors involved with this vehicle that neither one of us knows about. One thing we do know though, with just a bit of reading, is that vehicles do go 1,800+ miles with no other power source except solar energy from onboard panels. It's been done over and over.
 

DonTom

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Are things like solar charging while underway and regenerative braking worthless then? As I said, there are a lot of factors involved with this vehicle that neither one of us knows about. One thing we do know though, with just a bit of reading, is that vehicles do go 1,800+ miles with no other power source except solar energy from onboard panels. It's been done over and over.
Regenerative breaking is many KWs. On my Energica Motorcycle, I have seen the regen as high as 30,000 watts. On my Chevy Bolt, twice that. Tesla probably has even more but AFAIK, it has no KW display. Or if it does, I have not yet found it.

Regen is great in stop & go traffic. But its real benefit is not so much in recharging the battery. Its time is too short to make much difference unless downhill for a long time at a slow speed. The big benefit of regen is not having to brake at all when going down hill. No matter how steep, no matter what speed. BTW, if the car in front of you is flashing the brake light steady, that means the brakes were NOT touched. It means the EV in front is slowing down from regen. Even my Energica motorcycle does that. Zero Motorcycles doesn't because they have very little regen even when set to the max.

At freeway speeds, one normally gets better range with regen totally OFF. Even when hilly. You're better off to coast down the hill at full speed to help get up the next hill. One can waste a lot of energy by using too much regen even going down hill on a freeway.

Solar at 1.2 KW is just that. Another 1.2 KW in bright sunlight, perhaps added to say, a 70 KWH Tesla battery. The 70 KWH battery is 4.56 miles range per KWH at 65 MPH. An extra 1.2 KW will add about 5 miles in an hour of driving. So get 70 miles instead of 65 miles in ideal conditions in an hour on a Tesla. A lighter car's gain will be more miles, but the same percentage of increase. Range increase with 1.2 KW of solar will be around 7 percent more range. Better than nothing, but not a lot better. Wind direction will make a larger difference in the range than that 7%. 7% most people won't even notice the difference. You can lose 20% of your range in an EV just with cold weather, and I don't even notice that difference in my normal driving.

-Don- Reno, NV
 

DonTom

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is that vehicles do go 1,800+ miles with no other power source except solar energy from onboard panels.
Not possible.

The solar must be charging a battery. How many KWH is that battery? If the battery is large enough, you can remove the solar and go 5,000 miles.

Way too many facts are left out from that article. But a KWH is still a KWH. A watt is still a watt. And you can only do so much with 1.2KW and with EVs that is considered LOW power.

I charge my Energica motorcycle at as high as 30KW.

My Zero SR as high as ten KW.

My Zero DS (my smallest electric motorcycle, the one I take on my RV trips) as high as 6.3 KW.

Riding takes quite a bit more than the above numbers, especially if going fast uphill.

If you have a battery of 12 kW, it will take more than ten hours to charge at 1.2 KW. If it were 100% efficient (nothing is) it would take ten hours. But there are heat loses and other issues. Also, charge currents vary with the battery SOC.

-Don- Reno, NV
 

JayArr

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Don!

They are doing it whether you believe it or not. That is a fact!

You can sit behind your keyboard and scream "impossible" all day long ... but they are doing it.

I suspect their solar panels are a bit more efficient than what is bolted to the top of the average RV. The vehicle is probably super light and they are driving in Spain, isn't it really sunny in Spain in the summer? Maybe they don't drive everyday, maybe they only drive at night.

Instead of being the ranting lunatic yelling "it can't be done" go read the article and do some research on how they do it and learn some of their tricks. Maybe it'll help you get more motorcycle time in from the sun.
 

DonTom

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"They are doing it whether you believe it or not. That is a fact!"
(quote function not working for me today).

They are doing exactly what?

I am not sure if we're communication well. So let's clear this up.

Are you making the claim they have a 1,800 mile range on 1200 watts of solar alone and have no battery involved? That is not possible on level ground at any speed.

If they do have a battery, how many KWH is it?

Let's get the facts before we waste more time on this!

And I read the article a few times. The most important facts were left out.

-Don- (near Lake Davis, CA on my Harley)
 

JayArr

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Of course it has a battery! Who said it didn't? that doesn't mean it's not a solar car.

I don't know where this 1.2KWH number came from, it's not on the Stella website.

I did find that there is a 60KwH LI battery in it that is recharged by the solar panels.

It only weighs 1700 Kg for the whole RV. (3700 lbs?)

8.8 square meters (27 sq ft) of solar panel folded, which is the state of the car in motion.

17.5 square meters (157 sq ft) when all folded out.

They did not post any stats on the capacity of the solar panels but since this is a highly funded university challenge I would assume they have the very best solar panels made, likely far better than any of us can get our hands on (if we could even afford them).

With full batteries it can drive 600km, if it is sunny and the solar panels are also used it can drive 730km.

Once depleted the batteries take 2-3 days to charge with the solar panels unfolded (17.5 sq m)

So you can't drive the full range every day but it looks like you can get 130km from the solar panels alone on a sunny day. There will be trade offs between how far you drive and how long you recharge but it's a solar powered car and it has been built and it exists and they are driving it around Europe today.

The challenge appears to have been completed, they drove from Eindhoven in Holland, through Paris and France, 3000km to Toledo Spain in 30 days. They charged the batteries with only solar power and camped and lived in the RV.
 
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JayArr

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So, to apply the math, they can charge a 60Kwh battery in 2-3 days. Lets take the longest time, 3 days. and lets say they can get 10 hours of sunlight a day. 30 hours charges 60kWh so the solar panels must be delivering somewhere around 2kWh.

I gets much better mileage than a Tesla, at 600KM from a 60KWh battery, that's basically 10km per kWh (6.25 miles per kWh) you said your tesla was only 4.7?
 

DonTom

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I don't know where this 1.2KWH number came from, it's not on the Stella website.
Message number three. in this thread. Sounds about right to me, as the very max possible for that size as shown in motion. I doubt it could be much more than 1.2KW for the size shown.

I did find that there is a 60KwH LI battery in it that is recharged by the solar panels.
17.5 square meters (157 sq ft) when all folded out.
Once depleted the batteries take 2-3 days to charge with the solar panels unfolded (17.5 sq m)
Yes, all that makes perfect sense. I am glad you found the facts. The article in the OP left out all the most important facts, making it seem as if the impossible was possible. Very poorly explained there.

Thanks for finding the info!

-Don-



 

DonTom

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I gets much better mileage than a Tesla, at 600KM from a 60KWh battery, that's basically 10km per kWh (6.25 miles per kWh) you said your tesla was only 4.7?
The Tesla was based on no wind, at 65MPH, level ground, 70F.

At 38 MPH, my Tesla will get 420 miles. That is where it gets the best range.

Range is tricky on EVs. Take my electric motorcycles, for an example. The best range is at ~5 MPH, every time the speed is doubled the range drops by ~50%. Even more so at higher speeds. So how does one give a range of an EV without mentioning the speed, temperature, wind, road conditions, hills, etc. Too many variables with EVs compared to ICE engines.

Of course the much lighter vehicle will do even better range than my rather heavy Tesla M3. I was using it for an example as we needed some facts. I know the facts with the Tesla, unlike the article in the OP.

-Don- (now back to riding)
 

Lou Schneider

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It still comes down solar alone powering that vehicle at an average gain of 13 km/h (130 miles additional range / 10 hours of sunlight per day). Not too different than the 25 mph average lap speed with lightweight, aerodynamic vehicles in the solar race referenced on the site. And nowhere near enough power for practical use - you might as well try to drive using a Honda EU2000i to provide the motive power.

You could also cover the distance gained by the solar input in about the same amount of time - it's called riding a bicycle. And you'd probably not even break a sweat.
 

JayArr

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You could also cover the distance gained by the solar input in about the same amount of time - it's called riding a bicycle. And you'd probably not even break a sweat.

But where would you sleep that night? LOL

I get your point Lou and it's not for everyone but in Europe the towns and cities are closer together and it might just suit the way some folks camp/RV, more camping less traveling. A young couple with no kids could see most of europe without buying any gas/fuel and have a reasonably comfortable place to stay while doing it. It won't be for full timers or seasonal, just too small but it may be great for rentals, time shares or sharing among the family.
 

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