Table of Range possible at Differing Speeds.

[iMiEVNZ7]

I have been thinking, , Is there a readfily available table of speed and range out there ?.

I have Seen the Autoplaut Range of 220 km, but I do not know at what speed they did this at. They said Highway and town speeds, and I read somewhere that 50 km / Hr gives a good range.

On this forum, people do get close to or better than, 100 mile / 160 Km range, yet the best we could do @ 100 km / Hr is 108 or so Km, That is about 80 miles range or so.

I am thinking that from memory one needs four times the energy to travel twice as fast, I should achieve 200 km at 50 Km / Hr over four hours, rather than the 100 Km I can go now, at 100 Km / Hr

I guess but would not be that keen to try, at 25 Km / Hr I could go 400 Km ? That would take me 8 hours, though for that long I would need a few rest stops and I guess I could comfortably use a recharger during the breaks.

Or, if the iMiEV uses about 280 watts per km at normal speeds and at 1 km per hour it would be less, say 50 watts, possibly more, a 200 watt solar panel would run it all day during daylight hours......@ 4 or five Km/ hour !

Or another way of thinking, it could supply another 40 km per day over 8 hours, but of course there are so many variables that this might be impractical.

Me, I only want to be all electric to the bach and back. Bach is a NZ word for small house for holiday home. Travel distance is 400 km. each way. I am in discussions with a charger supplier here and one in Canada, to try and achieve a two hour recharge time.

I don't mind takeing 12 hours to get to the batch. Lots to see while having a break recharging along the way.

 

[NeilBlanchard]

It would take at least 1kW of PV panels to run an i MiEV. They cannot all get sun at once, and you'd need to use the battery as a buffer. The SolarWorld GT solar car from Bochum University that is currently driving around the world has 800+ watts of panels, and it only carries 2 people, weighs just ~574 pounds (almost 1/5th as much as the i MiEV?) and has a Cd of 0.137, which is about 2.5X better than the i MiEV.

http://www.hochschule-bochum.de/en/solarcar/models/solarworld-gt.html

Here's a video of the SolarWorld GT car traveling in New Zealand -- a beautiful car in a beautiful country:

http://vimeo.com/35036300

 

[Don]

I am thinking that from memory one needs four times the energy to travel twice as fast, I should achieve 200 km at 50 Km / Hr over four hours, rather than the 100 Km I can go now, at 100 Km / Hr

I guess but would not be that keen to try, at 25 Km / Hr I could go 400 Km ? That would take me 8 hours, though for that long I would need a few rest stops and I guess I could comfortably use a recharger during the breaks.

I don't know if your numbers are accurate, but your theory is surely correct. The faster you go, the more range you lose. Part of this is due to the aerodynamics and the co-efficient of drag and part of it is due to Peukert's Law - You can Google that, but basically it says that a battery which will give you 20 amps for 5 hours (100 amp/hours) will NOT give you 100 amps for one hour . . . . it will be something less, maybe much less, depending on the type of battery. Lithiums are among the best (most efficient) but they still give more usable energy when loaded lightly . . . . which is the big reason why jackrabbit starts really shorten your range

Driving fast kills you both ways - Aerodynamics AND the loss of battery power caused by the higher amperage drain required to move the car faster through the air

The range remaing meter is very well engineered and you can use it to evaluate what your driving speeds and technique are costing you or gaining you. You can actually see in real time when you're making gains or losses. I recently drove for 10 or 15 minutes at a pretty steady 50mph (80kms) and noticed that my RR dial fell to 38. I came into town at that point and reduced speed to about 25mph (40kms) and the RR dial quit going down. Actually, after I drive a mile or two it went UP to 39 and after another couple miles it went up again to 40. It was telling me that if I was to maintain 50, that I had about 38 miles remaining, but once I cut the speed in half, it began giving me new numbers which indicated that I could go much farther

I'm sure there's a 'sweet spot' somewhere there - Best range at a certain speed. The window sticker on the USA cars says 112MPGe . . . . it also says the highway MPGe is only 99, while the city number is 126. The 112 is a combination of the two. Your personal results will vary . . . . but the numbers will always be better at slower speeds

Don

 

[NeilBlanchard]

I think the Peukert's effect only really matters in lead acid batteries?

Wind resistance goes up with the square of the speed, so aero mods that lower drag will definitely give you longer range. At ~40-45MPH, aero drag is about 50% of the load, and at 70-75MPH is is at least 75% of the load.

 

[Don]

No - Peukert's Law applies to every type of battery, to some degree. The faster the discharge rate, the less amp hours you get. It's just more pronounced in lead acid batteries. http://www.39pw.us/car/peukertEffect.html

Don