Air Temperature Site

[Luft]

Does anyone know of a site where I can find the average air temperature for any given area broken down by the hour?

I know our range is effected greatly by the air and battery temperatures. I'm guessing that the morning temperature will be the most important because the battery will cool over night to that temperature and then during travel and charging will warm up a lot.

Tony, when you made your solo trip did you get a sense for how much air temperature vs battery temperature affected range?

The LEAF's battery temperature gauge seems next to worthless for calculation purposes.

 

[cwerdna]

Average? http://www.weather.com" onclick="window.open(this.href);return false; has hourly forecasts.

 

[apvbguy]

try:

http://www.wunderground.com/" onclick="window.open(this.href);return false;

 

[TonyWilliams]

try:

http://www.wunderground.com/" onclick="window.open(this.href);return false;

http://www.wunderground.com/history" onclick="window.open(this.href);return false;

Then type in the location (generally an airport) and the date you want the hourly "METAR" data for.

 

[TonyWilliams]

Tony, when you made your solo trip did you get a sense for how much air temperature vs battery temperature affected range?

The LEAF's battery temperature gauge seems next to worthless for calculation purposes.

Well, I use a simple rule of thumb of 1% increase/decrease in range per 1000 feet deviation in density altitude. You can calculate that on this site:

http://wahiduddin.net/calc/calc_da.htm" onclick="window.open(this.href);return false;

Battery temperature, use 1% loss per 4F degrees below 70F.

So, with on a beautiful sea level day at 70F, with a 70F battery, I expect XX range. If the battery temperature drops to 30F, I expect XX-10%.

The 30F degree temperature changes air density based on ISA standards with 0F dew point, and 29.92 pressure, 0 elevation, which is less than a 3000 feet change, or about 2.Y% decrease in range that you will see as a decrease in economy. For practical purposes, you could just add the two together to get a XX + 2.Y% = 12.Y% decrease in range at 30F ambient and battery temps compared to 70F.

By the same token, with just an increase in elevation to 8000 feet elevation mountains, with the same 30F/30F ambient/battery temperatures, I expect an 8% increase in range due to 8000 feet density altitude to counter the 10% loss of battery performance.

With 70F/70F at the 8000 feet elevation town, the battery would have no loss of capacity and the car would increase in range by 10.5% for the 10,500 feet density altitude.

I really should change the rule of thumb from density altitude to pure air density (sorry, pilots just think in density altitude terms). The above example is 72.7% air density, or a loss of 28.3% of air divided by 4 = 7% gain in range... probably close enough.

So, to summarize, battery temperature is the huge killer to range compared to any air density issues based on a sea level world.

Hope this helps.

 

[Luft]

Average? http://www.weather.com" onclick="window.open(this.href);return false; has hourly forecasts.

Yeah, I wasn't very clear. By average I mean I would like to know what the average temperature has been on a particular day of the year over a number of years. i.e. What temperature might I expect on July 2nd at 7:00 am in Grants Pass Oregon based on what the temperature has been on July 2nd at 7:00 am in Grants Pass Oregon over the last twenty-five years.

With not too much work I can get this information from the sites given.

Thanks.

 

[Luft]

Tony, when you made your solo trip did you get a sense for how much air temperature vs battery temperature affected range?

The LEAF's battery temperature gauge seems next to worthless for calculation purposes.

Well, I use a simple rule of thumb of 1% increase/decrease in range per 1000 feet deviation in density altitude. You can calculate that on this site:

http://wahiduddin.net/calc/calc_da.htm" onclick="window.open(this.href);return false;

Battery temperature, use 1% loss per 4F degrees below 70F.

So, with on a beautiful sea level day at 70F, with a 70F battery, I expect XX range. If the battery temperature drops to 30F, I expect XX-10%.

The 30F degree temperature changes air density based on ISA standards with 0F dew point, and 29.92 pressure, 0 elevation, which is less than a 3000 feet change, or about 2.Y% decrease in range that you will see as a decrease in economy. For practical purposes, you could just add the two together to get a XX + 2.Y% = 12.Y% decrease in range at 30F ambient and battery temps compared to 70F.

By the same token, with just an increase in elevation to 8000 feet elevation mountains, with the same 30F/30F ambient/battery temperatures, I expect an 8% increase in range due to 8000 feet density altitude to counter the 10% loss of battery performance.

With 70F/70F at the 8000 feet elevation town, the battery would have no loss of capacity and the car would increase in range by 10.5% for the 10,500 feet density altitude.

I really should change the rule of thumb from density altitude to pure air density (sorry, pilots just think in density altitude terms). The above example is 72.7% air density, or a loss of 28.3% of air divided by 4 = 7% gain in range... probably close enough.

So, to summarize, battery temperature is the huge killer to range compared to any air density issues based on a sea level world.

Hope this helps.

Thanks Tony, that does help. I think I'll just assume sea level. It's better to arrive at my destination with some charge left than to turtle to a stop a mile away from the next charging station. Air pressure will be effected by altitude and barometric pressure caused by weather and air temperature. Ughh... Sunny days will likely have higher air pressure (bad for range) but be warmer (good for range)... Ugh...

I'll definitely consider battery temperature but without something like Ingineer's LEAFscan I'm probably going to have to assume that my battery temperature is the morning air temperature. I'll monitor the battery temperature bars but the LEAF's battery temperature gauge just does not appear to have the granularity to be of much use.