Topic: Climbing hills and potential energy (Read 627 times)

Doug S · « **on:** September 15, 2017, 08:36:01 PM »

I just did a quick calculation, and thought it might interest other people. I've wondered how much energy it takes to climb hills, so I finally ran through the calcs. It turns out, to raise 300 kg of mass 1000 meters high requires 0.833 kWh of energy.

More than I thought. Clearly altitude changes will have to be taken into account if you're heading into the hills.

MrDude_1 · « **Reply #1 on:** September 16, 2017, 09:11:38 AM »

im curious how you came to that number. Can you show your work?

gt13013 · « **Reply #2 on:** September 16, 2017, 10:51:23 AM »

Its a simple question of physics. This energy is the product of the mass, the meters to climb, and convenient constants to take care of units.
https://en.wikipedia.org/wiki/Potential_energy#Potential_energy_for_near_Earth_gravity

I attach a spreadsheet if you want to make your own computations.

Doug S · « **Reply #3 on:** September 16, 2017, 06:42:06 PM »

I didn't work anywhere near that hard. https://www.easycalculation.com/physics/classical-physics/potential-energy.php gave me the potential energy in joules, then a simple Google query (go to Google.com and type in "3000000 joules in kwh") gave me the answer in kWh.

Keith · « **Reply #4 on:** September 16, 2017, 07:58:02 PM »

And "in theory" you get that energy back going down. Doesn't happen though.

Doug S · « **Reply #5 on:** September 17, 2017, 07:19:55 AM »

Quote from: Keith on September 16, 2017, 07:58:02 PM

And "in theory" you get that energy back going down. Doesn't happen though.

It sure doesn't. IMHO regen is totally overrated. By far the most energy you use is pushing air aside, and you're not getting that back.

hubert · « **Reply #6 on:** September 17, 2017, 08:53:12 PM »

Basically, downhill on standard roads, you will not regen that much. But you will cover miles and miles without any consumption. This combined with the added energy needed to climb makes the hilly range not shorter than on the flatland (when returning to approx same altitude as at departure). Don't worry!

gt13013 · « **Reply #7 on:** September 18, 2017, 02:54:56 AM »

Sorry to disagree with some of you, but you really retrieve this energy when you go downhill.
In fact, if you go downhill at a speed such as you use power, you will really save this amount of energy.
If you go downhill at a speed such as you use regen, you will save this energy multiplied by the conversion efficiency factor of the regen.
But generally you use the brakes more when you go downhill that when you go uphill. And brakes waste energy.
Conclusion: if you want to verify the rule exactly, brake the same when going uphill and downhill, and use regen the same also (or never!)...

hubert · « **Reply #8 on:** September 18, 2017, 03:25:55 AM »

Except if there is a motorway going uphill/downhill, the roads are usually very curvy in the mountains. Therefore your average speed, both upwards and downwards, will be less than on same categories of roads on the flat. This also helps keeping the range because you blow less air around you!

ElectricMotorcycleForum.com

News:

Author Topic: Climbing hills and potential energy (Read 627 times)

Doug S

Climbing hills and potential energy

MrDude_1

Re: Climbing hills and potential energy

gt13013

Re: Climbing hills and potential energy

Doug S

Re: Climbing hills and potential energy

Keith

Re: Climbing hills and potential energy

Doug S

Re: Climbing hills and potential energy

hubert

Re: Climbing hills and potential energy

gt13013

Re: Climbing hills and potential energy

hubert

Re: Climbing hills and potential energy