# Forums

## Stupid Charging Trick #73

When you're at the top of a hill, put a bunch of rocks in the trunk and frunk. When you reach the bottom, remove them. Let me know how it goes.

Yes, it *should* work, as long as your regen isn't maxed out without the rocks and the downhill isn't mostly down and not too much up-and-down.

(I'm collecting more serious tools for EV drivers at http://EVTripPlanner.com - soon to have a "Trip Energy Estimator" that takes into account real-world speeds and conditions)

Brian H | 3 marzo 2013

The energy you exert lifting the rocks will probably cost you more in food to replenish than you save falling downhill. >;p

lph | 3 marzo 2013

its a good way to flatten mountains over time!

lph | 3 marzo 2013

Called EVE (Electric vehicle erosion)

jat | 3 marzo 2013

Or just get a plunger and attach it to a speargun. Find a vehicle going where you want to go, fire the plunger, and let off the accelerator to regen. Get to your destination with more charge than when you left :).

DBT | 3 marzo 2013

Physics I should really be mandatory for anyone graduating High School. *facepalm*

Here's copy paste of ask dot com, I assume the result will be self-explanatory. Or not.

PE = mgh = 100kg x 9.8 m/s² x 10 m = 9800 Joules or 2.72 watt-hours

mthanos | 3 marzo 2013

The car has a mass of about 2091Kg. That means for every 1000m you drive down, you have the potential to regenerate 2091kg x 9.8m/sec^2 x 1000m = 20.5Mjoules or about 5.7Kwh. And that is without any wind resistance, tire rolling resistance, or any other inefficiencies in the drive train, electronics, or battery. To charge the car completely you would have to drive down a mountain that was 49,210 ft tall, or about 20,000ft higher than Mt Everest.

But luckily, we are't relying on regen to top off the tank, just reclaim what would otherwise be lost to heat through braking. And I'm happy enough with that. Res# 12397.

trydesky | 3 marzo 2013

on this topic, did anyone ever see their energy graph show green...that is, actually create energy? It happened to me once the other day. By the time I figured out what the "green" meant, I was a mile down the road, and forget exactly what happened. I know I was breaking, going down hill, sort of fast.

penguin_brian | 3 marzo 2013

Why do you need to worry about an engine? It is obvious all you need to do is to fill the car up with rocks at the top of a hill, and the car will go with absolutely no pollution. No petrol/electricity to pay for. Reduced maintenance costs, as no engine to maintain.

Its win/win!

Another great idea is sticking a wind turbine on top of the car. This can power GPS and other electronics while you are going down hill (literally and figuratively).

http://www.teslamotors.com/en_AU/forum/forums/frunk-turbines

:-)

lph | 3 marzo 2013

Jat..I like.the plunger idea. Now we just need to find a truck with a good flat surface for it to stick.

c.bussert67 | 4 marzo 2013

Rocks aren't cheap! I'd rather just pay for electricity.

lph, sounds like designated pullers are in demand... the future of hitchhiking!

GoTeslaChicago | 4 marzo 2013

Here's my all time favorite:

Rig up solar panels in front of the headlights. As long as you leave the lights on, you can charge and drive!

Brian H | 4 marzo 2013

@try;
you should see green every time you are using full regen.

Audio suckers:
Device that pulls in excessive audio from a neighboring car and converts it to DC to charge the Tesla.

shs | 4 marzo 2013

How about constantly speeding up and slowing down using regen to charge the battery. Oh wait, been tried (Broder) and didn't work.

Jolinar | 4 marzo 2013

hehe, troll science in practice :D

christurbeville | 4 marzo 2013

You people are all missing it... Backseat pedals!

Brian H | 4 marzo 2013

Even better, jumpseat pedals. Fueled by a steady supply of high-sugar snacks.

olanmills | 4 marzo 2013

Haha, this can be easily applied to a practical situation.

Suppose you're all visiting grandma's for thanksgiving, and she lives at a higher elevation. Work it out so one of your other relatives brings all the kids and all of the potluck food and whatever. Then on the way back, you helpfully offer to load up all of the stuff/people and take them back!

And of course, if your grandma lives in the valley, then just reverse the instructions!

lph | 4 marzo 2013

Extending the idea of using a plunger to back of a truck idea. If we use a strong bungie chord it could be used to go into a Broder mode and make the car lurch forward and back forcing you to use the re-gen mode violently to avoid the truck in front. Although in reality this does not generate any more energy, it will keep you awake and is really exciting.

lph | 4 marzo 2013

Also back to the rock idea... Maybe Cliff is on to something here ;-P
There are trucking companies all over transporting rocks from the mountains to the low lying areas where most of the cities are (humane erosion?) . Loading rocks into the Tesla while going down the mountain could be good business because this will be free/low cost transportation for the rocks. Think about all that stored energy locked up in those mountains!
However like all good things, it can't last for ever because the mountains will eventually be flattened.

brijam | 4 marzo 2013

@Brian H, I think what trydesky is talking about is green on the energy graph, not on the center dashboard.

@trydesky, I got the energy graph to show green last Sunday on my return trip back from the coast on a long downhill stretch. I've seen it happen before on other long downhill runs.

Brian H | 5 marzo 2013

A bungie cord rated to accelerate 2.3 tons would have to have about a 4 ton draw, and maybe a 7 ton breaking point. You might need a bundle, rather than one.

And bungies don't sing, so they have no chords. They're not budgie cords, you know!