Energy Balance Fun w/ ebikes

Not too sure about the amp meter but if I coast down a 16m hill I will get an average current reading of 1.7 amps ~ 1 watt-hr, in 45 seconds.

The potential energy at the top of the hill is 3.7 watt - hours.

If I regenerate I can go 0.4 miles in 2 minutes w/o peddaling.

If energy is stored as kinetic energy then its 0.3 miles in 1 minute.

On Saturday, 1 May 2021 at 04:50:03 UTC+1, wrote:
Not too sure about the amp meter but if I coast down a 16m hill I will get an average current reading of 1.7 amps ~ 1 watt-hr, in 45 seconds.

The potential energy at the top of the hill is 3.7 watt - hours.

If I regenerate I can go 0.4 miles in 2 minutes w/o peddaling.

If energy is stored as kinetic energy then its 0.3 miles in 1 minute.

Motorists need to put wind turbines on the roof of their cars. That way to forward motion will turn the wind turbine which will turn the generator which will produce energy to recharge the batteries which powers the engine.

On 01/05/2021 04:50, Bret Cahill wrote:
Not too sure about the amp meter but if I coast down a 16m hill I
will get an average current reading of 1.7 amps ~ 1 watt-hr, in 45
seconds.

48V battery?

The potential energy at the top of the hill is 3.7 watt - hours.

If I regenerate I can go 0.4 miles in 2 minutes w/o peddaling.

You assume that 1.7A/48V/45s is all saved in the battery. Battery
charging is not 100% efficient and you have already lost 75% before it
reaches the battery. Where is that going?

It is much more efficient to convert your PE to KE and back to PE. Even
if there is no next rise, your KE will overcome friction for a greater
distance than the energy you have put in the battery.

Regen is only useful if you can recover the energy you would normally
lose by using the brakes.

If energy is stored as kinetic energy then its 0.3 miles in 1
minute.

Your KE at 12mph is roughly 0.6Whr. If you slow to zero KE and recover
25%, that's only 0.15Whr. But as you slow down the efficiency is bound
to drop further. It would require a lot of discipline to start slowing
down early instead of the normal method of idling for many seconds then
braking for a few.

Not too sure about the amp meter but if I coast down a 16m hill I
will get an average current reading of 1.7 amps ~ 1 watt-hr, in 45
seconds.
48V battery?

36

The potential energy at the top of the hill is 3.7 watt - hours.

If I regenerate I can go 0.4 miles in 2 minutes w/o peddaling.
You assume that 1.7A/48V/45s is all saved in the battery.

The amp meter seems to be on the battery side of the rest of the electronics / motor.

Battery
charging is not 100% efficient and you have already lost 75% before it
reaches the battery. Where is that going?

The wind. Drag = velocity^2

It is much more efficient to convert your PE to KE and back to PE. Even
if there is no next rise, your KE will overcome friction for a greater
distance than the energy you have put in the battery.

That would be true if the % grade is low enough. Then the round trip battery efficiency loss doesn't waste the potential energy.

This hill averages 10% and maxes out at 16%.

It takes longer of course but you go further by reducing wind drag by storing the potential energy in the battery on a steep enough hill -- even with the round trip battery inefficiency loss!

The % grade for break even is next on the agenda.

Regen is only useful if you can recover the energy you would normally
lose by using the brakes.
If energy is stored as kinetic energy then its 0.3 miles in 1
minute.
Your KE at 12mph is roughly 0.6Whr. If you slow to zero KE and recover
25%, that's only 0.15Whr. But as you slow down the efficiency is bound
to drop further. It would require a lot of discipline to start slowing
down early instead of the normal method of idling for many seconds then
braking for a few.

Not too sure about the amp meter but if I coast down a 16m hill I
will get an average current reading of 1.7 amps ~ 1 watt-hr, in 45
seconds.
48V battery?
36
The potential energy at the top of the hill is 3.7 watt - hours.

If I regenerate I can go 0.4 miles in 2 minutes w/o peddaling.
You assume that 1.7A/48V/45s is all saved in the battery.
The amp meter seems to be on the battery side of the rest of the electronics / motor.
Battery
charging is not 100% efficient and you have already lost 75% before it
reaches the battery. Where is that going?
The wind. Drag = velocity^2
It is much more efficient to convert your PE to KE and back to PE. Even
if there is no next rise, your KE will overcome friction for a greater
distance than the energy you have put in the battery.
That would be true if the % grade is low enough. Then the round trip battery efficiency loss doesn't waste the potential energy.

This hill averages 10% and maxes out at 16%.

It takes longer of course but you go further by reducing wind drag by storing the potential energy in the battery on a steep enough hill -- even with the round trip battery inefficiency loss!

The % grade for break even is next on the agenda.

About 2.5% for my bike.

I lucked out with this as there was only one other hill nearby and it was 2.7%.

Regen is only useful if you can recover the energy you would normally
lose by using the brakes.
If energy is stored as kinetic energy then its 0.3 miles in 1
minute.
Your KE at 12mph is roughly 0.6Whr. If you slow to zero KE and recover
25%, that's only 0.15Whr. But as you slow down the efficiency is bound
to drop further. It would require a lot of discipline to start slowing
down early instead of the normal method of idling for many seconds then
braking for a few.