3 ms·

Is 50% a reasonable number? It seems low to me, given that electric motors are ~90% efficient, and battery charge efficiencies seem to be around 80%. To get tha

by lutorm 9y ago

Is 50% a reasonable number? It seems low to me, given that electric motors are ~90% efficient, and battery charge efficiencies seem to be around 80%. To get that to 50% overall, the gears and powertrain would have to be < 70% efficient.

Skunkleton 9y ago
Also, the trash has to be compacted. I doubt this will be a net positive. Just a nice side effect.
- woodandsteel 9y ago
  It's hauling mineral deposits, not trash, so no compacting.
  - Skunkleton 9y ago
    Right you are. There was another thread that was talking about this for garbage trucks. Whoops.
ChuckMcM 9y ago
Hard to say, perhaps the most efficient conversion of potential energy to electricity is hydroelectric which can hit 90%, but if you put it into batteries and take it out again that drops some additional points and what ever you lose from heating the batteries. You would want to look at friction losses in the wheels, and coupling losses between the wheels and the brakes. And on the way up, you're going through the power train. Based on the mass ratio the magic number is 69.2% to hit break even assuming you always load to 65 tons. If you load to 55 tons (15% margin of error) the magic number would be 82% efficiency. EDIT: See another comment that the ratio is 110 tons to 65 tons, not 65 tons to 45 tons. That improves things. Total system regen efficiency has to be above 41%. That number crosses 60% when the load is down to 30 tons.
olyjohn 9y ago
In a typical car with gears, you tend to lose about 15% of your power through the drive train on a 2wd vehicle. It approaches 30% with a 4wd vehicle. Since this is based on a diesel vehicle, I imagine it won't be too far off. Maybe worse because of the huge size of everything, but I'm not a mechanical engineer.
- jaclaz 9y ago
  Though it is not - I believe - the case of this specific Komatsu model, electric driven dumper trucks are in production, getting rid of the transmission, examples, JFYI: http://www.komatsuamerica.com/equipment/trucks/electric http://www.komatsuamerica.com/equipment/trucks/electric http://www.cat.com/en_ID/products/new/equipment/off-highway-trucks/mining-trucks/18232553.html# http://www.cat.com/en_ID/products/new/equipment/off-highway-... Basically this kind of trucks have a huge diesel engine and electric generator and four electric motors, one for each wheel. Power is lost in the generation and powering of the electric motors of course, but there is no transmission overhead (though there is a reduction gearbox on each motor anyway).

by lutorm 9y ago

Skunkleton 9y ago

Also, the trash has to be compacted. I doubt this will be a net positive. Just a nice side effect.

woodandsteel 9y ago
It's hauling mineral deposits, not trash, so no compacting.
- Skunkleton 9y ago
  Right you are. There was another thread that was talking about this for garbage trucks. Whoops.

ChuckMcM 9y ago

Hard to say, perhaps the most efficient conversion of potential energy to electricity is hydroelectric which can hit 90%, but if you put it into batteries and take it out again that drops some additional points and what ever you lose from heating the batteries. You would want to look at friction losses in the wheels, and coupling losses between the wheels and the brakes. And on the way up, you're going through the power train. Based on the mass ratio the magic number is 69.2% to hit break even assuming you always load to 65 tons. If you load to 55 tons (15% margin of error) the magic number would be 82% efficiency. EDIT: See another comment that the ratio is 110 tons to 65 tons, not 65 tons to 45 tons. That improves things. Total system regen efficiency has to be above 41%. That number crosses 60% when the load is down to 30 tons.

olyjohn 9y ago

In a typical car with gears, you tend to lose about 15% of your power through the drive train on a 2wd vehicle. It approaches 30% with a 4wd vehicle. Since this is based on a diesel vehicle, I imagine it won't be too far off. Maybe worse because of the huge size of everything, but I'm not a mechanical engineer.

jaclaz 9y ago
Though it is not - I believe - the case of this specific Komatsu model, electric driven dumper trucks are in production, getting rid of the transmission, examples, JFYI: http://www.komatsuamerica.com/equipment/trucks/electric http://www.komatsuamerica.com/equipment/trucks/electric http://www.cat.com/en_ID/products/new/equipment/off-highway-trucks/mining-trucks/18232553.html# http://www.cat.com/en_ID/products/new/equipment/off-highway-... Basically this kind of trucks have a huge diesel engine and electric generator and four electric motors, one for each wheel. Power is lost in the generation and powering of the electric motors of course, but there is no transmission overhead (though there is a reduction gearbox on each motor anyway).