http://www.triplepundit.com/2007/04/askpablo-well-to-wheel-efficiency-part-ii/ Business, Better. Since 2005 Fri, 10 Feb 2012 07:33:00 +0000 hourly 1 http://wordpress.org/?v=3.3.1 http://www.triplepundit.com/2007/04/askpablo-well-to-wheel-efficiency-part-ii/comment-page-1/#comment-14683 Tormod Tue, 24 Apr 2007 18:17:17 +0000 http://www.triplepundit.com/wordpress/2007/04/askpablo-well-to-wheel-efficiency-part-ii/#comment-14683 Good aritcle. If I may, I will contribute with some of my own obsevations. Why is a hybrid more efficient than a standard drive train? - Yes, regenerative braking, but that is only one out of many factors. Other factors: - No idling when stopped. - Picks up all sorts of ”free rides” where you momentarily don’t need any power, like slowing down for a red light or slower traffic ahead, or small downhil, but not necessarily so steep that you have to engage the brakes, i.e. if you don’t need the ICE, don’t use it. - It is also more effifient to run the ICE at 100% of optimal load 50% of the time and store excess energy in batteries than to run the ICE at 50% load fro 100% of the time, because then you will have to feed the parasitic losses like the valve train, oil and water pump etc. only half of the time. And numbers get better in favour of the electric motor the less power you need. An electric motor is vastly more scalable than an ICE, using only the energy needed on the driveshaft, and can take momentary overloads with great ease (A starter motor is overloaded with several hundred per cent compared to the effect it could sustain continuously). These benefits have to be balanced against having to carry the extra weight of the batteries. At opimal load, an ICE is at best 25-30% efficient, and all discussions I have seen assumes that this is the case throughout the power range, but I would like to see the efficiency of an ICE graphically as a function of power output. I assume that during low power demand, say 30 hp in slow moving traffic, the efficiency is down to single digits ( Good aritcle.
If I may, I will contribute with some of my own obsevations.
Why is a hybrid more efficient than a standard drive train?
- Yes, regenerative braking, but that is only one out of many factors.
Other factors:
- No idling when stopped.
- Picks up all sorts of ”free rides” where you momentarily don’t need any power, like slowing down for a red light or slower traffic ahead, or small downhil, but not necessarily so steep that you have to engage the brakes, i.e. if you don’t need the ICE, don’t use it.
- It is also more effifient to run the ICE at 100% of optimal load 50% of the time and store excess energy in batteries than to run the ICE at 50% load fro 100% of the time, because then you will have to feed the parasitic losses like the valve train, oil and water pump etc. only half of the time. And numbers get better in favour of the electric motor the less power you need.
An electric motor is vastly more scalable than an ICE, using only the energy needed on the driveshaft, and can take momentary overloads with great ease (A starter motor is overloaded with several hundred per cent compared to the effect it could sustain continuously). These benefits have to be balanced against having to carry the extra weight of the batteries.
At opimal load, an ICE is at best 25-30% efficient, and all discussions I have seen assumes that this is the case throughout the power range, but I would like to see the efficiency of an ICE graphically as a function of power output. I assume that during low power demand, say 30 hp in slow moving traffic, the efficiency is down to single digits (

]]> http://www.triplepundit.com/2007/04/askpablo-well-to-wheel-efficiency-part-ii/comment-page-1/#comment-14682 Nick Aster Tue, 24 Apr 2007 00:51:23 +0000 http://www.triplepundit.com/wordpress/2007/04/askpablo-well-to-wheel-efficiency-part-ii/#comment-14682 Brilliant post! I love the part about the Round-a-bouts. Brilliant post! I love the part about the Round-a-bouts.

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