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Hybrid Vehicles Hybrid Vehicles - Archived Discussions How do Hybrids work? Newbie questions encouraged! 
139 messages, Last post on Aug 02, 2007 at 5:38 PM
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Replying to: shadow11 (Aug 29, 2005 11:31 pm) Here is a simple answer. You are right conversion is not 100% efficient. In a normal car none (0%) of braking energy is recovered. In a hybrid with regenerative braking some of the enegry is recovered and used to charge the batteries. Later the batteries use this recovered energy to run electic motors to provide some of the car's power. Essentially this electric power is free. That reduces the power need from the gas engine and in some case also the size of the gas engine needed. This effectively increases the miles per gallon of hybrid cars. YMMV (Your mileage may vary), MidCow
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Replying to: midnightcowboy (Sep 15, 2005 5:52 am) Thanks for the response. I realize that the electric power generated by braking is one way that hybrids become more efficient. I believe the battery also charges when you let the engine do the breaking by coasting to a stop. However, I was under the impression that the majority of charging of the battery was performed by the ICE. Is this not the case? |
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Replying to: shadow11 (Sep 19, 2005 8:58 pm) Most of the charging comes from regenerative braking. In the Prius and other cars/vehicles that use the HSD system from Toyota, there is a small motor/generator ( MG1) which also charges the battery when you are driving because it is always spinning. Many critics say this is inefficinet in that it continues to take some power away from the ICE and try to charge fully charged batteries. The Hondas ( Accord Hybrid, Civic Hybrid, Insight) use an IMA (intergrated Motor Assist) and it primarily provides battery charging through regenerative braking. In both cases you will also obtain some charging when you let off the gas and coast in your vechicle. . However, in both cases this amounts to only a small amount of charging. Good Luck, MidCow P.S. -For what it is worth I think the Prius is probably the best hybrid car. The primary reason I didn't get one was because it doesn't ot have a manual shift transmission and I really like to shift 
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Replying to: midnightcowboy (Sep 20, 2005 4:36 am) That blanket statement doesn't apply to Prius and other HSD vehicles. They are hybrids with *PERSISTENT* electrical systems. Regenerative braking only contributes a small amount of electricity with respect to how much the generator creates... which is far from small. It is 10kW, which is the same size as the current Civic-Hybrid uses for its thrust motor. With the 2006 Civic-Hybrid, that increases to 15kW... which is still considerably smaller than the 50kW Prius currently uses. Civic-Hybrid and the other IMA vehicles are hybrids with *PASSIVE* electrical systems. With them, the regenerative braking is the primary source of electricity. JOHN
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Replying to: midnightcowboy (Sep 20, 2005 4:36 am) That is a misconception. In reality, the electricity is simply directed back to the thrust motor immediately, rather than using it to recharge the battery-pack. This is surprisingly efficient, due to the way the Planetary-CVT is designed. The reason for the misconception is that people don't realize how frequently this happens. 10 times per minute is quite common, which is fast enough to take advantage of an efficiency opportunity without allowing the penalty of charging to take place. In other words, their are inefficiencies with the gas engine that it prevents from occuring. JOHN
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Replying to: john1701a (Sep 20, 2005 4:50 am) This is one of the primary reasons the highway mileage on the Prius and other Toyota HSD deriviative hybrid systems is lower than the city mileage. EPA Prius 60/51 60=city mileage 51=highway mileage. |
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Replying to: john1701a (Sep 20, 2005 4:57 am) This has been discussed over and over. You might want to look at some of the early discussions in the Prius 2004+ thread This is one of the primary reasons the highway mileage on the Prius and other Toyota HSD deriviative hybrid systems is lower than the city mileage. EPA Prius 60/51 60=city mileage 51=highway mileage. |
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Replying to: midnightcowboy (Sep 20, 2005 5:31 am) |
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Replying to: midnightcowboy (Sep 20, 2005 5:31 am) That most certainly is not how HSD works! JOHN
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Replying to: john1701a (Sep 20, 2005 8:06 am) "What are you talking about? That most certainly is not how HSD works! JOHN" The EPA on a Prius is 60/51 The first number means the expected miles per gallon in the City, 60 miles per gallon. The second number is the highway miles per gallon, 51 miles per gallon. The City miles per gallon is 9 miles higher than the highway. All cars are more efficient on the highway, but the Prius and other HSD based vehicles are not. One wonders why the little motor generator MG1 spins and spins needlessly converting ICE to electrical at the penalty of energy conversion loss when the traction battery is fully charged! Have a good day, MidCow
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