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TEG · 02-05-2008, 02:01 PM

Some of the talk about "charge to 80%" and "draw to 30%" could be based on the idea that battery life is substantially shortened if you try to push it to the limits. As Tesla mentioned, they plan to offer the option of a "less than totally full" recharge to help save the battery life. When Volt says they plan to fire the ICE at 30% they may mean that they have to do that to get expected battery lifespan. That lower 30% may be intended to never be used unless it was a dire emergency (such as you ran out of gasoline too).

Because of this there could be some "numbers games" played.
Someone could publish range numbers based on situations where you are "abusing" the batteries. In practice, most batteries don't like to be cycled between 0% and 100%. The Prius batteries are kept in a "happy range" to avoid early failure as well.

So, the firmware to control ICE behavior isn't just designed to maximize BEV only range, or improve performance, but it also needs to be designed to protect the batteries within some limits.

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The whole REEV thing brings up some debate... What qualifies to be called a REEV?

Is it just if the motive force is 100% electric motor? So what if you just take a Ford F150, and replace the transmission with a DC generator hooked directly to a DC motor. Then it is a 100% electric motor driven vehicle (although 100% powered by an ICE generator). I assume that this would not be called a REEV. But what if you put in a very small buffer battery that could give you 1 mile of electric motion with the ICE turned off. Would that be a REEV? I suppose so.

Customers are going to have to research their PHEVs to find what suits their driving habits.

Do you want a vehicle with a 10 mile battery pack, and large ICE?
How about a 40 mile battery pack and medium sized ICE?
How about an 120 mile battery pack with a very small ICE?

02-05-2008, 02:01 PM	#20 (permalink)
TEG PV->EV Join Date: Aug 2006 Posts: 2,752	Some of the talk about "charge to 80%" and "draw to 30%" could be based on the idea that battery life is substantially shortened if you try to push it to the limits. As Tesla mentioned, they plan to offer the option of a "less than totally full" recharge to help save the battery life. When Volt says they plan to fire the ICE at 30% they may mean that they have to do that to get expected battery lifespan. That lower 30% may be intended to never be used unless it was a dire emergency (such as you ran out of gasoline too). Because of this there could be some "numbers games" played. Someone could publish range numbers based on situations where you are "abusing" the batteries. In practice, most batteries don't like to be cycled between 0% and 100%. The Prius batteries are kept in a "happy range" to avoid early failure as well. So, the firmware to control ICE behavior isn't just designed to maximize BEV only range, or improve performance, but it also needs to be designed to protect the batteries within some limits. -------------------------------------- The whole REEV thing brings up some debate... What qualifies to be called a REEV? Is it just if the motive force is 100% electric motor? So what if you just take a Ford F150, and replace the transmission with a DC generator hooked directly to a DC motor. Then it is a 100% electric motor driven vehicle (although 100% powered by an ICE generator). I assume that this would not be called a REEV. But what if you put in a very small buffer battery that could give you 1 mile of electric motion with the ICE turned off. Would that be a REEV? I suppose so. Customers are going to have to research their PHEVs to find what suits their driving habits. Do you want a vehicle with a 10 mile battery pack, and large ICE? How about a 40 mile battery pack and medium sized ICE? How about an 120 mile battery pack with a very small ICE?