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I notice that during the test drives one author said they used 53 KW of the 60KW capacity of the battery. With my Volt it is 11KW from a 16.5KW battery. This was done to insure battery life. Does the Bolt have that much different battery chemistry to allow almost total discharge of the battery.
 

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That is what GM claims.

And I, for one, am inclined to trust them.

They have proved to me, with my nearly six year old Volt, that they know how and intend to keep building long life reliable electric drivetrains.
 

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Something to keep in mind is that the Volt is engineered for a use case where the battery is completely discharged and then fully recharged on an almost daily basis. This is undoubtedly why such a large portion of total capacity is reserved as an under/over charge buffer.

By comparison, the Bolt will only very rarely get near its "completely discharged" point, and on typical days it will not use nearly as large a percentage of battery capacity. That means either that the daily range of battery State Of Charge will be less (for example, something like ranging from 100% down to 70% and then back to a 100% charge daily) or that it will be charged less often. That, along with the new battery chemistry are probably why GM feels comfortable in using a greater percentage of the battery's capacity.
 

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Something to keep in mind is that the Volt is engineered for a use case where the battery is completely discharged and then fully recharged on an almost daily basis. This is undoubtedly why such a large portion of total capacity is reserved as an under/over charge buffer.

By comparison, the Bolt will only very rarely get near its "completely discharged" point, and on typical days it will not use nearly as large a percentage of battery capacity. That means either that the daily range of battery State Of Charge will be less (for example, something like ranging from 100% down to 70% and then back to a 100% charge daily) or that it will be charged less often. That, along with the new battery chemistry are probably why GM feels comfortable in using a greater percentage of the battery's capacity.
This is the key difference between EREVs and BEVs. And well explained here.

(Also, "KW" ≠ "kWh". It's an important distinction.)
 

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This may be comparing apples to oranges, but our 2010 Prius has nearly 150,000 miles and we purchased it brand new in May of 2009.

The battery today appears to still have the same usable capacity as the day we purchased it. MPG recently has been in the 57-60 mpg range calculated by miles driven divided by gal's used. The computer readout on the dash is always off 3.5-4 mpg over reading as it is for all Gen 3-Gen 4 prius's, 2010-2016 year models...
.
 

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Something to keep in mind is that the Volt is engineered for a use case where the battery is completely discharged and then fully recharged on an almost daily basis. This is undoubtedly why such a large portion of total capacity is reserved as an under/over charge buffer.

By comparison, the Bolt will only very rarely get near its "completely discharged" point, and on typical days it will not use nearly as large a percentage of battery capacity. That means either that the daily range of battery State Of Charge will be less (for example, something like ranging from 100% down to 70% and then back to a 100% charge daily) or that it will be charged less often. That, along with the new battery chemistry are probably why GM feels comfortable in using a greater percentage of the battery's capacity.
Now that's a good point I hadn't considered before.

I do wonder what the impact of "very cold" days will be, you know the same kind of weather where a Volt does ERDTT.
I know we had some days last winter where it was far more efficient to run the REX and warm the car up that way and then switch over to the battery pack, you won't be able to do that with a Bolt EV so it'd be steady draw on the electric heater.
 

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I'm sure GM also incorporated some sort of thermal management system into the Bolt as well which should help with longevity. As for the Prius, I believe the 2010's still relied on NiMH technology, but also, their decision to use an Atkinson engine which runs more efficient helps as well as not being completely reliant on battery power over about 45 Mph which is my understanding when the engine kicks on to provide the propulsion.
 

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This may be comparing apples to oranges, but our 2010 Prius has nearly 150,000 miles and we purchased it brand new in May of 2009.

The battery today appears to still have the same usable capacity as the day we purchased it. MPG recently has been in the 57-60 mpg range calculated by miles driven divided by gal's used. The computer readout on the dash is always off 3.5-4 mpg over reading as it is for all Gen 3-Gen 4 prius's, 2010-2016 year models...
.
I think your Prius has a NiMH battery and not Li-ion. Also, if your Prius operates like my old 2002 Prius then the SOC range is very limited. I think the early Priuses used a range of 40-80% SOC. The Prius battery is engineered for power, while the BEV battery is engineered for energy. So I think one can't easily make a direct comparison between the two technologies.
 

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Something to keep in mind is that the Volt is engineered for a use case where the battery is completely discharged and then fully recharged on an almost daily basis. This is undoubtedly why such a large portion of total capacity is reserved as an under/over charge buffer.

By comparison, the Bolt will only very rarely get near its "completely discharged" point, and on typical days it will not use nearly as large a percentage of battery capacity. That means either that the daily range of battery State Of Charge will be less (for example, something like ranging from 100% down to 70% and then back to a 100% charge daily) or that it will be charged less often. That, along with the new battery chemistry are probably why GM feels comfortable in using a greater percentage of the battery's capacity.
Exactly.

Consider this: If you drive a first generation Volt for 100,000 electric miles and you only charge the battery when it's completely empty it will have about 2,600+ complete battery cycles. A Bolt EV driven the same distance and only charging when empty will have about 400 complete battery cycles.
 

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...With my Volt it is 11KW from a 16.5KW battery. This was done to insure battery life.....
This is also done because when you use up the 11kW and the gas engine starts running you now have a 150 HP Hybrid.
The battery has a big buffer for Hybrid duties.
You don't want to drive an 84 HP gas only Volt.
 

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The other thing that hasn't come up yet is discharge rates. Battery cells are rated for discharge as a fraction of their capacity (called a C rate - 1C is discharging at a rate in Amps or kilowatts equal to the capacity in Amp Hours or Kilowatt-Hours.)

Hybrids have tiny batteries and even though they have weak electric motors by comparison, they are asking for very high discharge levels from the batteries - often over 20C, deep in LiPo (or NiMH) territory.

The Volt actually uses an energy biased chemistry Lithium Ion system, and pushes it pretty hard - 7C in the original Volt is very aggressive for the chemistry.

The Bolt, despite having more power, is much less aggressive here - around 2.5C if the preliminary numbers hold up. That means less stress on the battery and makes it safer to use more of the battery.

(This is a smaller effect - the relatively few cycles needed and relatively rare deep cycles is the biggest of the various aspects, with the need to keep an engine buffer being another big piece.)
 

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Exactly.

Consider this: If you drive a first generation Volt for 100,000 electric miles and you only charge the battery when it's completely empty it will have about 2,600+ complete battery cycles. A Bolt EV driven the same distance and only charging when empty will have about 400 complete battery cycles.
I'm curious about this on the Bolt as well. The Volt battery is said to be tested good for 6000 cycles. At 70% charge per cycle, the 100,000 EV mile cycle count is really closer to 1700.

Has it been stated anywhere how many charge cycles the Bolt battery will be good for? If 1000 is standard for a fully utilized battery, will it be closer to 2000 at 90%?
 
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