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Discussion Starter #1 (Edited)
The Volt battery seams bigger in size but has much less energy storage.


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The Bolt battery is flat and compact, does not look like you can replace sections at the Dealership level.

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It does appear you can replace sections of the battery, just looked it up.
 

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Extended range electric vehicles have different battery needs than EV only. When the generator is running it puts out a lot power that needs to be used or it goes back into the battery, so EREVs never charge to max battery capacity to prevent damage to the cells when the generator is running. Also, the Volts battery is designed to have many thousands of charge cycles, where the Bolt EV only needs maybe 1000 cycles. For instance, sparkies 400k plus mile Volt with 140k plus miles EV has been cycled maybe 4000 plus times, but a Bolt EV would need less than 600 for the same EV miles.
 

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Does the Bolt also require a 12V AGM battery like the Volt?
 

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Does the Bolt also require a 12V AGM battery like the Volt?
Yes, unlike the Volt the Bolt's 12V AGM battery is in the front of the Bolt under the hood.
 

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Yes, unlike the Volt the Bolt's 12V AGM battery is in the front of the Bolt under the hood.
That's interesting. So I wonder how it gets charged when the vehicle is running down the road? Must be done through regen? (or is there a generator driven by the electric motor?)
 

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That's interesting. So I wonder how it gets charged when the vehicle is running down the road? Must be done through regen? (or is there a generator driven by the electric motor?)
Nothing so complicated as a generator. It's solid-state, a DC to DC converter that takes the battery high voltage and converts it to 14V to charge the little guy, same as Volt.
 

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Discussion Starter #9
My point was that you may be able to stuff the Bolt cells in to the same space as the Volt giving the Volt a much higher all EV range.
 

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My point was that you may be able to stuff the Bolt cells in to the same space as the Volt giving the Volt a much higher all EV range.
Exactly, that'd be great. It's a shame Volt gen2 and Bolt development teams weren't working together (timing probably wasn't right), because a 1/3 or 1/4 Bolt pack in the Volt would be awesome... more range, more cabin space (5 real seats!), lighter, etc. Curious to know if/how their chemistries differ.
 

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Exactly, that'd be great. It's a shame Volt gen2 and Bolt development teams weren't working together (timing probably wasn't right), because a 1/3 or 1/4 Bolt pack in the Volt would be awesome... more range, more cabin space (5 real seats!), lighter, etc. Curious to know if/how their chemistries differ.
Personally I'd love a Volt with 1/2 Bolt battery pack but I don't see it ever happening. The Bolt is killing the Volt because people who are looking for an EV will prefer a pure EV vs a EREV unless they can't live with the Bolt's 238 mile range. The next generation Bolt's range will be boosted at least into the 300s, the Model 3 already offers a 300 mile option, which will make it suitable as an only car vs a second car, that doesn't leave much room for the Volt. I don't think Voltec is dead, just future generation Volts. It makes sense to move Voltec into Chevy's big vehicles. A BEV Suburban or Silverrado won't be practical for quite a while but a Voltec Suburban or Silverrado is quite doable now and it would make a much bigger impact on Chevy's CAFE than anything they do in small cars.
 

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It will be interesting to see what happens in 10 years when the Volts are in the hands of the garage mechanics and batteries are more readily available.

Aftermarket 200 mile range Volt battery packs custom built into the same compartment?
 

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My point was that you may be able to stuff the Bolt cells in to the same space as the Volt giving the Volt a much higher all EV range.
Possibly, but as already pointed out, the chemistry of the Volt's batteries might be different to enable it to discharge and recharge more deeply (and more frequently). "Chemistry" may not be syntactically correct: it might be more about the energy per volume. More compact batteries may not be as well suited for shorter ranges and quicker depletion.

Mike
 

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My point was that you may be able to stuff the Bolt cells in to the same space as the Volt giving the Volt a much higher all EV range.
It doesn't work like that. The chemistry in the Bolt EV battery cell is somewhat different from that in the Volt's. The Volt cells are more power dense. The Bolt EV cells are more energy dense.

Sure if you could find a way to pack the Bolt EV cells into the smaller Volt pack in theory the capacity would be around 25KWh. But the Volt batteries maximum discharge rate of 120KW would likely need to be reduced to about 70KW (94hp).
 

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Personally I'd love a Volt with 1/2 Bolt battery pack but I don't see it ever happening. The Bolt is killing the Volt because people who are looking for an EV will prefer a pure EV vs a EREV unless they can't live with the Bolt's 238 mile range. The next generation Bolt's range will be boosted at least into the 300s, the Model 3 already offers a 300 mile option, which will make it suitable as an only car vs a second car, that doesn't leave much room for the Volt. I don't think Voltec is dead, just future generation Volts. It makes sense to move Voltec into Chevy's big vehicles. A BEV Suburban or Silverrado won't be practical for quite a while but a Voltec Suburban or Silverrado is quite doable now and it would make a much bigger impact on Chevy's CAFE than anything they do in small cars.
Until charging becomes as fast and easy as a stop at the gas station, the Voltec system is best for long distance traveling. And I agree that it would make sense for GM to utilize the system in larger vehicles that are practical for families or anyone needing more space and capabilities. For me, driving in electric mode is more enjoyable and I wish the Volt had more EV range, but at least the gas engine works well and takes the worry out of travel. We are just returning from a trip to the Oregon Coast and there were no "practical" options for charging our Volt. So I just kept it on Hold and try to maintain about 30 miles of EV range so that when I get close to home I can use up that remaining range. Towing my little aluminum kayak trailer with two kayaks and two standup Paddleboards we have been getting an average of 34 mpg. The weather has been cold and stormy and that has taken its toll on mileage. So it looks like we will have put about 550 miles of all gas driving on the car this week.
 

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The Gen 2 Volt pack is 18.7 kWh and can deliver 110 KW of power. That's 5.8 kW/kWh. The Bolt pack is 60 kWh and can deliver 150 kW. That's 2.5 kW/kWh. The Volt's cell chemistry is optimized to be very "power dense" - ie - can deliver a lot of watts per kWh or or cubic foot of storage. The Bolt's cell chemistry is "energy dense" - optimized for kWh per lb and kWh per cubic foot of storage. The kW/kWh ratio is of less concern.

Even if you could pack 30 kWh of Bolt pack into a Volt, you could only get 75 KW of power out of the pack. Also, the thermal management is entirely different. To deal with the heat coming off the high-kW demand in a small pack, the Volt's pack thermal system circulates glycol through out the pack and between every cell to provide maximal cooling. The Bolt uses a lighter, more compact "bottom plate" glycol cooling system that only circulates glycol through the bottom of the pack. There is a heat-conductive aluminum plate between each cell conduct the heat from the face of each cell down to the glycol-cooled bottom plate. This saves space, weight, and assembly cost, but is not as robust as the Volt's cooling. If you tried to push the same amps through a Bolt cell as you do through a Volt cell, you'd fry the cell.
 

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That's interesting. So I wonder how it gets charged when the vehicle is running down the road? Must be done through regen? (or is there a generator driven by the electric motor?)
Probably a similar dc-to-dc APM as the Volt has.
 

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Until charging becomes as fast and easy as a stop at the gas station, the Voltec system is best for long distance traveling.
Or until the battery packs increase in capacity/efficiency to the point where a day's driving is already in there. A 500-600 mile battery doesn't need a charger that can put 500 miles in an hour, because almost nobody is ever going to need to get the SECOND 500 miles driving in a day. That's 10 hours of driving, that's enough that you're beat and about to become a road hazard if you drive any more. And putting back 100 miles in an hour (easy to do charging at 25 kw -- Bolt can take nearly 50 under many conditions) then you only need a 6-hour charge time to get it filled up again for another day of driving. Lunch and dinner stops can extend that another 200 miles for Really Long Days at the same easy 25kw rate, and now you're into territories that can basically keep TWO drivers going for 7-8 hours each, and you can STILL come out to a fully-charge 600 mile range in the morning.

Basically, at that point, the human drivers become the limit before the car does.
 

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Basically, at that point, the human drivers become the limit before the car does.
That's where autonomous driving comes into play. Coast to coast interstate driving with minimal human driver input required.
 

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The Gen 2 Volt pack is 18.7 kWh and can deliver 110 KW of power. That's 5.8 kW/kWh. The Bolt pack is 60 kWh and can deliver 150 kW. That's 2.5 kW/kWh. The Volt's cell chemistry is optimized to be very "power dense" - ie - can deliver a lot of watts per kWh or or cubic foot of storage. The Bolt's cell chemistry is "energy dense" - optimized for kWh per lb and kWh per cubic foot of storage. The kW/kWh ratio is of less concern.

Even if you could pack 30 kWh of Bolt pack into a Volt, you could only get 75 KW of power out of the pack. Also, the thermal management is entirely different. To deal with the heat coming off the high-kW demand in a small pack, the Volt's pack thermal system circulates glycol through out the pack and between every cell to provide maximal cooling. The Bolt uses a lighter, more compact "bottom plate" glycol cooling system that only circulates glycol through the bottom of the pack. There is a heat-conductive aluminum plate between each cell conduct the heat from the face of each cell down to the glycol-cooled bottom plate. This saves space, weight, and assembly cost, but is not as robust as the Volt's cooling. If you tried to push the same amps through a Bolt cell as you do through a Volt cell, you'd fry the cell.
To be fair, we really don't know the specifics here... the limiting factor could the motor or battery (or inverter, gearbox, cooling capacity, etc), you can't accurately make a blanket statement like that. And the usual way to compare things like this is percent C (capacity), which you effectively did but just labeled it differently. Gen2 Volt can do (briefly) 120kW, which is about 6.5C, Bolt can do about 2.5C but I suspect the batteries could handle much more than that (has GM published specs on the cells, I only see speculation?). I'd bet the limiting factor is something else, or that 150kW was deemed good enough (because it is plenty, for sure) so it's just a software limit so you don't go through tires so fast.
 
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