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Discussion Starter #1 (Edited by Moderator)
volt_power1.jpg volt_power2.jpg

The gas engine generates maximum 53KW. When the battery is completely depleted (no electric range left) and the car demands access of 53KW then where does that additional power come from ? If it comes from the battery then why not power the car from the battery itself ? What am I missing ?

In the attached pictures you can see that the car is consuming 115KW and if the engine tops out at 53KW where does the extra 62KW come from ? If the battery is capable of providing that much power then why is the electric range 0, why doesn't it use the battery power until the battery can really no longer provide any power ?
 

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The Volt always keeps the battery partially charged with some reserve power, even when it says the range is zero. It uses that reserve power when accelerating hard or climbing hills. Then once the power demand goes down, it will use the engine to recharge the battery to maintain the reserve.
 

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. . . . why doesn't it use the battery power until the battery can really no longer provide any power ?
Because if it did that, the $10K battery would not live as long as the car's warranty

Don
 

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What I have read is the car never fully charges, and never fully discharges the batteries.
As Don mentioned- it is to make those batteries last 10 years.
They did quite a lot of help make the batteries last longer, like the extensive cooling/heating system on the batteries the monitors every cell pair.
Seeing the tear down of the bank is pretty interesting (check out Weber Automotive videos)

mark
 

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Discussion Starter #5
The Volt always keeps the battery partially charged with some reserve power, even when it says the range is zero. It uses that reserve power when accelerating hard or climbing hills. Then once the power demand goes down, it will use the engine to recharge the battery to maintain the reserve.
Thats a lot of reserve power that could be used for pure electric range, in my opinion.In fact in my 6-7 months of using this car I have noticed that even though it shows 0 electric miles, it does putt around on battery only as long as the power demand is under 18-20KW. Only when the power demand goes above that, the gas engine kicks in.
I would imagine/expect that a electric + gas car would be either 100% electric or 100 gas (when battery runs out).
Now I am curious what do other phev hybrid cars do ?


Because if it did that, the $10K battery would not live as long as the car's warranty

Don
Not just that, it would need a much larger engine + generator to produce the full 100KW+.
 

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That extra buffer is actually a very nice thing to have. First of all the Volt doesn't have a traditional starter motor and uses one of the motors to spin up the engine to start which requires sufficient remaining charge. If the battery were to go completely flat, you wouldn't be able to start the engine to keep going. Additionally it acts as a power reserve when the ICE can't provide enough power as your initial observation of 53kW output shows. Finally, one can think of it also as an emergency reserve in the event that you've depleted the initial charge and are running on engine power. If something were to happen to the engine to cause it to stop such as out of gas or even an engine failure, the Volt has the capability to use that very small remaining charge to maneuver the car to a safe location or to a gas station for a short distance, some have said as far as 2-3 miles. Personally I think having an extra 1-2 miles of range vs. the longer life of the main battery and use as a buffer and emergency backup makes more sense to have the latter. I sure wouldn't want to be caught out on the road only having engine power and trying to pass someone in a reduced power state once the battery has depleted.
 

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To top it off, the Gen 2 Volt's engine is sufficiently powerful enough to haul the car over the highest paved mountain passes in the US at the posted speed limits. I know this because I took mine over Independence (CO 82), Vail (I-70), and Eisenhower Tunnel (I-70) with a "depleted" battery and the car never used the battery's low buffer except while I was accelerating.

https://gm-volt.com/forum/showthread.php?326679-Mountain-Mode-not-needed-(Gen-2)

 

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on my gen 1 2012 VOLT I get to use about 10 KWH of the 16 KWH battery. (to use round numbers)
 

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Thats a lot of reserve power that could be used for pure electric range, in my opinion.In fact in my 6-7 months of using this car I have noticed that even though it shows 0 electric miles, it does putt around on battery only as long as the power demand is under 18-20KW. Only when the power demand goes above that, the gas engine kicks in.
I would imagine/expect that a electric + gas car would be either 100% electric or 100 gas (when battery runs out).
Now I am curious what do other phev hybrid cars do ?
You can go up to half a mile on a "depleted" battery by keeping it below 19 KW. From a stoplight near my house it's 0.4 miles one way and 0.6 miles the other way. If I go the short way I can get into my driveway without the engine restarting. When I go the long way the engine restarts in front of the neighbor's house.
 

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You can go up to half a mile on a "depleted" battery by keeping it below 19 KW. From a stoplight near my house it's 0.4 miles one way and 0.6 miles the other way. If I go the short way I can get into my driveway without the engine restarting. When I go the long way the engine restarts in front of the neighbor's house.
In a Gen 1, I get from the end of the off ramp (which is descending about 30 feet) all the way to my parking stall on the reserve buffer. 3/4 mile. There's a stop sign, a left turn, three stoplights (of which I get stopped by typically two of) and waits for lot gate and garage door as well. Engine's usually hot if I've been on the freeway so heating losses aren't a consideration. That's why I don't really miss not having Hold Mode: short of heavy snows, I'm gonna make it home with 0 miles on the clock and no wasted gas.
 

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Thats a lot of reserve power that could be used for pure electric range, in my opinion.In fact in my 6-7 months of using this car I have noticed that even though it shows 0 electric miles, it does putt around on battery only as long as the power demand is under 18-20KW. Only when the power demand goes above that, the gas engine kicks in.
I would imagine/expect that a electric + gas car would be either 100% electric or 100 gas (when battery runs out).
Now I am curious what do other phev hybrid cars do ?
There was an interesting chart posted a little while back (I think it was re Tesla but would apply to every EV using lithium ion). Charging from 0 to 100% of battery it lasted 500 charge (a year and a half?) while one of the other options was charging 30% to 70% was something like 40,000 charges. The less of the top and bottom you use, the longer the battery lasts, just not into infinity and beyond.
 

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What I have read is the car never fully charges, and never fully discharges the batteries.
As Don mentioned- it is to make those batteries last 10 years.
They did quite a lot of help make the batteries last longer, like the extensive cooling/heating system on the batteries the monitors every cell pair.
The temperature sensors turn out to be something of an issue, though. I'm pretty sure more battery sections have been replaced by failure of the thermometer than any other part of the battery as a unit.
 

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The battery is limited to 20-80% charge. 20% is 0 on the battery gauge and 80% is full on the gauge. This enable the battery to last the life of the car. Damage to the battery chemistry occurs outside these limits. Since we carry the engine, range anxiety is not an issue.

Now if you run out of battery and then run out of gas, the car will give you back the battery for a few miles then shut off.

Another cool feature is bumper to bumper traffic using the engine. The engine will cycle on, run for a few minutes to charge a couple miles of range, then shut off. I got 66 mpg while in stop and go traffic. Really smart car!
 
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