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Discussion Starter #1
OK.. for those of us with over 40 mile round trip commutes... I'd love to see an optional "external / removable" battery pack that you could put in the trunk... being able to add an extra 10-20 miles of all electric range, at the expense of temporarily sacrificing some trunk space would be a really spiffy thing to be able to do...

If you need the trunk space, you take out the battery... If you need the range, you can buy the extra module and put it in the trunk.

Or possibly a set of 20 pound battery modules? I think you could get approximately 1kwhr or about 5 miles per module and still keep them at a reasonable weight where your average soccer mom could put them in without straining something...

On the production side, you would just have to put in some kind of electrical connector socket in the trunk, and program the computer to recognize when there was additional capacity added.

Does anyone know what the cargo capacity (both cubic feet & weight) of the trunk is supposed to be?
 

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Why add more weigh? Why add more cost to the car for extra battery? Is that what the engine is for to recharge the battery? I see, you want 100% gas free. Then go buy a car from teslamotors. I'm sure you did not think of the reason why there is not a spare battery in the first place. I'm willing to pay for gas just to recharge the battery over the total cost of the car itself if it does not go higher then $35,000.

Welcome to the GM-volts forum.
 

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When does a Prius become a Volt?

ClaBerCla,

The idea of a add-on battery is appealing if you want to add weight to the car. The range extender engine and a tank of gasoline will take you a really long way. The equivalent battery will still have to be charged, maybe not even at the end of your drive. Rats!

The notion behind the Volt is that a majority of the excursions driven are less than 40 miles. That is why the Volt's battery design is "limited" to 40 miles. Range extension will let you go as far as you want. The rolling efficiency and aerodynamics of the electric Volt, combined with the constant-speed engine will result in a remarkable overall efficiency.

A Prius becomes "less that a Volt" when larger batteries are added to the small ones already installed. I question the durablity of this modified Hyper-Prius because the electric drive system is not intended for long distance and continuous operation. The Prius has an engine and transmission that spins the wheels. the Volt has a Serial Hybrid configuration. Electric motor(s) drive the wheels. No gears, no chains, no belts.

Why settle for less, a modified Hyper-Prius?

Go Volt!
 

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What siggy was saying from my understaind is to have a spare battery that can added or remove when it needed. I'm assume siggy does not know how heavy and costly the battery is. Thanks ClaBerCla for the second link that point out how costly the battery is.

The cheaper way without added weight is to get solar to keep chargeing the battery to gain an extra 10 miles of the car when it sunny. I know solar is not ready for a car,yet.
 

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I'm sure that the aftermarket will offer range extending battery packs for the Volt to maybe get you up to 50 miles. However they won't be easy to put in and out when you need them, they're just too heavy.
 

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All in due time

I'd rather just wait tilll the 2nd generation comes online. Why add one more thing for a soccer mom to remember? There's usually one or two things left behind already.

BDP
 

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I am sure people will come up with lots of things, like giving up the trunk to add more batteries or possibly pulling the ICE out completely and add even more but that is a little more drastic.

With the new Lithium-ion batteries I don't see why a car of that size couldn't get at 60/65 miles easy in a single charge without giving up passenger space.
 

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Discussion Starter #9
battery size .. 20/40/60 mile range

OK... so currently the 16 kwhr pack gets you 40 miles... but wait! .. it only discharges down to 30% and charges up to 80% .. so in reality, you get 40 miles on 8 kwhr, ( or 5 miles per usable kwhr) and the other 8 is some kind of standby/reserve/cushion...

on the bottom end.. I understand kicking in the extender at 30%, since you could be getting ready to go up a long hill, requireing more power than the ICE can provide... (reserve 4.8 kwhr)

on the top end.. I can understand shutting down the charger at 80%, cuz you may live at the top of a mountain, and immediately start dumping additional power into the batteries with the regen braking.. (reserve 3.2 kwhr)

On both ends.. It is my understanding that if you push the batteries to 0/100% charge, you reduce the usable life of the batteries...

my question... how much of each end is the "save the batteries" vs "covering the extremes" ..

so.. if a 20 mile range version were to be released.. wouldn't a larger than 8kwhr pack be needed? To accomidate the 4.8 kwhr bottom cushion + 3.2 kwhr top cushion + 4 kwhr usable?

likewise, if a 60 mile range (gen2) version were to be release, wouldn't it need less than a 24kwhr battery? Since with greater total capacity, you could go under 30% and over 80% and still safely handle the extremes?

I guess to summarize.. just what is the min/max charge you can do with these batteries, and not degrade their usable life?
 

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OK... so currently the 16 kwhr pack gets you 40 miles... but wait! .. it only discharges down to 30% and charges up to 80% .. so in reality, you get 40 miles on 8 kwhr, ( or 5 miles per usable kwhr) and the other 8 is some kind of standby/reserve/cushion...

on the bottom end.. I understand kicking in the extender at 30%, since you could be getting ready to go up a long hill, requireing more power than the ICE can provide... (reserve 4.8 kwhr)

on the top end.. I can understand shutting down the charger at 80%, cuz you may live at the top of a mountain, and immediately start dumping additional power into the batteries with the regen braking.. (reserve 3.2 kwhr)

On both ends.. It is my understanding that if you push the batteries to 0/100% charge, you reduce the usable life of the batteries...

my question... how much of each end is the "save the batteries" vs "covering the extremes" ..

so.. if a 20 mile range version were to be released.. wouldn't a larger than 8kwhr pack be needed? To accomidate the 4.8 kwhr bottom cushion + 3.2 kwhr top cushion + 4 kwhr usable?

likewise, if a 60 mile range (gen2) version were to be release, wouldn't it need less than a 24kwhr battery? Since with greater total capacity, you could go under 30% and over 80% and still safely handle the extremes?

I guess to summarize.. just what is the min/max charge you can do with these batteries, and not degrade their usable life?
You will be able to know better in a few weeks when they announce the battery contract winner. It depends on the particular battery chemistry. If they choose A123, you might be able to choose a higher (>80%) charging limit. Some may live at the top of a hill and may only want 80% while us flatlanders might want 95%. The 30% charge point is dictated by reserve needs to be able to maintain performance in normal driving scenarios as you mention, but I hope GM gives driver control over this too since us flatlanders also don't need this much reserve.
 

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Part of the "reserve" is to lengthen battery life. LiIon batteries don't like being totally charged or discharged. 80/30 does seem a little conservative though, 90/20 sounds good, and you know they'll go there if it works.

From one of the Lutz interviews, I believe he said they were consistently hitting the 40 mile target in the test mules. Hopefully, the Volt will be lighter and sleeker than the Malibu based mules, so why shouldn't we see possibly 50 or 60 miles from the production car?
 

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Motor - generator option

Why not make the volt with the option to add a second battery pack or motor-generator set? Weight Balance might be an issue. P.S. I do not go more than 40 miles a day back and forth to work and will have a second gas car for trips.
 

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Why add more weigh? Why add more cost to the car for extra battery? Is that what the engine is for to recharge the battery? I see, you want 100% gas free. Then go buy a car from teslamotors. I'm sure you did not think of the reason why there is not a spare battery in the first place. I'm willing to pay for gas just to recharge the battery over the total cost of the car itself if it does not go higher then $35,000.
You're overlooking that people already do this for both parallel (Prius, Escape) and series (bus) hybrids. The Volt, despite the REEV euphamism, is another series hybrid so persons may be interested in extending the EV range as demonstrated by the same existing interest with other vehicles.

If it isn't your cup of tea, that's fine; that's no excuse for being snide towards others who's opinions and choices differ from yours.
 
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