# Electric car question

There's a lot of hype about saving money by buying a hybrid but what I want to know is if you save money in general and not just gas? I understand that you can get 100 or 200 extra miles per gallon but you still have to plug your hybrid into a power outlet. Are you saving money by paying more for your electric bill then using gas?

mgb_phys
Homework Helper
Generally a hybrid (at least the current generation) isn't a plugin - it uses the gasoline engine to charge it's batteries. The next generation (including the Volt) can also be pre-charged from an outlet. They both only have a limited range on battery (30-40mi).

How economic it is depends on your driving, if you do a lot of stop start in-town driving they are fantastic. Taxi drivers love them - the claims here are that they are spending $20/day on gas instead of$100.
If you do >50miles/day on freeways you are likely to do better with a diesel or any small hatchback that does 50mpg.

Once plugin electric vehicles become available it is likely that the cost of running them on off-peak electric will be much lower than gasoline (unless the tax man comes up with a 'solution')

I think you missed my question. Let me try to rephrase it with an example. What I'm trying to figure out is if you are really saving money, not gas.

Lets try and use your example.
Lets say I spend 100$on gas for a regular car and it gives me a total of 400 miles. If I decide to buy a hybrid, will i have to spend 20$ on gas and 80$on electricity to get 400 miles? He did answer the question, it depends on what driving. Electricity is cheaper than petrol per mile, so you could potentially save money. 40 miles of stop start low speed city driving works perfectly with an electric motor as you never ue the engine. Endless long range driving at motorway speeds and you'll be spending much more on fuel as you are using both the engine and the electric motor and would be better with a small diesel. So in general yes a hybrid will save you money, but is it the best/cheapest option? 400 miles of town driving != 400 miles motorway driving. Ah.. nice nice. Thanks. The average cost of electricity is$0.11 per kWh.

The Volt is expected to use 25 kilowatt hours per 100 m. This means that for the first 40 miles, it will use 10 kwh, which costs $1.1. So, your cost per mile is 2.75 cents per mile. After that, you switch over to gasoline at 50 mpg. The cost of gaslone is...lets say.$4.60, so your cost per mile is then 9.2 cents per mile.

In other words, the first 40 miles are about 3 times cheaper than later miles. Only 3x?

mgb_phys
Homework Helper
Rough figures, the chevy volt has a 16 kWh battery but apparently is only used 85%, so assuming the manufacturer's figures of 40mile/charge are correct - you are doing 40miles/9kWh = 4.5 miles / unit of electricity.
Depending on location and off-peak deals you are probably paying around 10c/unit for electricity - so if you can just use the plugin range it is very very cheap

Do the Volt's batteries last longer when recharged more often for the same usage?

The average cost of electricity is $0.11 per kWh. The Volt is expected to use 25 kilowatt hours per 100 m. This is surely the draw from the batteries. Converting the AC line to battery charge should lose 25% in converter and batteries. So the cost should be 3.66c per mile. This means that for the first 40 miles, it will use 10 kwh, which costs$1.1. So, your cost per mile is 2.75 cents per mile.

After that, you switch over to gasoline at 50 mpg. The cost of gaslone is...lets say. $4.60, so your cost per mile is then 9.2 cents per mile. In other words, the first 40 miles are about 3 times cheaper than later miles. Only 3x? The volt will sell for$50K. Is this number correct? If my $5K scrapyard SUV gets 15 miles per gallon, what is the break even mileage? Shall we use$3 per gallon?

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50,000 = 5000 + 4.6/15*miles
miles = 146,739

So if you sold your SUV and bought a Volt, the break even point would be after you put 150k miles on your Volt.

Pengwuino
Gold Member
A few things to note, gasoline in the US is only about $2.5/gallon on average. Also, the Volt is extremely expensive (around$42,500 after government rebates) and the batteries only have a 10 year life span which works against people who would use the car in the ideal situation of short trips back and forth between work seeing as how the batteries are expensive. Other hybrid cars are pretty much cheaper in any case though. Even if you use the car almost exclusively for long cross country trips... they run on pretty efficient engines so that's good no matter what.

That's another thing...I have a hard time trusting these lithium ion batteries. They never seem to work as advertised. A lithium ion battery loses charge faster when in warm weather (when not in use). If you ever stop charging a lithium battery before it is fully charged, it suffers permanent memory loss. If you ever let a lithium ion battery fall close to zero charge, it is permanently whacked.

When I had an IPod, that damn battery kept dying after about 25 minutes. I even got a replacement battery. My laptop which originally lasted 7.5 - 8 hours on a charge now only lasts about 2.5 hours -- and I am pretty anal retentive about good battery manage. Heck, I used to even store the battery in the freezer when not in use for long periods of time.

Oh and another thing...if the Volt runs on battery until the battery runs down, then you turn off the car before the batter can be recharged, you might have trouble turning it back on!!!

Pengwuino
Gold Member
Oh and another thing...if the Volt runs on battery until the battery runs down, then you turn off the car before the batter can be recharged, you might have trouble turning it back on!!!

From what I read, it charges to 85% and allows drainage until 30%. Then the engine takes over.

A few things to note, gasoline in the US is only about $2.5/gallon on average. Also, the Volt is extremely expensive (around$42,500 after government rebates) and the batteries only have a 10 year life span which works against people who would use the car in the ideal situation of short trips back and forth between work seeing as how the batteries are expensive. Other hybrid cars are pretty much cheaper in any case though. Even if you use the car almost exclusively for long cross country trips... they run on pretty efficient engines so that's good no matter what.

Battery life is tricky and dependent on battery technology, which is why I didn't bring it up. If you use very little off the top of the battery charge you get disproportionately more discharge cycles than if you take it down further. More simply, the deeper the discharge the less total energy output you get before the batteries die.

Pengwuino
Gold Member
Yes it sure is. Also, an article I read claimed that the engine would turn on if the batteries weren't at the proper temperature range. Considering the temperature dependent properties of batteries, is there going to be problems running this vehicle in the various climates you see around the US?

Yes it sure is. Also, an article I read claimed that the engine would turn on if the batteries weren't at the proper temperature range. Considering the temperature dependent properties of batteries, is there going to be problems running this vehicle in the various climates you see around the US?

Yeah. I have little doubt they are using anything other than Lithium Polymer batteries. There aren't any other battery techologies that can compete at this time. They can't run cold. Optimum is 50C internal temp(?). If they are too hot,usually through self heating to get this hot, they become dangerous. So hot weather is probably not a problem, but in the northern states in winter they won't do well. Actually, what's the problem? If you can run the engine and batteries in parallel, the high resistance of the cold batteries would let them heat up, but at a premium in heating current. ---Obviously I don't know enough to comment on temperature stuff, so nevermind, but these sort of issues are what you should be looking for if you wish to investigage.

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mgb_phys
Homework Helper
but in the northern states in winter they won't do well
IIRC They don't suffer damage in cold but don't work very well - specifically they can't efficiently be charged when cold so they have a heater system that keeps them above 0C while charging.

No the Volt isn't the ultimate perfect cheap electric car, this is from a company (and a country!) that can't make a small economical gas/diesel hatchback that can do 60mpg.
It's expensive and limited, it's going to be sold to people who would have bought a BMW but like the green image (plus a lot of taxi drivers) you will get your 100mi range cheap reliable PHEV from the Japanese (and Chinese) in a few years.

Pengwuino
Gold Member
No the Volt isn't the ultimate perfect cheap electric car, this is from a company (and a country!) that can't make a small economical gas/diesel hatchback that can do 60mpg.
It's expensive and limited, it's going to be sold to people who would have bought a BMW but like the green image (plus a lot of taxi drivers) you will get your 100mi range cheap reliable PHEV from the Japanese (and Chinese) in a few years.

Yah it's definitely a PR stunt hoping to get a government push with the EPA rating. I'm just waiting for another company to come out and do it three times as well. I don't really get the taxi driver thing though considering the tremendous cost (and I don't see how the battery will help since they cant charge up during their work day).

mgb_phys
Homework Helper
I don't really get the taxi driver thing though considering the tremendous cost (and I don't see how the battery will help since they cant charge up during their work day).
It's a hybrid, the engine charges the battery on the longer stretches where you get above 20mph on the way to the airport or the suburbs.
The hour you are sitting in traffic or at walking pace in downtown is free. Conventional taxis probably get only half the makers 'city' mileage because of the stop -tart congested driving.

If you are doing 50-100,000 miles/year the capital cost of the car is irrelevant - reliability and fuel economy are all that matter, that's why most taxis in europe are E class mercedes.

If I were Toyota I would have made sure that the first years production of the Prius went to taxi drivers and tracked the repair/fault rate very carefully.

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Pengwuino
Gold Member
Oh yah, I keep forgetting the Volt has regenerative braking too :rofl:. It does make me wonder how much do the batteries cost? With a 10 year battery life on normal use, I would hope you arent replacing all those batteries every year or so.

Ivan Seeking
Staff Emeritus
Gold Member
The real problem is that any financial gains for fuel are overwhelmed by the purchase price. The car cost GM something close to $35,000 to build. Who wants a$40,000 Corolla?

If instead one buys a fuel-efficient diesel that gets 50 mpg, for $25,000, and drives the car for 150,000 miles, the cost of fuel would be about$9000. So the combined price of the car and a lifetime fuel supply is less than just the purchase price of the Volt.

For the moment at least, the Volt is nothing more than a novelty.

Pengwuino
Gold Member
Does anyone know how much of the manufacturing cost are the batteries?

russ_watters
Mentor
I don't really get the taxi driver thing though considering the tremendous cost (and I don't see how the battery will help since they cant charge up during their work day).
Note that the OP incorrectly differentiated between (or rather just mixed together) plug-ins, traditional hybrids and electric cars...

The taxi comment is only relevant to traditional hybrids, where all of the energy comes from gasoline. What the OP really wanted to know about was plug-in hybrids.

Ivan Seeking
Staff Emeritus
In case you all missed the bad news about plug-in hybrids: You also have to add about $20K to the purchase price for the really long extension cord. Pengwuino Gold Member In case you all missed the bad news about plug-in hybrids: You also have to add about$20K to the purchase price for the really long extension cord.