"Homebrew" Chevy Volt: Possible?

[ncc74656m]

Originally Posted by elhigh

Mother Earth News magazine did this in the 80's. First they reviewed a guy who'd done it with an Opel GT (!?), then they did their own using a Subaru glider and a Lombardini compact diesel. I think they used a serial-hybrid system, so it could roll all-electric for a limited distance or run essentially unlimited with the ICE running.

I found on the Web one fine day, just wandering around, Mr. Sharkey. I'm not sure who this guy is, but he's got a converted Volkswagen Rabbit which is fine for around town, and a pusher trailer made from the front end of a Rabbit Diesel. It's funny, it looks like he's being tailgated. It's a long but fascinating read.

I saw that. There was some doubt as to whether the Opel GT was for real or not.

[cfg83]

elhigh -

Originally Posted by elhigh

Mother Earth News magazine did this in the 80's. First they reviewed a guy who'd done it with an Opel GT (!?), then they did their own using a Subaru glider and a Lombardini compact diesel. I think they used a serial-hybrid system, so it could roll all-electric for a limited distance or run essentially unlimited with the ICE running.

I found on the Web one fine day, just wandering around, Mr. Sharkey. I'm not sure who this guy is, but he's got a converted Volkswagen Rabbit which is fine for around town, and a pusher trailer made from the front end of a Rabbit Diesel. It's funny, it looks like he's being tailgated. It's a long but fascinating read.

It still seems a bit vague, but the Volt seems to be a series hybrid. Here are the ideal definitions :

HowStuffWorks "Gasoline-electric Hybrid Structure"

...

You can combine the two power sources found in a hybrid car in different ways. One way, known as a parallel hybrid, has a fuel tank that supplies gasoline to the engine and a set of batteries that supplies power to the electric motor. Both the engine and the electric motor can turn the transmission at the same time, and the transmission then turns the wheels.

...

By contrast, in a series hybrid (below), the gasoline engine turns a generator, and the generator can either charge the batteries or power an electric motor that drives the transmission. Thus, the gasoline engine never directly powers the vehicle.

...

The good thing about the series hybrid is that you can optimize the engine for *one* RPM. This helps engine efficiency and emissions.

CarloSW2

[Blue Bomber Man]

ncc74656m,

I have actually spent the last 4 weeks researching exactly what you are talking about and have been able to learn much. A few weeks ago I posted a thread about building a car from scratch, that it would be all electric, and have a 100 mile range.

Im still working on the conceptual stages of the project as I have yet to obtain my copy of solidworks or a new computer to aid in the actual design.

But here is some useful information:

This is a link to a Phd's Research on vehicle loads and specs.
PAMVEC: Parametric Modelling of Road Vehicle Energy Consumption

His spread sheet allows you to enter in vehicle weight, rolling resistance, CdA (value for combined Coefficient of drag and frontal Area), range, performance, and other variables.

Entered in numbers from my current car and it basically nailed my epa rating for gas mileage. It also provides data for various drivetrains such as: gas, diesel, electric, parallel hybrid and series hybrid.

My current specs/goals are:
<1200 Lbs
120 mile range
0-60 14 seconds
onboard energy usage of 250 watts for vehicle functions (not propulsion)
Cd ~ .13 Frontal area 20 sq feet
RRC of .065

For the electric version it recommends about an 11kw hour battery back
Current price for the lithium polymer ion version is around 10k

Fortunately I will not be building this for around 1-2 years, so I HOPE the prices come down on those.

Estimated MPGe (equivalent comparing kw hour prices to gasoline) is around 380 mpg.

The gas version of the same car would be around 100 mpg, which seems reasonable, diesel would be higher.


His spreadsheet takes into account passengers weight, vehicle driving cycles, different drivetrain efficiencies, and even regenerative breaking.

My current guestimate price for batteries, motors (found these SWEET wheel hub motors with everything built in, not sure if they will sell directly though), BMS (battery management system) is around 20-25k

The nice thing about an electric car is that it would be extremely low maintenance. Only real maintenance is battery replacement (old batteries should certainly be sellable).

Also, I am completely sold that all electric is the future for the industry, especially as battery or capacitor tech evolves. The only exception would be with onboard generators, similair to what chevy and others are doing.

[ncc74656m]

Originally Posted by Blue Bomber Man

ncc74656m,

I have actually spent the last 4 weeks researching exactly what you are talking about and have been able to learn much. A few weeks ago I posted a thread about building a car from scratch, that it would be all electric, and have a 100 mile range.

Im still working on the conceptual stages of the project as I have yet to obtain my copy of solidworks or a new computer to aid in the actual design.

But here is some useful information:

This is a link to a Phd's Research on vehicle loads and specs.
PAMVEC: Parametric Modelling of Road Vehicle Energy Consumption

His spread sheet allows you to enter in vehicle weight, rolling resistance, CdA (value for combined Coefficient of drag and frontal Area), range, performance, and other variables.

Entered in numbers from my current car and it basically nailed my epa rating for gas mileage. It also provides data for various drivetrains such as: gas, diesel, electric, parallel hybrid and series hybrid.

My current specs/goals are:
<1200 Lbs
120 mile range
0-60 14 seconds
onboard energy usage of 250 watts for vehicle functions (not propulsion)
Cd ~ .13 Frontal area 20 sq feet
RRC of .065

For the electric version it recommends about an 11kw hour battery back
Current price for the lithium polymer ion version is around 10k

Fortunately I will not be building this for around 1-2 years, so I HOPE the prices come down on those.

Estimated MPGe (equivalent comparing kw hour prices to gasoline) is around 380 mpg.

The gas version of the same car would be around 100 mpg, which seems reasonable, diesel would be higher.


His spreadsheet takes into account passengers weight, vehicle driving cycles, different drivetrain efficiencies, and even regenerative breaking.

My current guestimate price for batteries, motors (found these SWEET wheel hub motors with everything built in, not sure if they will sell directly though), BMS (battery management system) is around 20-25k

The nice thing about an electric car is that it would be extremely low maintenance. Only real maintenance is battery replacement (old batteries should certainly be sellable).

Also, I am completely sold that all electric is the future for the industry, especially as battery or capacitor tech evolves. The only exception would be with onboard generators, similair to what chevy and others are doing.

Did I mention this is the kinda stuff I come here for?

Like your above mentioned plans, my car is a pipedream, in that there is no way I can yet afford to build it, BUT I can start to plan and know what it is I'm looking for.

I'd like to be able to keep my weight that low, but is that possible with the batteries in question?

I'd also like to know more about the hub based motors. I've mostly looked at the potential for the single motor like the Warp series. I've read and heard about the hub based motors, seeing videos of the power of the torque and efficiency, so I'm wondering which would be better, the hub or single motors?

Also, would you just put them on two wheels (front or rear) or all four corners? I should imagine that all four corners would be an impressive way to keep traction with the high torque in winter situations, and also improve reaction speeds.

I'm planning on using a '91-94 Tercel for this project in all likelihood, and if not, probably a similar period Civic hatch. What would you think of these as bases for the systems. I know the Civics are popular conversions, and the Tercel I have experience working on, so...?

Also, here's another idea/question: Without a front mounted single motor (using hubs), is there any reason you could/should not split the battery packs and divide them to attempt to get a close to 50/50 weight dist? Obviously I'm assuming that you find a way to weatherproof the engine bay and seal it off.

[Blue Bomber Man]

My car plan is from scratch, entirely my fabrication. A 10 kwh pack will weigh around 160 lbs with lithium batteries, they have 4-6 times the energy density of lead acid and NiCd batteries.

Yes you can split a pack up so long as you wire it properly, and many all electric cars do this.

The wheel hub motors I want are made by BluWav. They have all wheel drive communication built in, regenerative breaking, ABS, traction control and disc breaks in each wheel hub. I do not know the cost of them at the moment, I would guess anywheres between 1500-5000/wheel but I dont think they are availible to consumers, only to manufactures.

If you are converting a car, you can expect the car to weigh between 2000-3000 pounds completed, if you use light lithium ion batteries, other wise expect 4000 pounds. Additionally the car should be equiped with low rr tires, and I would completely redesign the exterior to drastically improve the aero.

Converting a car would probably require up to 50kwh pack unless you significantly reduce weight and drag, and would only get maybe 50 miles range without those improvements. It is likely far cheaper to cut as much weight and drag as possible to reduce the need for an expensive battery pack.

[trikkonceptz]

Kick this idea around bit, or call me crazy. Weight being the biggest issue, how about 2 battery banks. One would always be running the car while the other would be charging via, solar panels, small quiet Honda generator etc.

This idea would be for an extended range electric. I'm sure if multiple battery banks could be used they could be arranged in such a way that a car would not require a charge for some time.

I keep picturing many many Litium Ion batteries the size of the ones used in home alarms, laid out throughout every available space in the car ... LOL

Or in this case a car built around the batteries ..

[SuperTrooper]

I'm not sure how this gains anything. Instead of one bank providing 50 miles of range, you have two 25 mile banks. Any regenerative energy applied to either scenario would be the same. Unless there are some battery idiosyncrasies I'm unaware of that would apply here.

So, yes, trik is crazy.

[Blue Bomber Man]

The only reason to split up the pack would be for weight balancing. I would not break it down much further than 2 or 3 packs due to the extra weight from wiring (heavy gauge wire is needed for all electric drive).

Battery packs do indead use small cells like a phone battery, they are just all wired together with proper balancing systems in place.

[ncc74656m]

Originally Posted by Blue Bomber Man

The only reason to split up the pack would be for weight balancing. I would not break it down much further than 2 or 3 packs due to the extra weight from wiring (heavy gauge wire is needed for all electric drive).

Battery packs do indead use small cells like a phone battery, they are just all wired together with proper balancing systems in place.

And that's the answer I'm looking for. Weight Dist is indeed my goal for splitting the packs, and splitting into just two is fine, as far as I care.

So the gist of this is that if I am not using basically a custom or kit car, I shouldn't be able to ever expect more than 50 mi on batts alone, correct?

I would expect to use a car that has a base weight with ICE of around 1900 lbs, so I shouldn't be too surprised if without the engine that loses, what, 300 lbs? There are a hundred other things that can be done to shed weight, too, if done right. CF hood and trunk, for example. Removing back seats (if unused). Switching to lightweight rims and low RR tires. Granted, most of these items are obvious, but they add up.

My basic plans for weight loss would be:
- Fabbing or replacing panels with carbon fiber where possible
- Removal of unnecessary seats
- Removal and replacement of sound deadening material. The existing sprayed on rubber goop coatings are often very heavy, and in these older cars, frequently decayed anyway, minimizing their effectiveness. Strategically replacing that with modern equivalents can shed up to 50 lbs, if I recall my weights and measures from another forum.
- Unnecessary components, such as heavy subwoofers and amplifiers for stereos. If we're working on dropping weight anyway, and maximizing battery, this shouldn't be an issue.
- For the extreme users, removing interior paneling is a great way to strip weight, again, up to 50 lbs in some cases. Note that removing the dash is typically a bad idea.

I'm sure that most of this is covered elsewhere, so I'll stop talking right there, but I bet you could get the base car down about 400 lbs (before readding it all back in with the engine and batteries).

[Blue Bomber Man]

It all depends on your budget really. A 10 kwh pack is around 10 grand for lithium ion batteries, but would only weigh around 140 pounds. The same pack using deep cycle batteries from something like a forklift or golfcart would weigh maybe 550-600 pounds but would cost quite less.

I would suspect a car that weighed around 2000-2200 pounds, with a more typical Cd of around .28-.32 and with low RR tires the range on a 10kw pack would be perhaps 35 city, only 25 high way miles.

It is worth the effort to drive the tires directly without a transmission because you lose some serious energy there.

If you are using an existing car, due everything possible to reduce weight, improve aero etc. Look up car designs that have low Cd and see if you can emulate that exterior.

Steal ideas where ever you can. Look up the Aptera, Probe V, LoReMo.

LoReMo has an interesting idea I plan to put in my car: no side doors, it uses a front hood/windshield door that lifts up. It saves a lot of weight because you can design the side of the car to be much stronger with less weight.

Good luck!