Hubba hubba hubba....that is, hub motors :)

[MD2000]

Interesting thread.
Some real world experience to help bring things into perspective:

My Honda Insight has a drop down electrically powered wheel for EV operation.
I used a 4:1 reduction to a 12" scooter wheel.
Mikes Insight - MIMA Honda Insight Modified Integrated Motor Assist Tour De Sol
Finding The Best Hybrid Mix - MIMA Honda Insight Modified Integrated Motor Assist Tour De Sol

At full rpm on the e-tek motor, I can go 30 MPH.
The acceleration with current limited to 200A @48V is reasonable on a downhill standing start, pretty slow on flat ground, and very slow on an up hill start.
I will not try to start when stopped at a light as the people behind me will get nasty since I may cause them to miss the light with the slow acceleration.

I tend to use the e-wheel for cruising at 30 MPH with my gas engine off, and can get 30-40 miles on a charge.

In hub wheels without any gearing that would accelerate a caravan at reasonable speed would use 400-1000A, requiring a huge battery and high current controller, and as stated above, the unsprung weight issues could make handling on bumpy roads unsafe.
I hope to add an electric drive to my dodge caravan, but will do it with an e-wheel trailer.
E-wheel for any vehicle - MIMA Honda Insight Modified Integrated Motor Assist Tour De Sol

An idea that I will be pursuing soon as a drive system for converting any FWD vehicle to electric, is to use a modified Prius drive system and power Inverter, which can be purchased form a junkyard for $500-$1000.
EV Insight with a Prius heart - MIMA Honda Insight Modified Integrated Motor Assist Tour De Sol
This drive has an automotive quality forced oil lubricated dual electric motor drive with a built in 3:11 reduction and differential ready for the CV shafts to the wheels, and a liquid cooled high power AC drive inverter with regen. All that is required is to externally generate the 3 phase drive signals.
Happy new year, and keep on ecomodding, we need it.

[The Atomic Ass]

Originally Posted by MD2000

At full rpm on the e-tek motor, I can go 30 MPH.
The acceleration with current limited to 200A @48V is reasonable on a downhill standing start, pretty slow on flat ground, and very slow on an up hill start.
I will not try to start when stopped at a light as the people behind me will get nasty since I may cause them to miss the light with the slow acceleration.

I tend to use the e-wheel for cruising at 30 MPH with my gas engine off, and can get 30-40 miles on a charge.

In hub wheels without any gearing that would accelerate a caravan at reasonable speed would use 400-1000A, requiring a huge battery and high current controller, and as stated above, the unsprung weight issues could make handling on bumpy roads unsafe.

200A @48V is ~12.5hp. Please define "slow on flat ground".

I would not even attempt to run a vehicle as large as a Caravan with only 48V. When you step into heavy-weight vehicles, you need heavy-weight components. I would consider 300V to be the minimum voltage, and I would prefer to run at 700V+. At that level, 200A is good for ~180hp. And electric HP at that.

As for un-sprung weight, I'll say it again, I don't think that many people understand just how much weight there is there already, and can be done away with. The entire un-sprung assembly on your average Caravan weighs in excess of 100lbs.

[MetroMPG]

Originally Posted by The Atomic Ass

200A @48V is ~12.5hp. Please define "slow on flat ground".

Don't forget controller and motor inefficiency: a combined guesstimate of 85% efficiency brings us down to ~10.6 hp, theoretical.

Also, 200A is the peak available. I can't speak for Mike's motor/controller, but the combination in my EV only draws peak currents at a relatively low RPM range (on level ground, when accelerating), and only when the controller is cool (built in thermal protection).

To answer your question: 10-17-2007 - First 0-50 km/h (31 mph) acceleration test run: 36 seconds (on the 225A controller). The ForkenSwift is maybe 150 lbs heavier than Mike's Insight.

I've since upgraded to a 400A peak controller, and that has dropped to 21 seconds (but it's much harder on the lead acid batteries to draw high currents like that). Even with 400A, I avoid driving the car in "normal" traffic (because its max acceleration is still so much slower than the average driver), sticking instead to lightly traveled side roads, or off-peak times on otherwise busy streets.

[Blue Bomber Man]

Could throw some capacitors in there to allow for some short term high amp draw, and would greatly improve your ability to use regenerative breaking.

[The Atomic Ass]

Originally Posted by Blue Bomber Man

Could throw some capacitors in there to allow for some short term high amp draw, and would greatly improve your ability to use regenerative breaking.

I think any capacitor that could hold that kind of charge, (we'll say, 5k watt-minutes?) Would probably be unreasonably expensive. But then again I can't claim to have priced such a thing. I only remember 4 years ago, when I was building up a stereo in my truck, looking at ultra-capacitors for the amplifiers. And there, I was looking at peaks of ~100A for <1 second. Even then prices were sky-high.

[Clev]

Originally Posted by The Atomic Ass

200A @48V is ~12.5hp. Please define "slow on flat ground".

I would not even attempt to run a vehicle as large as a Caravan with only 48V. When you step into heavy-weight vehicles, you need heavy-weight components. I would consider 300V to be the minimum voltage, and I would prefer to run at 700V+. At that level, 200A is good for ~180hp. And electric HP at that.

As for un-sprung weight, I'll say it again, I don't think that many people understand just how much weight there is there already, and can be done away with. The entire un-sprung assembly on your average Caravan weighs in excess of 100lbs.

300V+ gear is very expensive, and 300V is highly dangerous. You can put in an ADC 9" and 144V 1000A controller for far cheaper than a 300V setup.
Keep the transmission and you'll have much better than stock performance.

[The Atomic Ass]

Originally Posted by MetroMPG

Don't forget controller and motor inefficiency: a combined guesstimate of 85% efficiency brings us down to ~10.6 hp, theoretical.

Also, 200A is the peak available. I can't speak for Mike's motor/controller, but the combination in my EV only draws peak currents at a relatively low RPM range (on level ground, when accelerating), and only when the controller is cool (built in thermal protection).

To answer your question: 10-17-2007 - First 0-50 km/h (31 mph) acceleration test run: 36 seconds (on the 225A controller). The ForkenSwift is maybe 150 lbs heavier than Mike's Insight.

I've since upgraded to a 400A peak controller, and that has dropped to 21 seconds (but it's much harder on the lead acid batteries to draw high currents like that). Even with 400A, I avoid driving the car in "normal" traffic (because its max acceleration is still so much slower than the average driver), sticking instead to lightly traveled side roads, or off-peak times on otherwise busy streets.

I forget what voltage you run the ForkenSwift at. Is it 48v or 72v? 400A doesn't have a lot of meaning without a voltage to go along with it.

[The Atomic Ass]

Originally Posted by Clev

300V+ gear is very expensive, and 300V is highly dangerous. You can put in an ADC 9" and 144V 1000A controller for far cheaper than a 300V setup.
Keep the transmission and you'll have much better than stock performance.

I'm thinking in terms of building a vehicle from the ground up, not conversion. For conversion, performance is almost always a trade-off with cost.

However, in a properly-designed production vehicle, I would have the expectation of higher voltages, and thus, higher efficiency and performance.

Still, just stepping up to 144V is significant from 48V in terms of available power.

I am in the blue-print dreaming phase of an all-electric RV. It will have 700V+, should I ever get around to building it.

Also, as for safety? There are several thousand volts going through the ignition system of a traditional ICE, but very few people ever get shocked. As for me, I build tube-based amplifiers, some of which run 500-700v on the plates. Low-current DC, sure, but it's still enough to kill you should you take it across the chest. I've been shocked before, but never fatally. Left hand in pocket, always.

[MetroMPG]

Originally Posted by The Atomic Ass

I forget what voltage you run the ForkenSwift at.

48V - same as Mike's car. That's why I offered the comparison. (Though I should have stated as much).

[MPaulHolmes]

Originally Posted by The Atomic Ass

I think any capacitor that could hold that kind of charge, (we'll say, 5k watt-minutes?) Would probably be unreasonably expensive. But then again I can't claim to have priced such a thing. I only remember 4 years ago, when I was building up a stereo in my truck, looking at ultra-capacitors for the amplifiers. And there, I was looking at peaks of ~100A for <1 second. Even then prices were sky-high.

Maxwell Ultracapacitors are used quite a bit for hard acceleration over several seconds, to protect battery packs. One guy has a blog about how he did it with a bunch of their ultracapacitors that they were selling on clearance (they were making a new version). He said it made the battery pack feel very stiff, meaning there was almost no voltage drop under acceleration. I don't remember where his blog is, but just do a search for maxwell ultracapacitors ev conversion or some such thing.

It is a very expensive option, though. You need like 50 - 100 of them, and they are around $100 each!