[Racetrack]

The idea of going with a fixed gear ratio for front and rear wheel drives is attractive because of its simplicity. There is a blog detailing an "advanced electric conversion" with a similar approach. This guy found that Toyota had differentials on some of its trucks and sport ut's that could fill the bill.

However, these units are almost as heavy as some of the lighter fwd transaxles. If you don't want to shift gears, you could still use a couple of these and just leave them in the gear which works best for your motors and the speads you will be traveling.

These transaxles using a transverse engine mounting have the virtue of not having hypoid gears, because the motor rotation is already in the same orientation as the half shafts turning the wheels. This saves a lot of weight and improves efficiency in the transaxle, as opposed to hypoid gears which have to turn the rotation 90 degrees, run in very heavy (80 or 90 viscosity) hypoid or gear lubes, and just can't be as efficient as gears running on the same axis.

Now that (maybe?) I have made you think about using a couple of light transaxles wouldn't it be worth working out the clutching and shifting problems in order to make use of all the gears available? There are some real advantages to this:

1. Starting from a stop in 1st gear multiplies motor torque and gives acceleration equal to a fixed gear motor with three to four times the torque.

2. The motor(s) use(s) a lot less current from you batteries to accelerate if it is kept at rpms closer to its rated power rpm, resulting in much better range.

3. With the gearing in these transaxles, you can get the performance you want with smaller (and cheaper) motors.

Good luck with your project!

[Bowser330]

so essentially have one shifter connected to two shift linkages and making sure it all connects/aligns perfectly, that seems to be do-able..

Another option is using transfer cases from 4x4s and replacing the gears inside to whatever gear is best...

144V 9" FB1 motor (1500$) can be connected to a transfer case that has a 5:1 ratio..., then use one of the half shafts to connect to one rear wheel...Cap off the other half shaft port...make 2 of these setups one for each rear wheel...

144V 1000A max controller (hopefuly no more than 1500$) need two of them...total 6000$ motor+controllers+TCs and gears (1000$ for 2), total 7K$....

FB1 motor at 144V and 1000A = 250ftlbs torque and 100hp.

2 of them side by side in the rear would give, 500 ftlbs and 200 hp...

0-2000rpm(0-25mph at 5:1 ratio) = 500ftlbs (190hp?)
3000rpm (35mph) = 290ftlbs (165hp?)
4500rpm (60) = 100ftlbs (85hp?)

Can we use the horsepower formula?...(Torque X rpm)/5252 = Hp?

5:1 ratio makes FB1 at 144V efficient in a large rev range...
4.5K-6K rpm = 90%+efficient (speeds of about 60 to 70mph)
6k-8k rpm = 80%+ efficient (speeds of about 70 to 100mph)
3K-4.5K rpm = 80% efficient (speeds of about 35-40 to 60mph)

35mph to 100mph is at least 80% efficient....

[DaElectric]

Try looking at the way that the Tropica did it.
http://www.getmsm.com/ev/tropica/default.htm

[Bowser330]

Twin 6.7" motors at 72V, each with its own belt driven reduction gear setup...

hmm...i wonder how two 6.7" motors at 144V would do...

i think making a chain or kevlar belt gear box is entirely possible...probably cheaper than the transfer-case idea...but would take more fabrication skill....

thanks!

[Racetrack]

Originally Posted by Bowser330

Twin 6.7" motors at 72V, each with its own belt driven reduction gear setup...

hmm...i wonder how two 6.7" motors at 144V would do...

i think making a chain or kevlar belt gear box is entirely possible...probably cheaper than the transfer-case idea...but would take more fabrication skill....

thanks!

Hello Bowser330
I followed the link for the info on the Tropica last night--fascinating, and a fabulous project for 10 years ago. Unfortunately, following the history of one of these vehicles through a little less than 10,000 miles made it quite apparent that this vehicle was loaded with reliability issues. One of the wheel motors was burned out (I believe) on three occasions. There was also a belt issue with one of the motors, which reminded me that belts, while quiet and light weight, require proper tensioning and maintenance, and are limited in their torque handling.

The whole car appeared to have been built from the ground up, which allowed the builders to design for a huge back bone battery tray which must have weighed more than the rest of the car. Maximum range appeared to be about 20 miles. I was not able to find a price for this vehicle, but considering that it was almost a hand-built vehicle, it must have been pricey.

Given all of the above, plus a huge number of repairs that I have not recounted from the owner's blog, I would run away very fast!!!

Available technologies have improved immensely over the past 11 years, which is, in my opinion, the most practical way to "role your own",as follows:

1. Start with the donor car of your choice.
2. For an every-day driver, use a front wheel transverse drive transaxle with adapters for your motor.
3. Use one of the high voltage (340 volt nominal) AC drive systems--75 HP should give good performance using the stock gearing in the transaxle, which also reduces battery draw on acceleration, thus improving range.
4. Use one of the Li battery systems which are becoming available.
5. Use an ultra capacitor to provide extra current for acceleration and to absorb re-generative braking current. This will reduce wear and tear on your very expensive batteries, extending their service life.

If you want a HOT ROD, which will put most carbon fueled cars to shame, put a second power train in the rear for AWD. Another nice thing about this is it gives you the possibility of balanced Regenerative Braking, front and rear, and twice the acceleration (or deceleration) without spinning the wheels--especially great in wet weather!

The power train and storage I have listed is pricy, but considering the reliability gained and money saved by eliminating major repairs every 200 miles might even allow you to break even on the dollars.

When (and if) Eestor makes good on its promise of a 52KWHr energy storeage unit that weighs about as much a a full fuel tank and takes about the same amount of space, you can swap out the lithiums and have yourself a 200 mile highway capable cruiser.

If Eestor does come through, you will be able to buy whole electric power train kits from Zenn Motor Company in a couple of years.

I can dream, can't I?

Cheers

[Bowser330]

http://www.tropicaev.org/#sticker

Here is the info for price and components...

From the pictures I've seen the motors were geared on this flimsy looking belt...I think this may have contributed to the burning out and other problems.

A proper chain drive or kevlar belt with plenty of teeth would be used in a setup I would consider...

The link claims a range of 60-80 miles but I am not sure how accurate it is...although the T-125 have about 120AH at a 1HR rating..

the batteries used originally were 12 x 66lb ea. = 792lbs of Trojan T125s

lets not hold our breath for eestor...

the plan you have sounds good..getting a nice AC system that is worth the money is another challenge... So far severeal people are unimpressed with the solectria systems both the AC-24 and AC-55, over priced, overly heavy, and underpowered is what ive been hearing...

[booksix]

I've been thinking about the transfer case idea for a while. I'm running two inline 9" GE's and was personally thinking about coupling them to a standard 231 case (2:1 low, 1:1 high) and then on to my 3.15:1 rear resulting in roughly 6:1 and 3:1 gear ratios. To make it fit better, I was thinking about removing the chain drive to the front shaft, cutting the housing in half and closing it back up for a small 2 spd box that would fit under the trans hump of my bmw. I'd also want it to be electronically actuated from inside the car, most likely steering wheel buttons...

Anyway, could be an option. I have yet to see if they can be shifted from low to high while cruising and if the case can be cut in half while retaining high/low etc...

[Racetrack]

Originally Posted by Bowser330

http://www.tropicaev.org/#sticker

Here is the info for price and components...

From the pictures I've seen the motors were geared on this flimsy looking belt...I think this may have contributed to the burning out and other problems.

A proper chain drive or kevlar belt with plenty of teeth would be used in a setup I would consider...

The link claims a range of 60-80 miles but I am not sure how accurate it is...although the T-125 have about 120AH at a 1HR rating..

the batteries used originally were 12 x 66lb ea. = 792lbs of Trojan T125s

lets not hold our breath for eestor...

the plan you have sounds good..getting a nice AC system that is worth the money is another challenge... So far severeal people are unimpressed with the solectria systems both the AC-24 and AC-55, over priced, overly heavy, and underpowered is what ive been hearing...

Thanks for the link to the Tropica info. The sticker price seems amazing. If the weight given includes the batteries, that is amazing too. Their 60 - 80 mile range claim apparently was not expenienced by the owner whose blog we were linked to--he experienced 20 mile range?

Anyway, the aluminum frame and plastic body sounds great! If one had a chance to acquire one of these it would be tempting even if the plan was to completely re-power it.

Yes, the AC systems are extremely pricey at the moment. Hopefully when some of these systems reach a mass production point, the price will go down. I would personally like to repower something like a 2000 Regal GS--cheaper than a BMW--and end up with an everyday driver.

Re: Eestor, you are right, and I am not turning blue either, but wouldn't it be nice?

Cheers,

Racetrack

[Bowser330]

it sure would be nice...range that can truly compare with the current ICE setups...and ethen imagine if you have a little propane genset onboard for emergency...


Ebay Item number: 270321834010

electronic shift transmission from Ford truck...should work...although that does open yourself up for potential failures, a nicely styled, manual shifter wouldnt be a bad idea...

how are you liking your inline 9's? what controller(s) are you using? how many amps are you using while cruising on highway? Whats your overall setup?

I say dont cut anything out, just let the other end "freewheel" or if you wanted to get complicated you could attach another alternator or generator to act as a regen system...maybe...

[Racetrack]

Originally Posted by Bowser330

it sure would be nice...range that can truly compare with the current ICE setups...and ethen imagine if you have a little propane genset onboard for emergency...


Ebay Item number: 270321834010

electronic shift transmission from Ford truck...should work...although that does open yourself up for potential failures, a nicely styled, manual shifter wouldnt be a bad idea...

how are you liking your inline 9's? what controller(s) are you using? how many amps are you using while cruising on highway? Whats your overall setup?

I say dont cut anything out, just let the other end "freewheel" or if you wanted to get complicated you could attach another alternator or generator to act as a regen system...maybe...

Sorry Bowser330, I don't have a project under way at the moment, although I do have a Valkyrie with one of those gas guzzling v8's in my garage awaiting a complete re-build. My knowledge of ev's comes from research and the fact that I am an Electronic Systems Technologist, so you could slay that I have a foot in both camps.

Re: your suggestion on letting the end with no drive freewheel, this could become a safety issue during braking if you are using rear wheel drive. The ideal is to blend your hydraulic brakes to work progressively with your regenerative breaking. This should be very do-able if you are driving the front wheels. If you are only driving the rears, and doing significant breaking--renenerative--on the rears, you could find your rear end coming around on you--severe overstear. Even with moderate rear wheel only Regenerative Braking on the rear with no braking on the front, the rear end could break loose in slippery conditions.

Re: using add-on alternator or generator to the un driven end for regen, I don't think this would be worth it, as even a 200 amp alternator can only soak up a little over three horse power. To get an idea of how much braking this would give you, try to imagine how long it would take a 3hp motor to accelerate you car. The other thing is, you would have to go through mechanically connecting your alternator or generator to the undriven wheels--more weight, more complications. If you were going to go to this trouble, I would be inclined just to put the same power train on both ends. You could actually use smaller motors at each end.

Good luck!

Racetrack