# will it go up the hill?



## Elanimal28 (Nov 18, 2013)

I'm building an electric trike that I estimate to weight about 900 (curb weigh) and I'm about 210  . the motor is a 6.7" advance DC motor. With no transmission.
I'm hoping to gear it to do 55mph . finally, where I live there are a lot of hills. 
Will this thing go up? And if not, what type of small trany couldi use? Or do I simply need a bigger motor?
Did I mention the trike is a two sitter (pass behind driver) and space is at a premium. ?


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## major (Apr 4, 2008)

Elanimal28 said:


> I'm building an electric trike that I estimate to weight about 900 (curb weigh) and I'm about 210  . the motor is a 6.7" advance DC motor. With no transmission.
> I'm hoping to gear it to do 55mph . finally, where I live there are a lot of hills.
> Will this thing go up? And if not, what type of small trany couldi use? Or do I simply need a bigger motor?
> Did I mention the trike is a two sitter (pass behind driver) and space is at a premium. ?


I don't know the details of your build, but I'd say if you have a decent controller and batteries, it could handle hills. But 6.7" motors come in various designs. And hills come in various sizes. So you may need extra motor (and controller) cooling for long hills.


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## electricpolo (Mar 15, 2011)

I built an electric car about 3 years ago & drive it every day.
Car weighs 1200kg uses a 9" Netgain Impulse motor, has 45 x 130Ah LiFePo batteries & has a controller that can go to 500A but I limited it to 320A
From my experience to your trike.
If you gear a 6.7" DC motor to do your 55mph (which it can do easily), it will not have enough torque to get you off the line very fast at all. 
It will be woefully slow to accelerate without a gearbox unless you feed it huge amps in which case you will probably melt the motor windings or kill your batteries.
All direct drive electric cars use very large motors that can supply the starting torque.
You will only need a 2 speed gearbox though. I only ever use 2nd & 3rd gears.


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## ken will (Dec 19, 2009)

Elanimal28 said:


> the motor is a 6.7" advance DC motor


What are the voltage and current limits on this motor?


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## major (Apr 4, 2008)

electricpolo said:


> If you gear a 6.7" DC motor to do your 55mph (which it can do easily), it will not have enough torque to get you off the line very fast at all.
> It will be woefully slow to accelerate without a gearbox unless you feed it huge amps in which case you will probably melt the motor windings or kill your batteries.


A lower gear will give a better hole shot, but a direct drive can provide more than adequate acceleration. Practically all electric drag race vehicles (the top competitors) use direct drive. And the high current used for motor torque to get off the line actually requires little battery current. I doubt he will melt motor windings accelerating from standstill. That is a very short duration. He may have thermal issues if those hills are lengthy and if that is the case, a shifting gearbox, larger motor or active cooling should be considered. 



electricpolo said:


> All direct drive electric cars use very large motors that can supply the starting torque.


All the production electric cars use direct drive and have motors which are smaller than the typical DIY motor used with transmissions (ie. WarP9). Compare that to the motor used in the Tesla or Leaf.

In some cases the use of a multi ratio gearbox allows for a smaller motor to be used. But then you do have to consider the mass and size of that gearbox. Is it better to use that available space, mass and cost for a gearbox or more motor? The car companies are very good at making gears. Don't you think if there was a real advantage to using a shifting transmission at least one of them would do so in their EVs? But no, all use direct drive.


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## Elanimal28 (Nov 18, 2013)

ken will said:


> What are the voltage and current limits on this motor?


The motor is a K91-4003


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## electricpolo (Mar 15, 2011)

An associate of mine used a 6.7" Advanced DC motor in his electric car. He used 45 x 90Ah LiFePo batteries & a 500A controller limited to about 300A as well.
LiFePo batteries are limited to 3C discharge or their life is reduced lots.
His car was only just adequate and really needed the gearbox to get it moving. He also burnt out 1 set of motor windings.
My comments are about a 6.7" DC motor in a trike application for continuous daily use not what OEM or drag racers do.

OEM motors in production electric cars are generally very high voltage AC motors with very high rpm limits. Somewhere around 15,000rpm if memory serves correct.
This type of motor can be direct drive because it can be geared low enough to get of the line quickly but also have enough rpm limit to allow the vehicle to get to its top speed.


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## major (Apr 4, 2008)

Likely his car was a lot heavier than 900 lbs. And the motor he has should do 500A just fine for a current limit. And that would be 500A motor current so the battery could still be limited to 300A if needed. 

Some situations can benefit from a shifting gearbox. But, with the limited information the OP has supplied, I suspect he could go direct drive.


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## Elanimal28 (Nov 18, 2013)

major said:


> Likely his car was a lot heavier than 900 lbs. And the motor he has should do 500A just fine for a current limit. And that would be 500A motor current so the battery could still be limited to 300A if needed.
> 
> Some situations can benefit from a shifting gearbox. But, with the limited information the OP has supplied, I suspect he could go direct drive.


I'm still in the process of acquiring the parts for my build. I have the motor but the batteries I had planned on purchased fell true ( calb 100ah) so I’m thinking of buying 21 CA60AH from CALB. This will be my daily driver to work. However my commute is 8 miles round trip and includes two steep hills. My Cushman Truckester with its twin cylinder can do an easy 45mph but going up those two hills it drops to 26 MPH.
I’m still hoping to find a set of used 100ah calb batteries but until then, 60ah is all I can afford. 

Ps. Here is a look at what I have done so far:


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## Elanimal28 (Nov 18, 2013)

I added another 20 feet of 1.5" steel tubes after that picture was taken, for a total of 100 feet. That's 1.769 pounds per foot. That's less than 200 pounds on tubes plus the VW front axel tube and tires, batteries and the motor is 55 pounds. if I use the 60Ah calb bat. they add up to 92.5 pounds. There are several component missing but the heavy stuff is all there. I think that this thing can be built close 1200 pounds. A 1977 VW Bettle weight is 1830 pounds and people use a gear box when they convert them. that's why I'm worry about not using a gear box.


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## major (Apr 4, 2008)

Use the transmission then. It keeps getting heavier. It will be difficult to add the transmission if you don't plan for it. You can use reverse gear not worry about reversing contactors and motor advance. Besides, you never did quantify those hills. Better safe than sorry


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## Elanimal28 (Nov 18, 2013)

major said:


> Use the transmission then. It keeps getting heavier. It will be difficult to add the transmission if you don't plan for it. You can use reverse gear not worry about reversing contactors and motor advance. Besides, you never did quantify those hills. Better safe than sorry


I wish I could find one with reverse. I don't know how to quantify those hill any better. I tried google maps but I cant seem to find a way to see the grade or how steep they are. 
The frame is 30" wide and I'll be using a chain and sprocket, so the only transmission that will fit there is a Harley Davidson type like this one:


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## slimdawg (Mar 7, 2012)

The motor is small IMO my kart is pushing #325 with driver to hit 71mph we were at a 1.21 to 1 ratio and when we hit 55mph I think we were at 2.4 or 2.2 to 1 but fast out of the hole that's with an #86 motor 7.2" diameter 

http://youtu.be/YjMTe8cLe2U


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## ken will (Dec 19, 2009)

Do you have access to a low power Vehicle?
If so try going up the biggest hill with the least amount of throttle that makes it to the top.
Then knowing the weight of the vehicle and estimating the minimum horsepower, you can be in the ball park.


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## Elanimal28 (Nov 18, 2013)

ken will said:


> Do you have access to a low power Vehicle?
> If so try going up the biggest hill with the least amount of throttle that makes it to the top.
> Then knowing the weight of the vehicle and estimating the minimum horsepower, you can be in the ball park.


I think I do. I have a Ninja 250 that wights 355 pounds and the specs are:
Horsepower: 36 @ 12,500rpm (26 @ rear wheel) 
Torque: 18.1 Ft/Lbs @10,000 RPM (*14 @ rear wheel)*
Gear Ratio: 1st 39/15, 2nd 34/19, 3rd 31/22, 4th 29/25, 5th *27/27*, 6th 25/28
Front / Rear Sprocket 14T / 45T 
Rear Tire 130/80x16

my plan is to drive it in 5th gear up the hills and see what happens


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## Elanimal28 (Nov 18, 2013)

I rode to one of the biggest hills and this is what happened:
Rolling on flat ground 40 mph at 9K
Holding the throttle steady once I got to the hill the rpm started to drop 
and when I reached the top It had drop to 25mph and 5K

What can we make of that data?


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## Yabert (Feb 7, 2010)

Elanimal28 said:


> What can we make of that data?


Nothing of especially interesting!

For your requirement of direct drive, you should design the gearing as best as you can with what you know (voltage vs speed, ratio).
After, if you have problem to maintain adequate speed up hill, you will need to play with gear ratio. If that isn't enough, you will need more power (more volt in your case). So, more cells or bigger cells to limited the voltage sag under load.

What controller do you think use?


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## Elanimal28 (Nov 18, 2013)

Yabert said:


> Nothing of especially interesting!
> 
> For your requirement of direct drive, you should design the gearing as best as you can with what you know (voltage vs speed, ratio).
> After, if you have problem to maintain adequate speed up hill, you will need to play with gear ratio. If that isn't enough, you will need more power (more volt in your case). So, more cells or bigger cells to limited the voltage sag under load.
> ...


I don't know yet. Obviously I would like to spend at least as possible But I'm not sure. I bought 2 Chevy volt 96v 45ah battery modules And a controller is my next purchase. Any suggestions would be greatly appreciated.


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## Yabert (Feb 7, 2010)

Good battery! 
But because of the higher voltage of those cells type and despite you use 24S cells configuration, you can't use the available cheap 72v controller (400-500$ Alltrax AXE and SPM in mind). 

So, the only good value choice I can think about: 
http://www.evworks.com.au/index.php?product=CTL-MC600SP
http://www.evdrives.com/category_s/1886.htm


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## ken will (Dec 19, 2009)

Elanimal28 said:


> I rode to one of the biggest hills and this is what happened:
> Rolling on flat ground 40 mph at 9K
> Holding the throttle steady once I got to the hill the rpm started to drop
> and when I reached the top It had drop to 25mph and 5K
> ...


At 25 mph the Ninja is putting out about 12 ft.lbs. of torque at full throttle.
Your electric motor puts out 60 ft.lbs. of torque. 5 times as much!

The Ninja weighs 375 lbs. you weigh 210 lbs. so 12 ft.lbs has trouble pushing 585 lbs. up the hill

So, 60 ft.lbs would have the same amount of trouble pushing 5 x 585 lbs. up the hill. Keep the trike and passengers under 3000 lbs. and you will make it up the hill.


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## Elanimal28 (Nov 18, 2013)

ken will said:


> At 25 mph the Ninja is putting out about 12 ft.lbs. of torque at full throttle.
> Your electric motor puts out 60 ft.lbs. of torque. 5 times as much!
> 
> The Ninja weighs 375 lbs. you weigh 210 lbs. so 12 ft.lbs has trouble pushing 585 lbs. up the hill
> ...


That sounds good. I was thinking of buying a hardly Davison transmission
Or and S&S but that's another $500 or more plus all the trouble of adding a shift lever and handle.
I can't see how I would come close to 3k pounds. I'm guesstimating around 1200 pounds
I think I will go with direct drive and see what happens. the roads I will be traveling are 30-45 MPH but I'm hoping to find a gear ratio that will allow me to do 50-55 mph and keep the motor in the happy zone.

Looking at the motor chart http://www.diyelectriccar.com/forums/attachment.php?attachmentid=19306&d=1402323104 what is the ideal RPM/AMP for steady driving? Also I'm not sure how the battery AH calculation works. My packs is 96V and 90AH. Does that mean that I want the cruising speed to not draw more than 90ah? Since I would be driving at 45-50 mph, does that mean I want to be at 5k rpm? If so that’s only 10 ft-lbs tork.


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## Yabert (Feb 7, 2010)

Elanimal28 said:


> My packs is 96V and 90AH. Does that mean that I want the cruising speed to not draw more than 90ah?


 No! You can discharge at more than 90A, but the battery will last less than an hour between charge. The Volt battery have enough power capacity to destroy your small motor. Proper controller will supply just what you need to maintain speed.



> does that mean I want to be at 5k rpm? If so that’s only 10 ft-lbs tork.


 10 lbs-ft of torque at 5000 rpm is close to 10 hp... that move a lightweight trike nicely on flat ground!

Choosing the right gearing is tough because you will ''probably'' be able to reach over 60 mph on flat ground with little power, but on the other hand you will ''probably'' have trouble to maintain over 35 mph at full power on a big hill.
If your gearing is too low, you will overheat the little motor. If your gearing is too high, you won't be able to maintain high speed on hill.

My suggestion: Your gearing should be easily changeable in case you need to maintain higher speed to go up hill.
The motor chart suggest you a ratio of 2 between highly load and lightly load motor (see 96v curve: 5000 rpm = 100A and 2500 rpm = 400A). So start with this and design your gearing to be able to maintain decent speed at 2500 rpm.


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## Elanimal28 (Nov 18, 2013)

Yabert said:


> Choosing the right gearing is tough because you will ''probably'' be able to reach over 60 mph on flat ground with little power, but on the other hand you will ''probably'' have trouble to maintain over 35 mph at full power on a big hill.
> The motor chart suggest you a ratio of 2 between highly load and lightly load motor (see 96v curve: 5000 rpm = 100A and 2500 rpm = 400A). So start with this and design your gearing to be able to maintain decent speed at 2500 rpm.


I think one of these might work.


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## Yabert (Feb 7, 2010)

Exactly! So, find or build a 60 to 70 tooth rear sprocket and play with the 12 to 15 tooth front sprocket to fine tune the perfect ratio.

Also, maybe start to think about adding an air forced cooling for your motor. Something cheap like DetMar Marine Tunnel Blower.


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## Elanimal28 (Nov 18, 2013)

Aahhhhh. New development, I found a Cushman transmission with 3 gears and reverse for $240. It’s only 14 inches long. The gear ratios are 1st 2.6:1, 2nd 1.6:1, 3rd 1:1 reverse 3.5:1. I think this is the perfect solution to my dilemma. I can mount it sideways and the motor on top (piggyback) Plus people talk about direct drive, but most keep their transmissions on their conversions. 

What do guys think?

By the way thanks everyone for having the patience to deal with newbie like me.


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## Yabert (Feb 7, 2010)

Most people keep their transmission because they aren't able to build a differential with proper gear ratio... it's totally another story for motorcycles.

About the transmission, I don't know if your transmission can take the 80-90 lbs-ft of torque that your motor will provide at 500-600A.
Verify first... If the answer is yes, go for it. Especially for the reverse gear


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## Elanimal28 (Nov 18, 2013)

Yabert said:


> I don't know if your transmission can take the 80-90 lbs-ft of torque that your motor will provide at 500-600A.
> Verify first... If the answer is yes, go for it. Especially for the reverse gear


The trany comes with a 22hp motor and can tow 1200 lbs, but We are about to find out if she can handle it  :


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## Elanimal28 (Nov 18, 2013)

Here's a picture of the main pack installed and my schematic. It's missing the pre-charge part. Feel free to offer any suggestions or comments. Also will a small motorcycle battery with 16Ah be enough for the accessory battery? Because the dc-dc converter will put out 30 amps constant


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## Elanimal28 (Nov 18, 2013)

Here’s a picture of the Delta-Q charger in action (Thanks Frodus )


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## Elanimal28 (Nov 18, 2013)

here is a short video: https://www.youtube.com/watch?v=E3to1cWt72Q&list=UU1fJBFQKGV-YjA5wtukry6A

I relocated the steering box and in order to that I had to cut and weld the tierods. 
Installed the brake, gas electric pedal and front brake hoses


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## Elanimal28 (Nov 18, 2013)

So I took it out for a short spin and that got me thinking about a windshield. My trike’s with is 29.5 inches so I need a windshield about 28 or 27.5 inches in width but obviously I can’t go to the store and pick one up. I am thinking of Buying a regular (the cheapest I can find) windshield and try to cut it down to the size I need. 

Does anybody have a better solution or Idea?


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## ken will (Dec 19, 2009)

http://www.homedepot.com/p/LEXAN-48-in-x-36-in-Polycarbonate-Sheet-GE-38/202038065


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## Elanimal28 (Nov 18, 2013)

ken will said:


> http://www.homedepot.com/p/LEXAN-48-in-x-36-in-Polycarbonate-Sheet-GE-38/202038065


Thanks for the suggestion. I planned on using that for the windows but the windshield wipers will mess that up quickly.


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## ken will (Dec 19, 2009)

How about a rear window/wiper from a scrap yard?


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## piotrsko (Dec 9, 2007)

It is possible to get standard two layer tempered safety glass in many architectural shapes including large radius curves. Will be a bit of a search, albeit pricey too. Abrasive cutting a standard windshield could lead to stress fractures, but there has to be some method.

Lean or polyacrillic have different toughness qualities, but as long as the wipers and shield are dirt free, could go a long time between replacement. We used a clear floor wax as a repair coating for scratching.


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## Duncan (Dec 8, 2008)

Hi
Instead of a windscreen fit a wind deflector
If you fit a windscreen you will need - washer, wiper and De-mister

A deflector is much simpler.
(You look over a deflector - through a windscreen)

I didn't bother with anything with my car


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## Elanimal28 (Nov 18, 2013)

Duncan said:


> Hi
> Instead of a windscreen fit a wind deflector
> If you fit a windscreen you will need - washer, wiper and De-mister
> 
> ...


That would be OK for an open car but my build is enclosed because it will be my daily driver

http://youtu.be/NV4NRNBLNmU


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## Duncan (Dec 8, 2008)

_That would be OK for an open car but my build is enclosed because it will be my daily driver_

I've had a home built with a top,
Its very difficult to end up with something that;
Keeps the water out 
Keeps the windows clear

After a lot of years I decided to go - motorbike
So I just treat my car as a four wheeled motorbike,

It's much easier to put a jacket and helmet on when it rains,


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## Elanimal28 (Nov 18, 2013)

toshhugger said:


> So, what happened? Did it go up the hill? I bet it had a hard time. I have the same one and I'm heavier than you. LOL


I haven’t tried it yet because it needs to be insured and registered. I’m hoping to do the lights and turn signals soon so that I can take it out for test drive.


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## Elanimal28 (Nov 18, 2013)

toshhugger said:


> I bet it had a hard time. I have the same one and I'm heavier than you. LOL


You have the same motor on a trike? Does it have a transmission?


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## Elanimal28 (Nov 18, 2013)

I don't know if anyone is following this thread but I'll update it just in case.

Let me start by reporting that it did go up the hill or hills.
I drove it to my old job and back (8 miles round trip) a few minutes ago under 24F degrees . The hills are very steep. The first is 3% grade and it's one city block long. The second it's down hill for 1/2 mile at 3% grade but remember I'll have to clime it up on my returned trip. Then I have 2 more 4% grade climb for about 3/4 of a mile a piece and the final hill before work is a 5% grade lasting .38 of a mile. On the last hill the trike was pulling 225 amps in 3rd gear to maintain a steady 40 mph. I could have gone faster but I wanted to take it easy on my first run. I must say that the voltage lag was at 89.6 volts and I started to worry because it was 98.4 V when I left the house. 
When I got home, After the batteries had settled for about 5 minutes the voltage went up to 93.6v .

But motor was very hot. So hot I couldn't leave my hand on it when I touched it.


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## Elanimal28 (Nov 18, 2013)

By the way she's doesn't look good but it worked and that's all I care about for now.


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## Yabert (Feb 7, 2010)

Thanks for the update. Interesting data.
Don't bother about the voltage sag. 3,73v per cell isn't critic, especially if the battery was cold. Heat the battery is important during discharge and super important during charge.

225A x 89v mean 20Kw to climb a hill. Seem ok for me. That a bit high power to maintain 40 mph, but the small 6,7" motor isn't specially efficient under high load.
If you can, spin the motor faster (stay under 6000 rpm), that will increase the air flow generate by the internal fan and decrease the motor amps.


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## Elanimal28 (Nov 18, 2013)

When I traveled on level ground at 30 mph ( in 3Rd gear) the amp meter read 90-100 amps . Does that sound ok?

Also , how are you heating your batteries? I don't have any of the cooing plugs for the volt modules and they were disassemble several time so I don't know if they will hold antifreeze without leaking. 





Yabert said:


> Thanks for the update. Interesting data.
> Don't bother about the voltage sag. 3,73v per cell isn't critic, especially if the battery was cold. Heat the battery is important during discharge and super important during charge.
> 
> 225A x 89v mean 20Kw to climb a hill. Seem ok for me. That a bit high power to maintain 40 mph, but the small 6,7" motor isn't specially efficient under high load.
> If you can, spin the motor faster (stay under 6000 rpm), that will increase the air flow generate by the internal fan and decrease the motor amps.


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## miscrms (Sep 25, 2013)

Elanimal28 said:


> But motor was very hot. So hot I couldn't leave my hand on it when I touched it.


Definitely sounds like you should be looking at a blower to force air through the motor.

When I got it my Sonett had a 90s vintage 96V system with a 6.7" GE motor and controller limit set to ~300A. Here's a few pics of what the blower setup looked like just to give you an idea.

At the far right you can see the motor end cap with the inlet for the blower. Hopefully something similar is available for your motor?









At the bottom left you can see the air filter for the blower intake, which was then connected to the motor air inlet with PVC.


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## Yabert (Feb 7, 2010)

Elanimal28 said:


> When I traveled on level ground at 30 mph ( in 3Rd gear) the amp meter read 90-100 amps . Does that sound ok?


If you mean 100 Amps from the 96v battery (not the motor) that give 9,6Kw and that is more power than my Smart need to travel at 30 mph. So it's a little bit high.
What controller do you have?



> Also , how are you heating your batteries?


30 foot of easy heat wire. That give me over 200w of heat when I'm plug to the 120v (wall or AC/DC converter 12v to 120v inside of the car).
Look for the black wires on post #309 : http://www.diyelectriccar.com/forums/showthread.php/smart-fortwo-ev-high-power-version-51472p31.html


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## Elanimal28 (Nov 18, 2013)

miscrms said:


> Definitely sounds like you should be looking at a blower to force air through the motor.
> 
> At the far right you can see the motor end cap with the inlet for the blower. Hopefully something similar is available for your motor?
> 
> ...


That's kind of what I was thinking. thanks for the pictures. I see most people force the air on the side of the brushes. Are all motors supposed to be cooled that way? Mine has a pathetic built in fan on the side of the shaft.


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## Elanimal28 (Nov 18, 2013)

Yabert said:


> What controller do you have?


It's a Curtis 1231c


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## Elanimal28 (Nov 18, 2013)

Yabert said:


> 30 foot of easy heat wire. That give me over 200w of heat when I'm plug to the 120v (wall or AC/DC converter 12v to 120v inside of the car).
> Look for the black wires on post #309 : http://www.diyelectriccar.com/forums/showthread.php/smart-fortwo-ev-high-power-version-51472p31.html


Thanks. I bought 18 foot of the black wire and it was more than enough. I'll post some pictures latter on.

I just realized that this thread is on the "non road going vehicles " and we're definitely going on the road with it. Although today I got a little help from uhaul to get to the weigh master


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## Elanimal28 (Nov 18, 2013)

By the way I was right on the money with my 1200 pounds weigh guess:


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## Elanimal28 (Nov 18, 2013)

I chopped ugly Betty's ears off


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## tommypress (Jul 20, 2016)

I feel like the motor size will matter here. Go for a bigger powered one and you will be satisfied with the results.


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## Sunking (Aug 10, 2009)

To go direct drive requires a motor with very high operating RPM and strong torque at 0 to 5000 RPM, and then constant HP from 5000 RPM up to 10,000 rpm. I know of NO DC motor capable of that. 

What I can tell you from experience is I have a vehicle very similar in size and weight as you want. It is a racing golf cart of roughly 850 pounds plus 200 pounds of dead weight in my butt. 0 to 70 mph in less than 8 to 9 seconds. I have it RPM limited to 6500 RPM and can go to 10K RPM if I had the brass balls to do so. 70 mph in a golf cart is to fast. 

To do it required a HPEV AC15 motor, 550 amp VFD Controller. 100 volt 66 AH battery. It will smoke the tires if I want it to. The motor Peak HP is 65 hp @ 5100 RPM, and 17 HP continuous at 6200 RPM. Direct drive with 6:1 differential ratio and 23 inch tires.


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