# Multiple electric motors in tandem



## rbgrn (Jul 24, 2007)

Was just thinking about this... I've heard certain cars have put a motor on each wheel, which seems like an engineering headache to me, but has anyone linked multiple motors up in tandem for a single very high-torque output? I would think that if you could rig it up reliably that pumped into a high gear ratio you could achieve some very high speeds as well as a solid low-end. Links? Info?


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## Snax (Jul 26, 2007)

Search the EVDL. Oh I kill me . . 

Seriously, yes. I don't have links readily available, but there are a few cars on the austinev site. I think most people who do this use a Zilla controller with series-parallel current path switching.

I forget where I saw it, but I've also seen a parallel motor drive setup into a single transmission vs. the in-line arrangement I refer to above.


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## rbgrn (Jul 24, 2007)

So far I've been unable to locate this in the EVDL or on austinev...


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## DaElectric (Jul 26, 2007)

*You mean something like this??*










Or better yet this.










You can read all about this car here.
http://www.plasmaboyracing.com/reviews.php
Not work safe as you will spend all day going ever every detail and wont get any work done.


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## rbgrn (Jul 24, 2007)

Yeah like that! Has anyone done more than 2? Maybe chain linked or something?


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## Wirecutter (Jul 26, 2007)

If you check MetricMind's website (www.metricmind.com), they sell the Brusa ASM810 motor I mentioned before. This is a 3PAC motor, and it's made flat on each end. It's designed to be "stackable" with itself, so for more power, you can add additional motors. (And of course, a pile of money.) I think the armature shaft is at least partially hollow, so you can wind up with several motors all driving the same shaft.

The Brusa is just one example, but I'm sure any motor maker can come up with a configuration that allows motor stacking this way.

The problem I have with the idea of wheel-hub motors is the large amount of unsprung weight. If you're going to go with a motor per wheel in a normal passenger vehicle, it would be better to have the motors inboard, in the chassis, then have drive shafts and CV joints going to the wheel. This is for handling and ride quality. 

-Mark


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## Snax (Jul 26, 2007)

That thought occurred to me as well Robert, but I have yet to see it done. It sounds to me like a viable solution to overcoming the lack of torque inherent with smaller motors if one wants to go with a direct drive setup through a gear reduction differential.


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## amidesign (Jul 26, 2007)

If you want simply connect the shaft of twoo DC motors is to connect together in serie and double the voltage needed.


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## rbgrn (Jul 24, 2007)

I guarantee you a belt would slip with high-power motors. You'd need a very heavy chain or even a geared setup. What I think would work well is a triangle of motors each with a small gear (maybe 15 teeth) attached to the output shaft, then a large gear in the center of the 3 with an output shaft in the center where the power of all 3 is transferred. I'd draw that up but don't have the time right now.

Side note - I forgot how the motors respond to series vs parallel wiring. I know it has something to do with the weakest one and balancing output but unbalanced draw.


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## amidesign (Jul 26, 2007)

You have right idea for the belt, is not a great idea, gears are better.
If you connect the shaft of two motors. It is obvious they are connected in series. Like this the same current pass through the two motor and theirs torque are equal. If you connect in parallel, the difference between internal resistances generates waste. One motor wants to run faster than the other and the other brakes the first.





I spend a little time to draw the twoo schematics for serie or parallel wiring of twoo DC motors.
I hope have time one day to explain the benefit of serie connection for connected safts.

Serie - parallel wirring of DCs motors.




Her you are:
The math show that in serie n the speed of shaft is capable to be the same for the twoo shafts without wast.
In parallel mode n1 is not equal to n2 then it work not at the optimum.


Maths to present the adventage of serie wiring for connected shafts.


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## MountainTrek (Aug 10, 2007)

I am interested in doing a four wheel drive jeep, I have a two wheel version now in full electric. Is this the forum that might be able to offer advice or can you suggest another place?

Eddie


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## amidesign (Jul 26, 2007)

Its a good place.
Aleksander Micsiz ETS Engineer.


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## MountainTrek (Aug 10, 2007)

Thank you for your reply
I have a two wheel drive Jeep that I use for getting back and forth to work. It is a fully converted electric Jeep. I want to buy a four wheel drive Jeep so that I can participate in the Jeep Jamborees they hold here. I bought the 2WD Jeep in October of 2006, and drive it about 80 miles per day to work and back. I have never driven the Jeep until the batteries were dead but I was told that the maximum range on this battery was not less than 120 miles under normal driving conditions.
My motor control module is made by Curtis. The motor is a DC made by Advanced DC motors. The charger, battery control module, and the battery pack is made by LionEV. I put the web pages to each of those below.
First, I did not do the conversion on my Jeep. I bought it from LionEV in 2006. It was a track test vehicle down in Forest, Virginia. I can hold my own with mechanical work, and I am fair with electrical. I am comfortable with trying a conversion, it does not look that complicated.
My questions are
Can I just move the electric equipment over from the 2WD to the 4WD?
Do I need to add a second motor, or just buy a bigger main motor?
Should I figure on my driving range being cut in half?
The LionEV battery control module has a selector switch. It is set at 103.6VDC/400Ah. The other position is labeled 207.2 VDC/200Ah. Does this need to be changed if I add a motor. If I don't have to add a motor is there any risk or advantage to changing this setting?
http://www.curtisinstruments.com/
http://www.adcmotors.com/
http://www.LionEV.com/
I think that covers most of my questions. Thanks again for your reply.
Eddie


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## amidesign (Jul 26, 2007)

Can I just move the electric equipment over from the 2WD to the 4WD?

Its possible.

Do I need to add a second motor, or just buy a bigger main motor?

I fink its better to use the same motor for test and use a bigger motor if you want much power. The 4WD Jeep is build for one motor. If you want twoo motor its need to connect motors in serie for road use and in paralelle for cross and wet use.

Should I figure on my driving range being cut in half?

You have to look the consuption of 2WD and 4WD. The twoo extra wheels use electricity, but no so much.

The LionEV battery control module has a selector switch. It is set at 103.6VDC/400Ah. The other position is labeled 207.2 VDC/200Ah. Does this need to be changed if I add a motor.

If you add a motor, its wired in serie with the first motor, it need a double voltage 207.2VDC, but on wet road, you risque that wheels slip and its important to use the paralelle wiring against that.

If I don't have to add a motor is there any risk or advantage to changing this setting?

Your motor is made for 103.6 VDC an extra voltage can damage the motor.


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## Hi Torque Electric (Dec 23, 2007)

Two conversions come to mind that use multiple PM motors (8+) as a drive source. Shawn Lawless' "Orange Juice" and Dave Cloud's racer, both of which worked well (although Clouds car was lost to a fire at the track earlierthis year). In general though you start adding up higher loses in eff due to friction and heat, ect when compared to using a single motor. With that said using as small a diameter a motor as possible (allowing quicker rotational rev up) can be an advantage for racing which is why you see twin smaller motors on racers such as White Zombie and Killacycle.

I'll have a little more input on this once Shawn Lawless get his new dragster "Juiced Up" running, which will use four modified ADC9" motors I built for him. Each motor will have it's own lithium batt pack and Zilla controller so it'll be as good a test as can be had on using multiple motors. In Shawn's case there really wasn't a valid "single" motor choice for a 374 volt 8000 amp drive motor, lol. If all goes as planned these will see at least 160 volts (to the motors) at 8000 amps (or what EVer 4 Zilla's will make) for some serious "hold on to your hat HP" and was IMO a better choice than using lets say Twin 13" motors. Anyway there really is more than one way to skin a cat and much depends on what it is you're looking to do, coupled with what is available, and or what's on hand for ones budget.
Cya

Jim Husted
Hi-Torque Electric


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## rbgrn (Jul 24, 2007)

Here is the link to the motors Jim built, btw..

http://hitorqueelectric.com/gallery/v/custom_motors/Juiced+Up/


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## Hi Torque Electric (Dec 23, 2007)

Hey Robert

I see someone's given me an honorary title of sorts, you have anything to do with that, hehe? I found it very funny being I had seen my "newbie" title after signing up and thought, Man I got to get some posts out there and start climbing that ladder, so you must of had some kind of ear burning thing going on LMAO! Honestly not an issue as I'm not a status kind of guy but it was fun to see 8^)

Anyway, thanks for the invite here, I'm still getting used to the way stuff works as I'm new to the forum format but hope I can be as good a member here as I try to be at the EVDL and in general as a member of the EV community.

Cya
Jim


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## rbgrn (Jul 24, 2007)

I saw your pictures and the title just popped into my head for some reason. You can change it if you want 

I'm going to add some way to allow members to customize their title once they've hit senior member. I want to wait until they are senior so that the trust is established (avoiding vandalism, immature crap, etc..)

You're already established as a motor builder / vendor so I just put that in there for you.


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## Alex Everett (Dec 26, 2007)

I am thinking of a dual motor set up for FWD minivan. Reasons for dual motors

1: switchable controller with 1/2 speed reverse
2: dual motors for increased power for heavier vehicle
3: independant motors to allow front steering with no bind

Question?
will one (example)500 amp controller actuate two 500 amp motors or will it burn up the controller. They will most likely be wired in paralell to accomodate free wheeling during a turn. If it will smoke, can the motors be series wired to the controller with nominal loss of power during cornering?

Will most likely set it up with each motor driving each front wheel independantly via C.V. axles through 6 to 1 reduction *HEVY DUTY* chain & gears.


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## John (Sep 11, 2007)

Alex, The way youv'e drawn your motors one will be rotating in the oposite direction to the other unless drive is off the auxilary shaft. Would silent chain be suitable for the reduction drive. I think that is what is used in some transfer cases.


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## Alex Everett (Dec 26, 2007)

Still trying to find availiability of ANY type chain/sprocket assembly.
As for the motors, just reverse the wires on the wrong turning motor as a D.C. motor will operate in either direction (providing the brushes and contacts are new) My understanding is a New/New rebuilt with new brushes will acclimate themselves to the intended direction shortly after break in. 

OOOORRRR am I wrong here?


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## John (Sep 11, 2007)

The motor that is running CWDE would need to be retimed to run in that direction. Motors are normally timed to run CCWDE.


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## Alex Everett (Dec 26, 2007)

Forgive me for my lack of understanding..
I get CW -Clockwise and CCW - Counter clockwise but the abbreviation DE I am unfamiliar with.
Having said that I will see if I can get it reclocked before I order it. If they cannot then I am sure Jim (High Torque Electric) would be able to take care of it for me.

Thanks For the heads up on that


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## John (Sep 11, 2007)

I think DE just stands for drive end.


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## John (Sep 11, 2007)

Check out Ramsey's for silents chains and sprockets. http://www.ramseychain.com/prod_pt.asp


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## Alex Everett (Dec 26, 2007)

Computer blinked out on me there for a moment, Had to re-set wireless router.

Thanks for the info. My Dad was famous for saying " If you don't learn something new EVERY day, then the day wasn't worth a flip." SO....
I have had a good day


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## theboy16 (Feb 28, 2008)

Has anyone looked into the dual motor scenario for daily drivers?

White zombie's siamese 8" warps are pretty freakin cool , but it also eliminates the need for a transmission.

two motors working at half capacity wouldn't be as efficient as one motor running at full capacity, but then we can eliminate the transmission, which has its own inefficiencies, lubricants, and moving parts; all of which need to be serviced and repaired. i'd be willing to dish out the extra dough for a tandem set up if it meant that i could get rid of my tranny. (not to mention the blast of power you'd have available, should you need it)

i realize running a tandem set up would need double the voltage, narrowing the controller choices to something like the zilla or a home-made controller (something i'm also working on)

let me know what you guys think!


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## 3dplane (Feb 27, 2008)

Running a tandem (motor) setup would not need double the voltage.Connecting them series the motors would "see" half the pack voltage,in paralell they would "see" full pack voltage.Thats what white zombie uses as means of "shifting"


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## theboy16 (Feb 28, 2008)

why would you want to runt he motor at half voltage?

running two 72-144v ADC 9.1" motors, for example, from a 240volt pack would have both motors "seeing" 120v.

a 120v pack would have the motors running at 60v each... maybe i'm missing something; but the higher voltage for a given current would result in more power

and a given power at a higher voltage would result in less current

everyone wins, no?


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## 3dplane (Feb 27, 2008)

theboy16! Your last statement is correct. My point was that just because you run two motors that does not mean you have to double the voltage.Therfore your controller options are not narrowed down.The reason white zombie takes off on half the pack voltage(as far as the motors concerned)cause its a drag racing car and already has a high voltage pack so i guess to keep stuff from blowing up on the start line .takes off in a series configuration and half way down the track when current draw(acceleration)drops it switches to paralell connection(full batt.voltage) So it launches again.Hope that helps


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## theboy16 (Feb 28, 2008)

heh, it would have probably helped if i would have mentioned that i'm going with a 240 volt pack, for lower current all around the car, and for using off the shelf heaters for the cab, and just cuz i think its cool


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## ngrimm (Oct 19, 2007)

So do the motors need to be the same size electrically in order to be paired up? Norm


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## theboy16 (Feb 28, 2008)

Motors in Parallel don't need to be of the same size, because the operate independently from each other (electrically speaking)

Motors in series need to be the same, because the same current flows through both motors, one after the other.

picture this: a small motor used in a sewing machine, wired in series with an ADC 9" motor. what would happen if you ran the amount of current which the ADC 9" usually draws, through the sewing machine motor? it would probably blow up in a cloud of smoke. and if you ran the amount of current which the sewing machine motor draws, the ADC 9" probalby wouldn't even budge.

when motors are in series, they should be of the same voltage and current rating. in fact, its best that they are identical to each other (same make/model)

that being said, motors hooked up in parallel need not be the same size, but we should pay attention to the speed of the motors. if one turns at 1000rpm and the other turns at 2000rpm (given the same voltage to both) they could not be set up in a tandem fashion, since the motors would be fighting, each trying to slow down/speed up the other.

motors of different speeds and powers can be wired up in parallel provided that 1) they have the same voltage rating and 2) they are linked to the wheels by such a means that makes their 'final' speed the same. ie, put a small pulley on the fast motor, and a big pully on the slow motor, with one belt to each motor connected to a doulbe collector pulley, which would then turn the transmission; this way, with the pulley size difference, both motors turn the transmission at the same speed

hope that clears things up!


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## 3dplane (Feb 27, 2008)

Good going theboy16!You got some good points there.I guess now i can give my wife's sewing machines back with those blown motors....


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## theboy16 (Feb 28, 2008)

the sewing machine motor was used as an extreme example 

using two similar motors would result in over/under current situations in both motors. you're also screwing with the efficiencies and lifespans of the motors, even if they're "pretty close"

cheers!


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## ngrimm (Oct 19, 2007)

To find out if the two motors run the same speed at the same voltage, could I connect 12 volts to them and measure the rpm or would they need to be under a load and possibly a higher voltage? Norm


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## 3dplane (Feb 27, 2008)

Norm! Yes to find out rpm/volt(or KV)you can spin them up on a known voltage (12v)unloaded if you got a way to mesure rpm,and that way you can calculate rpm for a higher voltage.(unloaded)Barna


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## 3dplane (Feb 27, 2008)

Norm!May I ask what two motors you got your hands on? And what the intended application would be? Maybe with that info your questions could be clarified quicker.Especially if some of the large dc motor gurus chime in.Or someone might have had personal experience with them.Barna


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## John (Sep 11, 2007)

Does anyone know what issues could come up running series parallel switching on a dual motor setup with one motor driving the front axle and the other driving the rear axle? Sort of a road connected arrangement if you like. The worst situation I can think of would be wheel spin on one of the axles where a large difference in speed between the motors would occur. If parallel mode was used for all slow speeds this situation would be unlikely to arise. In parallel mode both motors would see the same voltage but their amperages could be different. The motor that was turning slowly would generate a small back EMF and so would conduct a large current. The motor that was spinning fast would generate a large back EMF and so conduct a small current. The total current would still be limited by the controller. So the motor driving the skidding wheels would produce substantially less torque than the motor driving the wheels with grip. In series mode the motors both conduct identical current but the voltage drop across each motor can be different. If one motor is generating substantially greater back EMF (i.e. spinning faster) than the other motor its voltage drop will be greater. This I think would be a problem if I was applying 300v to the circuit and relying on the evenness of the motors for each to see only 150v as the faster motor would see a larger portion of the total voltage and might flash over. Is this right?


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## ngrimm (Oct 19, 2007)

Thanks Barna. Both motors are from a Hyster. The traction motor is a 6 3/4" x 11" 24volt 104 amp GE series wound dual shaft and the other is an Advanced DC 24 volt part number 140-01-4001 slightly smaller. I haven't pulled the Advanced yet to see if the shaft would couple to the GE yet. Btw, how do you measure the length of a motor? Norm


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## 3dplane (Feb 27, 2008)

Hey Norm! Looks like you got a 3.5 HP rated motor so far and another one similar.While it does not sound much i'm sure its a modest rating(Last forever on that load)I think Coley got away with a 5HP in his yugo(yuglet) for a while before it burned up,but that could have happend for many different reasons.Regarding your Q:how do you measure the lenght of a motor?...Tape measure?(sorry couldn't resist)I believe the outer dimensions but not including the shaft.Let us know what your project is sounds exciting so far...maybe you could be forkenDUALswift.Barna


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## Hi Torque Electric (Dec 23, 2007)

Hey all

Sorry I haven't been here in a while, been busy. I see some people here stating some wrong opinions on this though. It is unwise to use two differently wound motor together. EVen on a dual drive motor forklift (two exact motors) if one wasn't running as good, it'd cause the "better motor" to work harder causing it to overwork. I was taught that in twin motors, "my mentors" wanted both commutators to be within a close tolerance of difference. EVen using twin motors (lets say two Warp9's), I take care making sure they are timed as equal as can be had, in extreem cases like the racers. Anyway, just my input here.

I saw someone talking about the Siamese8 earlier in this thread so I thought I'd let you guys see some pics of the new Siamese9's I'm working up. I test fit the shaft yesterday, (no guts installed yet) but you'll get the jist of what they'll look like. Anyway, the pics are up at my site along with some other pics I got time to put up.

http://hitorqueelectric.com/

Hope you enjoy.
Cya
Jim Husted
Hi-Torque Electric


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## 3dplane (Feb 27, 2008)

Hey Jim! Thank you for posting.Now i dont get something.If they are that sensetive..Is that possible that the "better"motor is better off alone?What i mean is:Can the weaker motor actually "hold back" the stronger one instead of helping (to share the load)?This is just to better understand the principal behind it.Again Thank you for your opinion.Nice Jimpulse9 btw.Barna.


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## theboy16 (Feb 28, 2008)

Another question for Jim:

where can i find prices are siamese motors that you build?

i'm seriously considering doing away with the transmission; this would open up my options for a donor vehicle (auto or manual) and i would eliminated the losses in the transmission, and i would have fewer parts that can break

Do you think this is wise? 
how efficient would a siamese motor pair be in a daily driver EV?
and once again, where can i find ballpark costs for various siamese configurations?

Thanks alot!

Steph


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## Hi Torque Electric (Dec 23, 2007)

Hey all
I'm going to start with the mis-matched motor thing first. Okay so let's say we start with a Warp9 as our motor number 1.
Now for motor number 2 we're going to wind a slotcar motor for 160 volts (recommended voltage limit for a Warp9). Now do you think this little motor will have any input, or will it just be along for the ride? This is an extreem example but says alot really. Another great illistration (for those who watch Survivor) they tied a big brutus guy to a small whimpy guy where they had to run around. The big guy ended up dragging the little guy along the ground as he didn't nothing but slow the big guy down (hilarious footage for those who missed it) anyway I instantly thought of this thread, lol.
Problem number two in using mismatched motors is number 1 could want to draw 30 amps at 3000 RPM's at X voltage while number 2 might want to draw 40 at 4000 RPM's at X voltage, so what you'd find is you'd burn up motor number 2. Even with exact motor types there's a high / low execptable difference right from factory. Now I'm not saying that in EVery case one needs to be concerned of this but if asking from these it is importantant but even for the DIY guy on a budget it'd be far better to wait and get a bigger motor than to try and patchwork quilt a couple of mismatched guys.


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## Hi Torque Electric (Dec 23, 2007)

Hey all

I've had a few hits on these Siamese9's already and so 
I thought I'd throw out some pasted info and FYI's on them.
As to the motor spec questions, these are made from
two new Impulse9 motors. You won't be able to
correctly use the Impulse9's spec data though. When
they made the Impulse9's to replace the Advance8 motor
they found the RPM's were much lower than the ADC8. 
They affset (mis-alligned) the armature to pole shoe
laminations to increase the motors RPM's to match the
ADC8's, but they lost alot of torque as well. Being
we want the torque but don't need the RPM's on a direct drive
setup, I'll be alligning the armature and pole
laminations. I'm estimating about a 10 to 15%
increase in torque and about the same in lower RPM's.
George Hampstra (NetGain) and I have listed these at
$5500.00 (5K to Netgain dealers) and they will come
with the tranny end, and the front motor will have adjustable
timing (for reverse). The mount bracket and slipyoke
are extras with the mounting bracket at $125.00, and
the slipyoke at $200.00.
If compared to the Transwarp9 / Warp9 (plus
attachments) you're in the ballpark of 4300/4400 bucks
and you still need a coupler and mounting setup. Right now
we're needing to quote 4 to 6 weeks out for
these, Depending on availability from Netgain and subject to
availablity.
The nice thing about working with these Warp motors is the armatures
and shafts are keyed making a better shaft to armature mating.
I'll keep you all posted after I spin the first one up 8^)
They really will be about as plug and play as you can get.
Cya
Jim Husted
Hi-Torque Electric


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## theboy16 (Feb 28, 2008)

Dear Jim:

The adjustable timming you speak of, for reverse, how does that work exactly? From what i've gathered, one would need an actuator of sorts to shift the timming to go either fwd or reverse? Is that correct?

Furthermore, I am interested in a tandem motor setup, using a 240 volt pack.
Would you suggest using another motor pair (ones that run at 120 nominal) or would you recommend the siamese 9" in series, with the controller's max voltage set at 170v?

Thanks

Steph


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## noj (Mar 9, 2008)

alex, look into farm tractor drive chains. To my surprise they are not driven by a shaft and universal set-up, they actually use a set of sprockets and a chain. good luck


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## Hi Torque Electric (Dec 23, 2007)

Hey all

Here's my thought's on the adjustable brush timing and the "who, what, why" of it. First off, EVeryone's locked into a particular setting but yet EVeryone's running different loads, voltages, and driving conditions (flat or hills). The guy who's using a Warp9 (set at 12.5) at 120 volts will find that it's set to high, where as the guy who's running twice that needs it (maybe a tad more). The closer to neutral the brushes are the more torque you'll see but the more advanced it gets, the higher the RPM (at X voltage) and the power band also shifts to the higher RPM area as well.

Some people like the lower power band, some like it at freeway speeds. The higher the advancement the less likely you'll see arcing at higher voltages. The lower the advancement the better the eff. Being able to self adjust it makes for a more user friendly motor where you can adjust it for your own performance and or eff neds /wants.

As to "how" to use them, they can be set up to be static where you set it and lock it down. I use an insulated lever so you can attach it to a choke cable and run it into the cab and manually adjust it on the fly. What I'd like to see is it being set up to a little stepper motor where it could be timed (just like an ICE) which would need a way of detecting how much power is being thrown at the motor. I have motors with the first two on the road so it's just a matter of time before they get really tricked out. Killacycle's is switched via a soleniod as a one step neutral / advance way of doing it also.

Data is hard to come by, but as a general FYI, the Warp9's and ADC9's are in fact the same motor electrically (meaning same bar count, lam length, wire sizes, ect). If you look at the test specs though they are different. The reason for this is ADC sets theirs at 10 degrees while the Warps are set at 12.5 degrees, so this small 2.5 degree difference makes a big difference in motor performance.

Hope this helps
Jim Husted
Hi-Torque Electric


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## theboy16 (Feb 28, 2008)

Can anyone tell me if shifting the timming on the motors will result in a reverse direction? what if i bring the brushes back to -1 degrees?

i thought i read somewhere that the brush placement could result in a fwd/rev direction: is this true? or is the only way to achieve reverse is by switching the armature's polarity?

Thanks! 

Steph


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## Hi Torque Electric (Dec 23, 2007)

Hey 16

By rotating the brushes 90 degrees the motor would run the other direction. It would actually stall at about the 45 degree area and then switch direction (running in a retarded timing) untill it got to the 90 degree mark where it'd be in a neutral position in the other direction.
Hope this helps
Jim Husted
Hi-Torque Electric


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## theboy16 (Feb 28, 2008)

So, this tandem setup opens the doors in terms of possible donor vehicles.

It seems hard to find a fully loaded vehicle with a manual transmission, they usually come with auto's. but with dual motors, we can do away with the tranny, and be left with a fully loaded, comfortable EV. The gear shifter can be used to move the brush ring, from reverse to forward (maybe even a fwd hi and fwd lo, for highway/city use)

i think its worth the extra dough


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## John (Sep 11, 2007)

Would reversing the brush position while the motor was forced to rotate in the forward direction by the inertia of the vehicle cause the motor to act as a generator?


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## Hi Torque Electric (Dec 23, 2007)

So, this tandem setup opens the doors in terms of possible donor vehicles.

I couldn't agree more. Right now EVeryones locked into having to find manual donors. Besides being fast John Wayland's White Zombie is pretty eff to boot as far as the daily aspect of thing goes as well. I've heard that adaptor plates are running up to 800.00 to have made up so there are costs that this setup do get offset by when looking at doing a conversion.

There's a lot of interest from people right now who are wanting sporty street coversions and these should fit the bill.
Cya
Jim Husted
Hi-Torque Electric


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## Hi Torque Electric (Dec 23, 2007)

Hey John

Every motor is a generator but the nature of these series wound motors in that their coursely wound they make poor generators and arc at the higher voltages (even when set neutral). Sep-ex or interpolled motors are better suited for regen but there aren't many controllers for these as of yet.

You could find some improvement with adjusting brushes for gegen but feel it'd still be very hard on the motors as it's just not in their design or mayby better said their applicated voltages with EV use.
Hoep this helps
Jim Husted
Hi-Torque Electric


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## electrabishi (Mar 11, 2008)

Hey Jim,
The possibilities really are open. Putting the motors you built into a Pinto that was automatic really was a snap. And these hulky 9" twins are gonna rock the panels. The good thing going for the Pinto is that its made outta real steel. Thats good because recycled beer cans don't stand a chance against a pair of WarP9" motors. 

For those who don't know Jim put together my motors for a 1978 Pinto meant to run against the White Zombie (some day). http://www.evalbum.com/1093 The pair of these will be providing upwards of 1000 ft lbs of torque to direct drive the rear end. No Tranny needed. The series/parallel shifting of the ZIlla 2K will be implemented to increase HP on the second half of the track. 

Someone questioned earlier in this thread why you would want to run motors at half voltage. Its because since the controller is current limited at launch, at lower RPM the voltage on the motor is low and rises slowly with RPM. Because you can afford to split the voltage of your pack across two motors at low RPM, you force the max amount of current the controller can provide, in series therough the motors. This effectively doubles the Torque per Amp over that of 1 motor. When the voltage rises up to 1/2 the sagged pack voltage you are now voltage limited on your controller and current (and power) will taper off unless you do something. So to increase the power again you shift the motors into parallel and allow the full pack voltage across each motor. The controller is current limited again but now with only half the current flowing through each motor. But because the motor(s) now have full pack voltage they are allowed to accelerate again, albeit with reduced torque.

So to sum up the benefits of S/P switching.
Full current (1/2 voltage) through both motors in series at low RPM for launching torque.
Max voltage (but 1/2 current) on both motors in parallel at higher RPM for for continued acceleration.

Mike


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## theboy16 (Feb 28, 2008)

Jim:

The motors I've seen on your site with the adjustable lever for brush timing seem to have a range of movement in the 15-30 degree range. In a previous post you mentioned that in order to achieve reverse, the timing needs to be retarded by about 90 degrees.

Am I correctly understanding this? Or was that motor I saw not equipped with reversible timing?

(the blue 9" motor you have for sale on ebay is the one i'm refering to)


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## Hi Torque Electric (Dec 23, 2007)

Hey Mike

I see you found the place 8^) Of course it couldn't have been to hard I guess since I threw you a link. Mike's motors can be found under the CrazyHorse album at my site and he's getting close to finishing his racer.
As a general FYI, I asked Mike to come on over and help out here after he decided to sign off the EVDL, so I'm glad to see his post 8^) Besides Mikes general EV knowlege he likes to have a little fun, like me, and I thought he'd be a great member here so I'm hoping he enjoys it here as I do.

Hey 16
As to the timing / reverse question you asked, you switch the motors direction by swapping out the connections between the two "A" terminals (you can also swap out the two "F" terminals also). The timing ring on the "Blue Chip" motor (that's the name it's new owner calls it) is set for a neutral to 15 degrees advancement movement. I actually just fab'd up a small lever restrictor (it'll mount to the end plate) that will limit the rings movement to the 0-15 movement so it'll prevent people from trying to go overboard.

Just to be clear on this, just getting a thick enough cable connection from lead to terminal, that will rotate 15 degrees is tough enough, getting one that could pivit 90 degrees to self reverse the motor would be much tougher (not that I haven't thought about it as it would reduce the contactors that are needed.

Anyway, I hope all welcome Mike to the forum here, as he is a wealth of knowlege and someone I concider to be a good friend, so I for one am damn glad to see him come aboard 8^) Mike needs to do a CrazyHorse thread and post some of his newest pics here as it's coming out great. 
Cya
Jim Husted
Hi-Torque Electric


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## ngrimm (Oct 19, 2007)

I can't wait to see the your finished Pinto project. Over on Turboford.org where I used to hang out Pintos are a favorite four cylinder turbo conversion due to weight and parts availablily. We have a guy here in Medford with a turbo four Pinto that runs in the mid 10's in the quarter. Really surprises the V8 guys as I'm sure your car will do as well. Norm


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## electrabishi (Mar 11, 2008)

We should have the Pinto on the road by the end of the month. The car is pretty light, for an American car. The twin motors are slightly lighter than the V6 that was in it. Probably about the same weight as the 2.6L 4 cylinder. I frequent the FordPinto.com site as well and there are a lot of Pinto fans running around the race tracks. I'll start up a new thread on the car in a bit.


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## sharp21 (Mar 11, 2008)

I need something dumbed down...
If I am running a 144v setup with single motor & I add a second motor but leave the powerpack the same size, would I get twice the power but with half the range? Simplistically speaking of course...
Also, how does a direct drive system hook to the drive axle? Just a U-joint on the back of the motor then a long driveshaft? I would love to see some pictures!
S.


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## electrabishi (Mar 11, 2008)

You won't neccessarily get half the range. However you will get twice the torque throughout the rpm range of the motors that is there IF you want to use it. If you always use the extra power your range will be decreased, but maybe not quite half. Assume you use twice the power to take off but you still use the same amount of power for cruising constant speed. Figure the time you spend accelerating and the time spent at constant speed. It'll maybe be 10% accelerating and 90% cruising or 30% accelerating and 70% constant speed for short stop and go trips. Its kinda like having a turbo. You will have the power available and if you drive conservatively you can save your gas mileage. Same with going dual (or one bigger) motor set up.

You can see one pic of my motors with TH400 Shorty Tailshaft and 1350 slip yoke on the pics posted here http://www.evalbum.com/1093 There is also a shot of the rear end as well as the drive shaft that is in the pic with all the roll bar materials on my garage floor.

I have lots more pics posted on the NEDRA Yahoo Groups site http://sports.groups.yahoo.com/group/NEDRA/ but you'll have to join to be able to see them. When I get back to my home computer I can post a couple directly to this site.

Mike


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## electrabishi (Mar 11, 2008)

Here are some pics I promised of the Pinto Driveline that hooks the twin motors to the rear end:


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## electrabishi (Mar 11, 2008)

About the motors in my previous post. One is a WarP9 and one is a TransWarP9 from NetGain. The WarP9 has a 7/8 tail shaft and an 1-1/8" Drive shaft. The TransWarP9 has an 1-1/8" tail shaft and an 1-3/8" hardened splined drive shaft that fits a 1350 slip yoke and the Drive plate mates to a TurboHydramatic TH400 shorty tailshaft housing. The two 1-1/8" shafts facing each other are coupled with a standard Dodge Gear Coupler size 1 (smallest one they offer stock). 

The motors are bought new (through a dealer http://www.evsource.com/) from Netgain Technologies, LLC. http://www.go-ev.com/ and included the tailshaft housing and 1350 slip yoke adaptor. 

Jim Husted made some slight mods and race preps and you can see his pics of the build on his site http://hitorqueelectric.com/gallery/v/custom_motors/Mike+Willmons+Crazyhorse/
Jim, by the way is now a dealer as well and if you want mods to new motors is the best place to order from.

enjoy
Mike


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## sharp21 (Mar 11, 2008)

That looks awesome! Ive actually been browsing pages on go-ev.com since I made that last post.
So to use the 2 motors, the WarP9 basically plugs into the TransWarP9, which sits in the place of your tranny!
Is it possible to use a TransWarP9 as the only drive motor, with possibility of upgrading to a second later? Or is there not enough power/gearing to direct drive a vehicle with only the single motor?
Which brings me to another question... A direct drive setup will cruise comfortably on the highway or is for performance applications only?
Im giving up a small block s10 to get into EV's so this is the area I want to get into with it! 
Thanks for the great reply. I checked out the Mitsulectric too, real nice
S>


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## sharp21 (Mar 11, 2008)

Sorry, one more...
With that dual setup do you need dual controllers? Im also curious as to if you can program the controls to different power settings, like 100% power for the track but 80% for the drive home after.
S.


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## Hi Torque Electric (Dec 23, 2007)

Hey Sharp

One 9" motor isn't enough to go direct drive with as you'll find the motor will overwork and heat up. You can in fact use one controller for two motors (if it's big enough, and if it's a "Zilla" you can program it to do a series parallel shift which acts a bit like a two speed electronic shift.

As to the two motor vs one bigger aspect, the biggest plus in doing this is you get twice the brush / comm interface using two smaller motors which distibutes the current over a larger area keeping the motors happier.
Hope this helps.
Cya
Jim Husted
Hi-Torque Electric
PS: Hey Mike, is that a Transwarp9 shaft in that pic or you just happy to be here 8^o


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## electrabishi (Mar 11, 2008)

Just a quick comparison from personal experience. With a Zilla 1K controller, single WarP9, 4000 truck and the tranny in 4th gear (1:1) the truck would accelerate, but real slow, probably 30 seconds to 60. Wheras if I start from 2nd or 3rd I can hit 60 in 12 and 14 seconds respectively. Now with a 1000 lbs lighter vehicle and a Zilla 2K It would most likely launch like the Z1K in 2nd gear and get the 0-60 time back to about 12 seconds. But like Jim said the poor motor would be pulling double duty. 

Mike


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## sharp21 (Mar 11, 2008)

Looking at a lot of the 144v truck builds on EVAlbum (looking at EVERY truck build actually!) i noticed that not many mention rear gearing. Seems that that needs to be addressed for decent acceleration.
Also, there is only one truck using an 11" motor, while most others are using an 8" or 9". Why is that? Besides the cost of course...
Can the TransWarP11 be used as direct drive?
S.


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## Dennis (Feb 25, 2008)

I don't see why a 4.56:1, 4.88:1 or a 5.13:1 third member gear ratios would not be adequate. It should be low enough to not stress the motor without a transmission gear ratio.


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## rankhornjp (Nov 26, 2007)

Dennis said:


> I don't see why a 4.56:1, 4.88:1 or a 5.13:1 third member gear ratios would not be adequate. It should be low enough to not stress the motor without a transmission gear ratio.


A 4.88/5.13 would probally be good, with top speed at 3500rpm being 54/57mph with 245/60r15 tires, but in stop and go traffic I think that you would still use alot of amps. Most guys are using 2nd gear for in town driving, which is usually around a 2:1 (+-). If you have a stock 3.55 axle ratio, thats makes your overall ratio: 7.1:1 (2*3.55). 

You can check out this link, it has a Gear/MPH Calculator. You can put in your own gears and tire sizes and adjust it to see what works best for you.
http://www.f-body.org/gears/


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## Dennis (Feb 25, 2008)

Motor current usage depends on lots of factors other than gearing. A 13" warp would require less amps than a 9" warp for the same torque level. Likewise, a dual motor setup would require less amps to achieve the same torque level it would take versus a single motor setup. Now a single 9" motor or smaller setup would be stressed from the third member gear ratios without a transmission gear ratio.

Sharp21, a warp 11" would be perfect to connect to the third member without a transmission if the gear ratios are like 4.56 or lower, but not 1:1!


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## aeroscott (Jan 5, 2008)

looking at a large ac motor 200 lbs. 12 " x17 ", 6 pole so 1200 rpm @ 60 cps , rating because of low speed show 7.5 hp.In figuring power, weight ,wire etc are needed to estimate power. I was thinking of compound motors , but with ac motors in every size there is no need.


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## ViolentBlue (Apr 19, 2008)

I'm thinking of doing an AWD car with one in the front one in the back, each driving a limited slip diff. This will all be packaged in a custom built chassis.


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## Hampton (Mar 10, 2008)

hey guys I'm sorta new here, and i was just wondering how can 2 or more electric motors in tandem can eliminate the need of the transmission?
can someone please clarify this for me? im planning on doing an ev conversion and i think i might use 2 motors


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## 3dplane (Feb 27, 2008)

Hi Hampton!
You get lots of torque on take off.No need for a trans.The two motors share the amp load.One big enough motor would do it too,but the two motors also double the brush contact surface area.(assuming brushed motor).The setup obviously have it's pros and cons like anything else.Hope that helps. Barna


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## John (Sep 11, 2007)

If you want to do away with the transmission there are two competing parameters you must balance. One is the torque available at the wheels, particularly at start up, which determines the gradability of the vehicle and the second is the top speed of the vehicle before you over spin your motor. Torque at the wheels is motor torque multiplied by the gear reduction ratio while wheel revolutions is motor revolutions divided by it so with a given motor if you increase one parameter by changing the gearing you decrease the other. You can also increase the torque by increasing the size of the motor or by increasing the number of motors. In smaller diameter parts centrifugal forces reach the destructive levels at higher RPM so multiple smaller motors should be able to spin to higher RPM than a single large motor (provided the commutaters are also smaller in diameter). A higher rev range will allow for a small gearing advantage without having to lower the top speed. Tandem motors also open up the possibility of Series/parallel switching with a high voltage battery pack.


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## Hampton (Mar 10, 2008)

I have another question!!! lol

hypothetically, if i for some reason I wanted 4 motors, which one of these options would work (or be the best)
-- 1 transwarp 11, 3 warp 13 (or warp 11*)
-- 4 warp 13
-- 2 transwarp 11, 2 warp 13 (or warp 11*)

*would i have to use a warp 11 to connect with the transwarp 11, or 
could i use those 13's?? 

Thanks a lot guys.


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## Hi Torque Electric (Dec 23, 2007)

Hey Hampton

Works best for what purpose? Just about EVeryone's battery limited so carrying more motor than you need chews into battery carrying capacity.
Not sure why (or how) you'd cram in 1200+ lbs of 13" motor? The next thing is, when going direct drive you need twice the controller as well to chug up when starting, as the gearing is not there. As a general rule, pair (or quad) equal and identical motors, or one overworks as the other doesn't do much work and you'll burn the one that's doing the work.
Hope this helps.
Jim Husted
Hi-Torque Electric


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## Hampton (Mar 10, 2008)

well this might be for a project way in the future (10-20 yrs)
i want to attempt to make an electric airplane, that can go about 500-1000 miles and pretty fast, (300 mph maybe) idk. 

i was think of using both li-ion batteries and fuel cells. each system with about 300V in it. i plan on doing this project with some personal jet.
(of course i'm going to have to make some smaller proportional models for it)
but Jim, could a transwarp 11 and warp 11 be fitted together without making one overwork the other??


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## ViolentBlue (Apr 19, 2008)

I've got a set of motors for my project, and I'm wondering if its better to couple them together then direct drive the differential, or to use one to drive each wheel ( with a 3:1 reduction by chain drive)


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## ww321q (Mar 28, 2008)

ViolentBlue got pictures ? I would like to see what you scored . If not maybe some specs , dia ,length, weight , #brushes stuff like that . J.W.


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## ViolentBlue (Apr 19, 2008)

Will post pics tomorow, I'm picking them up in the morning.


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## antonis (Apr 28, 2008)

hi , im not sure if that you want, but look at the mitsubishi lancer evolution miev, thats a four motor evo and the motors cover the discs. smart


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## John (Sep 11, 2007)

Violentblue,
Take a look at the Tango T600. It uses the arrangement you're considering. http://www.commutercars.com/specifications.html


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## ViolentBlue (Apr 19, 2008)

I've been debating in my head how best to do this. space is a limiting factor.
I'm thinking the best way to do it is to build a rack mounting the two motors side by side, driving by chain the input of the differential. I'm not a big fan of chain drive , but with the space constraints of the Beetle engine bay, it might be the best option, as well if it doesn't work, I can easily pull it out and do something different.


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## waldoz (Oct 1, 2008)

Hi Torque Electric said:


> Hey Hampton
> 
> Works best for what purpose? Just about EVeryone's battery limited so carrying more motor than you need.


Jim, 
I have been reading this thread, wondering if two warp nines could replace my Grand National turbo 6 ice motor I have in my race car right now. the weight of the car after all the stuff is in it runs about 2900 lbs. I should be seeing low 11s with the ice. Would the motors and bat weights beable to keep up with the same times , I will be putting down you think? Part of the reason I ask this is the last time out I blew second gear band and burnt the converter in the tranny.  Any input would be great. 

Thanks


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## electrabishi (Mar 11, 2008)

waldoz said:


> Jim,
> I have been reading this thread, wondering if two warp nines could replace my Grand National turbo 6 ice motor I have in my race car right now. the weight of the car after all the stuff is in it runs about 2900 lbs. I should be seeing low 11s with the ice. Would the motors and bat weights beable to keep up with the same times , I will be putting down you think? Part of the reason I ask this is the last time out I blew second gear band and burnt the converter in the tranny.  Any input would be great.
> 
> Thanks


 
My ~3200 lb Pinto with twin WarP9's (850 lbs of which is lead) is running mid 12's. I could lose 600 lbs of lead and go with lithium-ion and be in the mid 11's. So assuming you could get the weight of your Buick to run at or less than stock you could be getting pretty close. Of course getting the WarP9's will be the easy part. Its finding a Zilla 2K to go with them that will be difficult. I'm not sure you can get anything near reliable enough cobbled together from whats on the market to feed a pair of those beasts. 

Mike


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## waldoz (Oct 1, 2008)

electrabishi said:


> So assuming you could get the weight of your Buick to run at or less than stock you could be getting pretty close. Mike


Well, 
LOL the motor and tranny are in a 2 door volvo.  with a 8.8 rear with a posi. I think the rolling shell would come in at about 2300 or so. Not really sure on that. With two of those motors the rear end would cry for sure. I would love to drive to the track and runs some times and drive home. I do think in the next few years we will be way ahead with the EVs though.


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## dtbaker (Jan 5, 2008)

There is a guy here in Santa Fe (James Keene) that has a homegrown setup with THREE permanent magnet motors linked w chain drive to tranny. A little strange, and he is wishing he had used series wound for low end torque. But it does work!

The chain drive is noisy as heck though....

He also complete home designed and built his own controller; pretty wild, kinda looks like a mad max job but seems to run fairly well. Big issue with the controller operates with an 800 hz pulse, and never stops, which is really annoying after a couple minutes.


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## themotorman (Jan 7, 2010)

rbgrn said:


> Was just thinking about this... I've heard certain cars have put a motor on each wheel, which seems like an engineering headache to me, but has anyone linked multiple motors up in tandem for a single very high-torque output? I would think that if you could rig it up reliably that pumped into a high gear ratio you could achieve some very high speeds as well as a solid low-end. Links? Info?


In wheel is great for high speed use as the efficiency for the motors would be good. ( Solar racers in wheel is ideal ) . At low speeds the efficiency at high torque like hill climbing and acceleration would be low. Best choice is a transmission to keep the motor RPM at the high efficiency high output region and the car or bike at the speed you want. Also unsprung weight is a concern. Usign multiple motor in board has some advantage and is used all the time for diesel-electric trains. 
My 3 wheeter has 4 motors and i can connect them in series or parallel giving me some advantages at the expense of alignment and mechancially connecting them. I have a pix if anyone is interested . The cost for surplus motors is often better for lower powers so this idea works for home builders. not good for a production EV ..as a single motor can do all you need.
I do have motor info on my website: http://www.members.cox.net/rdoctors.


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## CFreeman54 (Jan 14, 2009)

This raises a question I have, since I bought a Raptor 1200 last year when Zilla's were not available (and now wish I had waited). Is it possible to run dual controllers to feed double the amps to one motor? 2400A through my Warp 11 @160V in the custom Fiero I am building fed with Li Ion batteries might actually be competitive on the drag strip (I hope).


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## electrabishi (Mar 11, 2008)

waldoz said:


> Jim,
> I have been reading this thread, wondering if two warp nines could replace my Grand National turbo 6 ice motor I have in my race car right now. the weight of the car after all the stuff is in it runs about 2900 lbs. I should be seeing low 11s with the ice. Would the motors and bat weights beable to keep up with the same times , I will be putting down you think? Part of the reason I ask this is the last time out I blew second gear band and burnt the converter in the tranny.  Any input would be great.
> 
> Thanks



wladoz, have you gotten anywhere on your Grand National Build?


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## waldoz (Oct 1, 2008)

electrabishi said:


> wladoz, have you gotten anywhere on your Grand National Build?


 
No, up and sold everything at a heavy loss.  Paid some bills off and now out of debt.  I was just thinking of a elec. car project yesterday though.


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## Bowser330 (Jun 15, 2008)

CFreeman54 said:


> This raises a question I have, since I bought a Raptor 1200 last year when Zilla's were not available (and now wish I had waited). Is it possible to run dual controllers to feed double the amps to one motor? 2400A through my Warp 11 @160V in the custom Fiero I am building fed with Li Ion batteries might actually be competitive on the drag strip (I hope).


yes it is possible. 

http://www.evparts.com/article_zoom.php?ARTICLESTAG=Article1

Maniac Mazda used two T-Rex controllers for each motor in a dual motor setup.

T-Rex controllers are also made by Dc Power Systems just like your Raptor.

I would contact them directly with your interest in possibly buying another Raptor.

2400A into an 11" is what, 600+ftlbs of torque?

I would like to see that type of launch run through an AWD setup, maybe from a big truck diesel transmission and transfer case...2 times the grip would give you more power to the ground and less amps wasted as smoke and shreds...


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## Tahoe Tim (Feb 20, 2010)

Great thread. I am wondering about your opinions on a tandem set up to improve economy.

Can someone look at this from the angle of providing good off the line acceleration and good economy at higher speeds?

Example:
Zilla 1k controller with two 8 inch motors in tandem through a transmission in a S10. Instead of switching from series to parallel, electrically disconnect one motor at cruising speeds for economy. Have the extra motor available for hills and passing.

Crazy idea? 

I can't wrap my head around what will happen when the remaining motor is hit with a sudden doubling of voltage when one motor is dropped out. maybe series parallel is an economy setup in series/parallel if you keep your foot out of it. I am wondering are the SMALLEST two motors that can be mounted in tandem for an S10 truck.


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## gor (Nov 25, 2009)

mech link vs. par/ser switch vs tranny (between or after tandem) - interesting, but hard to tell how it actually will do ... 
pict: to spin shut-off(?) additional motor on rpms, few times of rated, - feels weird... 
p.s. parallel/ser with 3 smaller motors also seems not bad
http://www.diyelectriccar.com/forums/showpost.php?p=156803&postcount=21


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## Bowser330 (Jun 15, 2008)

Tahoe Tim said:


> Great thread. I am wondering about your opinions on a tandem set up to improve economy.
> 
> Can someone look at this from the angle of providing good off the line acceleration and good economy at higher speeds?
> 
> ...


nothing would happen to the motor that got double the voltage as long as you used dual kostov motors...the 11" has been proven to handle 300+Volts...additionally the motor will only see that 300V @ 100% PWM, during lower rpms the pwm will be 50% (150V)

I like your idea but you have to make sure you upgrade the transmission components to handle the torque, 1000A into two 8" motors will be about 400ftlbs instantly at 0rpm...


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## Tahoe Tim (Feb 20, 2010)

I tried to plot a warp11 vs two impuse 9's to get a comparison of the performance. I guess I'm not getting the concept.

Since most conversions seem to be warp9 size, can anyone suggest a siamese setup that matches a single warp9 motor at top end?


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## gor (Nov 25, 2009)

gap on the charts - is it just due to data collection/processing? - what actually happens in reality on parallel/series switch (both motors off for a moment or at least one should be on? three motors case, one-by-one switch would make difference? 
how fast it switches compare to gear shift?


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## major (Apr 4, 2008)

gor said:


> gap on the charts - is it just due to data collection/processing? - what actually happens in reality on parallel/series switch (both motors off for a moment or at least one should be on?


Hi gor,

The switch from 2 motors in series to 2 motors in parallel is done with contactors on the motor side of the controller. You simply must turn off current with the controller, switch the contactors and then re-energize with the controller. If not, you will weld the contacts due to the inductive load. Looks like the whole process takes about a third second. Likely comparable to a gear change.

If you got a better way, do it and beat these guys on the strip 

major


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## gor (Nov 25, 2009)

major said:


> Hi gor,
> 
> The switch from 2 motors in series to 2 motors in parallel is done with contactors on the motor side of the controller. You simply must turn off current with the controller, switch the contactors and then re-energize with the controller. If not, you will weld the contacts due to the inductive load. Looks like the whole process takes about a third second. Likely comparable to a gear change.
> 
> ...


sure, let's just figure out how (and don't tell them (or tell them opposite) : (((
: )))))))
-----------
what about 3? 1 is on when 2 off while switching?


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## gor (Nov 25, 2009)

one with trany - one direct? 
--- weight; (one or 2 smaller motors vs 2 motors+trany)
++ smaller (lighter) tranny (for 1 smaller motor vs twice bigger motor )
-----------
p.s. we can tell them -we putting three (or 4) humongous motors - beat that!


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