# Rewinding a SepEx into a Series?



## Clipper (Jan 30, 2011)

Howdy All,

I have a TEVan (Caravan) with a 27HP/180V GE SepEx motor. I'm trying to replace the controller, but nobody makes a SepEx controller for voltage that high.

Thought about going the 2-controller route, one for the armature, one for the field. Trying to find a field map for the motor.

I was reading some old posts (and reading, and reading, and...) and I came up with a thought: is it viable to rewind the field as a series motor? Then finding a controller becomes easy. And I don't have to adapt a new motor to the trans.

Any thoughts/observations/comments?

Thanks,
--Clipper


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## major (Apr 4, 2008)

Clipper said:


> is it viable to rewind the field as a series motor? Then finding a controller becomes easy. And I don't have to adapt a new motor to the trans.
> 
> Any thoughts/observations/comments?


Hi Clip,

Yeah, it can be done. Viable???? First you have to design the series field, ie. turns per coil and wire size. Second you need to get the proper wire. Most times this is rectangular conductor with class H coating. Not a standard stock item and the mills require a 1000 pound minimum run. Third, you need someone to wind the coils. Requiring forms, tools, equipment and skill. Forth, you need to have the coils formed, wrapped and varnished. Fifth, the coils need to be installed and connected.

A motor rebuilder (Jim Husted comes to mind) could do this for you. That size and value of motor is likely about the cutoff as to what they bother rebuilding now-a-days. You'd have to weigh the cost 

Regards,

major


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## DavidDymaxion (Dec 1, 2008)

Not a recommendation for or against, but Kelly sells a 144V 1000A sepex controller for about $2k. If you can live with a bit less Voltage that is probably the easiest path.

http://kellycontroller.com/hse141011000a144vsep-ex-with-regen-p-903.html


Clipper said:


> Howdy All,
> 
> I have a TEVan (Caravan) with a 27HP/180V GE SepEx motor. I'm trying to replace the controller, but nobody makes a SepEx controller for voltage that high.
> 
> ...


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## pm_dawn (Sep 14, 2009)

You can also have a look on this.

http://chennic.com/show-products.asp?id=45&JCECP

They list a 156v 400a controller.

Regards
/Per


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## Clipper (Jan 30, 2011)

DavidDymaxion said:


> If you can live with a bit less Voltage that is probably the easiest path.


Hi, David and Major,

If I go with the Kelly, I'm going to need to figure out a field map...I read your instructions here (comment #11):
http://www.diyelectriccar.com/forum...unning-larger-sepex-out-thereiii-34283p2.html

I *do* have the armature resistance (0.2 ohms) and the field resistance (3.2 ohms), (approx., per the service manual.) 
Attached is the nameplate from the motor and a photo of the motor.

What do I lose running a 180VDC motor on 144VDC? 
Torque/Acceleration? Top end speed? Efficiency/range?

At a lower voltage, can I feed it more amps? 
(The idea being to keep the peak KW or power about the same?)
27HP (max continuous) works out to about 20KW...or about 111 amps at 180V. The maximum climbing a hill at 180V is about 300A.
Does that mean at 144V, I can run it continuously at about 138A, or peak at 375A?

Another possible solution I've considered is to go with an AC50 AC motor/Curtis 1238-7501 AC Controller. I would have to adapt it to the trans, but there doesn't seem to be any easy solution here anyway...

Do you think the AC50 is powerful enough? It says it's 67 HP peak at 108V (existing GE motor is about 70HP peak) but the continuous is only 15HP, vs. 27HP for the existing DC motor. I don't have any torque specs for the existing motor.

If I get lithiums, at 108V vs 180V, I can drop the weight from 5150 lbs. to below 4000 lbs....current vehicle specs here:
http://tzev.com/files/TeVan_Original_Government_Statistics_Page.pdf

Current battery pack is 200aH at 180 volts and 1685 lbs., and range is (supposedly) about 60 miles. 

I really only need about a 40 mile range (drive about 30 miles max in a day, low rolling coastal hills...steepest grade is about 200 feet in 1/2 mile)...I'm thinking that if I drop to 144VDC or even 108VAC, I could probably get away with a 160aH or even a 100aH pack. That could make the pack as little as 252 lbs (36 cells x 7 lbs/cell for the 100aH) ...a 1400 lb. savings, dropping the car from 5000 lbs. to about 3600.

On the top end, 160aH at 144V (48 cell) x 12 lbs/cell works out to about 580 lbs...still an 1100 lb savings...

Everything is such a trade-off...too many decisions...my head is starting to hurt... |-b

You're right, David...at a glance, the simplest option seems to be to drop the existing motor to 144V, if I don't lose too much in doing so. Is the Kelly controller well built/reliable?

What would *you* do if you were me? All I really want is a freeway-capable (60 mph is ok) reliable daily driver with about a 40-mile range.


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## major (Apr 4, 2008)

Clipper said:


> What would *you* do if you were me? All I really want is a freeway-capable (60 mph is ok) reliable daily driver with about a 40-mile range.


1) Take the motor in for an estimate for the series rewind. Find a couple of motor repair shops in your area. Get a few estimates. Use EASA shops. http://www.easa.com/

2) Get a modern series controller.

3) Get a Lithium battery pack.

That would be my advice for you. Personally I'd probably try to somehow get the SepEx system up and running. But it sounds like your interest lie in having it on-the-road and not a project in the garage 

major


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## MN Driver (Sep 29, 2009)

If the system is SepEx, the motor says Shunt on it? Can you just run the motor as a shunt-wound motor? With shunt the field and armature coils are in parallel. Is it not possible to run it in this way without the SepEx function?


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## major (Apr 4, 2008)

MN Driver said:


> If the system is SepEx, the motor says Shunt on it? Can you just run the motor as a shunt-wound motor? With shunt the field and armature coils are in parallel. Is it not possible to run it in this way without the SepEx function?


Hey MN,

Don't get me started on shunt vs SepEx .....

But with an 180V source and a 3.2Ω field, those coils will smoke real fast  And just applying the proper constant voltage to the field you lose the overexcitation from the SepEx control system, so acceleration will suck and you're likely to burn the comm.

Regards,

major


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## MN Driver (Sep 29, 2009)

Thanks Major. The part that confused me was when I saw that the image that was posted indicated it had a shunt winding rather than with a nameplate indicating SepEx. Is it normal for there to be a discrepancy like that?


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## major (Apr 4, 2008)

MN Driver said:


> Thanks Major. The part that confused me was when I saw that the image that was posted indicated it had a shunt winding rather than with a nameplate indicating SepEx. Is it normal for there to be a discrepancy like that?


Yes ............My reason for this:



major said:


> Don't get me started on shunt vs SepEx .....


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## MN Driver (Sep 29, 2009)

Gotcha major


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## Clipper (Jan 30, 2011)

major said:


> Don't get me started on shunt vs SepEx .....
> 
> But with an 180V source and a 3.2Ω field, those coils will smoke real fast  And just applying the proper constant voltage to the field you lose the overexcitation from the SepEx control system, so acceleration will suck and you're likely to burn the comm.


Actually I read your post on shunt vs. SepEx., post #19 of:
http://www.diyelectriccar.com/forums/showthread.php?p=131407

And from it I concluded that my motor fit your description of a SepEx, despite that the motor label says "winding: shunt." I figured there was no way I could put armature current through the field without smoking it.

I have been tying to find a motor place that will rewind it, and I haven't given up yet, but it's proving difficult.

So in keeping my options open, the questions remain:
What do I lose running a 180VDC motor on 144VDC? 
Torque/Acceleration? Top end speed? Efficiency/range? Does it overheat?

I have already looked into developing a "field saturation curve" (field magnetization curve) for the motor, from which I can derive a field map, right? post #11 here:
http://www.diyelectriccar.com/forum...unning-larger-sepex-out-thereiii-34283p2.html

There is a motor control engineer in our EV group that has offered to help. She has a CitiCar with a 48VDC compound motor in which she used an AllTrax SepEx controller for the armature and field and made her own controller for the interpoles (hope I got that right...??!!) If I can get a field map for my motor, I can probaby use a Soliton for the armature, and adapt a smaller controller for the field, or have her design one.

I read about somebody doing something similar, but performance seems kind of clunky:
http://home.earthlink.net/~evtkw/controller/TechPage.html

I believe I can get the car running again; perhaps I can map the existing controller's function. How would I do that? Measure field volts and amps With an E-meter with a data interface? Don't I need RPM too?

According to the fellow who has been repairing the logic card in my controller, it is in "bad shape" and the controller is "obsolete." He has a spare card, so I can probably get it running long enough to test the field under power.

Thanks for any advice you can give me; it would seem a shame to waste a perfectly good, low mileage EV in otherwise good shape because of a poor controller design. I would consider putting in a new motor *and* controller if I have to; maybe even go to AC. I'm just trying to explore my options. 
--Clipper


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