# Sepex, almost...



## major (Apr 4, 2008)

green caveman said:


> According to the programmer attached to the controller, the field current was ~30A BUT the motor current was reporting 350A, which I find unlikely, and the voltage is being reported as 44V, so maybe a controller issue in play and all the numbers are wrong.
> 
> However, if we run the motor forwards, the car is now in reverse but going forwards. It seemed to run fine for the short distance we ran it. (Maybe a little slow, but we didn't run it far or fast because I'm not sure this is good for the tranny to be running backwards).
> 
> ...


To reverse motor rotation, switch either the armature or field polarity, not both. I think this GE motor was from a forklift so would likely be neutral timed, that is the same either rotation.

And 30A field current for 350A armature could be the source of poor torque. I looked at the ad for the controller and didn't see where it had provisions for field map programming. I'd get higher field current for high armature currents.


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## green caveman (Oct 2, 2009)

major said:


> To reverse motor rotation, switch either the armature or field polarity, not both. I think this GE motor was from a forklift so would likely be neutral timed, that is the same either rotation.
> 
> And 30A field current for 350A armature could be the source of poor torque. I looked at the ad for the controller and didn't see where it had provisions for field map programming. I'd get higher field current for high armature currents.


I've been looking for the manual, and have asked Chennic again. There seems to be a large number of parameters, including (IIRC) "Field Map" field with a value of 120A. No idea what this means or what the limits are.

If I can't find the manual, I'll go through the other parameters and see if any ring a bell with you or anyone else. There are acceleration percentages, and similar as well as a number of regen related values. (It's too dark to get the values now, plus it's taken the whole day to finishing wiring all this up!).

I haven't looked at the spreadsheet that was developed for that motor, but my recollection is that 50A represented the knee in the curve. I'm not trying to build a hotrod, but would it be reasonable to expect that much loss of torque (non-linear?).


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## green caveman (Oct 2, 2009)

I think I lost a post, but if this is a dup, please let me know.

With the field parameter set to the maximum the controller permits (40A) there's enough power to move the vehicle. The controller is still reading a battery voltage of 44V, no word from Chennic yet on why. 

I've ordered a 50A shunt since I'd be very surprised if the field is getting 40A (and the armature 350A) with so little power. The 35kW would have to go somewhere and it's not into motive power and nothing seems to be getting hot. Our guess is that the power is correct if the voltage were 44V, so scale by 44/110 = 0.4 and you have 16A of field and 140A in the armature - just a guess.


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## green caveman (Oct 2, 2009)

We took the cover off the brushes on the motor last night to watch for sparks. The motor is 36/48V and we're running it at (we hope) nominal 105V (Li).

Running in neutral, or just slowly backwards and forwards we saw no arcing, sparking, whatever, at all.

Is there anything more we should do to make sure that this motor is going to work for us before (possibly) replacing the controller?

The big Sepex has been the risk all along since we have to run it at 2x rated voltage without advance. So far, it seems good. Going downhill you can feel the effect of regen. Since it's hilly here, the purpose of regen is mostly to save the brakes, but any bonus range is fine.


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## onegreenev (May 18, 2012)

Running your motor at 96 volts neutral should be NO problem. I have a 9" GE and have run that with no problem at 96 volts and 700 amps. GE motors are very good motors and very stout and well built. I recommend them if you can find them. SepEx or Series. Mine are series GE motors. I have two.


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## onegreenev (May 18, 2012)

Yes my GE 9" is neutral timed.


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## green caveman (Oct 2, 2009)

onegreenev said:


> Yes my GE 9" is neutral timed.


Good to know. I don't know enough about motors to understand what parameters allow them to run at high voltage with neutral timing, but have heard reports of people running neutral forklift motors to 120V without a problem (that's partly what lead me to think the SepEx should work).

We hadn't really looking inside the motor since the shop reassembled it. But with a renewed armature, new brushes and cleaning (steam?), it looks really nice in there. Who knew that the field coils were red and not black!


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## onegreenev (May 18, 2012)

Color of the field windings are a result of the lacquer used to coat the whole thing. I think the neutral timing should still be OK at 120 volts. Beyond that they should be advanced a bit. I have a Kostov that is slightly advanced but these have interpoles which help so you don't really need to advance much at higher voltages. So far at 120 volts the Kostov is working fine. I will be bumping it to 156 here shortly and doing a video run.


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## green caveman (Oct 2, 2009)

onegreenev said:


> Color of the field windings are a result of the lacquer used to coat the whole thing.


Well, hopefully, the brush dust from driving will turn them black again before too much longer!


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## onegreenev (May 18, 2012)

You talking field coils or commutator bars? If your talking about the bars then they are copper and will turn black as your brushes break in. If your talking about the actual field windings then they will remain red unless they get nasty dirty. 

Im kinda thinking your talking about the commutator. Take some photos of the items your mentioning and post them.


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## green caveman (Oct 2, 2009)

OK, things are moving, but badly. Anyone have suggested cures for the symptoms or ideas of what might be causing the problems, feel free to chime in. Any help much appreciated. I think we're almost there, but at the minute it's not pleasant to drive.

*Quick Specs*

11" GE Sepex motor. Optimal max field current 50A. Rewound with new bearings and brushes. Suzuki Sidekick 4WD manual with clutch/flywheel in place. 105V nominal - 33 Thunderskys.

*Jerky Driving*

The car moves, but tends move jerkily. This is true at any speed, but more common at low speeds. It's about the same effect as an ICE that about to stall. This tends to be on acceleration typically after gear changes.

*Serious Jolts*

At more or less random times, the car just jolts. It feels to be a braking effect and not just a loss of power. I could imagine I would get this effect if something jambed and then freed, if regen cut in while driving, etc. You're driving forward, get a sudden, half second brake, then power again. This doesn't seem to be speed related, although it does seem to happen mostly in 3rd gear (I don't think exclusively, but maybe).

*Things we know. *

The car does 40mph (the most we've tried) without significant vibration, so the coupler is probably fairly true and there doesn't seem to be anything that's a permanent bind.

The transmission and transfer case, front/rear diff, etc. have 222K miles on them. However, when it was (just about) running as a gas car I don't remember there being a problem with the drive chain - but it's been sitting around for a while since then. The clutch is new.

Possible problem is the taper-lock that's attaching the flywheel to the motor shaft. Last time we had the car running, this came loose, we've ground the shaft down a little an put on a slightly smaller bushing (1610 - 1 9/16). That could have come loose, but the symptoms didn't seem to change of the couple of miles we drove it. So the jolting effect could be a loss of power as the taper-lock slips and the picks up again. Feels more like a positive breaking action than just a total loss of power, but that might be hard to judge.
*
Underperforming Controller*

I think that we're clear the controller is under powered (no word from Chennic). Nominal 120V 400A controller, but the max available field is 40A and the controller always says 44V even though the pack is at 110V, so I doubt we're getting much power.

I'm willing to buy a new controller, either the Kelly HSE line or an Elektrosistem. I'm fairly convinced this would solve the jerky startup, but would like opinions on whether there might be a more terminal problem lurking in the jolting before I spend the cash.


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## green caveman (Oct 2, 2009)

Put the 75mv, 50A shunt on the field and watched with a DVM in the cab.

When the car is driving normally the max voltage is ~50mv (33A), (not the programmed 40A). It often seems to be running with less than that, say ~35mv, 23A. I think this is normal for sepex control, but I assume this would explain the low power, since the field saturation is 50A.

When we felt the jolt in the car (we've only done this once so far with the shunt/DVM in place - I don't like to test too often unless I know I'm not doing appreciable damage), the field went up to ~100mv ~70A momentarily. It's hard to see if this is positive or negative, but I think it was positive.

So, is this a cause or effect? Would a mechanical binding cause a rise in the field current, or could a rise in the field current be a symptom of the problem (I don't have an armature shunt in place).

Should I drive round again and see if it's really -100mv? Which I assume would indicate that the controller had reversed the motor.

I'm sure the controller needs replacing, but will that solve this problem, or will I still be chasing it? If it's not the controller, it would be good to render the car drivable while we make controller decisions, wait for delivery, etc. (except for this it is drivable, but horribly under powered).


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## major (Apr 4, 2008)

green caveman said:


> Put the 75mv, 50A shunt on the field and watched with a DVM in the cab.
> 
> When the car is driving normally the max voltage is ~50mv (33A), (not the programmed 40A). It often seems to be running with less than that, say ~35mv, 23A. I think this is normal for sepex control, but I assume this would explain the low power, since the field saturation is 50A.
> 
> ...


Assuming the armature voltage remains the same, an increase in field current increases the flux, increases the generated voltage (that is Eg or BEMF) which reverses armature current and therefore reverses torque which is regenerative braking. In the vehicle, the physical feeling of this would be the same as stomping on the brake pedal.



> Would a mechanical binding cause a rise in the field current, or could a rise in the field current be a symptom of the problem (I don't have an armature shunt in place).


Good point. A mechanical load increase would cause an increase in armature current which could cause the controller to increase field current to produce more motor torque to overcome it. You need an ammeter on the armature or on the battery.


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## green caveman (Oct 2, 2009)

major said:


> Good point. A mechanical load increase would cause an increase in armature current which could cause the controller to increase field current to produce more motor torque to overcome it. You need an ammeter on the armature or on the battery.


Added the shunt (busy weeks, sorry for not getting back to this sooner).

I can't watch two meters, but the ammeter on the field was around the 30A mark when driving.

800A 50mv shunt on the armature.

Accelerate 15mv 240A

Normal driving 5-10mv ~100A or so

Regen -5mv 80A (that's a negative 5mv)

All is good.

Sudden jolt. Negative numbers on the meter (-23mv??? about 400A??).

Is there any other possible explanation other than a controller malfunction?

We're going to try with regen disabled.


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## major (Apr 4, 2008)

green caveman said:


> Sudden jolt. Negative numbers on the meter (-23mv??? about 400A??).
> 
> Is there any other possible explanation other than a controller malfunction?


The way I read it....That is -400A. Or big time negative torque, meaning regen. This would require a spike in the field current. Can you confirm?

Sounds like a controller malfunction to me.


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## green caveman (Oct 2, 2009)

major said:


> The way I read it....That is -400A. Or big time negative torque, meaning regen. This would require a spike in the field current. Can you confirm?
> 
> Sounds like a controller malfunction to me.


So the first observation (a couple of posts back) was a spike in the field current. Now we see negative, regen, spike in the armature current. 

Separate observations because it's hard to watch two meters on an event that is unpredictable and lasts about a half second. Seems reasonable to assume that if they happen separately, they happen together.

This is out of my area of expertise, but I wonder if, with the help of smart people on the list, this is fixable. We have three symptoms:

1) Field current spike = regen jolt. I'm assuming that a field current spike would cause the regen.
2) The controller has this other "feature" where the armature current jumps around between ~5-12mv when you're accelerating (or change torque after a gear change). You get about the effect of a gas car hesitating on a cold day/start, then it "picks up" and you go, but it's 5-10 seconds and it's pretty frequent. I was watching the armature current, is it possible that the root cause is the field?
3) Occasionally, the controller will fault with a "field short" beep-code.

All seem to suggest a problem with the field control electronics (could be software, but I doubt you could mess up software *that* badly and not catch it in testing).

These are all occur in short, gentle driving (no heating, no high speed, etc.)

I have heard nothing from Chennic and am starting the think that I have nothing to loose by taking the controller apart and posting photos. (Probably nothing to gain either, but sometimes you have to get lucky).


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## major (Apr 4, 2008)

Hi green,

I forgot about your field spike observation; should have reviewed  



green caveman said:


> 1) Field current spike = regen jolt. I'm assuming that a field current spike would cause the regen.


I'm sure it would.



green caveman said:


> 2) The controller has this other "feature" where the armature current jumps around between ~5-12mv when you're accelerating (or change torque after a gear change). You get about the effect of a gas car hesitating on a cold day/start, then it "picks up" and you go, but it's 5-10 seconds and it's pretty frequent. I was watching the armature current, is it possible that the root cause is the field?


Certainly is possible that it is due to the field. A change in the armature PWM could also do this.



green caveman said:


> 3) Occasionally, the controller will fault with a "field short" beep-code.


It sounds like a bad field controller one way or the other, software or hardware. 

major


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## green caveman (Oct 2, 2009)

We'll pull the controller and, if it's not potted or similar (quite probably), post photos to a new thread. I'm sure some people will be interested in seeing them.


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