Dcx400 pds and excessive heat

kgsc

Okay folks have a pds cart with a dcx400 and recently rebuilt motor. Previous motor was doing the same but assumed motor. Voltage is dropping to like 30 volts under light load and cables are getting hot. No error lights on the controller. Ideas?

BGW

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JohnnieB

Check the F1/F2 cables for worn through insulation.

If they are okay, check the voltage between them at the controller. (Or put an ammeter in series with one of them)

The stock PDS controller is supposed to put 2.7v +/- 0.5V between F1 and F2 when wide open with wheels off ground, so the DCX ought to be in that neighborhood. Don't have any specs for low speed, but the voltage should be higher.

AS for amps, I'm guessing, but with wheels on ground it ought start out at about 20A to 30A and decrease to no less than about 3A at max speed.

If you're getting low field amps at low RPM, the sepex motor is going to draw a ton of amps and get mighty hot mighty fast.

I suspect there is a field weakening (Field Mapping) issue. Alltrax ought to be able to give you a better idea what the field volts and amps ought to be.

kgsc

Log file I got. Saw over 100 volts dc on f1 f2 and pulling a bunch with the wheels in the air and just pushing the pedal. . Motor was shaking the cart. Bad newly rebuilt motor or controller ...

TimeStamp,ThrottlePos,DiodeTemp,BatteryVoltage,Out putCurrent,BatteryCurrent,ErrorFlags
12/31/04 23:04:22.182 0,,,0.0,0.0,0x00
12/31/04 23:04:23.180 0,,,0.0,0.0,0x00
12/31/04 23:04:24.194 0,,,0.0,0.0,0x00
12/31/04 23:04:25.208 0,,,0.0,0.0,0x00
12/31/04 23:04:26.222 0,,,0.0,0.0,0x00
12/31/04 23:04:27.236 0,,,0.0,0.0,0x00
12/31/04 23:04:28.250 0,,,0.0,0.0,0x00
12/31/04 23:04:29.264 0,,,0.0,0.0,0x00
12/31/04 23:04:30.278 0,,,0.0,0.0,0x00
12/31/04 23:04:31.292 0,,,0.0,0.0,0x00
12/31/04 23:04:32.306 0,,,0.0,0.0,0x00
12/31/04 23:04:33.320 0,,,0.0,0.0,0x00
12/31/04 23:04:34.334 28,,,163.0,46.0,0x00
12/31/04 23:04:35.348 29,,,187.0,54.3,0x00
12/31/04 23:04:36.362 47,,,278.0,130.8,0x00
12/31/04 23:04:37.376 63,,,220.0,138.0,0x00
12/31/04 23:04:38.390 65,,,374.0,242.0,0x00
12/31/04 23:04:39.404 71,,,384.0,271.1,0x00
12/31/04 23:04:40.418 81,,,316.0,256.5,0x00
12/31/04 23:04:41.432 0,,,0.0,0.0,0x00
12/31/04 23:04:42.446 0,,,0.0,0.0,0x00
12/31/04 23:04:43.460 0,,,0.0,0.0,0x00
12/31/04 23:04:44.474 0,,,0.0,0.0,0x00
12/31/04 23:04:45.488 0,,,0.0,0.0,0x00
12/31/04 23:04:46.502 0,,,0.0,0.0,0x00
12/31/04 23:04:47.516 0,,,0.0,0.0,0x00
12/31/04 23:04:48.530 0,,,0.0,0.0,0x00
12/31/04 23:04:49.544 0,,,0.0,0.0,0x00
12/31/04 23:04:50.558 0,,,0.0,0.0,0x00
12/31/04 23:04:51.572 0,,,0.0,0.0,0x00
12/31/04 23:04:52.586 0,,,0.0,0.0,0x00
12/31/04 23:04:53.600 0,,,0.0,0.0,0x00


92206 fm 4

JohnnieB

Battery Voltage and controller temperature are missing.
Also, sampling interval is set to 1 second.

Go to monitor screen in Controller Pro and check all boxes, and select Continuous sampling rate.

Save as a .csv file, zip and attache .zip file to post.

I had to cut and pasted from your post into notepad and play with it some to get into a spreadsheet.


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However, I'm pretty sure the controller's output to the field windings is screwed up someway or other.

First, disconnect the F1 & F2 from controller and verify there is only about 1Ω or 2Ω measured from the F1 cable end to the F2 cable end through the motor's field windings. (Might be a bit over 2Ω since that is the spec at the motor terminals and the way we're doing it has got several feet of 10Ga wire in the loop.)

If that is good, do a diode check on the DCX controller, per the attached Alltrax Technical Note #6.

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FWIW, if the motor's field windings are connected to the controller and the field MOSFETs in the controller are good, I don't see how it is possible to measure 100V between F1 & F2.

Attached Files

Doc120-042-C_TN006-Diode-Checking-DCX-Controllers.pdf (224.2 KB, 0 views)

kgsc

Thanks JB, I will do everything above when I can get back on it. Hopefully Thursday night. Using the older version of the software because I couldn't get it to connect with the new version on a DCX400. Bat voltages were dropping to like 35 and temp was 34C/93F. I didn't want to hold the throttle too long as everything is getting hot quickly. Already have a burning smell and thinking the just rebuilt motor we put in there a couple of weeks ago is now also toast.. I have a new XCT400 in hand also that might get thrown in there after doing the above tests plus test the motor by wiring it directly after checking for shorts first.

And all this said, if a diode is bad I wonder if that would cause the screwy field voltages..

I will report what I find if I haven't burnt it down :)

JohnnieB

The diode tests don't actually test diodes, it is just that the circuitry between the test points give diode-like readings.

I suspect the field MOSFETs are bad, or their drivers are bad and whatever it is, it is placing a high resistance in the field loop.

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I wouldn't take any more chances of burning out the motor and put the XCT in. It has short circuit protection on the armature and field outputs, but I would definitely check the motor & cables for wanted and unwanted continuity.

Also, the data logging from the XCT is far more comprehensive. Forty something columns for the XCT and a half dozen or so for the DCX.

kgsc

The annoying part is when we put the replacement motor in a few weeks ago it ran fine.. Can't win sometimes I guess. All this just trying to help someone out..

JohnnieB

Hopefully, the speed sensor is still laying around someplace, the XCT-PDS is a dog without the speed sensor installed.

kgsc

If it hasn't cooked it it is still installed in the end cap to keep dust and dirt out.

This cart is one of my very first builds so I know it fairly well. It had made it 15 years or so without troubles so not too bad but when it went it went big.

kgsc

Update. Did diode check and passed. F1-F2 resistance good and none to ground. A1-A2 resistance good but shorted to the case. Pulled motor and crunchy stuff fell out. I would say it’s toasted. Going to call PQ tomorrow and see what he has. May pull controller also because I bet he could test it. Oh well I needed more crap broken in my life.