85VWCabrioletEV wrote: > I feel lose connection or something is confusing the controller to make it > cut output to motor. Possibly internal to controller also. > <Need to see what the potbox is doing too. Eventually, they lose their > carbon and give erratic readings (but you usually at <least get _some_ > vehicle movement. > > Pot box appeared to be in range with 0 at one extreme and 5.8k at other > end.
I think it is highly likely that your problem is related to the throttle pot and/or its wiring. From the manual: "High Pot Input Lockout circuitry is included to reduce the possibility of the dangerous situation in which the speed control input was set to greater than zero before the enable or contact switch is turned on. The Controller will not switch power to the motor until the speed control has been set to zero Ohms for at least 250 milli-seconds before the enable is set high." "Auburn Scientific motor controllers have an open Pot shutdown feature. This feature will shut the controller off and put it in a 'sleep' state in the event that the Pot circuit is opened, or the Pot resistance exceeds about 6K Ohms. To recover from an 'open Pot' situation, all power must be shut off from the controller, and it must be allowed to completely discharge. At that time the error which caused the condition must be corrected before power is reapplied and normal operation is restored." "Note: In our experience, we have found that a few Pot Boxes labeled 5K Ohms, actually exceed 7K Ohms full scale. Consequently, we recommend as part of the installation process, the pot values be measured at both extremes. The Pot value measurements should yield the following for a good quality Pot Box. 1. A value of 0 (or very close to 0) exists at one extreme 2. A value of 5Kohms (+/-10%) exists at the other extreme" The open Pot 'sleep' state sounds very much like the condition you have experienced at least part of the time, since to restore controller operation you had to remove power and let the controller completely discharge. This also seems likely since you've measured about 5.8K ohms at full scale and the open pot fault will be tripped at around 6K ohms. Given the dubious nature of your meter (unfortunately, Home Depot is not a premier source of electronic test equipment ;^), it is entirely possible that the 5.8K you measure is really closer to 6K (or even more), or that the resistance can jump higher periodically. The controller may only need to see the resistance very briefly exceed "6K" to shutdown. Another common pot box issue is the adjustment of the enable switch referred to in the first paragraph (discussing the high pedal lockout). Although you have confirmed that your pot box goes to zero ohms, you also need to confirm that it does not increase significantly from zero ohms before the enable switch closes. I would suggest [re-]checking the wiring between the controller and potbox to ensure that there are no loose or intermittent connections (e.g. insulated crimp terminals or splices that may not be the correct size for the wire, or that may not be crimped tightly). Then check the mechanical linkage to the potbox; something may have slipped a bit during your initial parking lot circles that is not resulting in the pot not fully returning to zero ohms when released, or getting too near to 6K ohms when pressed fully. Finally, check the enable swtich. Assuming a typical Curtis potbox configuration, the enable signal to the controller will be wired through a micro switch on the pot box that closes as soon as the throttle is pressed slightly. This switch can be adjusted to operate earlier or later, and it may need to be shifted to operate a little sooner or later. The controller needs to see zero ohms before the enable signal is applied, so I would first check to ensure that the enable switch is not closing too early. If your potbox has more than one microswitch, or if the microswitch has both normally-open and normally-closed contacts, ensure that the enable signal is wired through the proper switch so that the controller sees the enable signal when the throttle is depressed rather than when it is released or only when it is wide open. While the Auburn manual doesn't mention it, I know that Curtis controllers want to see the enable signal before the pot resistance is over a few hundred ohms, so it is probably wise to adjust the switch to close after the pot increases from zero ohms, but before it exceeds a few hundred ohms. One last thing to check: where is the enable signal coming from? The Auburn manual states that the enable signal can be anything from 12V to pack voltage, which might result in someone thinking that they can use the vehicle 12V system to provide the enable signal. E.g. use the switched +12V ignition line from the keyswitch and run it through the potbox enable switch to the controller enable input. This will not work (or not reliably), because the vehicle 12V system ground should not be connected to the traction pack. The result may be that the controller enables unreliably. The proper way to wire this is to run the +12V ignition line from the keyswitch through the potbox enable switch to the coil of a relay whose contacts are rated to switch full pack voltage. The contacts of this relay switch full pack voltage to the controller enable input. I would wire this relay to take pack voltage from the controller side of the main contactor. Although the main contactor will not close until the controller is enabled, pack voltage will be present here through the precharge relay (hopefully only when the keyswitch is on, by virtue of a small pack-voltage-rated relay in series with the precharge resistor that is only on when the keyswitch is on...). The wiring diagram in the Auburn manual shows the enable signal being taken from the controller side of the precharge resistor, as I suggest, but also shows a diode between this point and the controller side of the main contactor. Does your installation have this diode fitted? I don't know that the diode is essential, but it will prevent the enable signal from being held on for some time by the charge stored in the controller bus caps after you try to disable the controller. Hope this helps, Roger. _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
