[monkmonkey]

Originally Posted by major

Do you mean this?

Yes. Thats the part thats going on/off. I believe its the cause of the problem.

[major]

Originally Posted by monkmonkey

Yes. Thats the part thats going on/off. I believe its the cause of the problem.

That is not an F/R (Forward/Reverse) contactor set, it appears to be the main contactor. And yes, if it is going off and on, you have a big problem. I recommend you not drive it on the street until you get it fixed. You can start by answering some of the questions I've been asking. What supplies the coil voltage for the contactor?

[monkmonkey]

Here is a scan of the blueprint here...

http://s848.photobucket.com/albums/a...3Deleopard.jpg

[PStechPaul]

I'm not sure I understand this sketch:



It looks like there are two battery packs wired in series. The upper pack is charged by the LiIon charger, while the negative of the lower pack is connected to the controller (-) terminal. The top (+) of the pack goes through a fuse and the contactor (with precharge) to the controller (B+) and one terminal of the motor (Field?). There are two motor terminals connected together (Armature and Field?) to the controller (A) terminal. And the other motor terminal (Armature?) connects through another fuse to the controller (M-) terminal. So I'm assuming that the controller M- uses PWM to adjust current through the series wound motor and it shunts some current from B+ to A for field weakening?

But what really confuses me is the ON/OFF switch which connects the midpoint of the battery packs to ground. This won't do anything unless something else is connected to ground. I'll make a WAG and say that the coil of the contactor (which is not shown) connects from the lower battery pack (-) to ground, and the switch completes the circuit. If these grounds are the car chassis, rather than a separate wire, then the connection may be intermittent. AFAIK most EVs do not like to have anything grounded. But if the bottom battery pack is actually the 12VDC accessory circuit the its (-) terminal should be connected to the chassis so the lights and fans and other things will work as usual, although I think most modern cars do not rely on the chassis for current return.

I had to redraw the schematic. It looks like a bucket of worms!

[major]

Originally Posted by PStechPaul

I'm not sure I understand this sketch:



It looks like there are two battery packs wired in series. The upper pack is charged by the LiIon charger, while the negative of the lower pack is connected to the controller (-) terminal. The top (+) of the pack goes through a fuse and the contactor (with precharge) to the controller (B+) and one terminal of the motor (Field?). There are two motor terminals connected together (Armature and Field?) to the controller (A) terminal. And the other motor terminal (Armature?) connects through another fuse to the controller (M-) terminal. So I'm assuming that the controller M- uses PWM to adjust current through the series wound motor and it shunts some current from B+ to A for field weakening?

Look back at his photos http://www.diyelectriccar.com/forums...ad.php?t=75379 And check the standard wiring diagram for a Curtis. http://www.kta-ev.com/v/vspfiles/ass...t%20manual.pdf page 9.

He has no LiIon charger. It is an Elcon, which is typically a higher voltage "pack" charger but the diagram shows it connected across a single 6 volt battery. Clearly a big mistake.

His symptoms of contactor chatter lead me to believe he has no idea what's going on and may not have his 12V aux battery charged (if he even has one). Then there is the switch grounding the pack at 72V Some yellow wire running from mid pack to somewhere

I don't know where monk got this mess, or why, but like I said in his previous thread, it is a hazard if driven on the public street. He needs to rewire the thing properly. And likely replace some of the parts. I wouldn't trust that contactor from the looks of it.

[monkmonkey]

Where would a reference be so I can correct all mistakes?

[major]

Originally Posted by monkmonkey

Where would a reference be so I can correct all mistakes?

A lot can be found on this forum. I also suggest books. Build Your Own Electric Vehicle by Bob Brant is a good one.

Do you have a 12V auxiliary battery on the car? What is the measured voltage of it?

[monkmonkey]

Originally Posted by major

A lot can be found on this forum. I also suggest books. Build Your Own Electric Vehicle by Bob Brant is a good one.

Do you have a 12V auxiliary battery on the car? What is the measured voltage of it?

No. Aux comes from total voltage. Same as my citicar. Works fine on citicar.

[PStechPaul]

I've pretty much given up trying to help. In a case like this I think the OP needs to enlist the services of a professional to just rip out everything and redo it according to the manual. So I'm just continuing this out of curiosity and as a learning experience about this sort of EV using series wound traction motors.

From the previous post, it appears that one terminal of the contactor coil is connected to the chassis, and the other goes to one of the main battery terminals:


So it's anybody's guess as to the voltage being applied to the coil and how much voltage drop and intermittent connectivity may be present. At this point I might put down my magnifying glass and prepare my pipe and say, "Elementary, my dear Watson". A couple minutes of testing with a multimeter in the hands of a skilled technician should determine the cause absolutely. And even a skilled mechanic might be able to just clean up the connections and the vehicle may work as well as it did originally.

[mk4gti]

Not very familiar with that motor, is A2 on the curtis supposed to be connected that way ? I left that connection open on my 1221b