curtis slow down

AC, DC, amps, volts and kilowatt. It's all discussed in here
Post Reply
User avatar
Posts: 9
Joined: Sat, 20 Dec 2008, 22:57

curtis slow down

Post by peterb »

Hi fellow EVers

Driving home last thursday there was a shudder in the drive but car continued and i stopped at the next ligt, i went to move but no power back to first gear and still only enough to move off, still had 145 volts showing in the pack but volts would only go down to 130 volts. pulled over check for over temp controller not overly hot, heat sink and fan working, motor revs with no load?

Checked pot box resistance as per curtis manual andy suggestions or can any help diagnose.

Thanks in advance

User avatar
Senior Member
Posts: 3603
Joined: Thu, 26 Apr 2007, 03:30
Real Name: Tuarn
Location: Perth,Australia

curtis slow down

Post by acmotor »

Just some thoughts... I have no experience with this fault. Hoops might have some ideas or check the US forums.

Sounds like a curtis internal fault although part power would not be common ?
The FET outputs either fail open/short or just do what they are told by the drive circuit.
The FETs must (all) be switching or they would let their smoke out if only some of the bank had failed or the gate drive was not turning them on correctly.
This makes me think that there is some limit being applied by the control circuit.
Either the accel demand signal is not correct or being correctly handled internally or the curtis thinks it is in current limit. Perhaps a current sense fault internally ?

Then again, you should look for the obvious. Check motor brushes and condition of commutator. The curtis may be supplying full voltage to the motor but its resistance has gone high and itself is not drawing current.
The same goes with all terminals, contactors and fuses. These would get hot if not passing full current of course.

Some time with a voltmeter, starting at the motor terminals might help.

Check the obvious first.

If you find the problem, do tell !
iMiEV MY12     110,230km in pure Electric and loving it !

User avatar
Senior Member
Posts: 3729
Joined: Mon, 23 Jun 2008, 16:26
Real Name: John Wright
Location: Melbourne

curtis slow down

Post by Johny »

Was the "shudder" something you have experienced before?

Post Reply