This blog documents the restoration, and conversion, of a 1965 Humber (Singer) Vogue to a fully electric vehicle. The Vogue will be powered by an 11kW(modified), 3 phase industrial AC motor, controlled by an industry standard Variable Speed Drive (VSD) or Inverter. To be able to produce the 400 volts phase to phase the VSD will need about 600 VDC of batteries. A big thanks to the contributors on the AEVA forum:

Tuesday, August 14, 2012

Some notes on the Second drive

The drive on Sunday showed up some minor problems.
  1. There was a "thump" from the driveline when I eased up on the accelerator too fast - even as very slow speeds. This was easy to avoid but it's a bug nevertheless.
  2. Regen braking didn't work at all. Pretty clever for me to muck up something that is hard to prevent.
  3. We only travelled about 5km before I got a battery low alert. Upon returning home, 5 out of the 12 packs were showing a low voltage event (blue LED off).
The thump happens when the accelerator transitions through the point where I am requesting full speed (variable torque), to the point where I am requesting zero speed - at about 10% pedal depression.
I left a 100mS ramp up/ramp down in the speed section of the controller, thinking it did not effect torque control - but it may.
If that doesn't help, the easy fix is to implement a ramp function on the Analog input (a function block in the controller), and limit the ramp down speed to that which doesn't cause the thump - but I'd rather identify and take the correct action. I'll put it up on axle stands and have a fiddle.

Weird. I will connect the laptop and monitor the internal controller signals and trace through while on the axle stands. This is pretty easy to do as the Lenze software lets you tap into any analog or digital code of function block output and display as a dial or digtal readout or both. Up to 8 at once.

Seven packs were at 52.5V and 5 (with LEDs off) were below 51 V. After a full charge, I pulled the lowest voltage one (as measured after the fault event) from the car and have so far put 12AH into one of the 20AH cell pairs. There were 4 cells pairs under 3.25V - the rest were 3.6V or higher - keep in mind this pack just got fully charged!
They are obviously way out of balance. To use an Americanism - "my bad". I thought since all chargers had cut out and all packs were at 58V they were balanced - not at all! The remaining 11 packs are on charge for the 4 days it will take for 180mA to charge all cells. It took me a whole night just to charge one cell pair in one pack so that's not reasonable to do for the 5 packs. I will change the the pack I have out to the same "trickle" or CV charge and monitor it closely to ensure I'm kind of OK. I don't like doing this but it's untenable to pull every pack.


Tim said...

Johny, could the thump just be mechanical? Backlash in the driveshaft caused by using smaller bolts, maybe? Hopefully its just something very minor.

Johny said...

I wish Tim. No, it quite definitely is an attack of torque at the wrong time. The relationship between torque demand and speed demand (flat out or zero) happens at exactly that accelerator position. I'm pretty sure it's minor, I just have to ensure that the torque demand doesn't go back up until the controller has finished making speed demand zero. It's all to do with regen braking based on the first 10% of accelerator movement.