Recent content by kevin

I have also seen this: I have seen similar profiles on Leaf and BMW i3. I attributed it to cell balancing or possibly running the battery cooling system following a charge. If the battery is being balanced resistive loads are put across the cells that reach the target full charge level and...

I found this chart in the Steven Tarnowsky paper you quoted from about the Spark design. The choice of gearing ratio is a trade off of acceleration, highway range and city range. It looks like in the 2015 (LG) version they aimed for more city range at the expense of acceleration and highway...

"Again, regardless of PWM, the basic Physics remains that the torque is directly related to current." True, on motors of this type the torque is pretty linear with respect to current up to some limit. "In effect, peak power drawn from the battery is at 0 RPM while the motor provides zero power...

"PWM means nothing if the duty cycle has to be practically 100% to deliver the current". I'm afraid you are not understanding some of the basics of the motor controller - it will never get to 100% duty cycle at low speed - the current limit will come into effect with the result that the duty...

The magnets can be harmed both by over-current in the windings or overheating. In short term scenarios the over-current is the important one. The motor may produce 400ft-lbs and that will be multiplied by the final drive (about 3 to 1) to give about 1300 lbs-ft at the wheels. However that is...

I don't have my Spark anymore but I'm skeptical that that there is actually 120kW going into the motor below the base speed, I seem to remember it increasing as speed increases. When I have tried balancing the car on a local extremely steep hill (steep enough so I fall off the back of my bike...

"It is true that instantaneous power at the wheels are 0 HP at 0 MPH, but the motor is sucking 140 HP at 0 MPH." The power at 0mph will only be the losses - it will not be 140HP. The torque(current) will be limited to the 400 lb-ft maximum. As you calculate, this is in the region of 300Amps...

That is completely incorrect. The motor controller will limit the torque to a specific level that is constant up to about 40mph. Since torque is proportional to torque the current will be approximately constant up to 40mph. I expect for the Spark the current is in the 300-500 Amp range. The...

That implies that the contactor is engaged without the ignition on - or the EVSE connected. The cooling system requires the high-voltage to operate the compressor, that in turn requires the contactor to be engaged. It is a potential safety issue in that applying HV to the motor controller...

The range depends a great deal on how you drive it. What was the range when the car was new? Mine declined from ~115 down to 98 over 22,000 miles. The battery reduced in capacity from 19.5kWh down to 16.5kWh. I have a few posts on this forum with the data from my 2014 Spark EV, but not every...

Field weakening is only used beyond the base speed - the motor is in the constant torque regime from 0 RPM up to the base speed. In the constant torque region the current is controlled to be constant by the motor controller - in an efficient motor such as the Spark's the voltage drop across the...

Actually they do reduce it above the base speed which is about 40mph for the Spark EV. This is the speed at which the torque starts reducing and the back-EMF reaches the battery voltage. Normally the motor wouldn't be able to go any faster than this without a higher voltage. However above that...

Hi, Here are a couple of other charts from the same data. As expected the range at full charge decreased from 113miles down to 98 while the efficiency increased slightly from 5.7mi/kWh to almost 5.9mi/kWh. I expect much of that was the tires wearing. I changed the front tires at 18000 miles...

Afraid I didn't get any more data - the lease ended just a few days after the graph. My usage was pretty much the same as yours. I would usually charge at work. That did mean that the battery was often at high SOC from 11AM to about 6PM in the heat of the day as I usually charged in the...

This was the capacity of my 2014 Spark EV over 3 years. It starts off at about 19.6kWh and degrades to about 16kWh at the end. The graph was created from readings off the energy screen after discharges of greater than 50%. I was disappointed at the level of degradation. kevin