Maximum regen rate?

3118 Views 15 Replies 12 Participants Last post by wordptom, May 4, 2017

homesteadelectric

Discussion Starter · May 2, 2017

Anyone know what the max regeneration rate on a Gen 1 is? I see up to -40 on the kw meter but is all of that being absorbed by the battery or at some point is just dissipated?

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wordptom

· #8 · May 3, 2017

telveer said:
The max I ever observed on my Gen 1 2013 Volt was 59kW, while braking from 55mph. Theoretically, it should not be higher than 55kW (which is what MGA/generator is rated)

My understanding is MGA is the smaller motor, which is clutched to the engine in Range Extended mode to generate electricity "on the fly" as fuel for MGB, the primary traction motor.

Braking regeneration is created by MGB using the car’s momentum when this motor is not providing propulsion torque to the wheels (e.g., when coasting in D or L, slowing down, or being pulled downhill by gravity).

When comparing recharging rate potential, note that Mountain Mode is capable of using MGA to recharge a fully depleted 2012 Volt battery to the 45% MM-maintained level (~4 kWh) in 15 minutes, using 0.36 gallons of gas (see the Self Charging Volt youtube video).

I would think max regen rates are not normally sustained for 15 minutes or more.

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wordptom

· #16 · May 4, 2017

canehdian said:
If you are driving in single motor mode, you will see maximum 55kW regen from the single large motor (half the max output)
If you were in dual motor mode, you might see up to 60kW regen as both motors work together. This isn't as common as the system usually declutches fairly quickly. Typically 55kW is max.

Thanks for this comment. It slipped my mind that when in two-motor mode, both motors are coupled to the drivetrain, and the car’s momentum could therefore use both to create braking regeneration. I would imagine the engineering would be remarkably complex. Surely it’s more efficient to use only a single powerful motor/generator to create regeneration, but that would require unclutching MGA from the powertrain in ev mode and from the engine and powertrain in power split mode. That process would introduce its own inefficiencies. And since regen often exists only for brief periods of time, subsequent demands for propulsion torque would require clutching the motor back into the drivetrain if the car’s speed and torque demands remained within the two-motor configuration parameters... whew!

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