Design service life of motor and battery

[PackardV8]

A gearhead friend asked if there was any testing as to the expected service life of the motor and battery.

Like all batteries, the amount of energy that the high voltage “propulsion” battery can store will decrease with time and miles driven. Depending on use, the battery may degrade as little as 10% to as much as 40% of capacity over the warranty period. If there are questions pertaining to battery capacity, a dealer service technician could determine if the vehicle is within parameters.”

d

Does anyone have info on motor service life? Does anyone have a cost for motor and/or battery replacement? I'd expect to be buying a self-driving Bolt in eight years, but the question was asked, so what do we know?

jack vines

 

[Pigwich]

God knows about a battery, and everybody's got an opinion about that, so I'll let people squabble amongst themselves on that question...

But since I love to speculate, I'm going to speculate that the motor is going to last WAAAAY longer than a comparable internal combustion engine, with the following reasons being the chief contributors to longer service life:

Ball bearings! A piston engine uses bushings, more or less, because of the abuse they must withstand. They last an awfully long time, but I think balls last longer where they can be used.

The bearings don't experience loads from pistons and connecting rods. They also don't experience the shock and vibration that's accompanied with firing cylinders.

Lower operating temperatures! Everything is happier when it's cooler.

Not operating against a pressure gradient - Not that a crank case ought to have much pressure or vacuum in the first place, but it's there.

Better lube - No weird gunky particles, varnishes, and corrosive chemicals resulting from combustion or degradation of the grease

Permanently sealed and permanently lubricated. The odds of the bearing losing lubrication is quite low. It's not as if the lube could ever blow by the pistons and end up leaving the bearings dry.

I like to cite computer hard drives. They spin at 5400 RPM for a decade. Some do anyway

What's a car engine go for before it starts rattling to pieces? 6000 hours in the absolute best cases?

I wish I had a quantitative answer, but I'm going to bet that motor life will exceed probably every other part in the car by a long shot, insofar as that I just wouldn't even worry about it.

 

[SeanNelson]

I like to cite computer hard drives. They spin at 5400 RPM for a decade. Some do anyway

When 15,000rpm hard drives were introduced I remember somebody arguing that the bearings could never be made to operate reliably at that speed for any reasonable length of time. He was silenced when somebody pointed out that the rotating mirrors in supermarket barcode scanners spin at over 20,000rpm and had been in use for over a decade.

 

[oilerlord]

Does anyone have info on motor service life? Does anyone have a cost for motor and/or battery replacement? I'd expect to be buying a self-driving Bolt in eight years, but the question was asked, so what do we know?

jack vines

The current list price of a Bolt EV HV battery pack is $15,734.29 and the part number is 24285978. I've read that the design of the battery is such that individual modules can possibly be replaced for less should a diagnostic point to a bad module (or modules).

Everyone will speculate how long the main battery will last, but the fact is: Nobody knows. It's too soon. Essentially, GM has provided an unlikely worst-case scenario - that that battery could lose up to 40% of it's original capacity before 8 years / 100,000 miles. In doing so, they have pretty much avoided having to replace them under warranty. It's highly unlikely your battery will degrade more than that during the warranty period.

The design of the motor is about the same as the one in a household motor that runs a furnace fan. They last a long time. Our house was built in 2001, and our furnace fan pretty much runs all the time - either to push heated air in the winter, or cool air in the summer. It lasted 15 years.

The main parts are rotor, stator, bearings, and copper winding. Here is a cutaway diagram of the Bolt's main drive unit:

(the motor is located in the middle where you see copper)

What do we know? The motor will easily outlast the battery.

 

[SeanNelson]

The design of the motor is about the same as the one in a household motor that runs a furnace fan. They last a long time. Our house was built in 2001, and our furnace fan pretty much runs all the time - either to push heated air in the winter, or cool air in the summer. It lasted 15 years.

I bought my house in 1978 and as far as I know the furnace was the original one installed when the house was built in 1949. The motor is still going strong after close to 70 years.

 

[PackardV8]

Agreed; a properly designed electric motor will outlive those who designed and installed it.

jack vines