why do we call the car generator "alternator" but not building one?

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K8MHZ

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Michigan. It's a beautiful peninsula, I've looked
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Hm, this reminds me an old question I wondered about since I was a kid. Why do we have separate starter and alternator? A motor is basically nothing else but the abverse of a generator?

At one time we didn't. Vehicles came with starter/generators back in the days of old.

I worked on a Harley golf cart that had one and the owner was totally baffled because he spent hours looking for the generator and couldn't find it.

;)

The reason the auto industry stopped the practice is now irrelevant as alternators can't be used as starters like generators could.
 

K8MHZ

Senior Member
Location
Michigan. It's a beautiful peninsula, I've looked
Occupation
Electrician
Just for anecdotal purposes.....

When I had my shop I had a customer with a 1968 Buick that wouldn't charge the battery. He drove it to the shop. It started fine, but would only start a few times before the battery was drained.

To make a long story short, the customer had left the lights on one night and ran the battery dead. He connected the charger backwards and charged the battery backwards. It started the car! The starter turned the correct way even though the polarity of the battery was reversed. Since it had points, the ignition system worked fine.

I didn't even know a car battery could be charged up backwards until then.
 

gar

Senior Member
Location
Ann Arbor, Michigan
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EE
110427-1656 EDT

weressl:

It is a practical design problem. Quite different design criteria. See the story of Charles Kettering and the electrified cash register, and then when he applied the same principle to the automotive starter. High torque, high power, short time, low speed, compared to steady power over a long time, lower power level, and high speed. Grossly different gear ratios (mechanical advantage) are required

Today with electrified vehicles the generator also can be the starter.

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gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
110427-2034 EDT

K8MHZ:

I don't know that I can provide a link. This is something that has been mentioned in some of the conferences that I have attended.

Obviously no need in a pure EV.

In a hybrid the philosophy is that if the engine and electric motor-generator can be mechanically coupled, then there is plenty of torque from the motor-generator to start the engine thru a direct drive.

I did a little Internet search and found these:

A nice article but does not directly address the issue here:
http://www.hybridcenter.org/hybrid-center-how-hybrid-cars-work-under-the-hood.html

The reference partially answers your question without much detail:
http://silverthorninst.org/Automotive and transport/AutoTrends2.htm

At a recent conference at Macomb Community College various teachers said that all of their graduates from the hybrid courses had no trouble finding jobs.

Next week's Spark meeting is on Michigan offshore wind farms. Spark is local group that was started in part by Rick Snyder a number of years ago to stimulate innovation, and to get innovators together.

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roanokejim

New member
I think because it is the way it is called. And the car generator will surely work as an alternative cars for every user. :D
 

Besoeker

Senior Member
Location
UK
Hm, this reminds me an old question I wondered about since I was a kid. Why do we have separate starter and alternator? A motor is basically nothing else but the abverse of a generator?
Different requirements and different characteristics.
Even when they were both DC machines.
The starter motor is a series would machine to get high torque to crank the engine.
The generator shunt wound.
 

G0049

Senior Member
Location
Ludington, MI
Hm, this reminds me an old question I wondered about since I was a kid. Why do we have separate starter and alternator? A motor is basically nothing else but the abverse of a generator?

Those of us who Uncle Sam graciously trained to work on Huey helicopters back in the 60's, know that they had a "starter/standby generator." It was a dual purpose device controlled by a switch on the overhead panel. Even if the switch was in the standby generator mode, it only kicked in when the voltage regulators detected that the system voltage had dropped below a preset level.
 

Besoeker

Senior Member
Location
UK
110427-1656 EDT
Today with electrified vehicles the generator also can be the starter.
Not really the starter as such though in the sense it isn't engaging with the starter ring gear on the flywheel of a reciprocating IC engine and cranking it into life.

In the EV, the motor is used to propel the vehicle in normal operation. That's not something a starter motor would really be capable of doing. The EV motor can (and does) operate as a generator to recover KE during deceleration that would otherwise be lost as heat dissipated in the brakes and pumping losses in a reciprocating engine.

This would work with either DC machines or AC machines but I think mostly permanent magnet brushless DC machines are used these days. Not sure I agree with that terminology.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
110428-1136 EDT

Besoeker:

When I said electrified vehicle that did not mean a purely electric vehicle. Obviously no need for a starter motor in a pure EV.

If you already have a high power electric motor-generator in an electrified vehicle, and the design of that vehicle is such that motor can be used to start the engine, then it makes sense to eliminate the normal starter motor.

In the reference I provided in the previous post it does describe this usage. Repeating the reference:
http://silverthorninst.org/Automotiv...utoTrends2.htm

.
 

Besoeker

Senior Member
Location
UK
110428-1136 EDT

Besoeker:

When I said electrified vehicle that did not mean a purely electric vehicle. Obviously no need for a starter motor in a pure EV.

If you already have a high power electric motor-generator in an electrified vehicle, and the design of that vehicle is such that motor can be used to start the engine, then it makes sense to eliminate the normal starter motor.

In the reference I provided in the previous post it does describe this usage. Repeating the reference:
http://silverthorninst.org/Automotiv...utoTrends2.htm

.
No argument with that. The only hybrid I've been in was my colleague's Lexus GS450h. The first thing you notice is that when it is "started" nothing appears to happen. It just glides off in EV mode. Above a certain speed or maybe accelerator pedal position the IC engine blends in. So, yes the electrical machine starts it.
 

iaov

Senior Member
Location
Rhinelander WI
Learning about the old three relay voltage regulators in auto shop class is what made me decide that I wanted to spend my life doing something with electricity. It left me going "WOW" this is cool!!
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
110501-1436 EDT

Following are some patents relating to automotive voltage regulation. The last one has a good circuit diagram.

Patent applied for 1919 issued 1922
http://www.freepatentsonline.com/1411311.pdf

Patent applied for 1920 issued 1921
http://www.freepatentsonline.com/1398463.pdf

Patent applied for 1921 issued 1926
http://www.freepatentsonline.com/1576768.pdf

Patent applied for 1927 issued 1930 relates to mechanical construction of a cutout relay.
http://www.freepatentsonline.com/1785887.pdf

The following patent was by the father of a classmate several grades above me.
Patent applied for 1934 issued 1936 relates to temperature compensation.
http://www.freepatentsonline.com/2037118.pdf

The following patent was by the father of an immediate classmate of mine.
This provides a very good circuit diagram and explanation of the operation of the regulator. It accurately describes a production Ford regulator.
Patent applied for 1946 issued 1950 relates to adjustment means.
http://www.freepatentsonline.com/2519093.pdf

These do not provide a direct path for the evolution of the automotive voltage regulator, but are pieces of it from the list of references in the Zoerlein patent.

.
 
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