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converting car alt. to 120v ac

H

harvy

Jan 1, 1970
0
has anyone ever converted a car altenator to ac 120 power.
I was kind of looking on the net for how to do this or not.
I am putting together a log splitter and I was kind of hoping to make
it an ac generator on top of it when it isnt driving the hydrolics.
 
You would need to rewind the stator, chuck out the diodes and the
voltage regulator, make your own voltage regulator. Then you need to
drive it at the right speed and finally you have to deal with the
3phase output.
 
K

kell

Jan 1, 1970
0
harvy said:
has anyone ever converted a car altenator to ac 120 power.
I was kind of looking on the net for how to do this or not.
I am putting together a log splitter and I was kind of hoping to make
it an ac generator on top of it when it isnt driving the hydrolics.
Obviously you're gonna have to open up the alternator. Do you know
anything about alternators? Tap two of the stator windings' three
outputs to get your single phase ac. And you have to take the diode
pack's dc output (this is the alternator's output, normally) and
connect it directly to the field (bypassing the voltage regulator).
If you don't need tight regulation of your ac power and the splitter's
engine has some abilitly to respond to load changes by adjusting its
torque, you might not need any electronics.
 
P

Pooh Bear

Jan 1, 1970
0
You would need to rewind the stator, chuck out the diodes and the
voltage regulator, make your own voltage regulator. Then you need to
drive it at the right speed and finally you have to deal with the
3phase output.

Not to mention the frequency.

Graham
 
harvy said:
has anyone ever converted a car altenator to ac 120 power.
I was kind of looking on the net for how to do this or not.
I am putting together a log splitter and I was kind of hoping to make
it an ac generator on top of it when it isnt driving the hydrolics.

just bypass the regulator, which controls the feed to the field. And I
guess dont use the rectifier, if you want ac. DC will run many ac loads
though.

This will of course give you an unregulated generator, which wont give
any voltage regulation. And the frequency will be high, too high for
some loads, but fine for many.


NT
 
L

Leon

Jan 1, 1970
0
You would need to rewind the stator, chuck out the diodes and the
voltage regulator, make your own voltage regulator. Then you need to
drive it at the right speed and finally you have to deal with the
3phase output.

How about removing the diodes and adding a suitable transformer?

Leon
 
S

Sjouke Burry

Jan 1, 1970
0
harvy said:
has anyone ever converted a car altenator to ac 120 power.
I was kind of looking on the net for how to do this or not.
I am putting together a log splitter and I was kind of hoping to make
it an ac generator on top of it when it isnt driving the hydrolics.

Yes,by accident. My regulator circuit regulated
the wrong way and when we touched the accelerator,
the whole board went bang!!!!!!
The IC missed its hat,and any trace of chip and
wire kind of disappeared.
My college was splattered all over with pieces
of electrolytic capacitor.
 
M

Mark

Jan 1, 1970
0
Something has always bothered me about this, maye some can explain
it....

I know a car alternator can put out about 100 Amps at 12Volts as it is
designed to by regulating the field winding which is on the rotor.
This is about 1200 Watts... Ok no problem for an alternator that
size...

I also know you can "full field" an alternator and it will put out a
higher voltage...

OK, so lets say we full field an alternator and it puts out say 50
Volts. The stator wires can still handle 100 Amps output , but since
its at 50 Volts...this is now 5000 Watts. I realize it will take a lot
more torque to turn the shaft but suppose we have the torque... that
still seems like a lot of power to get out such a small alternator...


Is the size required of an alternator detemrined by the current it can
supply, not the power... can we get more and more power out of an
alternator of a given size by raising the output voltage (given the
insulation holds) ?

What am I missing?


Mark
 
P

Paul Hovnanian P.E.

Jan 1, 1970
0
harvy said:
has anyone ever converted a car altenator to ac 120 power.
I was kind of looking on the net for how to do this or not.
I am putting together a log splitter and I was kind of hoping to make
it an ac generator on top of it when it isnt driving the hydrolics.

Wrong voltage, wrong frequency, wrong number of phases. Your best bet
(if its 120V, 60 Hz you're after) is to use it to power an inverter.
 
P

Paul Hovnanian P.E.

Jan 1, 1970
0
Mark said:
Something has always bothered me about this, maye some can explain
it....

I know a car alternator can put out about 100 Amps at 12Volts as it is
designed to by regulating the field winding which is on the rotor.
This is about 1200 Watts... Ok no problem for an alternator that
size...

I also know you can "full field" an alternator and it will put out a
higher voltage...

OK, so lets say we full field an alternator and it puts out say 50
Volts. The stator wires can still handle 100 Amps output , but since
its at 50 Volts...this is now 5000 Watts. I realize it will take a lot
more torque to turn the shaft but suppose we have the torque... that
still seems like a lot of power to get out such a small alternator...

Is the size required of an alternator detemrined by the current it can
supply, not the power... can we get more and more power out of an
alternator of a given size by raising the output voltage (given the
insulation holds) ?

What am I missing?

The effects of the series reactance of the alternator windings. The
device might be able to put out 50V at no load, but, for a given value
of field current (and RPM) the terminal voltage will drop off as load
increases. At full field, the alternator will put out significantly less
than he no-load voltage times the full load amps.
 
P

Paul E. Schoen

Jan 1, 1970
0
An automotive alternator is a three-phase configuration, so each winding
only handles roughly 1/3 the DC output current. So if you could rewind a 100
amp it for single phase output you might get 12 x 3 x 1.414 = 50 VAC at 33
amps, or about 1500 watts. However, the alternator is designed to provide at
least 12 VDC at idle speed, say 600 RPM, and will probably put out 6 times
that at 3600 RPM,or 300 VAC. The magnetics will probably limit it to
something lower than that, but it might be possible to get 120 VAC at 30
amps = 3600 watts. However, it's probably something like 400 Hz, so you
couldn't use it for motor loads, unless you want them to spin *really* fast!

I haven't thought this out completely, but it's worth discussing.

Paul E. Schoen
 
K

kell

Jan 1, 1970
0
Mark said:
Something has always bothered me about this, maye some can explain
it....

I know a car alternator can put out about 100 Amps at 12Volts as it is
designed to by regulating the field winding which is on the rotor.
This is about 1200 Watts... Ok no problem for an alternator that
size...

I also know you can "full field" an alternator and it will put out a
higher voltage...

OK, so lets say we full field an alternator and it puts out say 50
Volts. The stator wires can still handle 100 Amps output , but since
its at 50 Volts...this is now 5000 Watts. I realize it will take a lot
more torque to turn the shaft but suppose we have the torque... that
still seems like a lot of power to get out such a small alternator...


Is the size required of an alternator detemrined by the current it can
supply, not the power... can we get more and more power out of an
alternator of a given size by raising the output voltage (given the
insulation holds) ?

What am I missing?


Mark

Think about the fact that the regulator probably makes the alternator
go full field pretty much anyway, when the output has a very heavy load
on it -- your hypothetical 100 amps. It's already full field at 100
amps and you're only getting 15 volts -- not 50.
 
J

Jim Thompson

Jan 1, 1970
0
Mark wrote:
[snip]
What am I missing?


Mark

Think about the fact that the regulator probably makes the alternator
go full field pretty much anyway, when the output has a very heavy load
on it -- your hypothetical 100 amps. It's already full field at 100
amps and you're only getting 15 volts -- not 50.

You are forgetting that an automotive alternator is essentially a
current source.

As built, if you remove the diodes, they produce 3-phase AC. The
voltage will be a function of the load and the field current.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

"Don't mess with my toot toot!", Antoine 'Fats' Domino
 
K

kell

Jan 1, 1970
0
Jim said:
Mark wrote:
[snip]
What am I missing?


Mark

Think about the fact that the regulator probably makes the alternator
go full field pretty much anyway, when the output has a very heavy load
on it -- your hypothetical 100 amps. It's already full field at 100
amps and you're only getting 15 volts -- not 50.

You are forgetting that an automotive alternator is essentially a
current source.

As built, if you remove the diodes, they produce 3-phase AC. The
voltage will be a function of the load and the field current.

...Jim Thompson

I think we can agree Mark won't get an alternator to put out five times
as much power just from bypassing the voltage regulator.
 
J

Jim Thompson

Jan 1, 1970
0
Jim said:
Mark wrote:
[snip]


What am I missing?


Mark

Think about the fact that the regulator probably makes the alternator
go full field pretty much anyway, when the output has a very heavy load
on it -- your hypothetical 100 amps. It's already full field at 100
amps and you're only getting 15 volts -- not 50.

You are forgetting that an automotive alternator is essentially a
current source.

As built, if you remove the diodes, they produce 3-phase AC. The
voltage will be a function of the load and the field current.

...Jim Thompson

I think we can agree Mark won't get an alternator to put out five times
as much power just from bypassing the voltage regulator.

The alternator WILL put out the power... until it starts to melt ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

"Don't mess with my toot toot!", Antoine 'Fats' Domino
 
M

Mark

Jan 1, 1970
0
Jim said:
Jim said:
On 30 Jan 2006 07:55:53 -0800, "kell" <[email protected]>
wrote:


Mark wrote:

[snip]


What am I missing?


Mark

Think about the fact that the regulator probably makes the alternator
go full field pretty much anyway, when the output has a very heavy load
on it -- your hypothetical 100 amps. It's already full field at 100
amps and you're only getting 15 volts -- not 50.

You are forgetting that an automotive alternator is essentially a
current source.

As built, if you remove the diodes, they produce 3-phase AC. The
voltage will be a function of the load and the field current.

...Jim Thompson

I think we can agree Mark won't get an alternator to put out five times
as much power just from bypassing the voltage regulator.

The alternator WILL put out the power... until it starts to melt ;-)

...Jim Thompson

That is the point of my question...why would it melt...?

The stator is designed to deliver 100 Amps. When you full field it and
the voltage is say 50 Volts, if the current is still 100 Amps the I^2R
losses are still the same so it wouldn't get any hotter compared to
when it delivers 100 Amps at 12 Volts.

Mark
 
J

Jim Thompson

Jan 1, 1970
0
Jim said:
Jim Thompson wrote:
On 30 Jan 2006 07:55:53 -0800, "kell" <[email protected]>
wrote:


Mark wrote:

[snip]


What am I missing?


Mark

Think about the fact that the regulator probably makes the alternator
go full field pretty much anyway, when the output has a very heavy load
on it -- your hypothetical 100 amps. It's already full field at 100
amps and you're only getting 15 volts -- not 50.

You are forgetting that an automotive alternator is essentially a
current source.

As built, if you remove the diodes, they produce 3-phase AC. The
voltage will be a function of the load and the field current.

...Jim Thompson

I think we can agree Mark won't get an alternator to put out five times
as much power just from bypassing the voltage regulator.

The alternator WILL put out the power... until it starts to melt ;-)

...Jim Thompson

That is the point of my question...why would it melt...?

The stator is designed to deliver 100 Amps. When you full field it and
the voltage is say 50 Volts, if the current is still 100 Amps the I^2R
losses are still the same so it wouldn't get any hotter compared to
when it delivers 100 Amps at 12 Volts.

Mark

Good point.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

Global Warming is God's gift to the Blue States ;-)
 
P

Pooh Bear

Jan 1, 1970
0
Mark said:
Jim said:
Jim Thompson wrote:
On 30 Jan 2006 07:55:53 -0800, "kell" <[email protected]>
wrote:


Mark wrote:

[snip]


What am I missing?


Mark

Think about the fact that the regulator probably makes the alternator
go full field pretty much anyway, when the output has a very heavy load
on it -- your hypothetical 100 amps. It's already full field at 100
amps and you're only getting 15 volts -- not 50.

You are forgetting that an automotive alternator is essentially a
current source.

As built, if you remove the diodes, they produce 3-phase AC. The
voltage will be a function of the load and the field current.

...Jim Thompson

I think we can agree Mark won't get an alternator to put out five times
as much power just from bypassing the voltage regulator.

The alternator WILL put out the power... until it starts to melt ;-)

...Jim Thompson

That is the point of my question...why would it melt...?

The stator is designed to deliver 100 Amps. When you full field it and
the voltage is say 50 Volts, if the current is still 100 Amps the I^2R
losses are still the same so it wouldn't get any hotter compared to
when it delivers 100 Amps at 12 Volts.

I think you'll find the on-load voltage drops though on account of the alternator
impedance.

Graham
 
P

Pooh Bear

Jan 1, 1970
0
Yep that would work but he still needs speed regulation and a 3 phase
transformer.

A 3-phase transfomer still needs a 3-phase load !

Graham
 
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