Anyone ever re-wound a stock alternator?

[Scott Gardner]

I've got a '72 Mercedes that came stock with a Bosch 55-amp
alternator. There's obviously not a big aftermarket for performance
alternators for this car. There was a Bosch 65-amp model that
Mercedes used on later cars that's a drop-in replacement, but that's
not really enough of an increase to justify purchasing a new
alternator unless I have no other options.

Has anyone here ever taken their alternator to an electrical shop and
had it re-wound for higher capacity? I know it can be done, but I
don't know what kind of increase in current capacity is reasonable to
expect.




--
Scott Gardner

"This seems like a case where we need to shoot the messenger." (Charlie Kaufman on Cypherpunks list)

[Chris Mullins]

My uncle can/has done this, i've seen him rewind old broken alts and such,
i've even read online how to do it and it seems horribly simple but how much
of a gain can't really be told as far as i know. You just wind as much as
possible for the size of the casing.


"Scott Gardner" > wrote in message
...
> I've got a '72 Mercedes that came stock with a Bosch 55-amp
> alternator. There's obviously not a big aftermarket for performance
> alternators for this car. There was a Bosch 65-amp model that
> Mercedes used on later cars that's a drop-in replacement, but that's
> not really enough of an increase to justify purchasing a new
> alternator unless I have no other options.
>
> Has anyone here ever taken their alternator to an electrical shop and
> had it re-wound for higher capacity? I know it can be done, but I
> don't know what kind of increase in current capacity is reasonable to
> expect.
>
>
>
>
> --
> Scott Gardner
>
> "This seems like a case where we need to shoot the messenger." (Charlie
> Kaufman on Cypherpunks list)
>

[not i]

On Thu, 13 Oct 2005 16:01:23 -0400, Scott Gardner >
wrote:

>I've got a '72 Mercedes that came stock with a Bosch 55-amp
>alternator. There's obviously not a big aftermarket for performance
>alternators for this car. There was a Bosch 65-amp model that
>Mercedes used on later cars that's a drop-in replacement, but that's
>not really enough of an increase to justify purchasing a new
>alternator unless I have no other options.
>
>Has anyone here ever taken their alternator to an electrical shop and
>had it re-wound for higher capacity? I know it can be done, but I
>don't know what kind of increase in current capacity is reasonable to
>expect.


The core size determines the alternator output. It can not be
rewound to produce much more power than it does now.

[Chad Wahls]

"not i" > wrote in message
...
> On Thu, 13 Oct 2005 16:01:23 -0400, Scott Gardner >
> wrote:
>
>>I've got a '72 Mercedes that came stock with a Bosch 55-amp
>>alternator. There's obviously not a big aftermarket for performance
>>alternators for this car. There was a Bosch 65-amp model that
>>Mercedes used on later cars that's a drop-in replacement, but that's
>>not really enough of an increase to justify purchasing a new
>>alternator unless I have no other options.
>>
>>Has anyone here ever taken their alternator to an electrical shop and
>>had it re-wound for higher capacity? I know it can be done, but I
>>don't know what kind of increase in current capacity is reasonable to
>>expect.
>
>
> The core size determines the alternator output. It can not be
> rewound to produce much more power than it does now.
>

Sure it can

[Kirby]

"Chad Wahls" > wrote in message
...

>
> Sure it can

I'm actually interested in this as well, How is it done? And I feel like a
jerk asking this, but how is it possible?

[Scott Gardner]

On Sat, 15 Oct 2005 06:32:37 GMT, "Kirby" >
wrote:

>
>"Chad Wahls" > wrote in message
...
>
>>
>> Sure it can
>
>I'm actually interested in this as well, How is it done? And I feel like a
>jerk asking this, but how is it possible?
>

Remember Faraday's Law? Any movement of a wire through a magnetic
field will generate a current in the wire. If you can increase the
magnetic field, the number of wires passing through the field, or the
relative speed between the two, you can increase the current induced
in the wire.

In an alternator, you have a stationary "stator" that provides the
magnetic field, and a moving "rotor" that's turned by a drive belt.
The rotor has a bunch of wire wrapped around it, and the movement of
the rotor induces a current in those wires. "Re-winding" an alternator
involves unwinding the wire from the rotor and replacing it with a
longer length of wire.

Using a longer total length of wire than the factory did allows you to
get a higher number of wire loops around the rotor. Or, if there's
not enough empty space inside the case, you can use a smaller-gauge
wire to get more loops in the same amount of space, as long as you
don't exceed the current capacity of the wire.

I just don't know how much of an increase to expect. For most modern
cars, it's much easier to just buy an aftermarket high-output
alternator than to have a stock one re-wound, so I haven't found
anyone yet that's actually had it done, and had the currrent capacity
tested afterwards.




--
Scott Gardner

"A conclusion is the place where you get tired of thinking." (Arthur Bloch)

[Spokesman]

"Scott Gardner" > wrote in message
...
> On Sat, 15 Oct 2005 06:32:37 GMT, "Kirby" >
> wrote:
>
> >
> >"Chad Wahls" > wrote in message
> ...
> >
> >>
> >> Sure it can
> >
> >I'm actually interested in this as well, How is it done? And I feel like
a
> >jerk asking this, but how is it possible?
> >
>
> Remember Faraday's Law? Any movement of a wire through a magnetic
> field will generate a current in the wire. If you can increase the
> magnetic field, the number of wires passing through the field, or the
> relative speed between the two, you can increase the current induced
> in the wire.
>
> In an alternator, you have a stationary "stator" that provides the
> magnetic field, and a moving "rotor" that's turned by a drive belt.
> The rotor has a bunch of wire wrapped around it, and the movement of
> the rotor induces a current in those wires. "Re-winding" an alternator
> involves unwinding the wire from the rotor and replacing it with a
> longer length of wire.
>
> Using a longer total length of wire than the factory did allows you to
> get a higher number of wire loops around the rotor. Or, if there's
> not enough empty space inside the case, you can use a smaller-gauge
> wire to get more loops in the same amount of space, as long as you
> don't exceed the current capacity of the wire.



There's the catch. There is not enough room in the alternator to wind more
turns
of larger wire than at present. The wire that the alternator is wound with
is large
enough for the rated amps. If you put in more turns of smaller wire it will
overheat the
wire. You can produce a higher voltage but you cannot produce more watts
than
the frame is rated for. At the risk of burning it up you might get another
five
per cent more output. This is the same reason that a five horsepower motor
is larger than a one horsepower motor.


>
> I just don't know how much of an increase to expect. For most modern
> cars, it's much easier to just buy an aftermarket high-output
> alternator than to have a stock one re-wound, so I haven't found
> anyone yet that's actually had it done, and had the currrent capacity
> tested afterwards.
>
>
>
>
> --
> Scott Gardner
>
> "A conclusion is the place where you get tired of thinking." (Arthur
Bloch)
>

[mm]

On Sat, 15 Oct 2005 07:47:28 -0400, Scott Gardner >
wrote:

>On Sat, 15 Oct 2005 06:32:37 GMT, "Kirby" >
>wrote:
>
>>
>>"Chad Wahls" > wrote in message
...
>>
>>>
>>> Sure it can
>>
>>I'm actually interested in this as well, How is it done? And I feel like a
>>jerk asking this, but how is it possible?
>>
>
>Remember Faraday's Law? Any movement of a wire through a magnetic
>field will generate a current in the wire. If you can increase the
>magnetic field, the number of wires passing through the field, or the
>relative speed between the two, you can increase the current induced
>in the wire.

If we're going to be techical :) let me add a bit that will either be
news to you, or if not, maybe you can explain it to me.

Until about 1964, they used generators. I guess the brushes rode on
segmented rings, commutators, and by switching to alternators, where
the brushes ride on continuous rings on the armature, the brushes last
longer, but alternating current is generated. The invention of the
transistor diode made this possible.

Alternators were also good because they put out more power?, amperage?
at low speeds than generators did, but they were self limiting at
higher speeds. That's what I don't understand, either half of the
previous sentence. ??

BEcause they were self-limiting, mechanical regulators only required 2
relays, instead of the 3 required for generators.

Generators continue to put out higher and higher currents becuase a
portion of the current is fed back to the field windings , "increase
the magnetic field" your first example of how to increase output.
Somehow thiss isn't done with alternators, I think, because (I don't
think this is the reason) no current is fed back and they rely on the
magnetism of the field, or some other reason that I can't think of. My
second question. ??

Maybe you could fiddle with some of this other stuff, rather than the
windings, but otoh, if you could, someone else would have written
about it or suggested it here.

>In an alternator, you have a stationary "stator" that provides the
>magnetic field, and a moving "rotor" that's turned by a drive belt.
>The rotor has a bunch of wire wrapped around it, and the movement of
>the rotor induces a current in those wires. "Re-winding" an alternator
>involves unwinding the wire from the rotor and replacing it with a
>longer length of wire.
>
>Using a longer total length of wire than the factory did allows you to
>get a higher number of wire loops around the rotor. Or, if there's
>not enough empty space inside the case, you can use a smaller-gauge
>wire to get more loops in the same amount of space, as long as you
>don't exceed the current capacity of the wire.
>
>I just don't know how much of an increase to expect. For most modern
>cars, it's much easier to just buy an aftermarket high-output
>alternator than to have a stock one re-wound, so I haven't found
>anyone yet that's actually had it done, and had the currrent capacity
>tested afterwards.


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