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| Science Forum Index » Electronics - Design Forum » PWM a truck alternator... |
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| ChrisQ... |
 Posted: Mon Nov 02, 2009 5:19 am |
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David Lesher wrote:
[quote]Jim Thompson <To-Email-Use-The-Envelope-Icon at (no spam) My-Web-Site.com> writes:
Alternators often run at 6-7X engine RPM's.
...Jim Thompson
I seem to recall that car alternators were geared [well, pullyed] to spin
far faster than generators. Does that agree with your knowledge?
[Wound armature generators have far lower rpm limits than an alternator
with smaller, tighter, windings.]
[/quote]
About a 2:1 ratio, if you look under the hood, to get enough charge at
little above idle. When the engine is doing 6000, the alternator will be
doing 12k, but they are designed for that...
Regards,
Chris |
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| David Lesher... |
| Posted: Mon Nov 02, 2009 9:31 pm |
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ChrisQ <meru at (no spam) devnull.com> writes:
[quote]Alternators often run at 6-7X engine RPM's.
I seem to recall that car alternators were geared [well, pullyed] to spin
far faster than generators. Does that agree with your knowledge?
[Wound armature generators have far lower rpm limits than an alternator
with smaller, tighter, windings.]
About a 2:1 ratio, if you look under the hood, to get enough charge at
little above idle. When the engine is doing 6000, the alternator will be
doing 12k, but they are designed for that...
[/quote]
?? My question was: how fast were old generators spun, in contrast
to alternators?
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| ChrisQ... |
| Posted: Tue Nov 03, 2009 1:22 pm |
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Guest
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David Lesher wrote:
[quote]ChrisQ <meru at (no spam) devnull.com> writes:
Alternators often run at 6-7X engine RPM's.
I seem to recall that car alternators were geared [well, pullyed] to spin
far faster than generators. Does that agree with your knowledge?
[Wound armature generators have far lower rpm limits than an alternator
with smaller, tighter, windings.]
About a 2:1 ratio, if you look under the hood, to get enough charge at
little above idle. When the engine is doing 6000, the alternator will be
doing 12k, but they are designed for that...
?? My question was: how fast were old generators spun, in contrast
to alternators?
[/quote]
Sorry, brainfade. Around 1.4:1 speedup at a guess. Dynamo pulleys were
quite a bit smaller than the crank pulley...
Regards,
Chris |
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