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Ian Field
Guest
Guest
Fri Jan 06, 2012 10:03 pm
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified voltage.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to reduce
the current draw.
Any info on alternator characteristics & behaviour, or how to impedance
match them might be useful.
Thanks.
John Larkin
Guest
Guest
Fri Jan 06, 2012 10:14 pm
On Fri, 6 Jan 2012 21:03:18 -0000, "Ian Field"
<gangprobing.alien_at_ntlworld.com> wrote:
Quote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified voltage.
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified voltage.
Cool, they burn out together.
Quote:
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
Ian Field
Guest
Guest
Fri Jan 06, 2012 10:25 pm
"John Larkin" <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in message
news:qtoeg7tj03u6erv9g9ite8j445sdkudun1_at_4ax.com...
Quote:
On Fri, 6 Jan 2012 21:03:18 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified
voltage.
Cool, they burn out together.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to
reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
gangprobing.alien_at_ntlworld.com> wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified
voltage.
Cool, they burn out together.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to
reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
ATM my workshop is dismantled for refurb - even if it wasn't, I don't really
have the facilities to set up and drive the alternator under test bench
conditions.
It crossed my mind to maybe buffer the O/P of my signal generator and plot
f-Xl curves (whatever that might enable me to calculate).
It'd be handy if I could find an: alternators -> beginners start here,
webpage.
Jim Thompson
Guest
Guest
Fri Jan 06, 2012 10:43 pm
On Fri, 06 Jan 2012 13:14:26 -0800, John Larkin
<jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:
Quote:
On Fri, 6 Jan 2012 21:03:18 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified voltage.
Cool, they burn out together.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
gangprobing.alien_at_ntlworld.com> wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified voltage.
Cool, they burn out together.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
Crikey! Ian returns with his old post, "Very low power dynamo
(alternator actually)", renamed
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
John Larkin
Guest
Guest
Fri Jan 06, 2012 10:49 pm
On Fri, 6 Jan 2012 21:25:59 -0000, "Ian Field"
<gangprobing.alien_at_ntlworld.com> wrote:
Quote:
"John Larkin" <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in message
news:qtoeg7tj03u6erv9g9ite8j445sdkudun1_at_4ax.com...
On Fri, 6 Jan 2012 21:03:18 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified
voltage.
Cool, they burn out together.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to
reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
ATM my workshop is dismantled for refurb - even if it wasn't, I don't really
have the facilities to set up and drive the alternator under test bench
conditions.
It crossed my mind to maybe buffer the O/P of my signal generator and plot
f-Xl curves (whatever that might enable me to calculate).
That won't tell you anything about the alternator.
Can't you even carry a DVM and pedal? Open-circuit voltage and
short-circuit current would be a good start.
John
Oppie
Guest
Guest
Fri Jan 06, 2012 11:19 pm
In my cycling days (before high efficiency LED lamps and modern batteries
that imho obsoleted bicycle generators) it was true that if your headlamp
opened up (it was the major load) and you were going fast, you WOULD blow
the tail light. Would seem that the generator was designed for a maximum
current and output winding would saturate at rated load. This was in effect
a regulation but didn't help if you lost part of the load. I rarely lost a
lamp but did try using a shunt regulator just as a protective device.
Jon Elson
Guest
Guest
Fri Jan 06, 2012 11:31 pm
Jim Thompson wrote:
Quote:
Crikey! Ian returns with his old post, "Very low power dynamo
(alternator actually)", renamed :-)
...Jim Thompson
(alternator actually)", renamed :-)
...Jim Thompson
Sturmey Archer????!! I had one of those when I was a kid, so that is
like 50+ years ago. Do they actually still make these? It was a real
piece of junk then, and I even knew it as a kid.
Jon
mike
Guest
Guest
Fri Jan 06, 2012 11:36 pm
Ian Field wrote:
Quote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified voltage.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to reduce
the current draw.
Any info on alternator characteristics & behaviour, or how to impedance
match them might be useful.
Thanks.
You need to characterize the thing.
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified voltage.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to reduce
the current draw.
Any info on alternator characteristics & behaviour, or how to impedance
match them might be useful.
Thanks.
You need to characterize the thing.
Not sure if they do this on bicycles, but in the old days,
I had a motorcycle that used the leakage inductance of the alternator
to limit the current. As the RPM went up, the frequency of the ac
generated went up. The leakage inductance impedance is higher at the
higher frequency counteracting the increased voltage.
Worked very well for a carefully designed system.
Does your alternator put out DC? The ones I've seen have been AC, the
bulb doesn't care. So you may have to rectify it and incur those losses
as well.
Why SLA? In the general case, there are many advantages to 4-AA NiMH.
Jim Thompson
Guest
Guest
Fri Jan 06, 2012 11:53 pm
On Fri, 06 Jan 2012 16:31:14 -0600, Jon Elson <jmelson_at_wustl.edu>
wrote:
Quote:
Jim Thompson wrote:
Crikey! Ian returns with his old post, "Very low power dynamo
(alternator actually)", renamed :-)
...Jim Thompson
Sturmey Archer????!! I had one of those when I was a kid, so that is
like 50+ years ago. Do they actually still make these? It was a real
piece of junk then, and I even knew it as a kid.
Jon
Crikey! Ian returns with his old post, "Very low power dynamo
(alternator actually)", renamed :-)
...Jim Thompson
Sturmey Archer????!! I had one of those when I was a kid, so that is
like 50+ years ago. Do they actually still make these? It was a real
piece of junk then, and I even knew it as a kid.
Jon
They still make them, much better now-a-days. Ian is looking for his
typical free ride... literally ;-)
But his time would be better spent buying a new hub.
Besides he's not bright enough to take enough diagnostics to see if he
can boost the output
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Jim Thompson
Guest
Guest
Sat Jan 07, 2012 12:04 am
On Fri, 06 Jan 2012 13:49:40 -0800, John Larkin
<jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:
Quote:
On Fri, 6 Jan 2012 21:25:59 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
"John Larkin" <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in message
news:qtoeg7tj03u6erv9g9ite8j445sdkudun1_at_4ax.com...
On Fri, 6 Jan 2012 21:03:18 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified
voltage.
Cool, they burn out together.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to
reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
ATM my workshop is dismantled for refurb - even if it wasn't, I don't really
have the facilities to set up and drive the alternator under test bench
conditions.
It crossed my mind to maybe buffer the O/P of my signal generator and plot
f-Xl curves (whatever that might enable me to calculate).
That won't tell you anything about the alternator.
Can't you even carry a DVM and pedal? Open-circuit voltage and
short-circuit current would be a good start.
John
gangprobing.alien_at_ntlworld.com> wrote:
"John Larkin" <jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in message
news:qtoeg7tj03u6erv9g9ite8j445sdkudun1_at_4ax.com...
On Fri, 6 Jan 2012 21:03:18 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified
voltage.
Cool, they burn out together.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to
reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
ATM my workshop is dismantled for refurb - even if it wasn't, I don't really
have the facilities to set up and drive the alternator under test bench
conditions.
It crossed my mind to maybe buffer the O/P of my signal generator and plot
f-Xl curves (whatever that might enable me to calculate).
That won't tell you anything about the alternator.
Can't you even carry a DVM and pedal? Open-circuit voltage and
short-circuit current would be a good start.
John
Is Ian strong enough to pedal against a short-circuit ?
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Phil Allison
Guest
Guest
Sat Jan 07, 2012 12:18 am
"Ian Field"
Quote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front & rear bulbs to load the armature output to the specified
voltage.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to
reduce the current draw.
Any info on alternator characteristics & behaviour, or how to impedance
match them might be useful.
** Do any Goolge searching at all ?
http://pilom.com/BicycleElectronics/Dynamo.htm
" A dynamo is a current source"
.... Phil
John S
Guest
Guest
Sat Jan 07, 2012 12:37 am
On 1/6/2012 5:04 PM, Jim Thompson wrote:
Quote:
On Fri, 06 Jan 2012 13:49:40 -0800, John Larkin
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:
On Fri, 6 Jan 2012 21:25:59 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
"John Larkin"<jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in message
news:qtoeg7tj03u6erv9g9ite8j445sdkudun1_at_4ax.com...
On Fri, 6 Jan 2012 21:03:18 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front& rear bulbs to load the armature output to the specified
voltage.
Cool, they burn out together.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to
reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
ATM my workshop is dismantled for refurb - even if it wasn't, I don't really
have the facilities to set up and drive the alternator under test bench
conditions.
It crossed my mind to maybe buffer the O/P of my signal generator and plot
f-Xl curves (whatever that might enable me to calculate).
That won't tell you anything about the alternator.
Can't you even carry a DVM and pedal? Open-circuit voltage and
short-circuit current would be a good start.
John
Is Ian strong enough to pedal against a short-circuit ?
...Jim Thompson
jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote:
On Fri, 6 Jan 2012 21:25:59 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
"John Larkin"<jjlarkin_at_highNOTlandTHIStechnologyPART.com> wrote in message
news:qtoeg7tj03u6erv9g9ite8j445sdkudun1_at_4ax.com...
On Fri, 6 Jan 2012 21:03:18 -0000, "Ian Field"
gangprobing.alien_at_ntlworld.com> wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads to
the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of using
the front& rear bulbs to load the armature output to the specified
voltage.
Cool, they burn out together.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to know
whether I can get more power from the alternator by allowing the output
voltage to rise above the rated 6V by using a step down converter to
reduce
the current draw.
That will probably work, but you should test the actual alternator at
speed and measure its voltage and impedance.
John
ATM my workshop is dismantled for refurb - even if it wasn't, I don't really
have the facilities to set up and drive the alternator under test bench
conditions.
It crossed my mind to maybe buffer the O/P of my signal generator and plot
f-Xl curves (whatever that might enable me to calculate).
That won't tell you anything about the alternator.
Can't you even carry a DVM and pedal? Open-circuit voltage and
short-circuit current would be a good start.
John
Is Ian strong enough to pedal against a short-circuit ?
...Jim Thompson
1.8W/746W/hp = .0024hp
Probably.
John S
Tim Wescott
Guest
Guest
Sat Jan 07, 2012 2:32 am
On Fri, 06 Jan 2012 21:03:18 +0000, Ian Field wrote:
Quote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads
to the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of
using the front & rear bulbs to load the armature output to the
specified voltage.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to
know whether I can get more power from the alternator by allowing the
output voltage to rise above the rated 6V by using a step down converter
to reduce the current draw.
Any info on alternator characteristics & behaviour, or how to impedance
match them might be useful.
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads
to the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of
using the front & rear bulbs to load the armature output to the
specified voltage.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to
know whether I can get more power from the alternator by allowing the
output voltage to rise above the rated 6V by using a step down converter
to reduce the current draw.
Any info on alternator characteristics & behaviour, or how to impedance
match them might be useful.
Matching a load impedance to a source impedance is what you do when you
want maximal power transfer and don't mind about poor efficiency.
Alternators (generators, dynamos, whatever) are generally made to be far
more efficient than that, so matching your load impedance at all bicycle
speeds may well overstress the alternator and make it go Pfffft!
You want to do several things, all at once:
* Pull the maximum power you can out of the alternator when it's going
slow (I assume -- do you want it to bog you down going up hills?)
* Limit the current draw from the alternator at higher voltages so it
won't go up in smoke.
* Charge the battery appropriately (i.e. limit both current and voltage;
that's how SLA's like it).
You probably also want to do this in such a way that all of your precious
muscle energy is going to light production, rather than getting burnt up
in the electronics.
If this is so, you want something like a switching supply, and (I hate to
say it) you probably want it managed by a microprocessor. Since you'll
never know if the source is higher or lower than the load, you probably
want a SEPIC converter.
So, you just need a microprocessor with a PWM output, a gate driver, a
MOSFET, some caps, two coils, and a zillion lines of code.
It should be a snap.
Have fun!
--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
John Larkin
Guest
Guest
Sat Jan 07, 2012 3:08 am
On Fri, 06 Jan 2012 19:32:44 -0600, Tim Wescott <tim_at_seemywebsite.com>
wrote:
Quote:
On Fri, 06 Jan 2012 21:03:18 +0000, Ian Field wrote:
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads
to the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of
using the front & rear bulbs to load the armature output to the
specified voltage.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to
know whether I can get more power from the alternator by allowing the
output voltage to rise above the rated 6V by using a step down converter
to reduce the current draw.
Any info on alternator characteristics & behaviour, or how to impedance
match them might be useful.
Matching a load impedance to a source impedance is what you do when you
want maximal power transfer
The alternator in question is a 6V 1.8W (0.3A) Sturmey Archer (Normally
referred to as a "dynamo" in bicycle terminology).
Please can anyone direct me to any sources of info about matching loads
to the impedance of an alternator?
Apparently the original equipment uses the precarious arrangement of
using the front & rear bulbs to load the armature output to the
specified voltage.
What I am intending to do is charge a 1.2Ah SLA battery, I'd like to
know whether I can get more power from the alternator by allowing the
output voltage to rise above the rated 6V by using a step down converter
to reduce the current draw.
Any info on alternator characteristics & behaviour, or how to impedance
match them might be useful.
Matching a load impedance to a source impedance is what you do when you
want maximal power transfer
Actually, the maximun power transfer happens with a conjugate
impedance match.
and don't mind about poor efficiency.
Quote:
Alternators (generators, dynamos, whatever) are generally made to be far
more efficient than that, so matching your load impedance at all bicycle
speeds may well overstress the alternator and make it go Pfffft!
more efficient than that, so matching your load impedance at all bicycle
speeds may well overstress the alternator and make it go Pfffft!
Probably not. Alternators like this are designed to be current
sources, and operate with nearly-shorted loads. Current is what will
fry an alternator, so if you run it into a higher-impedance load than
normal, you can get more power out of it but run it at less current,
which will run cooler.
Quote:
You want to do several things, all at once:
* Pull the maximum power you can out of the alternator when it's going
slow (I assume -- do you want it to bog you down going up hills?)
* Limit the current draw from the alternator at higher voltages so it
won't go up in smoke.
It probably does that already. Higher speed makes higher frequency,
which makes higher open-circuit voltage but roughly constant loaded
current. That's why a little bicycle alternator can be connected
directly to incandescent bulbs.
John
Phil Allison
Guest
Guest
Sat Jan 07, 2012 3:48 am
"Tim Wescott"
Quote:
Matching a load impedance to a source impedance is what you do when you
want maximal power transfer and don't mind about poor efficiency.
Alternators (generators, dynamos, whatever) are generally made to be far
more efficient than that, so matching your load impedance at all bicycle
speeds may well overstress the alternator and make it go Pfffft!
** A bicycle dynamo is lucky to generate 5 watts and is a varying frequency,
highly inductive source.
Do stick to the context in hand.
Arguing from the general to a special case like this one is idiotic.
.... Phil
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