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Of drills, woods, bears, and PIV...

D

David Lesher

Jan 1, 1970
0
So Click & Clack's Puzzler this week
<http://cartalk.com/content/puzzler/transcripts/200918/index.html> was
"given a dead battery, 120vac generator, and an electric drill; how do
you get out of the woods before the bears get you..?"

I'm sure the Tappet Brothers answer involves spinning the alternator with
the drill. That's possible but slow; the average drill does not put out
all that many kilowatts.

Other discussions in rec.craft.metalworking touched on disassembling the
alternator for its diodes. But someone pointed out you do not need to
disassemble the alternator at all.

<http://www.eng.cam.ac.uk/DesignOffice/mdp/electric_web/Exper/05019.png>

Instead:

1) Disconnect the alternator output lead from car harness..
2) Put the following in series:

Alternator output to Generator AC out [N]

Generator AC out [L] to Battery Positive term

[With battery ground->alternator frame completing loop]

3) Fiddle with generator throttle to get idle speed, ergo less
voltage. Start...


One of my concerns is the PIV rating of the alternator diodes. Any
comments on a) what kind of ratings alternator diodes will have b) what
they should have in this misapplication....
 
J

Jim Thompson

Jan 1, 1970
0
So Click & Clack's Puzzler this week
<http://cartalk.com/content/puzzler/transcripts/200918/index.html> was
"given a dead battery, 120vac generator, and an electric drill; how do
you get out of the woods before the bears get you..?"

I'm sure the Tappet Brothers answer involves spinning the alternator with
the drill. That's possible but slow; the average drill does not put out
all that many kilowatts.

Other discussions in rec.craft.metalworking touched on disassembling the
alternator for its diodes. But someone pointed out you do not need to
disassemble the alternator at all.

<http://www.eng.cam.ac.uk/DesignOffice/mdp/electric_web/Exper/05019.png>

Instead:

1) Disconnect the alternator output lead from car harness..
2) Put the following in series:

Alternator output to Generator AC out [N]

Generator AC out [L] to Battery Positive term

[With battery ground->alternator frame completing loop]

3) Fiddle with generator throttle to get idle speed, ergo less
voltage. Start...


One of my concerns is the PIV rating of the alternator diodes. Any
comments on a) what kind of ratings alternator diodes will have b) what
they should have in this misapplication....

[1] Click and Clack are MIT graduates...

"CAMBRIDGE, Mass., April 1, 1999 -- Tom and Ray Magliozzi, hosts of
the National Public Radio series Car Talk, will be the featured
speakers at MIT's Commencement Exercises on June 4.

Known to millions of Americans as "Click and Clack, the Tappet
brothers," both Magliozzis are MIT graduates: Thomas L. Magliozzi
graduated in 1958 with a degree in Economics, while Raymond F.
Magliozzi is a member of the class of 1972 with a Humanities degree."

;-)

[2] Alternator diodes are _usually_ 400PIV.

...Jim Thompson
--
| James E.Thompson, P.E. | 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 |

Stormy on the East Coast today... due to Bush's failed policies.
 
D

David Lesher

Jan 1, 1970
0
[1] Click and Clack are MIT graduates...

Indeed; but I trust them anyhow....now that they
have a proper flag...

<http://tech.mit.edu/V119/N27/27vest.27n.html>
<http://cartalk.com/content/features/Commencement/flag.html>


[2] Alternator diodes are _usually_ 400PIV.

Thanks. I was curious; as in the automotive work they
have volumes large enough, and costing tight enough,
to design & build special diodes Just For Them.

The thread diverged into power mosfets replacing them.
Feel free to chase the References:
 
N

Nobody

Jan 1, 1970
0
So Click & Clack's Puzzler this week
<http://cartalk.com/content/puzzler/transcripts/200918/index.html> was
"given a dead battery, 120vac generator, and an electric drill; how do
you get out of the woods before the bears get you..?"

Does the dead battery come with a car? If not, leave the above three items
behind as you run away; they're just ballast.

Otherwise, just push-start the car.

[This could be a problem if it has automatic transmission, but unless
you're either lacking a (functioning) left leg or are just too stupid to
use manual transmission, why would it? Worse fuel economy, lower
performance, lower reliability, increased cost; what's the point?]
 
G

Glen Walpert

Jan 1, 1970
0
So Click & Clack's Puzzler this week
<http://cartalk.com/content/puzzler/transcripts/200918/index.html> was
"given a dead battery, 120vac generator, and an electric drill; how do
you get out of the woods before the bears get you..?"

I'm sure the Tappet Brothers answer involves spinning the alternator with
the drill. That's possible but slow; the average drill does not put out
all that many kilowatts.

Other discussions in rec.craft.metalworking touched on disassembling the
alternator for its diodes. But someone pointed out you do not need to
disassemble the alternator at all.

<http://www.eng.cam.ac.uk/DesignOffice/mdp/electric_web/Exper/05019.png>

Instead:

1) Disconnect the alternator output lead from car harness..
2) Put the following in series:

Alternator output to Generator AC out [N]

Generator AC out [L] to Battery Positive term

[With battery ground->alternator frame completing loop]

3) Fiddle with generator throttle to get idle speed, ergo less
voltage. Start...

Why not just use the drill as a current limiter, in series with
alternator pos terminal, generator, and the alternator positive wire.
Cut one lead on the drill (either one) and the alternator pos lead
with a sharp rock, strip with your teeth, twist the cut drill wires to
the two halves of the alternator lead wires, plug the drill into the
generator and turn the drill on. A variant of the old light bulb as a
battery charging current limiter trick.
One of my concerns is the PIV rating of the alternator diodes. Any
comments on a) what kind of ratings alternator diodes will have b) what
they should have in this misapplication....

[1] Click and Clack are MIT graduates...

"CAMBRIDGE, Mass., April 1, 1999 -- Tom and Ray Magliozzi, hosts of
the National Public Radio series Car Talk, will be the featured
speakers at MIT's Commencement Exercises on June 4.

Known to millions of Americans as "Click and Clack, the Tappet
brothers," both Magliozzis are MIT graduates: Thomas L. Magliozzi
graduated in 1958 with a degree in Economics, while Raymond F.
Magliozzi is a member of the class of 1972 with a Humanities degree."

;-)

[2] Alternator diodes are _usually_ 400PIV.

...Jim Thompson
 
D

David Lesher

Jan 1, 1970
0
Otherwise, just push-start the car.
[This could be a problem if it has automatic transmission, but unless
you're either lacking a (functioning) left leg or are just too stupid to
use manual transmission, why would it? Worse fuel economy, lower
performance, lower reliability, increased cost; what's the point?]

Or if it's a dirt road in the forest, uphill....
 
J

Jim Thompson

Jan 1, 1970
0
Nobody said:
[This could be a problem if it has automatic transmission, but unless
you're either lacking a (functioning) left leg or are just too stupid to
use manual transmission, why would it? Worse fuel economy, lower
performance, lower reliability, increased cost; what's the point?]

Much harder to talk on a cell phone, put on makeup, or eat your Big Mac with a
manual transmission. :)

I've read that fuel economy is pretty much a wash these days -- many people
don't have enough experience/skill with manuals that they actually end up with
worse performance than an automatic.

Clearly manuals are the way to go if you want performance or really enjoy the
driving experience itself. For the basic need of getting people from point A
to point B comfortably with as little hassle as possible, it should be no
surprise that automatics are preferred.

I was, for _many_ years, a "schtick" person, like BC to 1987, but
clutches, in traffic, get to be exhausting :-(

There's supposed to be a new "Z" (and a new "Q") in 2010, though who
knows with the current economy... I'll buy automatic ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | 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 |

Stormy on the East Coast today... due to Bush's failed policies.
 
D

Dirk Bruere at NeoPax

Jan 1, 1970
0
Joel said:
Nobody said:
[This could be a problem if it has automatic transmission, but unless
you're either lacking a (functioning) left leg or are just too stupid to
use manual transmission, why would it? Worse fuel economy, lower
performance, lower reliability, increased cost; what's the point?]

Much harder to talk on a cell phone, put on makeup, or eat your Big Mac with a
manual transmission. :)

I've read that fuel economy is pretty much a wash these days -- many people
don't have enough experience/skill with manuals that they actually end up with
worse performance than an automatic.

Clearly manuals are the way to go if you want performance or really enjoy the
driving experience itself. For the basic need of getting people from point A
to point B comfortably with as little hassle as possible, it should be no
surprise that automatics are preferred.

Esp if you spend a lot of time in traffic jams.

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.onetribe.me.uk/wordpress/?cat=5 - Our podcasts on weird stuff
 
N

Nobody

Jan 1, 1970
0
[This could be a problem if it has automatic transmission, but unless
you're either lacking a (functioning) left leg or are just too stupid to
use manual transmission, why would it? Worse fuel economy, lower
performance, lower reliability, increased cost; what's the point?]

Or if it's a dirt road in the forest, uphill....

A rolling start works fine in reverse.
 
N

Nobody

Jan 1, 1970
0
Clearly manuals are the way to go if you want performance or really enjoy the
driving experience itself. For the basic need of getting people from point A
to point B comfortably with as little hassle as possible, it should be no
surprise that automatics are preferred.

Only in America (although automatic transmission seems to be gaining in
popularity in East Asia).

In the UK (and most of Europe), automatic transmission is still quite rare.
 
J

Jim Thompson

Jan 1, 1970
0
[This could be a problem if it has automatic transmission, but unless
you're either lacking a (functioning) left leg or are just too stupid to
use manual transmission, why would it? Worse fuel economy, lower
performance, lower reliability, increased cost; what's the point?]

Or if it's a dirt road in the forest, uphill....

A rolling start works fine in reverse.

Often a better gear ratio.

...Jim Thompson
--
| James E.Thompson, P.E. | 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 |

Stormy on the East Coast today... due to Bush's failed policies.
 
G

gearhead

Jan 1, 1970
0
[This could be a problem if it has automatic transmission, but unless
you're either lacking a (functioning) left leg or are just too stupid to
use manual transmission, why would it? Worse fuel economy, lower
performance, lower reliability, increased cost; what's the point?]
Or if it's a dirt road in the forest, uphill....

A rolling start works fine in reverse.


But of course your foresight led you to avoid parking in a hollow.
 
G

gearhead

Jan 1, 1970
0
On Fri, 8 May 2009 17:41:42 +0000 (UTC), David Lesher
So Click & Clack's Puzzler this week
<http://cartalk.com/content/puzzler/transcripts/200918/index.html> was
"given a dead battery, 120vac generator, and an electric drill; how do
you get out of the woods before the bears get you..?"
I'm sure the Tappet Brothers answer involves spinning the alternator with
the drill. That's possible but slow; the average drill does not put out
all that many kilowatts.
Other discussions in rec.craft.metalworking touched on disassembling the
alternator for its diodes.  But someone pointed out you do not need to
disassemble the alternator at all.
<http://www.eng.cam.ac.uk/DesignOffice/mdp/electric_web/Exper/05019.png>
Instead:
1) Disconnect the alternator output lead from car harness..
2) Put the following in series:
Alternator output to Generator AC out [N]
Generator AC out [L] to Battery Positive term
[With battery ground->alternator frame completing loop]
3) Fiddle with generator throttle to get idle speed, ergo less
voltage. Start...

Why not just use the drill as a current limiter, in series with
alternator pos terminal, generator, and the alternator positive wire.
Cut one lead on the drill (either one) and the alternator pos lead
with a sharp rock, strip with your teeth, twist the cut drill wires to
the two halves of the alternator lead wires, plug the drill into the
generator and turn the drill on.  A variant of the old light bulb as a
battery charging current limiter trick.
Spinning the alt with the drill might not very effective, just way too
slow so
I agree, use the drill as a current limiter.
I couldn't follow your description of the connections exactly; but
I'm sure one would have to open the alternator to get at the
rectifiers.
Connect the current-limited ac to two of the three rectifier terminals
that normally
get connected to the stator (after disconnecting the stator).
I've hacked alternators before and there's just one thing I
remember getting caught by -- threre's actually two sets of rectifiers
in
the alternators I'm familiar with (Delco). There's an extra set of
much less
robust rectifiers for tickling the field, and it's easy to burn them
up if you do something wrong.
 
C

Clifford Heath

Jan 1, 1970
0
Jim said:
Often a better gear ratio.

Taller, but worse. 2nd is better than 1st. It's a simple impedance matching problem.
 
J

Jasen Betts

Jan 1, 1970
0
Automatics make a lot of sense in hilly landscapes. Hills are hell on
clutches.

automatics transmissions have clutches, dunno how long they last.

hills needn't be bad on the clutch in a manual transmission if you
match match the engine speed before engaging the clutch.
 
J

Jim Thompson

Jan 1, 1970
0
automatics transmissions have clutches, dunno how long they last.

Fluid coupling at low RPM's.
hills needn't be bad on the clutch in a manual transmission if you
match match the engine speed before engaging the clutch.

Spoken like one who's never had to hold at a San Francisco up-hill
traffic light.

I vaguely remember (from my teens) a vehicle where, when the clutch
pedal was pushed all the way to the floor, it engaged a brake... I
think the feature was called "hill holder".

Of course you have to be careful... I also had a car where the starter
button was under the clutch pedal.

Best stick vehicles have a hand brake lever between the seats.

...Jim Thompson
--
| James E.Thompson, P.E. | 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 |

Stormy on the East Coast today... due to Bush's failed policies.
 
J

Jim Thompson

Jan 1, 1970
0
Fluid coupling at low RPM's.


Spoken like one who's never had to hold at a San Francisco up-hill
traffic light.

I vaguely remember (from my teens) a vehicle where, when the clutch
pedal was pushed all the way to the floor, it engaged a brake... I
think the feature was called "hill holder".

Of course you have to be careful... I also had a car where the starter
button was under the clutch pedal.

Best stick vehicles have a hand brake lever between the seats.

...Jim Thompson

And I forgot, since you hardly ever need the feature in AZ, _most_
automatic trannies won't allow roll-back while in Drive. My present
vehicle will automatically up the RPM's to hold on a hill.

...Jim Thompson
--
| James E.Thompson, P.E. | 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 |

Stormy on the East Coast today... due to Bush's failed policies.
 
G

Glen Walpert

Jan 1, 1970
0
@panix.com> wrote:
So Click & Clack's Puzzler this week
<http://cartalk.com/content/puzzler/transcripts/200918/index.html> was
"given a dead battery, 120vac generator, and an electric drill; how do
you get out of the woods before the bears get you..?"
I'm sure the Tappet Brothers answer involves spinning the alternator with
the drill. That's possible but slow; the average drill does not put out
all that many kilowatts.
Other discussions in rec.craft.metalworking touched on disassembling the
alternator for its diodes.  But someone pointed out you do not need to
disassemble the alternator at all.


1) Disconnect the alternator output lead from car harness..
2) Put the following in series:
Alternator output to Generator AC out [N]
Generator AC out [L] to Battery Positive term
[With battery ground->alternator frame completing loop]
3) Fiddle with generator throttle to get idle speed, ergo less
voltage. Start...

Why not just use the drill as a current limiter, in series with
alternator pos terminal, generator, and the alternator positive wire.
Cut one lead on the drill (either one) and the alternator pos lead
with a sharp rock, strip with your teeth, twist the cut drill wires to
the two halves of the alternator lead wires, plug the drill into the
generator and turn the drill on.  A variant of the old light bulb as a
battery charging current limiter trick.
Spinning the alt with the drill might not very effective, just way too
slow so
I agree, use the drill as a current limiter.
I couldn't follow your description of the connections exactly; but
I'm sure one would have to open the alternator to get at the
rectifiers.

No need to open the alternator. When it is not running it is
essentially a diode between the output terminal and ground, actually 3
sets of two series diodes. The stator windings connect to the middle
of these diodes, and will draw no current when the alternator is being
used as a battery charger diode. Likewise the field diodes connect to
the stator windings (I think) and would see essentially no voltage.

Having looked at the puzzler now I see tools, the drill, an extension
cord and jumper cables are available, so no wire cutting is required.
Just lift the output wire from the alternator, plug the extension cord
into the generator, plug one side of the drill plug into the hot side
of the extension cord socket, one jumper cable from the exposed other
drill plug blade to the alternator output stud (your rectifier to
frame ground) and the other jumper cable from the generator frame
ground (conected to neutral) to the alternator output lead or the
battery plus terminal (where the alternator output wire connects). The
jumper cable connections to the car can be reversed.

The drill is a universal motor (DC motor with a bridge rectifier),
which will run on either polarity DC also, or at reduced power on half
wave rectified AC, rectified by the alternator diodes. Leave it
running until the battery is charged enough to start (battery could be
overcharged with this setup).

If my description is still not clear, try sketching the whole thing
including the drill bridge rectifier and the alternator bridge
rectifier. Drill current limits and alternator rectifies.
 
D

David Lesher

Jan 1, 1970
0
No need to open the alternator. When it is not running it is
essentially a diode between the output terminal and ground, actually 3
sets of two series diodes. The stator windings connect to the middle
of these diodes, and will draw no current when the alternator is being
used as a battery charger diode. Likewise the field diodes connect to
the stator windings (I think) and would see essentially no voltage.

I'd disconnect ALL the alternator wires, and the battery hot; just in
case.
The drill is a universal motor (DC motor with a bridge rectifier),
which will run on either polarity DC also, or at reduced power on half
wave rectified AC, rectified by the alternator diodes. Leave it
running until the battery is charged enough to start (battery could be
overcharged with this setup).

The drill is NOT a DC motor with bridge; it's a straight universal motor
that won't care about waveform. I think the trigger speed controller will
object, but non-fatally. I don't think it will do a good job limiting
current in locked rotor mode, however.

I was speculating about using a salt water resistor for current limiting
as I've seen before:
<http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19950013378_1995113378.pdf>
 
C

Clifford Heath

Jan 1, 1970
0
Jim said:
I vaguely remember (from my teens) a vehicle where, when the clutch
pedal was pushed all the way to the floor, it engaged a brake... I
think the feature was called "hill holder".

Subaru's still have that.
 
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