In article ,
Onetap scribeth thus
On Wednesday, October 24, 2012 11:30:15 PM UTC+1, tony sayer wrote:

Umm .. why should jump starting a car with a flat battery fry the

alternator diodes?...
Tony Sayer

Dunno, I was hoping someone could tell me in short words. It did though, honest
Guv.

I've had a car jump started by the AA some years ago and they have some gizmo
they connect and they checked something with a meter before disconnecting their
leads.



Well over many years I've started a lot of differing makes of vehicles
and have yet to have any alternator damage from a simple jump start.

I suspect the real plain old danger is getting the battery connected
arse about face;!...



On Thursday, October 25, 2012 9:55:49 AM UTC+1, Dave Plowman (News) wrote:
In article

Whatever. If you disconnect the alternator from the battery with the

engine running, there's a very good chance of damaging the alternator as

the output volts can go sky high if there's little load. And that high

voltage can kill diodes.


I didn't disconnect the alternator, I disconnected the jump leads and the engine
stopped.

The 'flat' battery was not simply flat, it was dead. Zero volts, zero amps. No
idea why that would happen but a new battery wasn't charging and the alternator,
previously good, was kaput.

That sounds like a simple alternator failure they can and do fail like
just any bit of equipment on a car....
--
Tony Sayer

In article
s.com, harry scribeth thus
On Oct 24, 9:28*pm, "Dave Liquorice"
wrote:
On Wed, 24 Oct 2012 18:01:20 +0100, Dave Plowman (News) wrote:
The diodes get fried if you try to jump-start a car with a flat
battery,

Where on earth did you get that daft idea?

A lot of modern car User Manuals warn against jump starting but not the
reason(s) why it is not recomended.

They are covering their arses in case some half wit connects black to
red.


Exactly!...
--
Tony Sayer

On Wed, 24 Oct 2012 06:29:20 -0700 (PDT), misterroy
wrote:

For a class in school I want to generate an AC signal.
The project is modelling a wind turbine. We will probably drive the input using a drill.
I'm going to need about 10 models. I am only wanting to show the very basics. The signal then needs to be processed, that bit I can handle.
Can someone give me a link to a suitable component to produce the ac voltage on ebay?

thanks

Record a sine wave from compuyer prog.. Burn to CD mp3 thingy or
whatever. Use speaker output.

In message , Jules Richardson
writes
On Thu, 25 Oct 2012 12:16:01 +0100, The Other Mike wrote:
A lot of modern car User Manuals warn against jump starting but not
the reason(s) why it is not recomended.

They are covering their arses in case some half wit connects black to
red.

Red isn't used that much for battery connections on cars today.

My truck has black for the positive and red running to the chassis,
despite being negative earth.

Is it french ?

--
geoff

In message , "Dave Plowman (News)"
writes
In article ,
Bill Wright wrote:
My first guess would be an old bike 'dynamo' - the type that is
friction driven from the tyre wall.

Or a hub dynamo.

I'd say the type I mentioned easier to mount on something and drive with
an electric drill?

We are talking about a school teacher so need to keep things as simple as
possible. ;-)

Does the school not have a pet hamster?

--
geoff

In message
,
harry writes
On Oct 24, 2:29*pm, misterroy wrote:
For a class in school I want to generate an AC signal.
The project is modelling a wind turbine. We will probably drive the
input using a drill.
I'm going to need about 10 models. I am only wanting to show the very
basics. The signal then needs to be processed, that bit I can handle.
Can someone give me a link to a suitable component to produce the ac
voltage on ebay?

thanks

A 13 amp socket. Obviously


I was SO tempted to say that


I must be getting soft



--
geoff

In message , polygonum
writes
On 24/10/2012 19:20, Bill Wright wrote:
misterroy wrote:
For a class in school I want to generate an AC signal. The project
is modelling a wind turbine.

So, you're one of these lefty/greeny Guardian-reading schoolteachers
who are brainwashing our children into believing all the global
warming ******** are you?

Windmills my arse.

Bill

Bill,

You are leaping to conclusions. The experiment, if done well, would show
that windmills are not the answer.

Especially if the whole experiment goes up in a cloud of smoke


--
geoff

In message ,
misterroy writes

No, I'm pretty pro nuclear and anti feed in tariff.
I try and give them a propaganda free view, but that is not what I am
supplied with.

I hope they also see your suitability to teach religious education

--
geoff

In message , Andy Champ
writes
On 24/10/2012 14:29, misterroy wrote:
For a class in school I want to generate an AC signal.
The project is modelling a wind turbine. We will probably drive the
input using a drill.
I'm going to need about 10 models. I am only wanting to show the very
basics. The signal then needs to be processed, that bit I can handle.
Can someone give me a link to a suitable component to produce the ac
voltage on ebay?

thanks

Have you still got the Nuffield kits we used all those years ago to
make electric motors? Make one with more than the usual number of
coils, and you should be away.


Needle on a cork former and crossed pin bearings?

--
geoff

On Thu, 25 Oct 2012 22:50:53 +0100, geoff wrote:

In message , "Dave Plowman (News)"
writes
In article ,
Bill Wright wrote:
My first guess would be an old bike 'dynamo' - the type that is
friction driven from the tyre wall.

Or a hub dynamo.

I'd say the type I mentioned easier to mount on something and drive with
an electric drill?

We are talking about a school teacher so need to keep things as simple
as possible. ;-)

Does the school not have a pet hamster?

Even if it does, trying to drive one with an electric drill sounds like a
recipe for disaster.

On Thu, 25 Oct 2012 09:54:41 +0100, "Dave Plowman (News)"
wrote:

In article
,
harry wrote:
I looked into it and found a web page about alternators with external
diodes for use in light aircraft. Apparently flicking off one of the
isolators (battery I think) required in an aircraft would wreck the
diodes in a conventional alternator.

With the engine running?


The battery isolator in light aircraft is so the battery can be
swiftly cut off if there is an accident to prevent fire.

Whatever. If you disconnect the alternator from the battery with the
engine running, there's a very good chance of damaging the alternator as
the output volts can go sky high if there's little load. And that high
voltage can kill diodes.

Hence why they are wired like this in competition vehicles.

http://www.holden.co.uk/productImagesWD/020_011.jpg

The main heavy duty contacts open on isolation to kill the battery feed,
simultaneously a pair of NO contacts close to shunt the alternator output via a
resistor to earth and a pair of NC contacts opens to kill the ignition feed.







--

Jules Richardson wrote:

On Thu, 25 Oct 2012 22:50:53 +0100, geoff wrote:

In message , "Dave Plowman (News)"
writes
In article ,
Bill Wright wrote:
My first guess would be an old bike 'dynamo' - the type that is
friction driven from the tyre wall.

Or a hub dynamo.

I'd say the type I mentioned easier to mount on something and drive with
an electric drill?

We are talking about a school teacher so need to keep things as simple
as possible. ;-)

Does the school not have a pet hamster?

Even if it does, trying to drive one with an electric drill sounds like a
recipe for disaster.

Just keep the duct tape handy.

Chris
--
Chris J Dixon Nottingham UK


Have dancing shoes, will ceilidh.

On Thursday, October 25, 2012 8:40:51 PM UTC+1, tony sayer wrote:

I looked into it and found a web page about alternators with external diodes for

use in light aircraft. Apparently flicking off one of the isolators (battery I

think) required in an aircraft would wreck the diodes in a conventional

alternator.



Thats sounds rather unlikely and if it did thats very poor design for an

aircraft electrical system.....

--

Tony Sayer

FFS.

That's why they don't use conventional alternators and why there was a web page about amending
a conventional alternator to make it suitable for aircraft, with external regulators and whatever else.

On Oct 25, 7:21*pm, Clive George wrote:
On 25/10/2012 17:24, harry wrote:

Well now we all know what an ignorant halfwit you are.
Tell us all how you can make a motor run on DC.

Didn't Hornby demonstrate that adequately for many years?

Tch Tch.
You are an ignorant git.
So-called DC motors are fitted with a mechanical inverter.
Called a commutator and carbon brushes.

I should perhaps explain to a dunce like you that a n inverter changes
DC into AC so the thing can function.

On Oct 25, 8:40*pm, tony sayer wrote:
In article ,
Onetap scribeth thus









On Wednesday, October 24, 2012 6:02:32 PM UTC+1, Dave Plowman (News) wrote:
In article ,

* wrote:

The diodes get fried if you try to jump-start a car with a flat battery,

Where on earth did you get that daft idea?

Where do you think?
From trying to jump start a car with a totally knackered battery. I've done it
dozens of times before, this was the only time I've had a problem; new
alternator required.

I looked into it and found a web page about alternators with external diodes for
use in light aircraft. Apparently flicking off one of the isolators (battery I
think) required in an aircraft would wreck the diodes in a conventional
alternator.

Thats sounds rather unlikely and if it did thats very poor design for an
aircraft electrical system.....
--
Tony Sayer

Light aircraft electrical systems differ very little from cars.
The main difference is that they have twin ignition systems using
magnetos.

On Oct 26, 7:35*am, Onetap wrote:
On Thursday, October 25, 2012 8:40:51 PM UTC+1, tony sayer wrote:
I looked into it and found a web page about alternators with external diodes for

use in light aircraft. Apparently flicking off one of the isolators (battery I

think) required in an aircraft would wreck the diodes in a conventional

alternator.

Thats sounds rather unlikely and if it did thats very poor design for an

aircraft electrical system.....

--

Tony Sayer

FFS.

That's why they don't use conventional alternators and why there was a web page about amending
*a conventional alternator to make it suitable for aircraft, with external regulators and whatever else.

Everything about light aircraft is low tech. Most of the engines are
1930's technology and a lot of the electrical systems.
It stems from the costs of getting anything new approved. Not enough
are sold to make it economic.

On Thursday, October 25, 2012 8:58:01 PM UTC+1, tony sayer wrote:



Well over many years I've started a lot of differing makes of vehicles

and have yet to have any alternator damage from a simple jump start.



I suspect the real plain old danger is getting the battery connected

arse about face;!...

Right, so your theory is that it has never happened to you;
you do not understand how it could happen;
therefore it cannot happen;
I had conected the jump leads negative to postive;
and that I am lying.

My theory is that it happened exactly as described;
and that Tony Sayer is a smug thick **** who does not know as much
about alternators as he likes to think.

There's a page here that explains how disconnecting the alternator output
"causes a high, momentary, voltage surge that will damage the electronics in the regulator and the diodes".

http://www.tb-training.co.uk/MarineE08.html

If you have any disagreements with that, then take it up with the author. Then do likewise with the thousands of other pages on the internet that you haven't bothered to read that say much the same.

If the jump leads had been wrongly connected, I would not have expected
the engine to start and run normally, until I disconnected the jump leads.

What happened was that my 'flat' battery was not flat, it was open circuit. Disconnecting the donor battery caused a voltage surge and wrecked the alternator.

You should apologise for questioning my word and my competence.
This would require you to have the intelligence to understand that you are mistaken and
the integrity to admit it.
I doubt that you will apologise.

In article ,
Onetap wrote:
What happened was that my 'flat' battery was not flat, it was open
circuit. Disconnecting the donor battery caused a voltage surge and
wrecked the alternator.

Quite. But then jump starting didn't cause the alternator to fail - it
would also have failed if the engine was started by any other method with
this faulty battery still in circuit.

--
*A 'jiffy' is an actual unit of time for 1/100th of a second.

Dave Plowman London SW
To e-mail, change noise into sound.

On Friday, October 26, 2012 10:10:19 AM UTC+1, Dave Plowman (News) wrote:

Quite. But then jump starting didn't cause the alternator to fail - it

would also have failed if the engine was started by any other method with

this faulty battery still in circuit.

Defective (or disconnected) battery + jump start = dead alternator.
Which is what I have said repeatedly to a chorus of derision.

I didn't know that could happen and it cost me an alternator to learn.

You usually don't have a battery charger or a multi-meter to hand when you need to jump start a car.

It would probably be safest to run the engine until the flat (?) battery had enough charge, then turn both off and disconnect the jump leads.

On Friday, October 26, 2012 10:17:54 AM UTC+1, Onetap wrote:

Defective (or disconnected) battery + jump start = dead alternator.

A bump start wouldn't have worked.
If you had tried to start the engine by mechanically spinning it somehow, that would also have wrecked the alternator.
The regulator tries to maintain 14V or so and on seeing 0V sends the output sky-high.

In article , harry wrote:

Tell us all how you can make a motor run on DC.

http://en.wikipedia.org/wiki/Homopolar_motor
Runs on DC. No commutator, no inverter. Not a lot of practical use,
but it works.

http://en.wikipedia.org/wiki/Railgun
Has practical use, and is at least arguably a kind of linear motor.
No commutator, no inverter. You put a DC pulse in, and get movement out....

On 26/10/12 10:17, Onetap wrote:
On Friday, October 26, 2012 10:10:19 AM UTC+1, Dave Plowman (News) wrote:

Quite. But then jump starting didn't cause the alternator to fail - it

would also have failed if the engine was started by any other method with

this faulty battery still in circuit.

Defective (or disconnected) battery + jump start = dead alternator.
Which is what I have said repeatedly to a chorus of derision.


A running engine on a disconnected battery does NOT guarantee a broken
alternator.

A had it happen to me. Car came to traffic lights and died, and the
lights went out..a seconds thought revealed the most likely problem was
a loose battery terminal. It had in fact shaken right off over a bump.

Putting it back on and bashing it with a boot heel restored normality.

There are ways to blow and alternator,, but total loss of a battery to
charge is not one of them.

A shorted battery is a different matter.


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

On 26/10/12 10:34, Alan Braggins wrote:
In article , harry wrote:

Tell us all how you can make a motor run on DC.

http://en.wikipedia.org/wiki/Homopolar_motor
Runs on DC. No commutator, no inverter. Not a lot of practical use,
but it works.

http://en.wikipedia.org/wiki/Railgun
Has practical use, and is at least arguably a kind of linear motor.
No commutator, no inverter. You put a DC pulse in, and get movement out....

:-)

However harry is MOSTLY right in that a so called 'DC' motor is in fact
an AC motor driven by a 'mechanical inverter'.

Oh and a DC pulse has an AC component :-) and 'motor' implies more or
less continuous movement which a railgun is NOT.



--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

In article ,
Onetap wrote:
On Friday, October 26, 2012 10:10:19 AM UTC+1, Dave Plowman (News) wrote:

Quite. But then jump starting didn't cause the alternator to fail - it

would also have failed if the engine was started by any other method with

this faulty battery still in circuit.

Defective (or disconnected) battery + jump start = dead alternator.
Which is what I have said repeatedly to a chorus of derision.

No - you said with a 'flat' battery. A very different matter from an open
circuit one. The first is likely why someone would jump start a car - the
second a fairly unusual occurrence.

I didn't know that could happen and it cost me an alternator to learn.

An breakdown service would have jump started it too with the same result.

You usually don't have a battery charger or a multi-meter to hand when
you need to jump start a car.

It would probably be safest to run the engine until the flat (?)
battery had enough charge, then turn both off and disconnect the jump
leads.

If the battery was totally open circuit it will never take a charge. Or
rather if it will, needs a very long slow charge at high voltage - days.

--
*Ambition is a poor excuse for not having enough sense to be lazy *

Dave Plowman London SW
To e-mail, change noise into sound.

On Thursday, 25 October 2012 07:41:55 UTC+1, harry wrote:

Car alternators can be used to demonstrate multi-phase generation,

But not a sine wave. They have been designe to produce as near a
square wave as they can manage.

Nope.


All rotating electric machine run on AC.

Nope^2

All can be used as a "motor" or "generator".

Nope^3

On Fri, 26 Oct 2012 01:40:26 -0700 (PDT), Onetap wrote:

There's a page here that explains how disconnecting the alternator output
"causes a high, momentary, voltage surge that will damage the electronics in the regulator and the diodes".

http://www.tb-training.co.uk/MarineE08.html

That page and the technology it is showing is like travelling back in time 40
years. Alternator design has moved on a bit since then.

Didn't you used to be called thirty six or something similar?


--

On Friday, October 26, 2012 11:24:06 AM UTC+1, Dave Plowman (News) wrote:

No - you said with a 'flat' battery. A very different matter from an open

circuit one. The first is likely why someone would jump start a car - the

second a fairly unusual occurrence.

I did say a 'flat' battery because it would not start the car and I assumed that it was "flat".
IMHO, that's not an unreasonable assumption, not having had a multi-meter or a battery charger
about my person that might have showed me otherwise.

Got that?

A breakdown service would have jump started it too with the same result.

And I'd want a new alternator from them, if they did.
See above; the AA jump started another car for me and used some gizmo and did some checking with a multi meter before disconnecting their leads.
I can now see why.



You usually don't have a battery charger or a multi-meter to hand when

you need to jump start a car.



It would probably be safest to run the engine until the flat (?)

battery had enough charge, then turn both off and disconnect the jump

leads.



If the battery was totally open circuit it will never take a charge. Or

rather if it will, needs a very long slow charge at high voltage - days.


Putting the "flat" battery on charge later for 24+ hours resulted in it having 0V. I then deduced that it was ****ed.

On Friday, October 26, 2012 11:47:23 AM UTC+1, The Other Mike wrote:

That page and the technology it is showing is like travelling back in time 40

years. Alternator design has moved on a bit since then.

So what new technology could I expect to find inside my alternator that would stop the diodes getting fried? I didn't notice any such gizmos. Please tell me and I'll have a look. I still have it in the shed.


Didn't you used to be called thirty six or something similar?

No. You're confusing me with someone else.

On 26/10/2012 12:14, Onetap wrote:
On Friday, October 26, 2012 11:24:06 AM UTC+1, Dave Plowman (News)
wrote:

No - you said with a 'flat' battery. A very different matter from
an open

circuit one. The first is likely why someone would jump start a car
- the

second a fairly unusual occurrence.

I did say a 'flat' battery because it would not start the car and I
assumed that it was "flat". IMHO, that's not an unreasonable
assumption, not having had a multi-meter or a battery charger about
my person that might have showed me otherwise.

Got that?

A breakdown service would have jump started it too with the same
result.

And I'd want a new alternator from them, if they did. See above; the
AA jump started another car for me and used some gizmo and did some
checking with a multi meter before disconnecting their leads. I can
now see why.



You usually don't have a battery charger or a multi-meter to hand
when

you need to jump start a car.



It would probably be safest to run the engine until the flat (?)

battery had enough charge, then turn both off and disconnect the
jump

leads.



If the battery was totally open circuit it will never take a
charge. Or

rather if it will, needs a very long slow charge at high voltage -
days.


Putting the "flat" battery on charge later for 24+ hours resulted in
it having 0V. I then deduced that it was ****ed.


And how do you know the alternator was not blown BEFORE you tried to
jump start?

--
Rod

On Friday, October 26, 2012 12:20:40 PM UTC+1, polygonum wrote:
On 26/10/2012 12:14, Onetap wrote:

And how do you know the alternator was not blown BEFORE you tried to

jump start?

FFS!
Because the battery charge light (or whatever it's called) wasn't lit when I last used the car, nor when I restarted it with jump leads. I disconnected the jump leads, the engine spluttered and died. On restarting again with jump leads or a good battery, the lamp was on.

Do you think the alternator was eaten by copper-boring beetles whilst it was parked or can you offer a rational explanation?

Have I stumbled into the UK.dullards newsgroup?

On Friday, October 26, 2012 11:18:17 AM UTC+1, The Natural Philosopher wrote:
On 26/10/12 10:17, Onetap wrote:

A running engine on a disconnected battery does NOT guarantee a broken

alternator.



A had it happen to me. Car came to traffic lights and died, and the

Yeah. Been there and the alternator survived.
I've jump started cars dozens of times and never had an alternator problem, except this once.

In article ,
The Natural Philosopher wrote:
Defective (or disconnected) battery + jump start = dead alternator.
Which is what I have said repeatedly to a chorus of derision.


A running engine on a disconnected battery does NOT guarantee a broken
alternator.

Pretty well nothing guarantees anything. But it can be the cause of some
makes failing.

--
*Bills travel through the mail at twice the speed of cheques *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Onetap wrote:
No - you said with a 'flat' battery. A very different matter from an
open

circuit one. The first is likely why someone would jump start a car -
the

second a fairly unusual occurrence.

I did say a 'flat' battery because it would not start the car and I
assumed that it was "flat". IMHO, that's not an unreasonable
assumption, not having had a multi-meter or a battery charger about my
person that might have showed me otherwise.

Got that?

Anyone with sense would have looked to see if there was any sign of life
from the battery - like dim panel lights. If absolutely nothing, get
professional help. Since you obviously didn't know of the possible hazards
of attempting to jump start an engine with an effectively disconnected
battery.

--
*Sticks and stones may break my bones but whips and chains excite me*

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Onetap wrote:
So what new technology could I expect to find inside my alternator that
would stop the diodes getting fried? I didn't notice any such gizmos.
Please tell me and I'll have a look. I still have it in the shed.

Modern semiconductors could stand a higher peak voltage.

--
*When cheese gets it's picture taken, what does it say?

Dave Plowman London SW
To e-mail, change noise into sound.

On Friday, October 26, 2012 12:57:30 PM UTC+1, Dave Plowman (News) wrote:
In article ,

The Natural Philosopher wrote:

Defective (or disconnected) battery + jump start = dead alternator.

Which is what I have said repeatedly to a chorus of derision.





A running engine on a disconnected battery does NOT guarantee a broken

alternator.



Pretty well nothing guarantees anything. But it can be the cause of some

makes failing.

It wrecked my alternator.
But I'm highly delighted to learn that it can't happen and that I'm wrong.
I have a Mondeo alternator in my shed that cannot have been damaged in this manner,
so it must be worth at least £30 to one of you internet alternator experts.
You'll get double that on E-bay. Any offers?
No?
Thought not.

On Friday, October 26, 2012 1:02:39 PM UTC+1, Dave Plowman (News) wrote:

Anyone with sense would have looked to see if there was any sign of life

from the battery - like dim panel lights. If absolutely nothing, get

professional help. Since you obviously didn't know of the possible hazards

of attempting to jump start an engine with an effectively disconnected

battery.

No, I didn't. I do now.

But this discussion has resulted from the internet alternator experts'
assertions that it could not happen.

I do not recall whether the lights were dim or off completely, but the car had run some weeks previously.
You're saying that in those circumstances you wouldn't have jump started the car, since you knew the risk of damaging the alternator.

I say you're full of bull****.

On Friday, October 26, 2012 1:02:40 PM UTC+1, Dave Plowman (News) wrote:

Modern semiconductors could stand a higher peak voltage.

Clearly, not high enough.

So, there are no alternator-saving gizmos in modern alternators, other than better semiconductors?

On 26/10/2012 12:46, Onetap wrote:
On Friday, October 26, 2012 12:20:40 PM UTC+1, polygonum wrote:
On 26/10/2012 12:14, Onetap wrote:

And how do you know the alternator was not blown BEFORE you tried
to

jump start?

FFS! Because the battery charge light (or whatever it's called)
wasn't lit when I last used the car, nor when I restarted it with
jump leads. I disconnected the jump leads, the engine spluttered and
died. On restarting again with jump leads or a good battery, the lamp
was on.

Do you think the alternator was eaten by copper-boring beetles whilst
it was parked or can you offer a rational explanation?

Have I stumbled into the UK.dullards newsgroup?

In my opinion, a perfectly sensible question. After all, a failing
alternator is fairly likely to end up causing (at least in part) a dead
battery.

--
Rod

In article ,
Onetap wrote:
On Friday, October 26, 2012 1:02:39 PM UTC+1, Dave Plowman (News) wrote:

Anyone with sense would have looked to see if there was any sign of life

from the battery - like dim panel lights. If absolutely nothing, get

professional help. Since you obviously didn't know of the possible hazards

of attempting to jump start an engine with an effectively disconnected

battery.

No, I didn't. I do now.

But this discussion has resulted from the internet alternator experts'
assertions that it could not happen.

Never say never.

I do not recall whether the lights were dim or off completely, but the
car had run some weeks previously.

So at least you've learned something.

You're saying that in those circumstances you wouldn't have jump
started the car, since you knew the risk of damaging the alternator.

I say you're full of bull****.

Why is it so difficult for you to understand that many have far more
knowledge about these things than you?

I've known for years it was bad practice to disconnect the battery with
the engine running - due to the possibility of damage to the alternator
and other car electrics.

You've only recently learned this. Get over it and move on.

--
*Tell me to 'stuff it' - I'm a taxidermist.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Onetap wrote:
On Friday, October 26, 2012 1:02:40 PM UTC+1, Dave Plowman (News) wrote:

Modern semiconductors could stand a higher peak voltage.

Clearly, not high enough.

So, there are no alternator-saving gizmos in modern alternators, other
than better semiconductors?

It's easy to make things fool proof. Making them c**t proof is the
difficult part.

--
*I never drink anything stronger than gin before breakfast *

Dave Plowman London SW
To e-mail, change noise into sound.