In article ,
Roger Hayter wrote:
Once the alternator is fixed I recommend a new battery, even if the old
one seems to work.

You'd simply lash out up to about £100 or so without testing the old one?

--
*If a pig loses its voice, is it disgruntled?

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

"D.M. Procida" wrote in
message
...
alan_m wrote:

On 03/03/2017 20:03, Joe Bloggs wrote:

6. More than once recently though I've stopped the car for a few
moments
after driving several miles, and will find that it doesn't start and
needs a push to get going again.



That wouldn't explain number 6.

A few miles on a uncharged battery results in a still uncharged battery

The battery on both those occasions was charged well enough to start the
car.

That does suggest that the battery isn't charging after it has started the
engine and during the subsequent running - either because the
alternator/charging circuitry has failed or because something is drawing a
large current so the alternator cannot supply sufficient current both to
supply that load and at the same time replenish the battery charge that has
been taken out during starting.

I'd suggest:

- If you can manage without the car for a day, charge the battery using a
battery charger and then leave it for 24 hours without being connected to
anything: this will eliminate self-discharge.

- If you have an ammeter that can measure large currents, connect it in
series with the battery in the car with a) the ignition and everything else
switched off, b) the ignition on but engine not running. DO NOT LEAVE IT IN
PLACE WHEN YOU START THE ENGINE because the starter motor current will
probably blow the ammeter or fry its leads. If there is a significant spark
when you reconnect the charged battery (without the ammeter) then that
suggests that a large current is being drawn, so maybe it's not wise to use
the ammeter in that case.

- Measure the charging voltage (voltmeter across the battery) when the
engine is idling and when it's revving at 2000 rpm. Certainly in the latter
case you should see around 14V - higher than the voltage without the engine
running.

- Measure the battery voltage with the ignition on but the engine not
running - does this cause the battery voltage to fall below the no-load
voltage of about 12V?

- Get the battery tested at a garage or at Halford's.

On 04/03/2017 11:16, Dave Plowman (News) wrote:
In article
,
D.M. Procida wrote:
Tim Watts wrote:

8/10 of my votes are simply on a dead battery.

That's what I thought, which is why this battery is fairly new.
Unfortunately, despite the change of battery, the problem slowly
continued to get worse.

In fact, after I changed the battery, I realised I'd changed the battery
once before and had simply forgotten that!

So I don't believe the problem is the battery itself.

Batteries are very expensive items. And are easy enough to test with the
correct equipment. Not something I'd fit a new one of on a whim.

Any auto electrician should be able to test the battery, charging system
and check for high quiescent load in a matter of minutes.

You mean one who sells new batteries?

--
Max Demian

"Brian Gaff" wrote in message
news
No if it were the starter the clock would not reset.

If the current drawn by the starter motor causes the terminal voltage to
drop too far (eg due to high internal resistance of battery or its contacts)
then it will drop below the threshold that the clock needs to make it work.
That will reset the clock.

Dave Plowman (News) wrote:

In article ,
Roger Hayter wrote:
Once the alternator is fixed I recommend a new battery, even if the old
one seems to work.

You'd simply lash out up to about £100 or so without testing the old one?

If I knew it had been too flat to start the car a few times, yes.
Life's too short.
--

Roger Hayter

In article ,
Max Demian wrote:
Any auto electrician should be able to test the battery, charging
system and check for high quiescent load in a matter of minutes.

You mean one who sells new batteries?

No. I mean an auto electrician. Might be hard to find one, of course.

I bought myself an ACT battery tester ages ago. Not cheap, but does test a
battery quickly and easily. I'd hope any place claiming to test batteries
would have something similar.

--
*Artificial Intelligence is no match for Natural Stupidity *

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

D.M. Procida wrote:
Here are the facts:

1. The car is used once or twice a week, mostly for short trips.

2. Nearly every time we use it, the battery is too dead to turn the
engine over and it needs to be charged. In fact it's so dead that even
trying will produce nothing but a click and drop the voltage across
the electrical system so low that it resets the clock.

3. After 20 minutes or so of charging, it'll start without difficulty
(it's only a 1.2l engine).

4. Alternatively, a quick push will do the trick.

5. If it has just recently been on a long drive (in the previous day
or so), or has been used once that day already, it will start without
problems, though.

6. More than once recently though I've stopped the car for a few
moments after driving several miles, and will find that it doesn't
start and needs a push to get going again.

7. It's getting worse.

8. The battery is fairly new.

I'm assuming that the problem is the alternator failing to charge the
battery properly, but no. 6 is a puzzle to me.

Thanks,

Daniele

There's a bad connection from the battery.

Take both leads off, clean the terminals and the connectors with wire wool /
wire brush and reconnect.
If it's the same, I'd be looking at the negative lead where it connects to
the car body or where the live goes to the alternator.

If it's neither of those then it's a new alternator required.

In article ,
Roger Hayter wrote:
Dave Plowman (News) wrote:

In article ,
Roger Hayter wrote:
Once the alternator is fixed I recommend a new battery, even if the
old one seems to work.

You'd simply lash out up to about £100 or so without testing the old
one?

If I knew it had been too flat to start the car a few times, yes.
Life's too short.

If you have a charging fault, the new battery will be exactly the same.

--
*HOW DO THEY GET DEER TO CROSS THE ROAD ONLY AT THOSE YELLOW ROAD SIGNS?

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

"Dave Plowman (News)" wrote in message
...
In article ,
Max Demian wrote:
Any auto electrician should be able to test the battery, charging
system and check for high quiescent load in a matter of minutes.

I bought myself an ACT battery tester ages ago. Not cheap, but does test a
battery quickly and easily.

But now comparatively cheap
http://www.ebay.co.uk/itm/142053137962

-

In article ,
Mark wrote:

"Dave Plowman (News)" wrote in message
...
In article ,
Max Demian wrote:
Any auto electrician should be able to test the battery, charging
system and check for high quiescent load in a matter of minutes.

I bought myself an ACT battery tester ages ago. Not cheap, but does
test a battery quickly and easily.

But now comparatively cheap
http://www.ebay.co.uk/itm/142053137962

No idea if that is as good. The ACT principle is covered by patents?

What is does is calculate the actual capacity of the battery in amp.hrs,
which you can check against that stated on the case. Once it falls by more
than a given percentage, it is replacement time. Never known it to be
wrong. But of course with me it usually just confirms what I already knew,
with my own batteries. But handy for testing one you don't know.

--
*This message has been ROT-13 encrypted twice for extra security *

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

On Sat, 4 Mar 2017 14:59:08 -0000, Phil L wrote:

Take both leads off, clean the terminals and the connectors with wire
wool / wire brush and reconnect.

With a smear of vaseline, it helps keep the acid fumes from corroding
the connenctions.

If it's the same, I'd be looking at the negative lead where it connects
to the car body or where the live goes to the alternator.

And each end of the engine block to chassis straps.

--
Cheers
Dave.

On Sat, 04 Mar 2017 13:53:56 +0000 (GMT), Dave Plowman (News) wrote:

I bought myself an ACT battery tester ages ago. Not cheap, but does test
a battery quickly and easily. I'd hope any place claiming to test
batteries would have something similar.

I think our local garage's battery tester is BFO wire wound resistor
(foot long 1" dia) attached to a frame with a couple of hefty hinged
probes. A volt meter is wired across the resistor. Firmly push one
probe onto one terminal, whack the other onto the other hold for a
few seconds as 100 odd amps flow and watch the voltage... Hopefully
the first probe on doesn't weld itself to the terminal, the other
might if you are a bit slow whacking it on and pulling it off. B-)

--
Cheers
Dave.

In article l.net,
Dave Liquorice wrote:
On Sat, 04 Mar 2017 13:53:56 +0000 (GMT), Dave Plowman (News) wrote:

I bought myself an ACT battery tester ages ago. Not cheap, but does test
a battery quickly and easily. I'd hope any place claiming to test
batteries would have something similar.

I think our local garage's battery tester is BFO wire wound resistor
(foot long 1" dia) attached to a frame with a couple of hefty hinged
probes. A volt meter is wired across the resistor. Firmly push one
probe onto one terminal, whack the other onto the other hold for a
few seconds as 100 odd amps flow and watch the voltage... Hopefully
the first probe on doesn't weld itself to the terminal, the other
might if you are a bit slow whacking it on and pulling it off. B-)

Yes - that's the old way. The ACT unit is more the size of a DVM - and no
sparks when you connect it. Or things glowing red hot. ;-)

It's a superb device.

--
*Income tax service - We‘ve got what it takes to take what you've got.

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

"Dave Plowman (News)" wrote in message
...
In article l.net,
Dave Liquorice wrote:
On Sat, 04 Mar 2017 13:53:56 +0000 (GMT), Dave Plowman (News) wrote:

I bought myself an ACT battery tester ages ago. Not cheap, but does
test
a battery quickly and easily. I'd hope any place claiming to test
batteries would have something similar.

I think our local garage's battery tester is BFO wire wound resistor
(foot long 1" dia) attached to a frame with a couple of hefty hinged
probes. A volt meter is wired across the resistor. Firmly push one
probe onto one terminal, whack the other onto the other hold for a
few seconds as 100 odd amps flow and watch the voltage... Hopefully
the first probe on doesn't weld itself to the terminal, the other
might if you are a bit slow whacking it on and pulling it off. B-)

So it all depends how quickly you whack off? ;-)

Yes that's the type of battery tester that I've seen used. Very primitive!


Yes - that's the old way. The ACT unit is more the size of a DVM - and no
sparks when you connect it. Or things glowing red hot. ;-)

It's a superb device.

Considerably better. But unless it draws a significant current, how does it
test the ability of the battery to supply that current? Can you extrapolate
and say "if the battery terminal voltage drops from A to B when a small
current is drawn, then there will be a correspondingly larger voltage drop
to C if a proportionally larger current is drawn"? In other words, are
voltage drop and current always proportional: does a lead-acid battery
behave as an infinite current source in series with a fixed resistance, and
does that fixed resistance remain constant as the battery discharges?

Evidently there is, given that ACT units give useful results :-)

"Dave Plowman (News)" wrote in message
...
In article ,
Mark wrote:

"Dave Plowman (News)" wrote in message
...
In article ,
Max Demian wrote:
Any auto electrician should be able to test the battery, charging
system and check for high quiescent load in a matter of minutes.

I bought myself an ACT battery tester ages ago. Not cheap, but does
test a battery quickly and easily.

But now comparatively cheap
http://www.ebay.co.uk/itm/142053137962

No idea if that is as good. The ACT principle is covered by patents?

What is does is calculate the actual capacity of the battery in amp.hrs,
which you can check against that stated on the case.

Yes works exactly the same
read the item description or look it up on youtube
its from China so Patents dont apply ;(

-

On 04/03/17 00:12, Dave Liquorice wrote:
On Fri, 3 Mar 2017 22:10:01 +0000, Tim Watts wrote:

It's ****ed Up Beyond All Recognition (IBM), ...

Thought FUBAR was military (army) in origin?

Opinions vary as they usually do with these things. I heard IBM, but
military is just as good a theory

... it's shagged (Python),

Donno.

... it's buggered (me).

Yep one must make the distinction between ****ed (spontaneously
broken) and buggered (some one broke it).

On 04/03/17 00:14, newshound wrote:
On 3/3/2017 10:07 PM, Tim Watts wrote:
8/10 of my votes are simply on a dead battery.

Take it to a garage and ask for a drop test - that will verify that one
way or another, quickly.

Next, get a volt meter that plugs in the cigarette socket (ebay, amazon,
cheap as chips).

+1. I have had a couple of vehicles which have shown these sort of
erratic symptoms, and one which still does. It's a van which only gets
intermittent use (and doesn't bleep at you if you park with the lights on).

After having to get a couple of the lads at Wickes to bump start me
after I had loaded half a ton of ballast in it, my fix is to carry one
of these all the time:

http://www.ebay.co.uk/itm/FLOUREON-1...AOSwp5JWbVe z


Even my wife can use it! Usually at Sainsburys though.

Also handy as it will recharge a mobile or satnav even when parked up.



I have the DBPower branded very similar version. It started a dead 2l VW
diesel twice without any effort on its part.

The only thing that makes me nervous is it being a very high density
lithium battery in a hot car - so I tend to take it out in summer. But
summer usually gives me less problems than winter.

On 04/03/17 06:51, Joe Bloggs wrote:
On 04-Mar-17 6:44 AM, The Natural Philosopher wrote:
On 03/03/17 20:27, Joe Bloggs wrote:
You know, there was a time in this country - not a million years ago -
when certain things were not said, and certain words were not used, in
general social situations. That has changed, and now this sort of gutter
language pervades almost all aspects of life. It hasn't improved
anything, quite the reverse, and all it demonstrates is the inability of
certain types to respect the language and other people.

Oh do **** off, there's a good chap.



If you mean by that don't bother to use this ng again, you needn't worry
about that. You fact that many of you are pure scum is all the incentive
any civilised person would need.


Bye troll boy...

"NY" wrote in message
o.uk...

Yes - that's the old way. The ACT unit is more the size of a DVM - and no
sparks when you connect it. Or things glowing red hot. ;-)

It's a superb device.

Considerably better. But unless it draws a significant current, how does
it test the ability of the battery to supply that current? Can you
extrapolate and say "if the battery terminal voltage drops from A to B
when a small current is drawn, then there will be a correspondingly larger
voltage drop to C if a proportionally larger current is drawn"? In other
words, are voltage drop and current always proportional: does a lead-acid
battery behave as an infinite current source in series with a fixed
resistance, and does that fixed resistance remain constant as the battery
discharges?

Evidently there is, given that ACT units give useful results :-)


they claim to measure the conductance of the battery
http://www.uobdii.com/upload/pro/ba1...ser-manual.pdf

-

In article ,
NY wrote:
It's a superb device.

Considerably better. But unless it draws a significant current, how does
it test the ability of the battery to supply that current? Can you
extrapolate and say "if the battery terminal voltage drops from A to B
when a small current is drawn, then there will be a correspondingly
larger voltage drop to C if a proportionally larger current is drawn"?
In other words, are voltage drop and current always proportional: does
a lead-acid battery behave as an infinite current source in series with
a fixed resistance, and does that fixed resistance remain constant as
the battery discharges?

Evidently there is, given that ACT units give useful results :-)

I'd guess it draws a *very* heavy current for an instant. Judging by the
clever crock clip design - to give it a very low impedance connection.

--
*It IS as bad as you think, and they ARE out to get you.

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

On Sat, 4 Mar 2017 06:51:49 +0000, Joe Bloggs wrote:

If you mean by that don't bother to use this ng again, you needn't worry
about that. You fact that many of you are pure scum is all the incentive
any civilised person would need.

The killfile should take care of this.

In article
,
D.M. Procida writes
Tim Watts wrote:

8/10 of my votes are simply on a dead battery.

That's what I thought, which is why this battery is fairly new.
Unfortunately, despite the change of battery, the problem slowly
continued to get worse.

In fact, after I changed the battery, I realised I'd changed the battery
once before and had simply forgotten that!

So I don't believe the problem is the battery itself.

Daniele

As has been suggested
1. Check voltage at battery terminals with engine running - should be
13.8 or greater. If not then you have an alternator/charging controls
problem.
2. Second likely problem is poor connection of the heavy duty leads
between battery negative and chassis/engine block. Check these. Grip the
cable and give a hard twist. ANY movement indicates problem. May be as
well to check the positive connection also.
No point discussing other possibilities until these two actions have
been completed.
--
bert

On 03/03/2017 21:02, Joe Bloggs wrote:
On 03-Mar-17 8:23 PM, alan_m wrote:
On 03/03/2017 20:03, Joe Bloggs wrote:

6. More than once recently though I've stopped the car for a few
moments
after driving several miles, and will find that it doesn't start and
needs a push to get going again.

That wouldn't explain number 6.

A few miles on a uncharged battery results in a still uncharged battery

Depends how many miles and whether or not on those specific occasions
the battery was actually 'uncharged' to start with - and he/she did say
'several miles'.

Several miles in winter when headlights tend to get used more may not be
enough to restore the energy taken from the battery to start the car.

A cheap DVM will show the state of charge of the battery.

Checking battery voltage with and without the engine running will show
if the alternator is performing.

--
Regards,
Martin Brown

On 03/03/2017 21:25, ARW wrote:
On 03/03/2017 20:27, Joe Bloggs wrote:
On 03-Mar-17 8:19 PM, Huge wrote:
On 2017-03-03, Joe Bloggs wrote:
On 03-Mar-17 8:09 PM, Huge wrote:
On 2017-03-03, D.M. Procida
wrote:
Here are the facts:

1. The car is used once or twice a week, mostly for short trips.

2. Nearly every time we use it, the battery is too dead to turn the
engine over and it needs to be charged. In fact it's so dead that
even
trying will produce nothing but a click and drop the voltage across
the
electrical system so low that it resets the clock.

3. After 20 minutes or so of charging, it'll start without difficulty
(it's only a 1.2l engine).

[12 lines snipped]

8. The battery is fairly new.

And ****ed. Buy a new battery.



You might be right, but is that the only way you're able to express
yourself?

Oh, dear, has the nasty man used a word you don't approve of? Well,
tough
titty.


You know, there was a time in this country - not a million years ago -
when certain things were not said, and certain words were not used, in
general social situations. That has changed, and now this sort of gutter
language pervades almost all aspects of life. It hasn't improved
anything, quite the reverse, and all it demonstrates is the inability of
certain types to respect the language and other people.



History says otherwise


"What the **** was that?" Mayor of Hiroshima
"Where did all these ****ing Indians come from?" General Custer
"Where the **** is all this water coming from?" Captain of the Titanic
"Thats not a real ****ing gun." John Lennon
"Who's gonna ****ing find out?" Richard Nixon
"Heads are going to ****ing roll." Anne Boleyn
"Let the ****ing woman drive." Commander of Space Shuttle "Challenger"
"What ****ing map?" Mark Thatcher
"Any ****ing idiot could understand that." Albert Einstein
"How the **** did you work that out?" Pythagoras
"You want what on the ****ing ceiling?" Michaelangelo
"**** a duck." Walt Disney
"Why?- Because its ****ing there!" Edmund Hilary
"I don't suppose its gonna ****ing rain?" Joan of Arc
"Scattered ****ing showers my ass." Noah
"I need this parade like I need a ****ing hole in my head." John F. Kennedy


You missed one.
Shut that ****ing door. Captain, Herald of Free Enterprise.

Mike

bert wrote:

In article
,
D.M. Procida writes
Tim Watts wrote:

8/10 of my votes are simply on a dead battery.

That's what I thought, which is why this battery is fairly new.
Unfortunately, despite the change of battery, the problem slowly
continued to get worse.

In fact, after I changed the battery, I realised I'd changed the battery
once before and had simply forgotten that!

So I don't believe the problem is the battery itself.

Daniele

As has been suggested
1. Check voltage at battery terminals with engine running - should be
13.8 or greater. If not then you have an alternator/charging controls
problem.
2. Second likely problem is poor connection of the heavy duty leads
between battery negative and chassis/engine block. Check these. Grip the
cable and give a hard twist. ANY movement indicates problem. May be as
well to check the positive connection also.
No point discussing other possibilities until these two actions have
been completed.

The only thing I would add is that it is possible to get a false
negative in test 1. The alternator can be producing a significant
charging current, sufficient to raise the voltage under test conditions,
but still unable to produce sufficient current to maintain battery
charge in ordinary driving. Especially in the dark or in Winter. To be
sure you need to actually measure how much current the altenator can
produce at highish revs, most easily with a DC clamp meter.


--

Roger Hayter

On 03/03/17 18:59, D.M. Procida wrote:
Here are the facts:

1. The car is used once or twice a week, mostly for short trips.

2. Nearly every time we use it, the battery is too dead to turn the
engine over and it needs to be charged. In fact it's so dead that even
trying will produce nothing but a click and drop the voltage across the
electrical system so low that it resets the clock.

3. After 20 minutes or so of charging, it'll start without difficulty
(it's only a 1.2l engine).

4. Alternatively, a quick push will do the trick.

5. If it has just recently been on a long drive (in the previous day or
so), or has been used once that day already, it will start without
problems, though.

6. More than once recently though I've stopped the car for a few moments
after driving several miles, and will find that it doesn't start and
needs a push to get going again.

7. It's getting worse.

8. The battery is fairly new.

I'm assuming that the problem is the alternator failing to charge the
battery properly, but no. 6 is a puzzle to me.

Thanks,

Daniele



If it is an older car, with a simple ignition circuit, does the ignition
light come on when you turn the ignition on?

If not, check the wiring and bulb.

Other possibilities:

Poor earth connection- battery to chassis or engine to chassis.

Assuming you've not added something recently which is drawing current
while the ignition is not only off, but the key is removed, a wiring
issue. Look at the door switch wires, they often get damaged.

Alternator

In article ,
Roger Hayter wrote:
The only thing I would add is that it is possible to get a false
negative in test 1. The alternator can be producing a significant
charging current, sufficient to raise the voltage under test conditions,
but still unable to produce sufficient current to maintain battery
charge in ordinary driving. Especially in the dark or in Winter. To be
sure you need to actually measure how much current the altenator can
produce at highish revs, most easily with a DC clamp meter.

Or simply switch on all the normal loads like headlamps and heater etc and
check the voltage again. With the engine at a fast idle. If the alternator
can't balance the load the voltage will be low too.

--
*Real men don't waste their hormones growing hair

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

D.M. Procida wrote:

1. The car is used once or twice a week, mostly for short trips.

2. Nearly every time we use it, the battery is too dead to turn the
engine over and it needs to be charged. In fact it's so dead that even
trying will produce nothing but a click and drop the voltage across the
electrical system so low that it resets the clock.

3. After 20 minutes or so of charging, it'll start without difficulty
(it's only a 1.2l engine).

4. Alternatively, a quick push will do the trick.

5. If it has just recently been on a long drive (in the previous day or
so), or has been used once that day already, it will start without
problems, though.

6. More than once recently though I've stopped the car for a few moments
after driving several miles, and will find that it doesn't start and
needs a push to get going again.

7. It's getting worse.

8. The battery is fairly new.

Thanks for the many replies.

On the basis of advice, I disconnected the battery five days ago
(Sunday), charged it up, and left it disconnected. This morning
(Thursday) I reconnected it; the engine started immediately without
issue (and the same for multiple subsequent starts).

The battery reads about 12.3v while connected and the same disconnected.
At idle, it reads just about 14.3v.

I couldn't read anything between the battery earth and the chassis.

So it sounds to me that the battery is fine.

What do you suggest for the next step in the investigation?

Daniele

In article
,
D.M. Procida wrote:
On the basis of advice, I disconnected the battery five days ago
(Sunday), charged it up, and left it disconnected. This morning
(Thursday) I reconnected it; the engine started immediately without
issue (and the same for multiple subsequent starts).

The battery reads about 12.3v while connected and the same disconnected.
At idle, it reads just about 14.3v.

I couldn't read anything between the battery earth and the chassis.

So it sounds to me that the battery is fine.

What do you suggest for the next step in the investigation?

As was said, check the voltage at the battery with the engine at a fast
idle and the headlights on main beam, heater and heated rear window on.

Anything less than about 13.5v probably means it's not charging properly.

If that is OK, you need to measure what current is being taken from the
battery with the engine stopped and everything switched off. That should
be something like 50 mA maximum.

But many DVMs will blow their fuse or worse if used for this.

--
*Why is it that most nudists are people you don't want to see naked?*

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

"D.M. Procida" wrote in
message
...
On the basis of advice, I disconnected the battery five days ago
(Sunday), charged it up, and left it disconnected. This morning
(Thursday) I reconnected it; the engine started immediately without
issue (and the same for multiple subsequent starts).

The battery reads about 12.3v while connected and the same disconnected.
At idle, it reads just about 14.3v.

I couldn't read anything between the battery earth and the chassis.

So it sounds to me that the battery is fine.

Yes, it sounds as if the battery is holding its charge.

What do you suggest for the next step in the investigation?

Take the fully charged battery and connect it into the car overnight, with
everything switched off. After dark, go round and check for any lights (eg
interior, boot) remaining on when the car doors are closed.

If the battery won't start the car the following morning, it's stray current
drain - something somewhere is drawing current when it shouldn't.

This is independent of whether or not the alternator is working properly to
charge the battery in situ, so as to replace the charge used to start the
engine, and to supply the car's needs while running.

Once you've eliminated stray current drain, then you can move onto the
second stage of whether or not the alternator is charging. The fact that you
are getting 14V at idle tends to suggest that the charging circuit is
working.

On 09/03/2017 11:27, Dave Plowman (News) wrote:

If that is OK, you need to measure what current is being taken from the
battery with the engine stopped and everything switched off. That should
be something like 50 mA maximum.

But many DVMs will blow their fuse or worse if used for this.


A dc clamp meter is useful at this point.
About £30 from cpc.

On Thu, 9 Mar 2017 11:01:09 +0000,
(D.M. Procida) wrote:


The battery reads about 12.3v while connected and the same disconnected.
At idle, it reads just about 14.3v.

I couldn't read anything between the battery earth and the chassis.

So it sounds to me that the battery is fine.

What do you suggest for the next step in the investigation?

Daniele

I haven't seen you mention a make/model/year of but it might be worth
perusing the WWW for any owners forums for your car and see if any
others have a battery drain problem or parasitic draw as some call it.
I gave an Astra to my parents which had been my company car,unlike me
they only drove it once a week and the battery was drained by some
draw in the alarm/ immobiliser that was greater than normal.
The local village garage did not have the knowledge/resources to get
to the bottom of it. Dad just lived with it and left the car unlocked
as it was kept in a shed on a farm miles from anywhere.

G.Harman

On 09/03/2017 11:42, NY wrote:


Take the fully charged battery and connect it into the car overnight,
with everything switched off. After dark, go round and check for any
lights (eg interior, boot) remaining on when the car doors are closed.


And don't forget that sneaky glove box light (if you have one). It can
be difficult to tell if the glove box light goes out when you shut the
door.


--
Chris B (News)

In article . com,
dennis@home wrote:
If that is OK, you need to measure what current is being taken from the
battery with the engine stopped and everything switched off. That should
be something like 50 mA maximum.

But many DVMs will blow their fuse or worse if used for this.


A dc clamp meter is useful at this point.
About £30 from cpc.

I've not found them very accurate for low loads. But haven't tried the
very latest ones.

What I do with a DVM is to connect it in current mode between battery and
terminal before disconnecting that terminal. So any switch on surge
doesn't go through the meter. And obviously use the 10 amp range on the
DVM initially. If that shows a nice low value you can then get the exact
reading using a lower current range.

--
*Ever stop to think and forget to start again?

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

In article ,
NY wrote:
Take the fully charged battery and connect it into the car overnight,
with everything switched off. After dark, go round and check for any
lights (eg interior, boot) remaining on when the car doors are closed.

If the battery won't start the car the following morning, it's stray
current drain - something somewhere is drawing current when it
shouldn't.

This is independent of whether or not the alternator is working properly
to charge the battery in situ, so as to replace the charge used to
start the engine, and to supply the car's needs while running.

Once you've eliminated stray current drain, then you can move onto the
second stage of whether or not the alternator is charging. The fact that
you are getting 14V at idle tends to suggest that the charging circuit
is working.

If that shows nothing on but the battery discharges, charge the battery
again and repeat with the alternator disconnected. Note the thick wire(s)
are live at all times so make sure they don't short to any metalwork.

If a diode in the alternator rectifier fails, the alternator may still
'work' but draw current from the battery when the engine is turned off.

--
*I'm already visualizing the duct tape over your mouth

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

On Thu, 9 Mar 2017 11:01:09 +0000,
(D.M. Procida) wrote:

What do you suggest for the next step in the investigation?

Measure the current draw of the car when off: disconnect one pole of the
battery, set multimeter to 10A, plug leads accordingly and connect multimeter in
series.

Do NOT start the car (turn on the headlights, the window heater, radio, etc.),
as this will draw far more that 10 amps and the leads will go up in smoke and
fire. (Cheap multimeters will not have fuse protection in the 10 amp range.
Please put the leads where them melting etc. will cause as little damage as
possible.)

Check the reading, and reduce the range if appropriate, which may entail
replugging the leads. The car should not be drawing more that say 100 milliamps.
It probably will be drawing more, because I'm assuming something is draining the
battery fairly heftily.

Start pulling fuses, one by one, replacing them for simplicity. Removing the
fuse protecting the circuit that is causing the drain (and likely faulty) will
cause the current drain to drop.

Then it is a question of finding what's wrong with the circuit. This can be
trivial, or not...


Thomas Prufer

Dave Plowman (News) wrote:
In article ,
NY wrote:
Take the fully charged battery and connect it into the car overnight,
with everything switched off. After dark, go round and check for any
lights (eg interior, boot) remaining on when the car doors are closed.

If the battery won't start the car the following morning, it's stray
current drain - something somewhere is drawing current when it
shouldn't.

This is independent of whether or not the alternator is working properly
to charge the battery in situ, so as to replace the charge used to
start the engine, and to supply the car's needs while running.

Once you've eliminated stray current drain, then you can move onto the
second stage of whether or not the alternator is charging. The fact that
you are getting 14V at idle tends to suggest that the charging circuit
is working.

If that shows nothing on but the battery discharges, charge the battery
again and repeat with the alternator disconnected. Note the thick wire(s)
are live at all times so make sure they don't short to any metalwork.

If a diode in the alternator rectifier fails, the alternator may still
'work' but draw current from the battery when the engine is turned off.

I've also had a leakage problem when water had got into the fusebox of
my sons mk11 focus. Even though it had all dried out there was corrosion
and growth between the metal busbars under the fuses. enough to give a
30mA continuous leak in addition to alarms, radio back up etc etc as
found in a modern car.

In article ,
Bob Minchin wrote:
If a diode in the alternator rectifier fails, the alternator may still
'work' but draw current from the battery when the engine is turned off.

I've also had a leakage problem when water had got into the fusebox of
my sons mk11 focus. Even though it had all dried out there was corrosion
and growth between the metal busbars under the fuses. enough to give a
30mA continuous leak in addition to alarms, radio back up etc etc as
found in a modern car.

Think some of the earlier Escorts also had a fusebox in a silly position.
Or just made so that is was prone to faults through damp.

--
*What boots up must come down *

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

In article ,
Thomas Prufer wrote:
Measure the current draw of the car when off: disconnect one pole of the
battery, set multimeter to 10A, plug leads accordingly and connect
multimeter in series.

Some cars can take more than 10 amps when the battery is connected
initially. And blow the DVM fuse - or worse.

Mine does. The central locking will trigger when the battery is first
connected.

--
*Nothing is foolproof to a sufficiently talented fool*

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

On 09/03/17 11:01, D.M. Procida wrote:
D.M. Procida wrote:

1. The car is used once or twice a week, mostly for short trips.

2. Nearly every time we use it, the battery is too dead to turn the
engine over and it needs to be charged. In fact it's so dead that even
trying will produce nothing but a click and drop the voltage across the
electrical system so low that it resets the clock.

3. After 20 minutes or so of charging, it'll start without difficulty
(it's only a 1.2l engine).

4. Alternatively, a quick push will do the trick.

5. If it has just recently been on a long drive (in the previous day or
so), or has been used once that day already, it will start without
problems, though.

6. More than once recently though I've stopped the car for a few moments
after driving several miles, and will find that it doesn't start and
needs a push to get going again.

7. It's getting worse.

8. The battery is fairly new.

Thanks for the many replies.

On the basis of advice, I disconnected the battery five days ago
(Sunday), charged it up, and left it disconnected. This morning
(Thursday) I reconnected it; the engine started immediately without
issue (and the same for multiple subsequent starts).

The battery reads about 12.3v while connected and the same disconnected.
At idle, it reads just about 14.3v.

I couldn't read anything between the battery earth and the chassis.

So it sounds to me that the battery is fine.

What do you suggest for the next step in the investigation?

Well you have remade the connections.

It should be fine now as the lost likely explanation was a bad connection.




Daniele



--
Microsoft : the best reason to go to Linux that ever existed.