Flat battery and booster battery problem

#11

beccy wrote:

Quote:

On 14:18 14 Oct 2009, Adrian C wrote:

beccy wrote:
I'm in the UK. Car is 1.3 litre.

QUESTION (1) I know this may not be the best way of doing it
but, in theory, if a car battery got flattened by leaving the
headlights on then why would a fully charged second battery
attached in parallel to the flat battery give almost no help
at all?

Jump leads not making electrical contact. Some cheap ones have
insufficient metal in the plastic jaws and I've come across
ones where the rest of the plastic prevents metal to metal
contact. Get a torch and take a good look when you have them
'attached'. It's probably not connecting ...

I wondered about the area of contact because the clips had a sort of
lipped shape on each surface which meant the contact area was a
metal edge. IYSWIM. It didn't seem much to me. But if the area is
too small then wouldn't the jump lead clip get hot where it did make
contact?

cheap leads often corrode where the cables meet the clips and no contact
results. A good healthy crackle as you connect the final clip shows
something is moving, then just leave them connected for a while before
trying to start the dead one.

#12

"Chris Bartram" <news (AT) delete-me (DOT) piglet-net.net> wrote

Quote:

beccy wrote:

"Pernanently knackered through being run totally flat"? Can it be
permanent? Is there an simple way to test this without going to a
garage?
Go to a motor factors that sells batteries. Most will do a free test.
Halfords, if you must, but they'll rob you blind for the new one...

You're missing the point - the battery is flat. Deal with that problem
first and then the car can be driven to places you suggest.

#13

In article <Xns9CA49C129671AF3QA2 (AT) newsfarm (DOT) ams2.highwinds-media.com>,
beccy <no (AT) not (DOT) here> wrote:

Quote:

If the second battery is good it means the connection between
them isn't. Most jump leads are incapable of carrying the full
starter current. Ones which can cost upwards of 50 quid.

The jump leads have worked well in the past but they're not £50+
leads! Maybe this time the spare battery is having to provide
even more power than the times in the past.

If the battery isn't totally flat it will provide some of the current
needed. It's totally flat ones that sort out the jump leads. ;-)

Quote:

QUESTION (2) If that's so then, to get the car started, is it
absolutely necessary to put a charger on the flat battery
which is in the car?

If the battery isn't permanently knackered through being run
totally flat, another car connected to it and the engine run
for a while might then charge it enough. But an overnight
charge with a charger is a better bet. Lidl have some decent
ones in at the moment for only 14 quid. Small enough to keep in
the car.

"Pernanently knackered through being run totally flat"? Can it be
permanent? Is there an simple way to test this without going to
a garage?

Try charging it. If it takes a charge you might be ok.

--
*Work is for people who don't know how to fish.

Dave Plowman dave (AT) davenoise (DOT) co.uk London SW
To e-mail, change noise into sound.

#14

In article <JzlBm.3090$KR3.1904 (AT) text (DOT) news.virginmedia.com>,
Mrcheerful <nbkm57 (AT) hotmail (DOT) co.uk> wrote:

Quote:

It is quite possible in emergency to jump start a car using thin bits of
household flex, just leave them connected for half an hour or so (then
remove the cables) and enough charge will have transfered to start it
up.

That's true if using a car to jump start from and you leave the engine
running. Just coupling two batteries together won't really charge the flat
one by much.

--
*Never underestimate the power of stupid people in large groups

Dave Plowman dave (AT) davenoise (DOT) co.uk London SW
To e-mail, change noise into sound.

#15

Roger wrote:

Quote:

"Chris Bartram" <news (AT) delete-me (DOT) piglet-net.net> wrote in message
news:hb4o1b$h4q$1 (AT) news (DOT) eternal-september.org...
beccy wrote:

"Pernanently knackered through being run totally flat"? Can it be
permanent? Is there an simple way to test this without going to a
garage?
Go to a motor factors that sells batteries. Most will do a free test.
Halfords, if you must, but they'll rob you blind for the new one...

You're missing the point - the battery is flat. Deal with that problem
first and then the car can be driven to places you suggest.

Indeed, but the question was 'how can the battery be tested'. If the OP

gets the car started, she can then go and have the battery tested.
Others have offered plenty of advice on getting it started.

#16

Dave Plowman (News) wrote:

Quote:

In article <JzlBm.3090$KR3.1904 (AT) text (DOT) news.virginmedia.com>,
Mrcheerful <nbkm57 (AT) hotmail (DOT) co.uk> wrote:
It is quite possible in emergency to jump start a car using thin
bits of household flex, just leave them connected for half an hour
or so (then remove the cables) and enough charge will have
transfered to start it up.

That's true if using a car to jump start from and you leave the engine
running. Just coupling two batteries together won't really charge the
flat one by much.

it works with a battery pack and is the official way to use them, so some
charge does transfer even without one being on charge.

#17

On Oct 14, 5:05*am, "Dave Plowman (News)" <d... (AT) davenoise (DOT) co.uk>
wrote:

Quote:

In article <Xns9CA4517B8AA07F3... (AT) newsfarm (DOT) iad.highwinds-media.com>,
* *beccy <n... (AT) not (DOT) here> wrote:

I'm in the UK. *Car is 1.3 litre.
QUESTION (1) I know this may not be the best way of doing it but, in
theory, if a car battery got flattened by leaving the headlights on
then why would a fully charged second battery attached in parallel
to the flat battery give almost no help at all?
It's was almost as if the second battery lost nearly all its charge
to the flat battery.
Can someone explain what is happening with the battery charge
please.

If the second battery is good it means the connection between them isn't.
Most jump leads are incapable of carrying the full starter current. Ones
which can cost upwards of 50 quid. *

QUESTION (2) If that's so then, to get the car started, is it
absolutely necessary to put a charger on the flat battery which is
in the car?

If the battery isn't permanently knackered through being run totally flat,
another car connected to it and the engine run for a while might then
charge it enough. But an overnight charge with a charger is a better bet.
Lidl have some decent ones in at the moment for only 14 quid. Small enough
to keep in the car.

--
*Go the extra mile. It makes your boss look like an incompetent slacker *

* * Dave Plowman * * * *d... (AT) davenoise (DOT) co.uk * * * * * London SW
* * * * * * * * * To e-mail, change noise into sound.

Qué is la Quid

--
Tom Horne

#18

Tom Horne wrote:

Quote:

On Oct 14, 5:05 am, "Dave Plowman (News)" <d... (AT) davenoise (DOT) co.uk
wrote:
In article <Xns9CA4517B8AA07F3... (AT) newsfarm (DOT) iad.highwinds-media.com>,
beccy <n... (AT) not (DOT) here> wrote:

I'm in the UK. Car is 1.3 litre.
QUESTION (1) I know this may not be the best way of doing it but, in
theory, if a car battery got flattened by leaving the headlights on
then why would a fully charged second battery attached in parallel
to the flat battery give almost no help at all?
It's was almost as if the second battery lost nearly all its charge
to the flat battery.
Can someone explain what is happening with the battery charge
please.

If the second battery is good it means the connection between them
isn't. Most jump leads are incapable of carrying the full starter
current. Ones which can cost upwards of 50 quid.

QUESTION (2) If that's so then, to get the car started, is it
absolutely necessary to put a charger on the flat battery which is
in the car?

If the battery isn't permanently knackered through being run totally
flat, another car connected to it and the engine run for a while
might then charge it enough. But an overnight charge with a charger
is a better bet. Lidl have some decent ones in at the moment for
only 14 quid. Small enough to keep in the car.

--
*Go the extra mile. It makes your boss look like an incompetent
slacker *

Dave Plowman d... (AT) davenoise (DOT) co.uk London SW
To e-mail, change noise into sound.

Qué is la Quid

google is your friend

#19

In article <9hpBm.3200$KR3.467 (AT) text (DOT) news.virginmedia.com>,
Mrcheerful <nbkm57 (AT) hotmail (DOT) co.uk> wrote:

Quote:

Dave Plowman (News) wrote:
In article <JzlBm.3090$KR3.1904 (AT) text (DOT) news.virginmedia.com>,
Mrcheerful <nbkm57 (AT) hotmail (DOT) co.uk> wrote:
It is quite possible in emergency to jump start a car using thin
bits of household flex, just leave them connected for half an hour
or so (then remove the cables) and enough charge will have
transfered to start it up.

That's true if using a car to jump start from and you leave the engine
running. Just coupling two batteries together won't really charge the
flat one by much.

it works with a battery pack and is the official way to use them, so
some charge does transfer even without one being on charge.

It really depends. If, as the OP says, a battery has been run totally flat
under load it's likely sulphated and will need a much higher voltage at
low current trickle for a long time to help reverse the process. Maybe
even days.

--
*If you remember the '60s, you weren't really there

Dave Plowman dave (AT) davenoise (DOT) co.uk London SW
To e-mail, change noise into sound.

#20

Quote:

the car.

"Pernanently knackered through being run totally flat"? Can it be
permanent? Is there an simple way to test this without going to
a garage?

A lead-acid battery that has been run completely flat will never be
quite as good as it was before, but if it was in good shape before and
wasn't flat for too long, it should mostly recover.

Most auto parts stores will test batteries for free, otherwise if the
car cranks fine on a cold morning then the battery is probably fine.