Flat battery, causes?
Discussion
a standard multi meter won't help very much
what you need is a clamp meter which goes over the main power line from the battery and can tell you how much power is being drawn
if you give a car a chance to settle, all the timed lights off etc the drain should go to almost nothing, especially on an older car newer cars it can take half hour or more for all the systems to fully shut down. If the drain seems high, then the easiest way to find it is to start pulling fuses hopefully you'll find one which stops the drain and you know what is causing it.
what you need is a clamp meter which goes over the main power line from the battery and can tell you how much power is being drawn
if you give a car a chance to settle, all the timed lights off etc the drain should go to almost nothing, especially on an older car newer cars it can take half hour or more for all the systems to fully shut down. If the drain seems high, then the easiest way to find it is to start pulling fuses hopefully you'll find one which stops the drain and you know what is causing it.
Have been in contact with the previous owner who tells me he had the same problem from time to time, thus bought the new battery just before he sold it thinking the old one was duff.
Using the car everyday was fine but if he left it a week the battery died.
So I'm thinking the previous answers saying a battery drain are the correct ones. Can anyone tell a numpty like me how to use the multimeter to test the fuses to try and narrow down the culprit.
Like where exactly do I stick the prongs and what readings to look for
Using the car everyday was fine but if he left it a week the battery died.
So I'm thinking the previous answers saying a battery drain are the correct ones. Can anyone tell a numpty like me how to use the multimeter to test the fuses to try and narrow down the culprit.
Like where exactly do I stick the prongs and what readings to look for
This could be dumb.... but is the battery up to the job?
Its a big motor, so must need a particular power of battery, is it the right one?
I only ask as I knew a bloke who had an old 2.0 pug and replaced the battery with a cheap one meant for a 1.2 pug 106 and whilst it sometimes worked, it didn't always turn over the engine, particularly if it was left more than a few days...
No expert, but something else to look at?
Its a big motor, so must need a particular power of battery, is it the right one?
I only ask as I knew a bloke who had an old 2.0 pug and replaced the battery with a cheap one meant for a 1.2 pug 106 and whilst it sometimes worked, it didn't always turn over the engine, particularly if it was left more than a few days...
No expert, but something else to look at?
Sounds like the alternator.
However. Before lashing out on one search for a voltage regulator online as 90% of the time it's this that causes the alternator to fail.
It's an odd car (found one in the US) so they'll probably be a cross reference part somewhere.
They typically cost between £10 and £30 and can usually be changed without removing the alternator.
However. Before lashing out on one search for a voltage regulator online as 90% of the time it's this that causes the alternator to fail.
It's an odd car (found one in the US) so they'll probably be a cross reference part somewhere.
They typically cost between £10 and £30 and can usually be changed without removing the alternator.
croyde said:
Have been in contact with the previous owner who tells me he had the same problem from time to time, thus bought the new battery just before he sold it thinking the old one was duff.
Using the car everyday was fine but if he left it a week the battery died.
So I'm thinking the previous answers saying a battery drain are the correct ones. Can anyone tell a numpty like me how to use the multimeter to test the fuses to try and narrow down the culprit.
Like where exactly do I stick the prongs and what readings to look for
On volts- red meter lead to +ve terminal, black to -ve. You say earlier that it's 13.75 on charge- that's about normal. I'd repeat that with every bit of electrics on . ( Lights/heater/rear screen etc) and check it's still 13.75Using the car everyday was fine but if he left it a week the battery died.
So I'm thinking the previous answers saying a battery drain are the correct ones. Can anyone tell a numpty like me how to use the multimeter to test the fuses to try and narrow down the culprit.
Like where exactly do I stick the prongs and what readings to look for
If that's ok, disconnect -ve battery terminal .Set meter to AMPS RANGE( start at least on 1amp range unless it's auto ranging) .connect +ve meter lead to negative battery, negative meter lead to removed terminal, and check current. I tried it on mine when I replaced battery as I got a spark on connection,and wondered if I had a leak, but on test current was far less than 1a initially and it decayed to a low constant. If that's result only other suggestion is to fully charge battery and leave disconnected for a few days,then see if the car will start. if you get problems, perhaps a trip to a fast fit place for a battery health check might be in order .
BTW- if it's a digital meter, then you cab interchange the meter leads, only difference will be in whether or not the reading is a +ve or -ve one.
IF the residual current is high, then it's a case of pulling fuses to try and eliminate /trace the cause.
ging84 said:
a standard multi meter won't help very much
what you need is a clamp meter which goes over the main power line from the battery and can tell you how much power is being drawn
if you give a car a chance to settle, all the timed lights off etc the drain should go to almost nothing, especially on an older car newer cars it can take half hour or more for all the systems to fully shut down. If the drain seems high, then the easiest way to find it is to start pulling fuses hopefully you'll find one which stops the drain and you know what is causing it.
And not wanting to state the obvious but not all clamp meters can read DC current, double check before you buy what you need is a clamp meter which goes over the main power line from the battery and can tell you how much power is being drawn
if you give a car a chance to settle, all the timed lights off etc the drain should go to almost nothing, especially on an older car newer cars it can take half hour or more for all the systems to fully shut down. If the drain seems high, then the easiest way to find it is to start pulling fuses hopefully you'll find one which stops the drain and you know what is causing it.
Ozzie Osmond said:
If that 12.42 is immediately after switch-off and read with a good voltmeter you've almost certainly got a duff battery. Let it stand overnight and check it again tomorrow before you start the car. I'd be interested to know where the voltage lands.
12.14v this morning ignition off. Clearly 12.14 is showing a battery that's below par. The question remains why.
The only way to rule out the battery itself is too make sure it's fully charged either by disconnecting and charging for several hours or by driving the car for more than an hour. Ideally after that you would get a battery specialist to do a high current drain test. This is the only way to test a battery completely. The DIY alternative is to leave it to stand for several hours after full charging and then repeat the voltage test. As mentioned before, anything less than 12.4 and it's had it.
As someone else has said, it may be the battery was too cheap/weak for the car. Although batteries all look the same the size and quality of the plates inside can vary massively.
I certainly wouldn't start changing parts until you've ruled out the battery 100%. If you want to see if it's draining when parked the easiest place to start is disconnect the battery overnight and reconnect in the morning. It will either improve things or it won't.
The only way to rule out the battery itself is too make sure it's fully charged either by disconnecting and charging for several hours or by driving the car for more than an hour. Ideally after that you would get a battery specialist to do a high current drain test. This is the only way to test a battery completely. The DIY alternative is to leave it to stand for several hours after full charging and then repeat the voltage test. As mentioned before, anything less than 12.4 and it's had it.
As someone else has said, it may be the battery was too cheap/weak for the car. Although batteries all look the same the size and quality of the plates inside can vary massively.
I certainly wouldn't start changing parts until you've ruled out the battery 100%. If you want to see if it's draining when parked the easiest place to start is disconnect the battery overnight and reconnect in the morning. It will either improve things or it won't.
croyde said:
Same question about the stereo as the previous owner took out the oem Ford cassette player and installed an all singing and dancing cd usb bluetooth Sony tuner.
It turns off with the ignition but surely there is a constant live feed so it can remember all its settings.
Yep the stereo will have a permanent live (for memory settings) and a switched live (for powering on).It turns off with the ignition but surely there is a constant live feed so it can remember all its settings.
Matt_N said:
Yep the stereo will have a permanent live (for memory settings) and a switched live (for powering on).
Would this be enough to drain the battery slowly say over a week. How do cars with modern stereos manage?My '98 BMW has a modern stereo with iPod and all sorts of settings yet I can leave it for weeks yet it still starts.
croyde said:
Just to add this to the mix, the boys over at CrownVic.net all have 850 amp batteries whilst the one fitted to mine is only 650 amps. Could this be the problem or just adding to it?
If you go on a US car battery site, they also say the battery should be 850 amps.
Thanks.
thats what I was saying (in a way)If you go on a US car battery site, they also say the battery should be 850 amps.
Thanks.
croyde said:
Matt_N said:
Yep the stereo will have a permanent live (for memory settings) and a switched live (for powering on).
Would this be enough to drain the battery slowly say over a week. How do cars with modern stereos manage?My '98 BMW has a modern stereo with iPod and all sorts of settings yet I can leave it for weeks yet it still starts.
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