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Sister no. 2 has an M-reg 2 litre Ford Probe. It is proving very efficient at draining the battery of power. If she leaves the car unused for 3 or 4 days, the battery goes flat, even after a period of repeated long trips. The car has been into several garages for investigation, but the problem is still there. Any clues out there?
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you must put a volt meter in series with the battery live terminal with everything switched of you should see no current drain (a miniscule amount for the clock is ok) if there is no drain then the fault is the battery or charging defect.If there is a current drain then something is switched on, common faults are boot lights.radios .mobilephones etc.
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PS I recommend the meter in line with the battery earth as it's safest to diconnect this first. Also, make sure you have the radio code before you disconnect the battery!
rgards
John
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I meant to say use the current load function ,my fluke measures upto 50amps
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Roger
You need an ampmeter, not a voltmeter, in series with the battery earth lead, but as Andrew says all modern cars have a continuous drain for radios, alarms, clocks, etc.
Alternators also take a small leakage current and a faulty diode pack is another potential problem. Overall you should see a current drain in the order of no more than a few tens of milliamps (I'm guessing here guys) but to drain it in a couple of days will show a current of about quarter/half an amp or so, depending on the battery capacity, so it should be clear if it's a battery fault or a wiring fault. You can usually isolate the problem by removing fuses to take circuits out of service, and so narrow down where the problem is. One classic problem is items like boot lights or glovebox lights, which may not be wired throught the ignition or light switch.
Regards
John
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The difficulty in using an ammeter is that you don't know what is an acceptable current drain for normal conditions. Most ammeters available for domestic use will only read up to about 500ma i.e half an amp. The normal current drain may well be over this so no accurate and meaningful measurements could be made.
If the car is going to be left for a few days the simpler solution may be to disconnect the battery and leave it disconnected until its required again. If the battery is then drained than the battery itself is likely to be at fault. If alls well then the fault lies with the cars electrics.
If a Voltmeter is available then measure the battery voltage after disconnection and after the battery has been left standing for an hour or two to let it settle. The voltage should be above 13v. Measure again just before Re connection and it should be a similar value. It should certainly be above 12v.
Regards
Adrian
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Disconnecting the battery could give problems with the radio if it's coded, or the immobiliser. Could the car have had a tracking device fitted during its life? I ask only because I believe it to be the cause of my car's short battery life when idle.
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Adrain
As you'd expect only a very small leakage current when idle, that isn't a problem. If the leakage is 500mA (half an amp) there's the fault. it's probably more important to use a decent multimeter to measure the small current.
regards
john
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Hadn't noticed myself but not the first time and been called much worse I'm sure!. Rather apt though!
Adrian
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John,
The level of humour on this site is getting better every day, or was your spelling of Adrian's name just a freudian typo?
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Stuart
No, Freud had nothing to do with it - just a straightforward typo!
Apologies to Adrian.
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I think most manufacturers state that a battery drain in excess of 20mA is unacceptable in car in a powered down state.
We recently had a car that would run its battery flat if left for any longer than a week
It had occurred since new
The car had been fitted with 2 batteries since 1998
Battery drain had been checked and measured over a 24 hour period
It EVENTUALLY transpired that the alternator was not producing quite enough output (but still indicated 14V on a meter!?) and the AA had fitted a low quality battery
So, the alternator regulator was replaced and a quality Bosch battery fitted and no more flat battery after being left for over 2 weeks!
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I had a Rover 214 with exactly the same problem different batteries, alternators and visits to auto electricians failed to solve it. There was no noticable drain on the battery when the car was stopped and the charging was OK. It let me down so many times with a flat battery, I got so fed up with it I sold the car!!!
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