Battery draining...
Discussion
Hi Chaps.
Bit of a problem you might throw some light on for me please.
Before Christmas the battery started dying on me and was getting slower and slower to turn the engine over, hot or cold.
As it was 3+ years old I got a new one and after only ten days this one is doing the same!
The voltmeter still says its usual 13.5 volts with no load, and about 12.5 if the lights are all on.Had the alternater checked and garage said it was showing a healthy 14.25 volts output so that is ok.
Car runs fine and lights,indicators etc all bright as ever(well actually as dim as ever but we all know they are crap
)
Alternator starts to charge above 1500 rpm from start on mine and that is the same as usual.
I have a battery isolator switch but that does not seem to stop the discharge.Otherwise its just the alarm ...and that's nowt!
Any inspired ideas???
Thought I might take the starter out and check its free running and clean,otherwise a fault on the ignition circuit? Solenoid,or altenator?
Thanks for any help.
Tim
Bit of a problem you might throw some light on for me please.
Before Christmas the battery started dying on me and was getting slower and slower to turn the engine over, hot or cold.
As it was 3+ years old I got a new one and after only ten days this one is doing the same!
The voltmeter still says its usual 13.5 volts with no load, and about 12.5 if the lights are all on.Had the alternater checked and garage said it was showing a healthy 14.25 volts output so that is ok.
Car runs fine and lights,indicators etc all bright as ever(well actually as dim as ever but we all know they are crap
) Alternator starts to charge above 1500 rpm from start on mine and that is the same as usual.
I have a battery isolator switch but that does not seem to stop the discharge.Otherwise its just the alarm ...and that's nowt!
Any inspired ideas???
Thought I might take the starter out and check its free running and clean,otherwise a fault on the ignition circuit? Solenoid,or altenator?
Thanks for any help.
Tim
Is the battery actually discharging? What I mean is, check the battery charge with a voltmeter as soon as you stop the car (ie when it's fully charged) and then again, say the next day or after a couple of days, before you start it - if the battery is still giving the readings you describe then it's not losing charge - the fault is elsewhere.
If the battery is fully charged just after you stop the engine, the it's unlikely to be the alternator (otherwise it wouldn't be fully charging, would it?) - again the fault is elsewhere. There is a slight possibility that the battery could be discharging through the alternator if it's faulty, but only a slight chance.
If the battery is still reasonably fully charged when you go back to the car, but won't turn the engine, then it would seem to point to one of two things:
1. Voltage drop - could be damaged main live feed. or poor earth, Check and clean all live connections between the battery and the starter solenoid, and don't forget also that it needs a good earth return - check and clean the engine-to-chassis earth strap (which might be on the gearbox, I can't remember) and also the chassis-to-battery-terminal strap.
2. If ALL of the above is ok and the starter is still slow, then it might be a sticky starter motor / worn brushes etc
If the battery is fully charged just after you stop the engine, the it's unlikely to be the alternator (otherwise it wouldn't be fully charging, would it?) - again the fault is elsewhere. There is a slight possibility that the battery could be discharging through the alternator if it's faulty, but only a slight chance.
If the battery is still reasonably fully charged when you go back to the car, but won't turn the engine, then it would seem to point to one of two things:
1. Voltage drop - could be damaged main live feed. or poor earth, Check and clean all live connections between the battery and the starter solenoid, and don't forget also that it needs a good earth return - check and clean the engine-to-chassis earth strap (which might be on the gearbox, I can't remember) and also the chassis-to-battery-terminal strap.
2. If ALL of the above is ok and the starter is still slow, then it might be a sticky starter motor / worn brushes etc
If mine is going to be longer than a wek i tnd to trickle chare it and never had a problem... i got a new battery but found 2 -1/2 weeks just took enough out of it not to tuirn it over
30 mins trickle charge and band normal service resumed...
it seems to me that the engines run a fine line between startind and clicking..... could be alarms.. could be imobnilizers.... could be earth faults... £15 fromm halford for a trickle charger sorts it anyway... turn the key and booooooooom ear deafening sounds first time every time!!
problem sorted and gtd grin!!!
30 mins trickle charge and band normal service resumed...
it seems to me that the engines run a fine line between startind and clicking..... could be alarms.. could be imobnilizers.... could be earth faults... £15 fromm halford for a trickle charger sorts it anyway... turn the key and booooooooom ear deafening sounds first time every time!!
problem sorted and gtd grin!!!
doddze said:
If mine is going to be longer than a wek i tnd to trickle chare it and never had a problem... i got a new battery but found 2 -1/2 weeks just took enough out of it not to tuirn it over
30 mins trickle charge and band normal service resumed...
it seems to me that the engines run a fine line between startind and clicking..... could be alarms.. could be imobnilizers.... could be earth faults... £15 fromm halford for a trickle charger sorts it anyway... turn the key and booooooooom ear deafening sounds first time every time!!
problem sorted and gtd grin!!!
Well that certainly addresses a symptom but perhaps not the underlying ailment. Making sure the car's starting system is in good nick is also a good way. I don't have a trickle charger. I don't have a garage so can't be bothered trailing extension leads out into the drive for days on end either. The longest I have left my car was 5 weeks, and it still started on the first turn of the key. I prefer it that way.
Even if the battery is fully charged, duff live or earth feeds or a sticky starter could still prevent it starting. I would still recommend finding and fixing the actual problem. You might not always be able to plug a trickle charger in overnight.
1st thing to do is measure the current drain from the battery when everything is switched off.
As an example, for mine with just the immobiliser and clock operating the current drain is 11mA.
....I remember a problem we had with a BMW318i (yeah I know
)
where the digital clock would draw either 0,5mA or 400mA
depending on how the battery was reconnected. If it drew 400mA just disconnect and try again.....
As an example, for mine with just the immobiliser and clock operating the current drain is 11mA.
....I remember a problem we had with a BMW318i (yeah I know
) where the digital clock would draw either 0,5mA or 400mA
depending on how the battery was reconnected. If it drew 400mA just disconnect and try again.....Thanks LeTiv... same line of thought.
When I get home in the evening I slap the battery on charge and the charger whips back to showing fully charged after only about 60 seconds! Engine is often still slow to turn over if I try to re-start it straight away which makes me think it's power loss in the circuit somewhere, not the battery or the performance of the alternator.
So it has to be a fault on the ignition circuit methinks, or the 630 Amp output battery ain't rated high enough?.The old one was 650 Amp.
What you chaps have in your battery tray?
When I get home in the evening I slap the battery on charge and the charger whips back to showing fully charged after only about 60 seconds! Engine is often still slow to turn over if I try to re-start it straight away which makes me think it's power loss in the circuit somewhere, not the battery or the performance of the alternator.
So it has to be a fault on the ignition circuit methinks, or the 630 Amp output battery ain't rated high enough?.The old one was 650 Amp.
What you chaps have in your battery tray?
F908 Tim said:
Thanks LeTiv... same line of thought.
When I get home in the evening I slap the battery on charge and the charger whips back to showing fully charged after only about 60 seconds! Engine is often still slow to turn over if I try to re-start it straight away which makes me think it's power loss in the circuit somewhere, not the battery or the performance of the alternator.
So it has to be a fault on the ignition circuit methinks, or the 630 Amp output battery ain't rated high enough?.The old one was 650 Amp.
What you chaps have in your battery tray?
The difference between a 630Ah and 650Ah isn't enough to affect the starting to that extent.
Think voltage drop like I said at first, and as you mention above.
Thanks Ian.Will likely do that.
Fellas...What if...
I make a circuit tester(a bulbholder with a length of wire to each terminal) and disconnect the Neg terminal on the battery from the earth strap so only the live terminal remains connected.
Then I connect one of the tester wires to the Neg battery terminal and the other to the earth strap,hence the chassis.
If the bulb illuminates I have a fault right? Power discharging from the battery to earth.
If I then remove fuses from the fusebox and anywhere else one at a time until the tester bulb went out I would have identified the circuit at fault...right?
Or...have I missed summit???
Reassurance please. Cheers, Tim
Fellas...What if...
I make a circuit tester(a bulbholder with a length of wire to each terminal) and disconnect the Neg terminal on the battery from the earth strap so only the live terminal remains connected.
Then I connect one of the tester wires to the Neg battery terminal and the other to the earth strap,hence the chassis.
If the bulb illuminates I have a fault right? Power discharging from the battery to earth.
If I then remove fuses from the fusebox and anywhere else one at a time until the tester bulb went out I would have identified the circuit at fault...right?
Or...have I missed summit???
Reassurance please. Cheers, Tim
Hmmm, good test method but depends on the bulb and the current drain you are looking for. Using smallest normal car bulb, an 8w interior lamp, this requires 0.67 Amps (670mA) at 12v to light up at full brightness (current = power/volts). So you might be able to see it glow at a bit less than this, guess 400mA. So if your drain current is less than this, you won't see anything, and would need a smaller wattage bulb or even an LED. What you really need is a cheap digital voltmeter (Halfrauds, Machine Mart, , Maplin, Screwfix, Focus DIY etc) with a dc ammeter option. Caution with these is that it must always be connected in series with some sort of load or else you will get a flash, some smoke and the meter stops working!
Ian.
Ian.
Yes you'll need a meter with a low current scale connected in series with the battery to measure the discharge current. The inrush current when you connect the battery may be enough to fry the meter, so best to short out the meter while you connect it up and then remove the short. Start on a high current rating and then work down ...
Hmmm. Clever chaps with meters and more knowledge of auto electrics than I! 
I tested at the weekend as above using a normal dash instrument illumination bulb, (I will check the ampage for it tonight) and found it lit up like a headlamp when connected between the earth battery pole and the earth strap.
Pulled fuses until it went out and it proved to be on the 15amp Clock/Hazard light/Interior lights/Horns, and in my case,Radio circuit.
Each having a different earth of course I guess the problem is on the live.
Strangely the problem occured sometimes when the circuit had been re-made for about 20 seconds or so.A sort of time delay...makes me wonder where the immobiliser is wired into???
Disconnected each in turn and still had the problem!
Anyway,I could not test the ignition circuit to the starter by this method because the battery is not connected nor the ignition switch turned.As the voltage drop seems so huge when the battery has only just been re-charged I gave it to my local garage to test out and trace the fault with notes of everything I had done so far.
They rang me to say they could not get the car to even turn over and that the problem is the starter/solenoid. (Strange,it was
still operating,though only just,when I drove it to them.)
I guess that would explain the huge drain which I can't otherwise explain even with a suspect higher than anticipated drain on the 15 amp circuit.
But I don't have much confidence left in this garage now.
They have ordered a new one, assuring me the other has been tested out of the car and does not work...Part costs £185!
They then say they have not had time to look at the other circuit yet but will do once the cars running again!
AGHHHHHH!!! Afraid!
I tested at the weekend as above using a normal dash instrument illumination bulb, (I will check the ampage for it tonight) and found it lit up like a headlamp when connected between the earth battery pole and the earth strap.
Pulled fuses until it went out and it proved to be on the 15amp Clock/Hazard light/Interior lights/Horns, and in my case,Radio circuit.
Each having a different earth of course I guess the problem is on the live.
Strangely the problem occured sometimes when the circuit had been re-made for about 20 seconds or so.A sort of time delay...makes me wonder where the immobiliser is wired into???
Disconnected each in turn and still had the problem!
Anyway,I could not test the ignition circuit to the starter by this method because the battery is not connected nor the ignition switch turned.As the voltage drop seems so huge when the battery has only just been re-charged I gave it to my local garage to test out and trace the fault with notes of everything I had done so far.
They rang me to say they could not get the car to even turn over and that the problem is the starter/solenoid. (Strange,it was
still operating,though only just,when I drove it to them.)
I guess that would explain the huge drain which I can't otherwise explain even with a suspect higher than anticipated drain on the 15 amp circuit.
But I don't have much confidence left in this garage now.
They have ordered a new one, assuring me the other has been tested out of the car and does not work...Part costs £185!
They then say they have not had time to look at the other circuit yet but will do once the cars running again!
AGHHHHHH!!! Afraid!
Depends on the wattage of the bulb you used, but it does sound like there is a battery drain there somewhere.
I have found in the past that many garages simply do not understand autoelectrics - some call in a specialist for stuff that can be diagnosed fairly simply if you know what you're doing.
I suppose we'll see when they replace the starter. I hope it is that, for your wallet's sake...
I have found in the past that many garages simply do not understand autoelectrics - some call in a specialist for stuff that can be diagnosed fairly simply if you know what you're doing.
I suppose we'll see when they replace the starter. I hope it is that, for your wallet's sake...
F908 Tim said:
Pulled fuses until it went out and it proved to be on the 15amp Clock/Hazard light/Interior lights/Horns, and in my case,Radio circuit.
Is the stereo wired to the accessory circuit?
I've heard many stories about certain face-off stereos drawing LOTS of current when they shouldnt.
Garage rang to say new solenoid/starter fitted and all is well
They reckon the draw on the 15w circuit is accepable but I will want to know what it measured and what else they did.
Get car back tonight, and think I will do a bit more testing at the weekend before I accept that was it.
Now...lets see what the bill is?
Thanks for the hand-holding again and will post what I learn.
Cheers, Tim.
They reckon the draw on the 15w circuit is accepable but I will want to know what it measured and what else they did.
Get car back tonight, and think I will do a bit more testing at the weekend before I accept that was it.
Now...lets see what the bill is?
Thanks for the hand-holding again and will post what I learn.
Cheers, Tim.
F908 Tim said:
What I learnt was...
Go with your gut feel!
Replacement starter motor has sorted it and it jumps to life now like it has an electic motor in it! £182 all incl.
A little knowledge is indeed a dangerous thing.
What I learnt was:
Don't try to help people save money by eliminating all possibilities.
Let them go with their gut feel, every time. It's not my money.
Over and out.
Hi Tim,
The reason for the failure of your starter motor is almost certainly explained here :
www.pistonheads.com/gassing/topic.asp?h=0&t=198047
It's a common problem. Be aware that once you start cooking starter motors - you may well not stop - I got through three in 9 months before fitting a heat shield. Touch wood it's been superb ever since and no degredation of starting performance. Fitting a heat shield is cheap and easy too - though I'd suggest you take the starter off the engine first to do so. The starter is held on by two bolts - one is a bit of a sod to get too - so you'll need a socket set with a two foot extender.
Cheers,
Danny
The reason for the failure of your starter motor is almost certainly explained here :
www.pistonheads.com/gassing/topic.asp?h=0&t=198047
It's a common problem. Be aware that once you start cooking starter motors - you may well not stop - I got through three in 9 months before fitting a heat shield. Touch wood it's been superb ever since and no degredation of starting performance. Fitting a heat shield is cheap and easy too - though I'd suggest you take the starter off the engine first to do so. The starter is held on by two bolts - one is a bit of a sod to get too - so you'll need a socket set with a two foot extender.
Cheers,
Danny
Thanks Danny. Interesting post and will have a look at the heatshield idea now I have such a lively starter.
tvr***.
I was of course referring to MY little knowledge having led me down some dead ends, not anyone elses.
As you saw from my first post I thought Starter motor/solenoid was the problem which you kindly confirmed as the likely cause.
It was ME that got sidetracked testing other circuits for an excessive power drain.
We all use this site to help one another, but we can't all be equally expert on every aspect of our S.
I for one am very happy to get help on this site and grateful to you for offering it!
Wrong side of bed this morning????
tvr***.
I was of course referring to MY little knowledge having led me down some dead ends, not anyone elses.
As you saw from my first post I thought Starter motor/solenoid was the problem which you kindly confirmed as the likely cause.
It was ME that got sidetracked testing other circuits for an excessive power drain.
We all use this site to help one another, but we can't all be equally expert on every aspect of our S.
I for one am very happy to get help on this site and grateful to you for offering it!
Wrong side of bed this morning????
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