AX 11TRE 1987
Car wouldn't start. AA stated a knackered starter motor. This was replaced. Ok for a day and then the battery (brand new) drained flat after about 4 to 5 hours.
Is the new (reconditioned I think) starter motor faulty? Or is it something else? I had noticed for a while prior to the breakdown that I lacked electrical power when idling after start-up - cured by revving the engine.
I've waded through all 107 pages of posts and can't gleen any clues.
Putting a meter (battery negative disconnected) to the positive connection on the starter solenoid I see a 3500 ohm resistance to the engine block - is this right? The manual makes me think to expect an open circuit.
??Any experience/ideas, ladies and gents - thanks??
AX - Have I bought a duff starter motor
Moderator: RichardW
Sounds to me like a charging fault all along.
What is you battery voltage? - simply read it after the engine has been stopped for a while. Should be something around 12.6 volts, or about 14 when the engine is running. Generally if the alternator has failed it will be a couple of volts lower.
Other points to check are the alternator drive belt tightness and the earth (and alternator) continuity. A rough check for the earth is to connect your meter between the battery negative and the engine block (without disconnecting the battery leads etc) and operate the starter. Any drop of more than about 1 volt indicates that the earth is dodgy.
I'm not quite sure what your 3500 ohm resistance represents but if your connection is simply in series between the battery positive and its terminal then this simply represents a leakage current. The starter itself is controlled from the solenoid which sits on top of it and also puts the gear into mesh. In fact it puts it into mesh and then turns on the motor in that order.
Another test is to see how bright the headlamps are without engine running and by how much they dim when the starter is operated. If the car is operating a couple of volts down usually the indicators seem slow and so do the wipers.
keep us informed and we will help you.
jeremy
What is you battery voltage? - simply read it after the engine has been stopped for a while. Should be something around 12.6 volts, or about 14 when the engine is running. Generally if the alternator has failed it will be a couple of volts lower.
Other points to check are the alternator drive belt tightness and the earth (and alternator) continuity. A rough check for the earth is to connect your meter between the battery negative and the engine block (without disconnecting the battery leads etc) and operate the starter. Any drop of more than about 1 volt indicates that the earth is dodgy.
I'm not quite sure what your 3500 ohm resistance represents but if your connection is simply in series between the battery positive and its terminal then this simply represents a leakage current. The starter itself is controlled from the solenoid which sits on top of it and also puts the gear into mesh. In fact it puts it into mesh and then turns on the motor in that order.
Another test is to see how bright the headlamps are without engine running and by how much they dim when the starter is operated. If the car is operating a couple of volts down usually the indicators seem slow and so do the wipers.
keep us informed and we will help you.
jeremy
You have not bought a duff starter motor.
There is no sense in checking the starter solonoid unless the starter won't turn at all - since the solonoid is only feeded when turning your starter key.
You've noticed prior to the starter problem a problem with batteri power - and new battery went flat.
I think this is the clue to your real problem : the generator is not charging as it should.
With engine idle you should have a voltage of approx 14.0-14.4V measured DIRECTLY over the battery poles.
Could even be duff cabling/earth on your generator.
On these engines the generator earth thru it's mountings is known to get duff over the y's - caused by surface corrosion on alloy parts.
In most cases the only effective solution is a heavy gauge wire run from (one of) the generator earth screw(s) directly to battery negative pole.
But a first check would always be the generator's brush lenght on the regulator module.
The brushes should protrude at least 6mm to reach the rotor rings - new brushes protrudes some 12-14mm.
There is no sense in checking the starter solonoid unless the starter won't turn at all - since the solonoid is only feeded when turning your starter key.
You've noticed prior to the starter problem a problem with batteri power - and new battery went flat.
I think this is the clue to your real problem : the generator is not charging as it should.
With engine idle you should have a voltage of approx 14.0-14.4V measured DIRECTLY over the battery poles.
Could even be duff cabling/earth on your generator.
On these engines the generator earth thru it's mountings is known to get duff over the y's - caused by surface corrosion on alloy parts.
In most cases the only effective solution is a heavy gauge wire run from (one of) the generator earth screw(s) directly to battery negative pole.
But a first check would always be the generator's brush lenght on the regulator module.
The brushes should protrude at least 6mm to reach the rotor rings - new brushes protrudes some 12-14mm.
Ground back to the battery is zero ohms. The battery has charged up twice from the alternator from flat condition in around 20 minutes, since the problem arose. The alternator produces a health 14.5V and battery reads 12.5V with engine off - until of course its has drained.
There was absolutely no problem with current drain until I changed the starter motor. The old starter had an intermittant fault with not starting for about 18 months - it took this long to narrow it down.
The resistance measurment was between the 12V main battery supply to the starter motor and not the ignition primary - it read 3.5Kohms.
If checked this with the removed old motor and I get an infinite resistance.
Any suggestions?
There was absolutely no problem with current drain until I changed the starter motor. The old starter had an intermittant fault with not starting for about 18 months - it took this long to narrow it down.
The resistance measurment was between the 12V main battery supply to the starter motor and not the ignition primary - it read 3.5Kohms.
If checked this with the removed old motor and I get an infinite resistance.
Any suggestions?
3.5k Ohms would be a likely value for the resistance of the windings in the starter but there should be no connection between the +12V connection to the starter and earth through the windings when the starter is not active. Is it possible that a short on the winding could be creating leakage to earth and draining the battery. Funny how calculating the number of ampere-hours used by a battery discharging through 3.5k Ohms for 4 hours roughly matches the capacity of the battery. The battery discharged in 4 hours from the car being left.
Its too much of a coincidence that the battery problem started wilth the replacement of the starter.
Its too much of a coincidence that the battery problem started wilth the replacement of the starter.
I'm confused about your continued thoughts on the ohm readings on the starter motor ?
The main positive terminal on the startermotor should of course read infinite ohms when solonoid not engaged/connected.
A resistance of 3500 ohms would give 12.5V/3500ohm = 0.0036Amp.
As your new battery would at least be rated at 40AmpHrs capacity, it then takes 40AmpHrs/0.0036Amp = 11,111Hrs to discharge the battery, or 11,111Hrs/24Hrs = 462days (or 1year 3months) to discharge the battery.
In practical terms the new battery self discharge is much larger.
You're simply chasing a shadow -
Instead you may try measure the Amperage drain from the battery - WITHOUT engine running - and WITHOUT ignition on (key out !!).
Connect your meter in series with either battery clamp.
With a battery drainage time of some 3days - you should expect 40AmpHrs/(3 x 24Hrs) = 0.56Amp of drain current.
12.5V x 0.56Amp = 7watts.
7watts is precisely within the power range of a single bulb constantly lit somewhere - either in the boot or the glove box.
Indeed a common problem. And would indeed be intermittent.
The main positive terminal on the startermotor should of course read infinite ohms when solonoid not engaged/connected.
A resistance of 3500 ohms would give 12.5V/3500ohm = 0.0036Amp.
As your new battery would at least be rated at 40AmpHrs capacity, it then takes 40AmpHrs/0.0036Amp = 11,111Hrs to discharge the battery, or 11,111Hrs/24Hrs = 462days (or 1year 3months) to discharge the battery.
In practical terms the new battery self discharge is much larger.
You're simply chasing a shadow -
Instead you may try measure the Amperage drain from the battery - WITHOUT engine running - and WITHOUT ignition on (key out !!).
Connect your meter in series with either battery clamp.
With a battery drainage time of some 3days - you should expect 40AmpHrs/(3 x 24Hrs) = 0.56Amp of drain current.
12.5V x 0.56Amp = 7watts.
7watts is precisely within the power range of a single bulb constantly lit somewhere - either in the boot or the glove box.
Indeed a common problem. And would indeed be intermittent.
Hmmm.... thanks for your analysis.
I think you might be correct with your maths - it's a number of years since college.
However the battery drains in 4 to 5 hours. The battery is rated at 44AmpHrs. I should therefore be expecting to see a current drain of around 10Amps - or 125 watts. Thats a lot. I'm doubting that my multimeter can take it. Everytime I reconnect the battery negative to use the car I do get an electrical spark. What could be drawing such energy?
Unless the battery is now far less charged having gone completely flat twice in the space of two days last weekend....
How long does it take to fully rejuvanate a battery?
My greatest concern is that this might eventually lead to an electrical fire!
Might the alternator have something to do with this?
Thanks again
I think you might be correct with your maths - it's a number of years since college.
However the battery drains in 4 to 5 hours. The battery is rated at 44AmpHrs. I should therefore be expecting to see a current drain of around 10Amps - or 125 watts. Thats a lot. I'm doubting that my multimeter can take it. Everytime I reconnect the battery negative to use the car I do get an electrical spark. What could be drawing such energy?
Unless the battery is now far less charged having gone completely flat twice in the space of two days last weekend....
How long does it take to fully rejuvanate a battery?
My greatest concern is that this might eventually lead to an electrical fire!
Might the alternator have something to do with this?
Thanks again
Ooops - misread your info [:I][:o)]
4-5 HOURS drainage is indeed severe [B)]
- definately NOT a bulb then.
But would precisely match the rear windscreen heater - with a stuck relay contact.
Any thunder stereo power modules fitted in car ?
Either the problem - a drainage power that huge will definately heat up the problem area - despite any cold weather.
No need to use a meter then - simply use your hand [8D]
Should only take a couple of minutes to locate a hot part somewhere.
4-5 HOURS drainage is indeed severe [B)]
- definately NOT a bulb then.
But would precisely match the rear windscreen heater - with a stuck relay contact.
Any thunder stereo power modules fitted in car ?
Either the problem - a drainage power that huge will definately heat up the problem area - despite any cold weather.
No need to use a meter then - simply use your hand [8D]
Should only take a couple of minutes to locate a hot part somewhere.
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uhn113x
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3.5k ohms will not be resistance of starter windings! More likely to be 0.35 ohms!
The only way your starter could be responsible would be if there was a leak across the main contacts in the solenoid. As Anders suggeste, stick a meter in series with the battery and see what current is being drawn, and disconnect things until it becomes zero.
May even be leak in alternator diodes
Mike
The only way your starter could be responsible would be if there was a leak across the main contacts in the solenoid. As Anders suggeste, stick a meter in series with the battery and see what current is being drawn, and disconnect things until it becomes zero.
May even be leak in alternator diodes
Mike
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BonceChops
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How about removing all the fuses in the fusebox. Then remove the battery positive terminal. Try touching the removed terminal onto the battery - do you get a spark? Replace 1 fuse and see if you get a spark. Remove the fuse again and try the next untill you do get a spark. This will hopefully tell you which circuit is pulling the current draining your battery. If you suspect the rear heated window just pull its fuse 1st and see if you get the spark when you connect the battery postive terminal. Most circuits should not pull any current with the key turned off, some like clock, alarm etc will.