Duff battery = duff starter motor ?
Discussion
My original starter motor was getting slower & slower & eventually stopped.
I bought a new one, which started the car ok, but seemed slow. After two weeks, it stopped turning over. I've since charged the battery & it turn's over but slowly.
So I'm thinking knackered battery.
I've had the original starter refurbed, re fitted, had a new battery fitted & everything seems ok.
With my basic knowledge of electrics, I'm guessing that the starter draws about 15amps at 12 volts. but if you've only got 6 volts (as an example) then you're going to draw 30amps, hence burning the contacts out inside the starter motor.
I can't understand why starter fuse doesn't pop, to protect the starter, or is the starter fuse just protecting a relay ?
My knackered battery has killed two perfectly good starters
>> Edited by RUSSELLM on Tuesday 25th April 10:22
I bought a new one, which started the car ok, but seemed slow. After two weeks, it stopped turning over. I've since charged the battery & it turn's over but slowly.
So I'm thinking knackered battery.
I've had the original starter refurbed, re fitted, had a new battery fitted & everything seems ok.
With my basic knowledge of electrics, I'm guessing that the starter draws about 15amps at 12 volts. but if you've only got 6 volts (as an example) then you're going to draw 30amps, hence burning the contacts out inside the starter motor.
I can't understand why starter fuse doesn't pop, to protect the starter, or is the starter fuse just protecting a relay ?
My knackered battery has killed two perfectly good starters
>> Edited by RUSSELLM on Tuesday 25th April 10:22
RUSSELLM said:
With my basic knowledge of electrics, I'm guessing that the starter draws about 15amps at 12 volts. but if you've only got 6 volts (as an example) then you're going to draw 30amps, hence burnibg the contacts out inside the starter motor.
I can't understand why starter fuse doesn't pop, to protect the starter, or is the starter fuse just protecting a relay ?
My knackered battery has killed two perfectly good starters
The starter draws several hundred Amps. It is connected directly to the battery, the main power supply is switched by the solenoid on the side of the starter motor and there is no separate fuse or relay for the main power supply. (The small current required to operate the solenoid is usually fused and switched by a relay but sometimes comes directly from the ignition switch.)
A flat or knackered battery cannot kill a starter. A knackered starter can kill a battery by taking too much current from it.
If you're having recurring problems then I would suspect either a wiring problem (poor earth being the favorite) or wrongly specified components. You may also be seeing side effects from some other problem, for example a charging problem leading to a partially flat battery leading to slow cranking/poor starting that you might interpret as a problem with the starter motor.
Russell,
Pete H is spot on as usual. It's more likely a problem with supplying the starter with enough current than with the starter itself. After all, in two weeks, you've used it only a few tens of times at most. If you can jump start the car from another vehicle, you've no problems with your starter. If you can get the car running, check the voltage across the battery, to make sure the alternator is charging it. Dead/dying alternator could give rise to the symptoms you describe here, as the battery will steadily drain.
Good luck,
Steve.
Pete H is spot on as usual. It's more likely a problem with supplying the starter with enough current than with the starter itself. After all, in two weeks, you've used it only a few tens of times at most. If you can jump start the car from another vehicle, you've no problems with your starter. If you can get the car running, check the voltage across the battery, to make sure the alternator is charging it. Dead/dying alternator could give rise to the symptoms you describe here, as the battery will steadily drain.
Good luck,
Steve.
GreenV8S said:
A flat or knackered battery cannot kill a starter..
Are you sure about that ? The contacts in the starter must have a rating, eg an ampage at a certain voltage.
If you half that voltage, you double the ampage & depending on the rating of the starter's contacts, your going to burn them out or weld them together.
Or am I missing something ?
TT Tim said:
Russell,
Where did you get your starter refirbished and may I ask at what cost?
I think mine's on the way out.
Thanks
Tim
>> Edited by TT Tim on Tuesday 25th April 09:46
Hi Tim, "Midland starter motors" have refurbed the original Tilton one, that's the one that's back on now. Tel 0121 525 5200. "orangeone" off PH works there. cost £80 by the way.
RUSSELLM said:
Russell,
Where did you get your starter refirbished and may I ask at what cost?
I think mine's on the way out.
Thanks
Tim
>> Edited by TT Tim on Tuesday 25th April 09:46
Hi Tim, "Midland starter motors" have refurbed the original Tilton one, that's the one that's back on now. Tel 0121 525 5200. "orangeone" off PH works there. cost £80 by the way.
Ta
Tim
RUSSELLM said:
A flat or knackered battery cannot kill a starter..
Are you sure about that ? The contacts in the starter must have a rating, eg an ampage at a certain voltage.
If you half that voltage, you double the ampage & depending on the rating of the starter's contacts, your going to burn them out or weld them together.
Or am I missing something ?
The resistance of the windings in the starter is constant. I = V/R, so when you drop the voltage you reduce the current.
Extra 300 Driver said:
Check your engine earth, I suspect it is this.
My starter was always very good on my Cerb, but I did have a ver simlar starter problem on the Mini, it took me ages to find it and guess what? It was the earth.
Where's this located exactly? I've got to give the chassis a cleanup some time soon and it sounds like a bit of preventative maintenance would be a good idea here.
Thanks,
Steve
Steve_T said:
Check your engine earth, I suspect it is this.
My starter was always very good on my Cerb, but I did have a ver simlar starter problem on the Mini, it took me ages to find it and guess what? It was the earth.
Where's this located exactly? I've got to give the chassis a cleanup some time soon and it sounds like a bit of preventative maintenance would be a good idea here.
Thanks,
Steve
NSF wheel arch, take the wheel off and you should see it.
if you sit in traffic in a v8 crb the alternator is probably bearly charging at tickover and chances are the fans are on sucking thirty or so amps plus radio/aircon.
if you look at alt pulley you`ll see that it is bearly bigger than the nut.
this is so the alternator is spinning as fast as possible [but the alt drive is quite slow at half crank speed]
"raise the idle a few rpm and no problems" but that leads to overheating/running on/clutch drag etc,
Ive checked three cerb`s now with expensive test equipment all three were registering discharge at idle with fans on/ alternator was charging fans off but not near enough to keep the battery in a charged state.
Obviously you are not idling continually but being in even moderate traffic we noticed over say ten minutes the battery would be down by about 50-60% but after a normal drive for 15 or so minutes the battery would be fine,
worth bearing in mind,check yours, a cheap ammeter will give you some idea. also when you start your car it takes about five minutes of charging to recover the power used by the starter even if your car starts almost immediately
>> Edited by dickkark on Friday 28th April 23:03
if you look at alt pulley you`ll see that it is bearly bigger than the nut.
this is so the alternator is spinning as fast as possible [but the alt drive is quite slow at half crank speed]
"raise the idle a few rpm and no problems" but that leads to overheating/running on/clutch drag etc,
Ive checked three cerb`s now with expensive test equipment all three were registering discharge at idle with fans on/ alternator was charging fans off but not near enough to keep the battery in a charged state.
Obviously you are not idling continually but being in even moderate traffic we noticed over say ten minutes the battery would be down by about 50-60% but after a normal drive for 15 or so minutes the battery would be fine,
worth bearing in mind,check yours, a cheap ammeter will give you some idea. also when you start your car it takes about five minutes of charging to recover the power used by the starter even if your car starts almost immediately
>> Edited by dickkark on Friday 28th April 23:03
Mines probably the opposite, my tick over's high (1400 rpm), I'll get it sorted at the next service.
But my alternator's throwing out over 15 volts.
The refurbed starter is still firing up at a great speed, now it's got the new battery on.
I keep reading about people getting through more than one starter in a month, and I can't believe there's that many bad starters out there.
>> Edited by RUSSELLM on Tuesday 2nd May 11:27
But my alternator's throwing out over 15 volts.
The refurbed starter is still firing up at a great speed, now it's got the new battery on.
I keep reading about people getting through more than one starter in a month, and I can't believe there's that many bad starters out there.
>> Edited by RUSSELLM on Tuesday 2nd May 11:27
its quite possible that these `once a month starters you are referring to are not being fitted properly because cables must be tight to pass power efficiently,
if they are not then there is resistance, then you get high temps and eventually failure.
cheap rebuild units are usually worse than a decent used genuine starter
also the manner in which these starters are fixed to the box means there is actually a bit of slack in the dowels through which the bolts travel which could allow the starter to be fitted slightly askew,
even a small amount would kill a starter in no time as its pulling the shaft off at an angle.
If your starter is slow its worth checking before buying new
bit tricky to check but if you just crack off the two mounting bolts enough to allow it to move slightly but without allowing it to lift
connect jumper cable from batt neg to stater casing and try cranking
if it turns faster you have possibly found your problem. then while its cranking get some one to nip the bolts up tight.
saved two customers and one friend cost of new starter this way
if they are not then there is resistance, then you get high temps and eventually failure.
cheap rebuild units are usually worse than a decent used genuine starter
also the manner in which these starters are fixed to the box means there is actually a bit of slack in the dowels through which the bolts travel which could allow the starter to be fitted slightly askew,
even a small amount would kill a starter in no time as its pulling the shaft off at an angle.
If your starter is slow its worth checking before buying new
bit tricky to check but if you just crack off the two mounting bolts enough to allow it to move slightly but without allowing it to lift
connect jumper cable from batt neg to stater casing and try cranking
if it turns faster you have possibly found your problem. then while its cranking get some one to nip the bolts up tight.
saved two customers and one friend cost of new starter this way
This thread has got me thinking.
I have had my starter off to do the clutch slave and I took the oppurtunity to test it with my starter/charger as it would spin but not crank. And then crank on the 3rd or 4th go.
Tried it on the starter/charger and it spun and threw the cog out as it would to engage with the flywheel.
Fitted it back to the car tonight and it spins fine but does not throw the cog out to crank the engine except maybe on the 3rd or 4th try.
Could this be a voltage problem? I have relocated an earth (not sure if it is the one for the starter) to the starter motor bolt that attaches it to the engine.
Any thoughts?
Ed
I have had my starter off to do the clutch slave and I took the oppurtunity to test it with my starter/charger as it would spin but not crank. And then crank on the 3rd or 4th go.
Tried it on the starter/charger and it spun and threw the cog out as it would to engage with the flywheel.
Fitted it back to the car tonight and it spins fine but does not throw the cog out to crank the engine except maybe on the 3rd or 4th try.
Could this be a voltage problem? I have relocated an earth (not sure if it is the one for the starter) to the starter motor bolt that attaches it to the engine.
Any thoughts?
Ed
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