Discussion
Officially, hello, from a previous TVR owner and hope I can be forgiven (eventually!) from straying the fold!??
My first serious post here on SCH is, what is wrong with the alternator/charging system on these cars? Is it a TVR 'bodge' whereby the alternator only charges when the engine is revved to 2k rpm due to using a mixture of gauges/alt/loom, or is there a problem with the diodes on my alternator?
How many of you with S3's have the same issue?
Have searched all the posts on here relating to this I can't get a definitive answer whether it is a 'common prob' that all the S3's suffer from or is there a fault with mine? Yes, I know it's all about resistance to 'excite' the b*gger to charge but I can't believe this was accepted as standard when these cars were produced?
When I had a 2.9 EFI Scorpio back in the 90's I don't recall having this issue!
And all the cars that I have owned from way back in the dark ages of the 60's never had an ignition warning light illuminated without there being an obvious problem, usually a thrown belt, giving me an excuse to wrestle the tights from the 'good lady' passenger!!
So (dreadful way to start a para, I know!), what is the answer???
My first serious post here on SCH is, what is wrong with the alternator/charging system on these cars? Is it a TVR 'bodge' whereby the alternator only charges when the engine is revved to 2k rpm due to using a mixture of gauges/alt/loom, or is there a problem with the diodes on my alternator?
How many of you with S3's have the same issue?
Have searched all the posts on here relating to this I can't get a definitive answer whether it is a 'common prob' that all the S3's suffer from or is there a fault with mine? Yes, I know it's all about resistance to 'excite' the b*gger to charge but I can't believe this was accepted as standard when these cars were produced?
When I had a 2.9 EFI Scorpio back in the 90's I don't recall having this issue!
And all the cars that I have owned from way back in the dark ages of the 60's never had an ignition warning light illuminated without there being an obvious problem, usually a thrown belt, giving me an excuse to wrestle the tights from the 'good lady' passenger!!
So (dreadful way to start a para, I know!), what is the answer???
A higher wattage bulb will lower the cut-in speed but could possibly melt the plastic part of the dash that it fits into (best to fit and wire a higher wattage bulb as an addon away from the dash)
A smaller pulley will lower the cut-in speed
If the warning light goes out and then comes back on glowing slightly then you could have a volt drop in the warning light circuit or a main supply and return problem at the alternator or a faulty alternator (diodes or stator fault will glow the light)
A smaller pulley will lower the cut-in speed
If the warning light goes out and then comes back on glowing slightly then you could have a volt drop in the warning light circuit or a main supply and return problem at the alternator or a faulty alternator (diodes or stator fault will glow the light)
Considering the cut-in speed of an alternator is approximately 1000 RPM give or take a bit, think now about the ratio crank pulley size to alternator pulley size, the alternator is going at some good revs even at engine tick-over
I doubt very much that the problem is a standard factory build problem
I doubt very much that the problem is a standard factory build problem
Penelope Stopit said:
Considering the cut-in speed of an alternator is approximately 1000 RPM give or take a bit, think now about the ratio crank pulley size to alternator pulley size, the alternator is going at some good revs even at engine tick-over
I doubt very much that the problem is a standard factory build problem
Quite so, that's why I believe there is a problem with my alternator although it charges once revved! Just asking the question as a few have said this is 'normal' behaviour????I doubt very much that the problem is a standard factory build problem
They all do that as standard.
Some owners have fitted bigger wattage warning lamps, others have fitted smaller pulleys to get the alternator to "kick in" earlier. All you have to do is rev it over 2000 once, then it all works as normally expected. If the warning lamps stays on or comes back on, THEN you have a problem.
Don't know why, but they all just do.
Some owners have fitted bigger wattage warning lamps, others have fitted smaller pulleys to get the alternator to "kick in" earlier. All you have to do is rev it over 2000 once, then it all works as normally expected. If the warning lamps stays on or comes back on, THEN you have a problem.
Don't know why, but they all just do.
Yep, my S3c is the same. On initial start-up, I wait until the oil pressure has come up before blipping the throttle to get the alt to kick in at about 1800rpm, then verify with a glance at the voltmeter.
On my S1 charging kicks in at about 1500rpm.
No worries. It's just part of the joys of S.
On my S1 charging kicks in at about 1500rpm.
No worries. It's just part of the joys of S.
Guys..
Just remember an alternator hasn't got a brain !
Its trigger point for charging is fixed by design. So it is the cars 'signal' (ie. Applied load/voltage to the warning light terminal) that will dictate when charging commences.
On one of my other classic cars, I was doing a dashboard rearrange, and stupidly used a set of those cheap (fixed bulb) idiot lights. All worked fine except for the Ign warning light, as it wouldn't go out !! So in temper I floored the throttle to see it go out at around 2500 revs. With the old dash lights in circuit the Ign light always went out at just above idle, which proves the above previously stated comments.
I resolved my issue by replacing the cheap fixed bulb idiot lights with good quality ones that have proper bulbs. 4-5 watts in value comes to mind.
So beware, that sometimes one can cause an issue where there previously wasn't one by simply by trying to improve matters
!!
TerryB
Just remember an alternator hasn't got a brain !
Its trigger point for charging is fixed by design. So it is the cars 'signal' (ie. Applied load/voltage to the warning light terminal) that will dictate when charging commences.
On one of my other classic cars, I was doing a dashboard rearrange, and stupidly used a set of those cheap (fixed bulb) idiot lights. All worked fine except for the Ign warning light, as it wouldn't go out !! So in temper I floored the throttle to see it go out at around 2500 revs. With the old dash lights in circuit the Ign light always went out at just above idle, which proves the above previously stated comments.
I resolved my issue by replacing the cheap fixed bulb idiot lights with good quality ones that have proper bulbs. 4-5 watts in value comes to mind.
So beware, that sometimes one can cause an issue where there previously wasn't one by simply by trying to improve matters
!!
TerryB
This may be of some help
Disconnect the indicator warning light and run 2 leads from that light to 2 x 5 terminal relays as shown, connecting them to terminal 30 of each relay
Extend the leads that have been disconnected from the indicator warning light and connect them to terminal 87a of each relay (Marked on the diagram "To LH Indicator Lts" and "To RH Indicator Lts")
Leaving the Alternator Light original wiring as is, connect a lead to each side of the alternator light and run those leads to the relays, connect them to terminal 87 of each relay as shown
Run a fused ignition supply to terminal 85 of each relay coil
With a short lead, link together terminal 86 of each relay coil and extend that same lead to a 3rd 5 terminal relay connecting it to terminal 87a
Connect terminal 30 of this same 3rd relay to earth (Return/Ground or whatever else you call it)
At this same 3rd relay, connect coil terminal 85 to earth (Return/Ground or whatever else you call it)
At this same 3rd relay, connect coil terminal 86 with a lead to the fuel pump wire that goes directly to the pump (After the pump control relay)
Someone somewhere has got something wrong with this vehicles alternator warning light circuit, the wattage of the bulb should be 3 Watts or more, higher than 3 watts is not a problem apart from heat from that bulb, lower than 3 watts highers the alternators cut-in speed, I don't think a 3watt bulb is made for the type of warning light that is used but I could be wrong
Carrying out the above modification will solve the high cut-in speed problem.
What the circuit does is connect the indicator warning light directly across the alternator warning light to up the wattage to something in the region of 4.4 Watts when in the ignition on position, once the engine starts and the fuel pump has a permanent supply the earth will be broken from the relays and the LH/RH indicator warning light circuit will be back to standard. Remember to allow a second or 2 for the fuel pump to prime before the relays kick in and the crank the engine, the alternator will now have a low cut-in speed
Disconnect the indicator warning light and run 2 leads from that light to 2 x 5 terminal relays as shown, connecting them to terminal 30 of each relay
Extend the leads that have been disconnected from the indicator warning light and connect them to terminal 87a of each relay (Marked on the diagram "To LH Indicator Lts" and "To RH Indicator Lts")
Leaving the Alternator Light original wiring as is, connect a lead to each side of the alternator light and run those leads to the relays, connect them to terminal 87 of each relay as shown
Run a fused ignition supply to terminal 85 of each relay coil
With a short lead, link together terminal 86 of each relay coil and extend that same lead to a 3rd 5 terminal relay connecting it to terminal 87a
Connect terminal 30 of this same 3rd relay to earth (Return/Ground or whatever else you call it)
At this same 3rd relay, connect coil terminal 85 to earth (Return/Ground or whatever else you call it)
At this same 3rd relay, connect coil terminal 86 with a lead to the fuel pump wire that goes directly to the pump (After the pump control relay)
Someone somewhere has got something wrong with this vehicles alternator warning light circuit, the wattage of the bulb should be 3 Watts or more, higher than 3 watts is not a problem apart from heat from that bulb, lower than 3 watts highers the alternators cut-in speed, I don't think a 3watt bulb is made for the type of warning light that is used but I could be wrong
Carrying out the above modification will solve the high cut-in speed problem.
What the circuit does is connect the indicator warning light directly across the alternator warning light to up the wattage to something in the region of 4.4 Watts when in the ignition on position, once the engine starts and the fuel pump has a permanent supply the earth will be broken from the relays and the LH/RH indicator warning light circuit will be back to standard. Remember to allow a second or 2 for the fuel pump to prime before the relays kick in and the crank the engine, the alternator will now have a low cut-in speed
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