New alternator, 65 in place of 35?

nobber · Mar 12, 2015

Its a Lucas A127 type, 3 pin plug. Original was 35 amp, new is 65 amp.
So I need to upgrade the wiring. I know a lot of people will say don't bother but there are a few looms listed for different size alternators and If I am doubling the output capacity of the alternator I would assume the wiring needs seeing to?

Which wires do I change?

nobber · Mar 12, 2015

So, obviously the two brown wires going to the starter solenoid, what about the white / red going to the ignition switch? Mine is pre 86 so doesn't have a starter relay.

gse1986 · Mar 12, 2015

Couldn't you add a starter relay? Would mean less current travelling through your ignition, which should extend the life of it.

nobber · Mar 12, 2015

Possibly , but getting the alternator sorted is my priority, mine has just died.

trax · Mar 12, 2015

if you need to, just the ones going to the starter stud from the alt will do.

nobber · Mar 12, 2015

Nice one, Ive left the 65 amp in to get reconditioned so will be putting it in the 90 in the morning, time to get some wiring done.

trax · Mar 12, 2015

nobber said:
Nice one, Ive left the 65 amp in to get reconditioned so will be putting it in the 90 in the morning, time to get some wiring done.

you might be alright, measure the core thickness of the wire. if they are two 4.5mm sq your'll be alright.

nobber · Mar 12, 2015

I might be, but it would be a dodgy way to find out through trial and error.
An alternator wont throw out the full 65 amps will it? I am under the impression that it will put out what the electrical system is drawing?

trax · Mar 12, 2015

nobber said:
I might be, but it would be a dodgy way to find out through trial and error.
An alternator wont throw out the full 65 amps will it? I am under the impression that it will put out what the electrical system is drawing?

no need to trial and error. measure the cable core thickness

yup, but you want to cover it for when it does go full belt.

nobber · Mar 12, 2015

Ill have a proper look at it in the morning, just got a call to say my alternator is done, 36 squibs to have it fixed, new slip rings and rectifier, cant complain with that, all done the same day as well.

boguing · Mar 12, 2015

You only need to upgrade any wires that will use the extra current.

Or. Your starter won't use any more power just because you have a bigger alternator, in the same way that the interior lamp won't be any brighter.

I doubt that your battery will draw any extra either, but you could upgrade that path (alt to solenoid, solenoid to batt, batt to earth).

Uprating the alternator doesn't really do anything for a standard car. What you do gain is the ability to simultaneous charge another battery or run heavy extra loads (like winches) and have a larger reserve.

Edit. That's not to say that changing the wiring is a bad idea. If your Landy is like either of mine were, it will be in poor condition.

nobber · Mar 12, 2015

boguing said:
You only need to upgrade any wires that will use the extra current.

Or. Your starter won't use any more power just because you have a bigger alternator, in the same way that the interior lamp won't be any brighter.

I doubt that your battery will draw any extra either, but you could upgrade that path (alt to solenoid, solenoid to batt, batt to earth).

Uprating the alternator doesn't really do anything for a standard car. What you do gain is the ability to simultaneous charge another battery or run heavy extra loads (like winches) and have a larger reserve.

Edit. That's not to say that changing the wiring is a bad idea. If your Landy is like either of mine were, it will be in poor condition.

Im hoping everything will work a little better, if I put the heater on the lights go a little dimmer, the old alternator was on its way out.

trax · Mar 13, 2015

boguing said:
You only need to upgrade any wires that will use the extra current.

Or. Your starter won't use any more power just because you have a bigger alternator, in the same way that the interior lamp won't be any brighter.

I doubt that your battery will draw any extra either, but you could upgrade that path (alt to solenoid, solenoid to batt, batt to earth).

Uprating the alternator doesn't really do anything for a standard car. What you do gain is the ability to simultaneous charge another battery or run heavy extra loads (like winches) and have a larger reserve.

Edit. That's not to say that changing the wiring is a bad idea. If your Landy is like either of mine were, it will be in poor condition.

starter pulls a lot more power than 60amps so the solenoid to batt and batt to earth don't need to be touched as they are already upto the job

nobber · Mar 13, 2015

Thats worked a treat, it now charges when idling, even with the heater on.

nobber · Mar 16, 2015

No it doesn't!
Bloody thing wont charge now unless I rev it, at idle when I start it the charge light comes on and the volt meter is reading well below normal. If I blip the revs the charge light goes out, it will settle down to idle and the charge light stays off.

Any ideas?

fanatic · Mar 16, 2015

Pulley size perhaps

nobber · Mar 16, 2015

fanatic said:
Pulley size perhaps

Cant be , it worked fine the other day, I need to check the voltage at the exciter wire tomorrow but if the light is lit and bright its getting 12 volts.

I'll clean up all the wiring connections but after blipping the throttle it runs fine.

Its not idling too slow, if anything it idles a wee bit higher than it should.

boguing · Mar 16, 2015

Obvious, but is the belt tight and not polished?

trax · Mar 16, 2015

what did you buy? britpart, etc?

nobber · Mar 16, 2015

boguing said:
Obvious, but is the belt tight and not polished?

All nice and tight.

trax said:
what did you buy? britpart, etc?

It was my spare Lucas alternator that I had reconditioned by a local auto electrics place.
Its had a new regulator and slip rings.

New alternator, 65 in place of 35?

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