SIV Alternator Last Time

mxp01 · Nov 25, 2007

I'm back Guys!!

This should be easy, right? Everything is working great. I replaced the alternator with a new one and problem solved. But the problem is only solved if I do this one thing on startup: When I start up the car the alternator will not work at all, then when I give it a good rev (3500 rpm) the alternator works great and will stay working great until I turn the car off. Everything works great under tthose circumstances. By the way I have yet to get my igniton light to come on (I have a good bulb). It's not that big of a deal to me, but should I be concerned?

BTW: Thank you all for your help on my last Thread!!

Thank you

Cade

howard · Nov 25, 2007

When you say the alternator's not working, do you mean the belt's not running or that the belt is turning but there's no charge going back into the system?

jumpinjan · Nov 25, 2007

mxp01 said:
By the way I have yet to get my igniton light to come on (I have a good bulb). It's not that big of a deal to me, but should I be concerned?

Yes, you should be concerned. There is no current passing through to the alternator field windings to get it started. I think it is self-excitation, being that the core still has some weak field in it and when you rev it up, it builds field strength without an external field current (your light bulb). You need to get that bulb lighted.
Jan

mxp01 · Nov 26, 2007

The link that i have been using to wire the alternator in is the link i have been puting on my postings, I wired the care to those exact drawings. Except the Ammeter, i have the ammeter wired to factory Specs. which i was told that was the correct way. but i have the ignition lights wired the way in the drawing. This is the second alternator i have put in this car and both have not got the ignition light to come on. Do i need to do any changes to the Ignition switch it self? Heres the link http://www.team.net/www/rootes/sunbeam/alpine/mk1-5/techtips/altconv.html
Thank you
Cade

Tom H · Nov 26, 2007

Cade,

Pull the "L" wire ("L" as indicated on the drawing you referenced) off the alternator. Then with the ignition switch in the ON position, ground that wire to the chassis. The light should come on. If not you've got a broken wire, broken lamp socket, or burned out bulb. If you get a BIG spark and no lamp lighting, then the wire you thought was the L wire is really the R wire. Better yet, just in case, instead of grounding the wire directly put a fuse between it and ground. If it doesn't light you need to trace the circuit to find why. If it does light when grounded, but doesn't light when connected to the L terminal let us know and we'll think of alternate tests.
Tom H

mxp01 · Nov 26, 2007

Well, since I started my switch to an alternator 2 MONTHS AGO I have put in 3 new ignition bulbs. Well before I was going to do what Tom said, I drove to my local auto store to get another new bulb. I have bought plenty of bulbs from auto stores that haven't worked (mostly #1157 for my trailer), I replaced it just to make sure and, Shazam!! It works! Goes to show you should always check your bulbs 5 times before you assume they are good or bad. Now I have a Series IV Negative Earth and no more dead batteries at idle!!!

Thank you all for your help
Cade

Nickodell · Nov 26, 2007

This may be a dumb question, but why do you need an idiot light and an ammeter? The ammeter, if it's correctly wired, will tell you all you need to know about the electrical circuit.

Tom H · Nov 27, 2007

Nick, see his beginning post in this thread. He said the indication is not a big deal. But he also, correctly, suspected that the lack of a light was also responsible for no charge at low revs. Apparently, as noted by Jan, the light circuit provides two functions - as an "idiot light" , but also as the source of the initial current to the field windings on the alternator. I did not have that understanding previously, but based on Jan's post and Cade's confirmation that with a good bulb, it now charges properly at low revs, I now understand the greater importance of the lamp.

Nice work, Cade,

Regards, Tom

Jay Laifman · Nov 27, 2007

The answers and conclusion you got about the light is correct. I am going to add a part that I learned when I did mine. I got the Hitachi alternator for my car - off of Nissans and Mazdas, and probably many more. When I got it, I went to Pep Boys and looked at the wiring diagram for the Nissan it came off of. They showed the wiring as you probably have - the L goes to one side of the dash light, the other side of dash light goes to keyed power. As others have indicated, that allows the fields to be charged. But, the additional thing the Nissan had was that it had a resistor parallel to the light. So, as long as the light bulb was good, the electricity went through the bulb and lit it. But should the bulb blow, the resistor was still there to keep the power flowing to the fields.

I've never actually figured out what size resistor should go with the bulb to install one. I figured if the light did not go on, I'd know I'd need to replace the bulb. It's been probably 15 years since I've done this - and never have I blown a bulb. So, it really isn't an issue.

That said, I don't understand why you are blowing so many bulbs, given the 15 years I've gone with the bulb in this condition - and that bulb has been in the car since I bought it 30 years ago, meaning it probably has been there since new.

Nickodell · Nov 27, 2007

Tom H said:
Nick, see his beginning post in this thread. He said the indication is not a big deal. But he also, correctly, suspected that the lack of a light was also responsible for no charge at low revs. Apparently, as noted by Jan, the light circuit provides two functions - as an "idiot light" , but also as the source of the initial current to the field windings on the alternator. I did not have that understanding previously, but based on Jan's post and Cade's confirmation that with a good bulb, it now charges properly at low revs, I now understand the greater importance of the lamp.

Nice work, Cade,

Regards, Tom

I understand that. However, there are several ways to connect an alternator to energize the field windings without having to go through a fragile bulb. I guess I am just going on my SV, which came with an ammeter and no light. Whatever floats your boat, as they say.

Tom H · Nov 27, 2007

Nick, OK, then that would have been a reasonable answer to Cade. He was looking for an answer as to how to get his alternator to charge his battery. He was not looking for a way to make the light work. Turns out that the simplest way to solve his charging problem was to simply use a good bulb. And he gets two things solved at once. By the way, based on another post by his father I think he does NOT have a working ammeter. I think Cade was verifying charging / not charging status by use of a portable voltmeter. So until he gets his ammeter working he may find the idiot lamp quite useful.

And I am surprised to read that your SV did not have a light. I'm pretty sure it did from the factory, even with an ammeter installed. All the wiring diagrams I have seen for SV show the ignition lamp and not as an option. There is even an extra relay just to light the lamp.

Tom H

Nickodell · Nov 27, 2007

I guess mine had the D.P.O. model dashboard.

Speaking of which; what a strange term we use for the instrument panel. A dashboard was originally a piece of wood placed on the front of a horse-draw trap, buggy, etc. to catch mud and stones thrown up by the horse's hooves. I guess that when the first "horseless carriages" were made, they kept most of the original design and this was where they placed the few instruments, such as oil pressure and speedometer.