Charging Question

[vegas paul]

I'm a little stumped.

This is for my 51, but it is a 12V converted car, with alternator, and new battery, so the question is probably just as valid for a newer car.

With car running, everything hooked up, I'm getting about 11.5 volts across the battery terminals at idle (and from alternator terminal to ground), when I rev the engine, no change in voltage. However, when I disconnect the positive terminal of the battery (effectively removing the battery), the car remains running (which indicates to me the alternator is working) and I get about 13V from alternator terminal to ground. When I rev the engine it goes up to about 14.5V.

Hooking the battery terminal back up, again, I get only about 11.5 V across the terminals AND from alternator terminal to ground, again with no change when revving.

I took the alternator to Kragen and they tested it under load and it passed, including the internal voltage regulator. I was almost hoping it would fail, since that would be an easy solution.

WTF? It seems that the alternator is not communicating with the battery, yet the car starts & runs, and BTW, the amp meter acts normal during driving (slightly up when revving, and slight down movement when turning on lights, etc.)

I just recently replaced the battery which was dead and would not maintain charge - now I am thinking the battery may have been OK, and that this new battery is going to drain as I drive and I still haven't figured it out.

Let the electical gurus speak...



Las Vegas, NV - Stop by, coffee's on!
'51 Champion Business Coupe G899965 10G-Q4-1434

[Guest]

Where is the alternator terminal hooked up? Started soleniod???

Bill, Many Fords and one great Stude!

[BobGlasscock]

or, little chance, a shorted battery cell.

'50 Champion, 1 family owner

[vegas paul]

The alternator is hooked up to the + coil terminal, battery is new. Keep in mind everything (hooked up like this) has worked fine for over a year...

Las Vegas, NV - Stop by, coffee's on!
'51 Champion Business Coupe G899965 10G-Q4-1434

[Guest]

OK, hook a #10 wire from the alternator +12 output terminal to the starter solenoid terminal (the side that comes from the battery and put a six inch length of #16 wire (fuse link) in line.....or go to your friendly auto parts guy the knows how to use a book (I know hard to come by these days) and get a wire designed for and having the fuse link built in. Sorry, forgot, something failed to stop it from charging the battery if it worked before. You were charging the battery through the ignition switch!

Bill, Many Fords and one great Stude!

[vegas paul]

Thanks Bill, I'll try it tomorrow - my social director (wife) tells me we're having company over in about an hour and I need to clean up.

By the way, Bill please tell me the theory/purpose of what you are suggesting. (edit) Also, do I leave all existing wires in place or do I replace the wire to the coil with what you suggest?

Las Vegas, NV - Stop by, coffee's on!
'51 Champion Business Coupe G899965 10G-Q4-1434

[wolfie]

Bill may be on to something but I would have someone that knows how to load test a battery do that.Here all the chain FLAPS will do it for free but it is rare to find anyone there that knows what he is doing.They just hook everything up and tell you you need a battery,unless you really do then they tell you need a starter or alternator.Same problem with a couple motorcycles and a battery fixed it every time.Steve

[Guest]

The alternator provides high current (immediately after the car starts) to charge the battery, given your alternator is an internal regulated it samples battery voltage and provides "charging" through the same wire. That alternator will put out 60 plus amps at full load. The wire to the coil is going to be a #16 max and will not carry that load for long, never mind it's track back to the battery is through the ingintion switch.

I assume this is a GM one wire, if so it needs to be wired straight to the +12 terminal on the battery, typically done on the starter solenoid.

Bill, Many Fords and one great Stude!

[Studeman]

GM wiring



**I'm sorry but I don't have the name of who contributed this...
I'll pull it immediately upon request.


Specializing in Studebaker Restoration

[Guest]

quote:Originally posted by Studeman

GM wiring



**I'm sorry but I don't have the name of who contributed this...
I'll pull it immediately upon request.


Specializing in Studebaker Restoration

That is it! But if it is a true one wire GM alternator eliminate the wire and diode from the coil.

Bill, Many Fords and one great Stude!

[Tom Bredehoft]

That's a lot like the set up on the alternator I got from Fifth Avenue Garage. I believe it used body ground.

[img=left]http://www.alink.com/personal/tbredehoft/Avatar1.jpg[/img=left]
Tom Bredehoft
'53 Commander Coupe (since 1959)
'55 President (6H Y6) State Sedan
(Under Construction 571 hrs.)
'05 Legacy Ltd Wagon
All Indiana built cars

[leyrret]

Check amperage into battery. High amperage with low voltage would indicated a shorted cell. Low voltage(at alt.& bat.) with low amperage would indicate insufficient alternator output. Make certain your belt isn't slipping when you apply a load.

[64V-K7]

The lead to the coil can be eliminated, as it was originally designed to operate an idiot light. It's not needed functionally to operate the alternator.
The T2 terminal switches on the internal regulator to start charge at a specified voltage/amperage drop. If, instead of the rear of the Alternator (BAT), you connect the T2 lead to somewhere under the dash (main buss), the regulator will sense the voltage drop in the circuit sooner and you'll get immediate charging. Many times, with the rear alternator connection, you have to rev the engine to get the unit to start charging.


Bob Johnstone

https://www.studebaker-info.org

64 GT Hawk
55 President State Sedan
70 Avanti (R3)

[leyrret]

Unless were talking about a one wire alternator don't see how wire #1 can be eliminated as it turns the regulator on. It usually run through a light or resistor initially feeding the alternator field winding. Voltage from #2 terminal turns off current to field windings.
Image 010 at link shows SI circuitry, http://oljeep.com/gw/alt/edge_Altern...html#Section_2 Terminal #1 turns on Transistor # 1
allowing flow through field, Terminal #2 through Zener Diode turns on Transistor #2 turning off Trans #1

[64V-K7]

T1 doesn't do anything but put out +12 when the alternator is charging. It supposed to be routed to a dash lamp with +12 on the other side coming from the IGN switch. When you turn turn the key to start the IGN voltage lights the bulb since it's now grounded thru the alternator. When you start the engine and the Alt starts putting out voltage, the +12v from T1 counters the +12v at the lamp (from the IGN) and it goes out. When you're running down the road and your light comes on, it's because the belt dropped off or the alt is toast.
When you see your light flickering at a stop light, it's because some of the diodes are bad and it's losing voltage


Bob Johnstone

https://www.studebaker-info.org

64 GT Hawk
55 President State Sedan
70 Avanti (R3)