why is my 1-wire alternator setup not charging?

Nugglet

Seaman Apprentice
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Apr 6, 2010
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47
i'll try to explain this the best i can... if more info is needed let me know

i have a 72 winner wildcat with a 307 small block chev... i believe it originally had the 160 i4...

after 1 battery went dead,,, i decided to look into it a little more... (pulling a cable off the battery when running kills the motor)

i had the old alt tested & was told it failed... i bought a new alt for a small block & installed it,,, ran the motor & tested the voltage with a meter & its the same as the battery voltage when not running...

the old alt had an internal regulator but nothing was connected to it... the new alt is the same & i installed it the exact same way as the old one...

i looked for an external regulator under the dash & in the engine compartment & found nothing... as far as i can tell,,, the bat wire from the alt runs to the dash ammeter & then runs from the meter back to the battery post on the starter solenoid...

so what gives??? i tried testing the bat wire right off the alt while it was running & its still the same voltage as the battery when not running...

i've looked for info on the web about 1 wire alt setups & theres something about "exciting the regulator to induce a charge"... what does that mean???

i either toasted or bought a junk new alt or the boat is wired wrong...

i'm at a loss,,, any suggestions???
 

solar7647

Lieutenant Junior Grade
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Apr 23, 2009
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1,218
Re: why is my 1-wire alternator setup not charging?

If you pull the cable off the battery with the new alt, does it kill the engine?

Edit

sorry if I understand the way its hooked up it will kill the engine when you disconnect it because your breaking the connection to the engine.

Hook the wire from the altinator to the starter and then disconect the battery. If it stays running the Alt is good.

As for the voltage reading, check it from the wire at the altinator. It will loose voltage as it runs through every thing.
 

bruceb58

Supreme Mariner
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Mar 5, 2006
Messages
30,454
Re: why is my 1-wire alternator setup not charging?

Stop disconnecting the battery with the engine running!

If you disconnect the battery while running your engine you will kill your alternator in a heartbeat. If you have already done that trick with your new alternator, you killed that one too.
 

EddiePetty

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Re: why is my 1-wire alternator setup not charging?

......you do realize that most one-wire alternators require an engine speed of approximately 1,000 r.p.m.s for the alternator to 'self-excite'. Afterwards, as the engine returns to idle, the alternator will continue to....well, alternate.
 

TiredoleBoy

Petty Officer 2nd Class
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Jul 11, 2010
Messages
172
Re: why is my 1-wire alternator setup not charging?

......you do realize that most one-wire alternators require an engine speed of approximately 1,000 r.p.m.s for the alternator to 'self-excite'. Afterwards, as the engine returns to idle, the alternator will continue to....well, alternate.

Beat me to it.:D
 

Nugglet

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Joined
Apr 6, 2010
Messages
47
Re: why is my 1-wire alternator setup not charging?

i had the old alt tested again,,, failed... i had the new alt tested,,, good... but was told the bearing is close to shot (made alot of noise on the machine)

yes i know it needs 1000+ rpms,,, but what i dont get is we tested it at about 2000rpms & it was still the same voltage as the battery when the motor was off...

is it because the new alternator doesnt have the self exciting regulator??? or possibly a bad ground on the alternator???

i think i'm going to get the old alt rebuilt & go from there...
 

bruceb58

Supreme Mariner
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Re: why is my 1-wire alternator setup not charging?

deleted...misunderstood previous post.
 

Bt Doctur

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Aug 29, 2004
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19,092
Re: why is my 1-wire alternator setup not charging?

When you have it back together, read the voltage on the Orange wire with the motor off.It should be the battery voltage.Is there by chance a square plastic looking block at the starter ?
 

Nugglet

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Messages
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Re: why is my 1-wire alternator setup not charging?

When you have it back together, read the voltage on the Orange wire with the motor off.It should be the battery voltage.Is there by chance a square plastic looking block at the starter ?

by orange wire,,, do you mean the wire thats off the alts bat terminal???

theres nothing at the starter except the starter itself & the solenoid...

i'll be bringing the old alternator in to a repair shop later this afternoon & hopefully he can steer me in the right direction so it will charge at a decent rpm...

i basically only use this boat for wakeboarding (2600-2800rpm),,, and slow cruising around the lake (1000-2000rpm)... anything above 3000rpms really eats the gas...
 

solar7647

Lieutenant Junior Grade
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Apr 23, 2009
Messages
1,218
Re: why is my 1-wire alternator setup not charging?

In most application the wire from the alternator is orange and it runs to the starter terminal directly. The batter cable also runs to the starter and that is how the power gets from the alternator to the battery, instead of how yours is hooked up, from alternator to battery then battery to starter.

So if you check the voltage from the location on the starter where those two wires meet, you should read 12 VDC, witch is what the battery is putting out when the motor is off. When you start the motor and bring it up to 1500rpm you should read 13-15 VDC at the same location.
 

Nugglet

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Apr 6, 2010
Messages
47
Re: why is my 1-wire alternator setup not charging?

mine is wired from the alternator to an ammeter & then back to the starter... but yea,,, i poked it at a bunch of different locations (directly off the alt, at the ammeter,,, at the starter etc) & it all read the same at different speeds...

i brought it to an alternator/starter repair shop & the guy told me it'd need to hit at least 3000rpms to start charging (again,,, which the boat is rarely run at,,, it uses WAY too much gas,,, unless a storm is coming & i need to get back to shore quickly lol)

but he said since its a 42amp,,, he could get it to start charging at around 850rpms...
 

bruceb58

Supreme Mariner
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Mar 5, 2006
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30,454
Re: why is my 1-wire alternator setup not charging?

If I were you I would ditch the ammeter and just run the wire directly to the starter solenoid. That way you don't have to run all the way to the dash and back. Replace the ammeter with a voltmeter.
 

Bt Doctur

Supreme Mariner
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Aug 29, 2004
Messages
19,092
Re: why is my 1-wire alternator setup not charging?

GM 1 wires "excite" at about 1000 rpm , once excited they will remain charging untill it stops spinning.
 
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