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Old 09-21-2019, 07:29 PM   #1
vern hodgson
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Default Charging?? Canít say it is

So alternator (6v)shows good output, but battery is not getting charged. Charges up just fine using a charger, and lasts a while. ( have not tried to get to s. Dakota yet) but would be nice to have benefit of an on board charger.
Where should I look?
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Old 09-21-2019, 08:24 PM   #2
Gary WA
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Default Re: Charging?? Canít say it is

On board charger.com,ha
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Old 09-21-2019, 09:14 PM   #3
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Default Re: Charging?? Canít say it is

Might put a volt meter on the battery before and after engine start and confirm voltage increases after the engine starts. This will confirm the battery is probably charging.
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Old 09-21-2019, 09:40 PM   #4
Curtis in MA
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Default Re: Charging?? Canít say it is

It is my understanding that the battery powers the starter and ignition while starting and then when the alternator gets excited it takes over. So if you then disconnect the battery the car should still run. Does it?
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Old 09-21-2019, 11:22 PM   #5
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Default Re: Charging?? Canít say it is

Bad idea to remove the battery connection and expecting alternator or generator to run car.
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Old 09-22-2019, 01:17 AM   #6
vern hodgson
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Default Re: Charging?? Canít say it is

Quote:
Originally Posted by Curtis in MA View Post
It is my understanding that the battery powers the starter and ignition while starting and then when the alternator gets excited it takes over. So if you then disconnect the battery the car should still run. Does it?
My thinking also and I have done it many times on modern iron. This car does not run when battery is disconnected.
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Old 09-22-2019, 07:57 AM   #7
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Default Re: Charging?? Canít say it is

Use a voltmeter and check battery voltage before and after starting, also check output voltage of alternator. Could be a connection/wiring issue. Wont know unless you take some readings. Dont start replacing parts until you verify what is bad.
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Old 09-22-2019, 09:17 AM   #8
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Default Re: Charging?? Canít say it is

Is the ammeter working as it should ? If the alternator is charging then the battery should charge. Sounds as though there is an open or poor connection somewhere in the circuit. I'm assuming the alternator has an internal regulator, if not, then the alternator can be good but the external regulator could be bad.
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Old 09-22-2019, 09:37 AM   #9
30 Closed Cab PU
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Default Re: Charging?? Canít say it is

Quote:
Originally Posted by Curtis in MA View Post
It is my understanding that the battery powers the starter and ignition while starting and then when the alternator gets excited it takes over. So if you then disconnect the battery the car should still run. Does it?




The battery acts to regulate the voltage output of a generator. Removing the battery while running allows the generator to run at their maximum voltage and will overvoltage the electrical system and most likely damage electrical components.

Last edited by 30 Closed Cab PU; 09-22-2019 at 11:51 AM. Reason: Corrected informatio that included alternators, mistake was pointed out politely in below posts.
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Old 09-22-2019, 10:17 AM   #10
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Default Re: Charging?? Canít say it is

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Originally Posted by Curtis in MA View Post
It is my understanding that the battery powers the starter and ignition while starting and then when the alternator gets excited it takes over. So if you then disconnect the battery the car should still run. Does it?

If the system is charging it will run with a battery cable disconnected , if the idle speed is fast enough for the generator or alternator to begin charging . Don't run or drive with a loose or disconnected cable or problems will likely follow .


For a quick check I have quickly loosened the ground cable with the engine running at a fast idle . If the engine quits running when the cable is lifted off the post , then the system isn't charging .Yes running with the battery disconnected can and will do damage but a quick and instant test will confirm if the system is charging. If the engine still runs after the cable is lifted off , quickly reconnect the cable and no harm will result . I'm not recommending this but I have done this many times on some of my model A's over the years . This test will confirm if the system is charging.
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Old 09-22-2019, 10:21 AM   #11
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Default Re: Charging?? Canít say it is

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Originally Posted by 30 Closed Cab PU View Post
The battery acts to regulate the voltage output of the alternator/generator. Removing the battery while running allows the alternator/generator to run at their maximum voltage and will overvoltage the electrical system and most likely damage electrical components.
Actually, the battery acts to regulate the voltage on a stock Model A with a stock generator (no aftermarket voltage regulator installed). You do NOT want to disconnect the battery from an engine that is running at a high enough RPM for the generator to be putting out current from a stock generator, because the voltage can go quite high.

The alternators that we use on a Model A have an electronic voltage regulator built into them that regulate the voltage coming out of the alternator. So they are different from stock generators. You can disconnect the battery for a test, if you want. (I don't do it, but you can, if you want to.)
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Old 09-22-2019, 10:39 AM   #12
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Default Re: Charging?? Canít say it is

Check your connections at every point in the path from the alternator, to the battery and to the frame. You need a complete path from the alternator to the battery to the frame and back to the alternator. The alternator should be putting out about 7.2 volts to charge the battery properly. Use an analog volt meter to check as others have said. You state that you see the alternator putting out current as indicated by the amp meter. Good indication of a bad connection somewhere.
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Old 09-22-2019, 11:19 AM   #13
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Default Re: Charging?? Canít say it is

Check for open fuse mounted on starter. (I'm guessing there is one.)
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Old 09-22-2019, 11:52 AM   #14
30 Closed Cab PU
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Default Re: Charging?? Canít say it is

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Originally Posted by Jim/GA View Post
Actually, the battery acts to regulate the voltage on a stock Model A with a stock generator (no aftermarket voltage regulator installed). You do NOT want to disconnect the battery from an engine that is running at a high enough RPM for the generator to be putting out current from a stock generator, because the voltage can go quite high.

The alternators that we use on a Model A have an electronic voltage regulator built into them that regulate the voltage coming out of the alternator. So they are different from stock generators. You can disconnect the battery for a test, if you want. (I don't do it, but you can, if you want to.)
Thanks Jim for pointing out correct info about alternators - corrected my post
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Old 09-22-2019, 05:56 PM   #15
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Default Re: Charging?? Canít say it is

Alternators are in a completely different class that a generator and especially a 3-brush unit. A person can run the electrical system with an alternator for a short period of time with the battery out of the circuit but I would only do it momentarily. The alternator has a control unit.

The 3 brush generator is paired with a battery and only works well with a battery in the circuit. A Fun Projects regulated 3-brush can destroy the regulator if you disconnect the battery from the circuit. Too many amps. A regular 3 brush can overvolt the lights if they are turned on when the battery is disconnected. No problem if you keep a lot of spares but not necessarily a good idea.
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Old 09-23-2019, 12:34 AM   #16
vern hodgson
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Default Re: Charging?? Canít say it is

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Originally Posted by Patrick L. View Post
Is the ammeter working as it should ? If the alternator is charging then the battery should charge. Sounds as though there is an open or poor connection somewhere in the circuit. I'm assuming the alternator has an internal regulator, if not, then the alternator can be good but the external regulator could be bad.
Amp meter shows nothing, never has. Was told it would not show a charge working or not.??
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Old 09-23-2019, 05:52 AM   #17
Patrick L.
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Default Re: Charging?? Canít say it is

Turn the lights on [ any lights] and the ammeter should show a discharge. The ammeter should then also show a charge when engine is running at fast idle. Even an alternator will show a charge for a short period until the battery charge is back. I can't imagine anyone saying the alternator will never show a charge, just not so.
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Old 09-23-2019, 07:39 AM   #18
Curtis in MA
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Default Re: Charging?? Canít say it is

With my 6volt alternator the ammeter runs at zero. If I turn the lights on it deflects for about a half a second and then comes back to zero.
When I first start the car the ammeter shows a slight charge but only for a minute.
I run the car every week so it never gets discharged much.
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Old 09-23-2019, 07:50 PM   #19
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Default Re: Charging?? Canít say it is

Check best tension, if you can turn the fan without turning the motor its too loose. Alternator needs to be tighter than a generator, alternator will not correctly charge with a loose belt.
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