The Ford Barn

Rich Largent · 09-08-2010, 04:34 PM

I'm contemplating installing a 60 amp alternator in my 29 Closed Cab Pickup. Should I change the ammeter to a 30+ - type?

Rich Largent

pdora · 09-08-2010, 04:40 PM

Yes, and don't forget to reverse the wires if you are converting a positive ground system to negative ground.

Charlie Stephens · 09-08-2010, 05:37 PM

You can also run a jumper wire across the ampmeter to carry part of the current. Your ampmeter will no longer read correctly (you need to mentally adjust the reading) but it will look original. I think you can install this jumper at the terminal box on the firewall. What are you going to do with 60 amps?

Charlie Stephens

Jerry Parr WI · 09-08-2010, 05:41 PM

It is not necessary. The ammeter is not showing the output of the alternator but rather the battery charge rate. The alternator unlike the generator has a regulator that limits the output to the amount of the load plus a small amount to keep the battery charged. Because of the regulator the ammeter should read near 0 most of the time. It would be possible to exceed 20 amps very briefly if the alternator were trying to charge a dead battery but the original ammeter is very resistant to overcharging damage. I would not expect this be an every start condition.

Tom Endy · 09-08-2010, 07:55 PM

I have an alternator on both my cars. One is a 6 volt, the other is a 12 volt. Both have the original ammeter. When I first start either car, and pull power out of the battery, the ammeter pegs over to the 20 showing the alternator is charging the battery back up at a high rate. After a while it pulls back to zero. It has been that way for years and has not done any damage to either ammeter. The existing shunt in the ammeter is apparently stout enough to withstand the high current.

As posted above, even though an alternator is rated at 60 amps, that much current is not going to go to the battery.

Tom Endy

Rich Largent · 09-08-2010, 08:50 PM

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I've been advised if I want to run halogen headlights the 60 amp alternator is the way to go.

Rich Largent · 09-08-2010, 08:51 PM

Thanks Tom,
The generator is on order.

Rich

Rich Largent · 09-08-2010, 08:53 PM

Thanks Jerry,
The alternator is on its way.

Rich

Jerry Parr WI · 09-09-2010, 09:30 AM

The link between the current and the needle is magnetic. Once the needle is against the stop increasing the magnetic field pushes harder against the stop but does no damage.

A weak point in the ammeter is the connection between the posts and the brass shunt. The posts are a carriage bolt that fits thru a square hole in the shunt. A loose connection here causes the meter to get hot and even burn. Increasing the current could cause a poor connection to fail sooner. I usually solder the bolts to the shunt.

09-08-2010, 04:34 PM	#1
Rich Largent Member Join Date: Sep 2010 Location: Cape Fear area, North Carolina Posts: 54	Alternator & Ammeter I'm contemplating installing a 60 amp alternator in my 29 Closed Cab Pickup. Should I change the ammeter to a 30+ - type? Rich Largent

09-08-2010, 04:40 PM	#2
pdora Senior Member Join Date: Jul 2010 Location: Rutledge, Georgia Posts: 184	Re: Alternator & Ammeter Yes, and don't forget to reverse the wires if you are converting a positive ground system to negative ground. __________________ Peter A. Dora -- Rutledge, GA (AE4XH)

09-08-2010, 05:37 PM	#3
Charlie Stephens Senior Member Join Date: May 2010 Location: Southern California Posts: 7,305	Re: Alternator & Ammeter You can also run a jumper wire across the ampmeter to carry part of the current. Your ampmeter will no longer read correctly (you need to mentally adjust the reading) but it will look original. I think you can install this jumper at the terminal box on the firewall. What are you going to do with 60 amps? Charlie Stephens

09-08-2010, 05:41 PM	#4
Jerry Parr WI Senior Member Join Date: May 2010 Posts: 619	Re: Alternator & Ammeter It is not necessary. The ammeter is not showing the output of the alternator but rather the battery charge rate. The alternator unlike the generator has a regulator that limits the output to the amount of the load plus a small amount to keep the battery charged. Because of the regulator the ammeter should read near 0 most of the time. It would be possible to exceed 20 amps very briefly if the alternator were trying to charge a dead battery but the original ammeter is very resistant to overcharging damage. I would not expect this be an every start condition.

09-08-2010, 07:55 PM	#5
Tom Endy Senior Member Join Date: May 2010 Location: Southern California Posts: 3,168	Re: Alternator & Ammeter I have an alternator on both my cars. One is a 6 volt, the other is a 12 volt. Both have the original ammeter. When I first start either car, and pull power out of the battery, the ammeter pegs over to the 20 showing the alternator is charging the battery back up at a high rate. After a while it pulls back to zero. It has been that way for years and has not done any damage to either ammeter. The existing shunt in the ammeter is apparently stout enough to withstand the high current. As posted above, even though an alternator is rated at 60 amps, that much current is not going to go to the battery. Tom Endy

09-08-2010, 08:50 PM	#6
Rich Largent Member Join Date: Sep 2010 Location: Cape Fear area, North Carolina Posts: 54	Re: Alternator & Ammeter Sponsored Links (Register now to hide all advertisements) I've been advised if I want to run halogen headlights the 60 amp alternator is the way to go.

09-08-2010, 08:51 PM	#7
Rich Largent Member Join Date: Sep 2010 Location: Cape Fear area, North Carolina Posts: 54	Re: Alternator & Ammeter Thanks Tom, The generator is on order. Rich

09-08-2010, 08:53 PM	#8
Rich Largent Member Join Date: Sep 2010 Location: Cape Fear area, North Carolina Posts: 54	Re: Alternator & Ammeter Thanks Jerry, The alternator is on its way. Rich

09-09-2010, 09:30 AM	#9
Jerry Parr WI Senior Member Join Date: May 2010 Posts: 619	Re: Alternator & Ammeter The link between the current and the needle is magnetic. Once the needle is against the stop increasing the magnetic field pushes harder against the stop but does no damage. A weak point in the ammeter is the connection between the posts and the brass shunt. The posts are a carriage bolt that fits thru a square hole in the shunt. A loose connection here causes the meter to get hot and even burn. Increasing the current could cause a poor connection to fail sooner. I usually solder the bolts to the shunt.