Increasing the output of the stock alternator?
11-27-2009, 03:49 PM
#17
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It can be done, and is commonly done in the marine business for cruising sailboats who want a fast recharge time on large battery banks. Lestek is one outfit that rewinds stock alternators for Balmar, Ample Power and others who put their own label on them.
But nothing is free. Getting more amps out of the same size case certainly means more heat, which is what kills the marine hi-output units in my experience. But I think it is worse than simply more amps-- to get more windings in the same frame means smaller wire, and smaller wire adds yet more heat.
But if you are willing to add some cooling then I think it would work. There's already a cooling duct, just add an extra blower inside the fender to help push air into the alternator.
Spinning faster generally doesn't work because the rotor wants to disassemble itself at high RPM from the centrifugal force.
But nothing is free. Getting more amps out of the same size case certainly means more heat, which is what kills the marine hi-output units in my experience. But I think it is worse than simply more amps-- to get more windings in the same frame means smaller wire, and smaller wire adds yet more heat.
But if you are willing to add some cooling then I think it would work. There's already a cooling duct, just add an extra blower inside the fender to help push air into the alternator.
Spinning faster generally doesn't work because the rotor wants to disassemble itself at high RPM from the centrifugal force.
I never had had a alternator come apart, but I have had a generator sling the solder out.
11-27-2009, 05:03 PM
#18
Nordschleife Master
I would think that the stock cooling is fine for a higher output. I run most of my cars with no ducting at all, and have had ZERO failures other than a regulator which failed due to the brushes wearing out.
Spinning it a little faster would not be a massive problem. But if you were to double the speed then you would have an issue IMO.
Unfortunatly though there is no space for extra diodes in our units.
Spinning it a little faster would not be a massive problem. But if you were to double the speed then you would have an issue IMO.
Unfortunatly though there is no space for extra diodes in our units.
11-27-2009, 05:35 PM
#19
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... the stock pulleys have a ratio of about 2.4:1. So, at 6800 engine rpm the alternator is spinning at just over 16k rpm. Not crazy rpm, but getting up there.
11-27-2009, 05:41 PM
#20
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Greg--
Figure out what the demands really are, and look at voltage drop in your wiring and grounds to make sure you are getting all available power at the places in the car where it's needed. Engine ground braid and its connections are very important and often overlooked. The cable between the alternator and the starter is another place, with all the connections and the exposure to the elements down there. I think Sterling (IIRC) can share some hints on his replacing the battery-to-starter cable with larger. The alternator-to-jump post cable and maybe a new larger jump post to CE cable would be next if the big loads are powered from the CE primary bus.
Easy test is at the alternator terminals directly with the engine running above idle. If voltage there is steady at 13.5+, and you see less at the ends including battery or CE bus, get to work on conductor and terminal condition. You can test voltage drop under load pretty easily with a test lead extension and the meter set on a low DC voltage scale.
Figure out what the demands really are, and look at voltage drop in your wiring and grounds to make sure you are getting all available power at the places in the car where it's needed. Engine ground braid and its connections are very important and often overlooked. The cable between the alternator and the starter is another place, with all the connections and the exposure to the elements down there. I think Sterling (IIRC) can share some hints on his replacing the battery-to-starter cable with larger. The alternator-to-jump post cable and maybe a new larger jump post to CE cable would be next if the big loads are powered from the CE primary bus.
Easy test is at the alternator terminals directly with the engine running above idle. If voltage there is steady at 13.5+, and you see less at the ends including battery or CE bus, get to work on conductor and terminal condition. You can test voltage drop under load pretty easily with a test lead extension and the meter set on a low DC voltage scale.
11-27-2009, 07:11 PM
#21
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Greg--
Figure out what the demands really are, and look at voltage drop in your wiring and grounds to make sure you are getting all available power at the places in the car where it's needed. Engine ground braid and its connections are very important and often overlooked. The cable between the alternator and the starter is another place, with all the connections and the exposure to the elements down there. I think Sterling (IIRC) can share some hints on his replacing the battery-to-starter cable with larger. The alternator-to-jump post cable and maybe a new larger jump post to CE cable would be next if the big loads are powered from the CE primary bus.
Easy test is at the alternator terminals directly with the engine running above idle. If voltage there is steady at 13.5+, and you see less at the ends including battery or CE bus, get to work on conductor and terminal condition. You can test voltage drop under load pretty easily with a test lead extension and the meter set on a low DC voltage scale.
Figure out what the demands really are, and look at voltage drop in your wiring and grounds to make sure you are getting all available power at the places in the car where it's needed. Engine ground braid and its connections are very important and often overlooked. The cable between the alternator and the starter is another place, with all the connections and the exposure to the elements down there. I think Sterling (IIRC) can share some hints on his replacing the battery-to-starter cable with larger. The alternator-to-jump post cable and maybe a new larger jump post to CE cable would be next if the big loads are powered from the CE primary bus.
Easy test is at the alternator terminals directly with the engine running above idle. If voltage there is steady at 13.5+, and you see less at the ends including battery or CE bus, get to work on conductor and terminal condition. You can test voltage drop under load pretty easily with a test lead extension and the meter set on a low DC voltage scale.
I have a digital volt gauge coming off the fuse panel, so I am getting almost 14 with no load.
All the grounds and the big power connections have been cleaned in the last 6 months, so I think i am ok with with the grounds.
I will check the total draw and out put next week to find out exactly what I have.
05-01-2024, 03:05 PM
#29
Burning Brakes
Here and this thread: https://rennlist.com/forums/showthre...errerid=100405
Yes, the ford 3G is a great apprach and worked for me. The only thing I will add is that the wiring has to be up to the task. The wiring is appracing 45 years old now. Grounds, connection issues and internal copper corosion is a real problem that has to be considered and elininate for any alternator to function properly.
05-01-2024, 04:47 PM
#30
Pro
His profile says he has a 79 so I don't think the Ford 3G is compatible with the 79 mounts and drive system, it would need a different pulley for sure. A custom rewire of the existing alternator would be needed but I think those have a very limited life expectancy due to the high heat generated to get the increased amperage.