Changing out alternator
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
Changing out alternator
Replacing weak 61amp alternator with a 105amp alternator. Stock alternator.
Assuming no wiring changes needed. 61amps is unbelievable weak.
Do I need to disconnect the battery or can I just reconnect (CAREFULLY) the new alternator without a disconnect of the battery.
Assuming no wiring changes needed. 61amps is unbelievable weak.
Do I need to disconnect the battery or can I just reconnect (CAREFULLY) the new alternator without a disconnect of the battery.
Melting Slicks
Joined: Apr 2001
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From: Lubbock Texas
DC
Race Director
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From: Chino CA
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
dISCONNECT THE bATTERY!! That 10 ga wire that hooks to the back of the alternator will act just like a mini arc welder- right up to the point the fusible links melt.
I used to wear a watch- until I got the metal band between the alternator output stud and a ground, I still carry that scar- and the engine was NOT running.
I used to wear a watch- until I got the metal band between the alternator output stud and a ground, I still carry that scar- and the engine was NOT running.
Le Mans Master
Joined: May 2007
Posts: 5,009
Likes: 1,116
From: North tonawanda NY
62 amp alternator is really plenty for stock setup? .. I had a 2,400 watt rms stereo system in my jeep and the stock 75 amp alternator did fine with a optima yellow top battery....
If you have electric fans they usually draw like 40-50 amps Max for dual fans....
The bigger the alternator the more HP draw when there is a heavy load...
My last car had a 20 amp generator that I upgraded to a 35 amp for the stereo amp...
If you have electric fans they usually draw like 40-50 amps Max for dual fans....
The bigger the alternator the more HP draw when there is a heavy load...
My last car had a 20 amp generator that I upgraded to a 35 amp for the stereo amp...
Last edited by augiedoggy; Aug 7, 2013 at 07:47 AM.
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
62 amp alternator is really plenty for stock setup? .. I had a 2,400 watt rms stereo system in my jeep and the stock 75 amp alternator did fine with a optima yellow top battery....
If you have electric fans they usually draw like 40-50 amps Max for dual fans....
The bigger the alternator the more HP draw when there is a heavy load...
My last car had a 20 amp generator that I upgraded to a 35 amp for the stereo amp...
If you have electric fans they usually draw like 40-50 amps Max for dual fans....
The bigger the alternator the more HP draw when there is a heavy load...
My last car had a 20 amp generator that I upgraded to a 35 amp for the stereo amp...
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Safety Car
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Le Mans Master
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Melting Slicks
Joined: Apr 2001
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From: Lubbock Texas
Most higher output alternators also have much better output at idle. Hopefully this is the case with your new 105 amp model.
DC
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
Your 61 amp alternator is probably fine when it is actually putting out 61 amps but that is its maximum output and occurs at higher rpms. The key factor is the output at idle. Your existing alternator isn't putting out enough at idle and so your battery is picking up the slack.
Most higher output alternators also have much better output at idle. Hopefully this is the case with your new 105 amp model.
DC
Most higher output alternators also have much better output at idle. Hopefully this is the case with your new 105 amp model.
DC
Safety Car
Joined: Mar 2007
Posts: 3,652
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From: Bridgewater nj
I'm pretty sure the stock 82 alternator is 80amps and under full load at idle it would drop down to 12 volts when the hazard lights blinked. Mr. Amp I think will be my next alternator but he's expensive!
I also thought about using my lathe to make a smaller diameter pulley. I think that's what Mr. Amp is doing or retrofitting the newer Delco alt. but for now it works!
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
My replacement aternator from a year ago is a 61 amp - stamped on body. It replaced a NAPA (do not buy) that was maybe a 65 amp that was OK but died after several years. Itself was a replacement for a NAPA alternator that died after only a few years. I will stay away from NAPA. I think stock is 65? I just want the extra capacity IF needed, which I doubt I will need. For <$70, why not.
Le Mans Master
Joined: May 2007
Posts: 5,009
Likes: 1,116
From: North tonawanda NY
Your 61 amp alternator is probably fine when it is actually putting out 61 amps but that is its maximum output and occurs at higher rpms. The key factor is the output at idle. Your existing alternator isn't putting out enough at idle and so your battery is picking up the slack.
Most higher output alternators also have much better output at idle. Hopefully this is the case with your new 105 amp model.
DC
Most higher output alternators also have much better output at idle. Hopefully this is the case with your new 105 amp model.
DC
There are a few dozen sellers with the chrome 100 amp models for between 55-$100 on eBay with shipping.... I saw that other thread and the price really is average but the pic was of a high quality non chrome unit... there are a lot of cheap poor performing china alternator's out there. Some are falsely rated higher than they are as well. Had a stock one in my 84 vette (75-85amps I think) it was more than enough for the thirteen years I owned it with dual factory read fans and an Orion hcca amp drawing 800watts for the subs and a 400watt alpine amp and digital dash .... I had to have it replaced once and I went to a shop that specialized in rebuilding them.... never had any issues with the rebuilt one...
Last edited by augiedoggy; Aug 8, 2013 at 09:53 PM.