Alternator
- Thread starter vobraman
- Start date
NorCal66
New Member
What electronics do you have in the car? A one wire is much easier and could make finding any future electrical problems much easier.
67coupe351w
New Member
Im using a 138 amp 1-wire alt. Didnt realize it was that big until I got it home...
I used to have a great article that gave rough estimates for power draws for diffrent components you may have. It broke them up into continuous and momentary loads. Continuous loads were things like headlights and your sterio system. Momentary loads were turn signals, brake lights, wipers, and that kind of thing.
Basicly it had you add up all the loads (i think it was only continuous here) and that would give you a minimum alt size. But then it went on to say that you want to get the biggest alternator you can afford thats bigger than this minimum size because alternators cycle on and off as power is required...the bigger one you get the less time it runs and the longer it lasts.
The article also said that chrome plating and other coatings inhibit the alternator's ability to dissipate heat (and heat kills electronics) so if you want a pretty alternator go with polished aluminum.
I used to have a great article that gave rough estimates for power draws for diffrent components you may have. It broke them up into continuous and momentary loads. Continuous loads were things like headlights and your sterio system. Momentary loads were turn signals, brake lights, wipers, and that kind of thing.
Basicly it had you add up all the loads (i think it was only continuous here) and that would give you a minimum alt size. But then it went on to say that you want to get the biggest alternator you can afford thats bigger than this minimum size because alternators cycle on and off as power is required...the bigger one you get the less time it runs and the longer it lasts.
The article also said that chrome plating and other coatings inhibit the alternator's ability to dissipate heat (and heat kills electronics) so if you want a pretty alternator go with polished aluminum.
Gellpak
Member
(similar concerns here, getting a bigger alt...) Are you running these alts on stock wiring or does all that need to be upgraded some how? Don't want to burn out my wiring...
Gellpak
Member
(similar concerns here, getting a bigger alt...) Are you running these alts on stock wiring or does all that need to be upgraded some how? Don't want to burn out my wiring...
67coupe351w
New Member
Im using a painless wiring harness. If you went with a 1 wire Alt. You would illiminate the voltage regulator because 1 wires are internally regulated.
A 1 wire alternator only requires 1 wire to be routed to the positive post of your battery, the higher the output and longer the length needed the thicker wire you will need to use. You shouldnt burn out you old harness as it wont be using any of your old harness's wiring until after the battery.
Id probably worry about burning up the harness if it wasnt a 1 wire though.
A 1 wire alternator only requires 1 wire to be routed to the positive post of your battery, the higher the output and longer the length needed the thicker wire you will need to use. You shouldnt burn out you old harness as it wont be using any of your old harness's wiring until after the battery.
Id probably worry about burning up the harness if it wasnt a 1 wire though.
65 fastback
Founding Member
brianj5600
Active Member
67coupe351 wrote
"Basicly it had you add up all the loads (i think it was only continuous here) and that would give you a minimum alt size. But then it went on to say that you want to get the biggest alternator you can afford thats bigger than this minimum size because alternators cycle on and off as power is required...the bigger one you get the less time it runs and the longer it lasts."
hmmmm..... I disagree:
1. adding up all the loads:
- go through a modern car fuse box, add'm up and get oh 200-300 amps
- there are VERY few continuous loads.
- stereo, turn lights, AC, wipers, ... either cycle or adjust, etc.
Suggested min/max/average load calculation method.
1. assume a 25 to 50% derating on all load fuses or load MAX i quotes
2. create scenarios e.g.
- MAX: at night, in the summer, in the rain, stereo blaring.....
- MIN: spring, quite, riding on a country road
- AVE: what, when, and how you drive
now you have something to actually start thinking about in terms of what is the minimum acceptable battery and alternator I need.
3. If you want actual measurements it's easy enough for common loads
The more concerning disagreement is considering that a higher current sourcing device will not wear as fast as one closer to actual need. If a battery spent it's stored charge THEN pulled on the alternator for a re-charge, I'd agree but that's not how it works. The alternator, battery and loads are all in parallel. At no time should you be pulling signifcant amps from the alternator into the battery for charge in a safe and normal running system. The critical element here is to maximize the voltage felt by the battery to cause a flow into the battery as early in a discharge condition as possible (don't use small wires from bat to alt!).
So, in my opinion, you can take several design tracks that vary cost and performance but all must consider the likely or average load in conditions of concern, i.e the foggy, raining, hot night...etc. If one is simply willing to turn off the PA system they have for a stereo 100 amps or less in an alternator should be plenty. Today's cars are far more power hungry and accessory rich so if a 65 mustang with an electric fan and a stereo needs 130 amp then a new mustang must have a 200+ amp alternator...and that's just not the case.
"Basicly it had you add up all the loads (i think it was only continuous here) and that would give you a minimum alt size. But then it went on to say that you want to get the biggest alternator you can afford thats bigger than this minimum size because alternators cycle on and off as power is required...the bigger one you get the less time it runs and the longer it lasts."
hmmmm..... I disagree:
1. adding up all the loads:
- go through a modern car fuse box, add'm up and get oh 200-300 amps
- there are VERY few continuous loads.
- stereo, turn lights, AC, wipers, ... either cycle or adjust, etc.
Suggested min/max/average load calculation method.
1. assume a 25 to 50% derating on all load fuses or load MAX i quotes
2. create scenarios e.g.
- MAX: at night, in the summer, in the rain, stereo blaring.....
- MIN: spring, quite, riding on a country road
- AVE: what, when, and how you drive
now you have something to actually start thinking about in terms of what is the minimum acceptable battery and alternator I need.
3. If you want actual measurements it's easy enough for common loads
The more concerning disagreement is considering that a higher current sourcing device will not wear as fast as one closer to actual need. If a battery spent it's stored charge THEN pulled on the alternator for a re-charge, I'd agree but that's not how it works. The alternator, battery and loads are all in parallel. At no time should you be pulling signifcant amps from the alternator into the battery for charge in a safe and normal running system. The critical element here is to maximize the voltage felt by the battery to cause a flow into the battery as early in a discharge condition as possible (don't use small wires from bat to alt!).
So, in my opinion, you can take several design tracks that vary cost and performance but all must consider the likely or average load in conditions of concern, i.e the foggy, raining, hot night...etc. If one is simply willing to turn off the PA system they have for a stereo 100 amps or less in an alternator should be plenty. Today's cars are far more power hungry and accessory rich so if a 65 mustang with an electric fan and a stereo needs 130 amp then a new mustang must have a 200+ amp alternator...and that's just not the case.
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