Alternator Upgrade
10-09-2013, 03:32 PM
#16
Developer
Excellent post Allen. Right on the money.
In addition to everything you said, I would also add this note about alternator ratings: (quote is from our website)
In addition to everything you said, I would also add this note about alternator ratings: (quote is from our website)
How Alternators are Rated:
Our alternators are SAE-rated, just like the OEM Porsche® alternators are. All alternators produce less as they heat up, so under-hood temps lower the output of the alternator. This is why the Society of Automotive Engineers test them in a lab - to remove the temperature variable. A 200 Amp SAE alternator will produce about 175 Amps in a hot engine compartment. The original 115 Amp alternator produced about 85 amps under the same circumstances.
Our alternators are SAE-rated, just like the OEM Porsche® alternators are. All alternators produce less as they heat up, so under-hood temps lower the output of the alternator. This is why the Society of Automotive Engineers test them in a lab - to remove the temperature variable. A 200 Amp SAE alternator will produce about 175 Amps in a hot engine compartment. The original 115 Amp alternator produced about 85 amps under the same circumstances.
10-09-2013, 10:55 PM
#18
Electron Wrangler
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Electrical noise is really created by the rectification process itself - it doesn't matter too much where it occurs. The three sinusoidal phases themselves aren't really noisy and don't couple to anything much.
Many wind generators have a simple alternator up top and the rectifiers and regulators (or converters) hundreds of feet below fed by three phase wiring. Such functional separation is common in heavy equipment since packaging them (and the regulator) together is a quite a compromise.
In automobiles its evolved to be this way for the convenience of a single (cheap) integrated solution.
Alan
10-10-2013, 08:56 AM
#19
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Mine has been in for over a year with no problems. The car is completely stock and original except for the alternator and Kuhl a/c kit. The thinking is it's overloading or not enough ram airflow?
10-10-2013, 12:08 PM
#20
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I don't see any reason why it would. We are talking about remote as in driver front fender maybe - a nearby cool place close to the alternator - so probably no more than 18" away.
Electrical noise is really created by the rectification process itself - it doesn't matter too much where it occurs. The three sinusoidal phases themselves aren't really noisy and don't couple to anything much.
Many wind generators have a simple alternator up top and the rectifiers and regulators (or converters) hundreds of feet below fed by three phase wiring. Such functional separation is common in heavy equipment since packaging them (and the regulator) together is a quite a compromise.
In automobiles its evolved to be this way for the convenience of a single (cheap) integrated solution.
Alan
Electrical noise is really created by the rectification process itself - it doesn't matter too much where it occurs. The three sinusoidal phases themselves aren't really noisy and don't couple to anything much.
Many wind generators have a simple alternator up top and the rectifiers and regulators (or converters) hundreds of feet below fed by three phase wiring. Such functional separation is common in heavy equipment since packaging them (and the regulator) together is a quite a compromise.
In automobiles its evolved to be this way for the convenience of a single (cheap) integrated solution.
Alan
I'm thinking about how to get a bundle of six #4 feeders from the alternator to the wheelhouse area under the headlight, plus the rest of the smaller sense and excitation wiring. Wind it into a coil on a vertical axis, support the bottom end well, and you can significantly reduce the load on the left-side motor mount.
10-10-2013, 12:37 PM
#21
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No E-M levitation intended 
Our alternators only have 3 star phases - so I'd assume 3 phase wires @ ~6AWG (~2/3 total load current rms per phase).
Of course if you move the rectifiers you move the regulator too to avoid the unreaslistic (wrt battery) temperatures - so add one more for positive field @~12AWG
Target here is hot reliability with slightly uprated performance (more like 150A - than 200A) but mainly for much better idle voltage regulation. You'd need a positive side regulator with remote battery temperature sense in that case to maintain some "reasonable" temperature compensation.
Wire length here is short - given the rather large rectifier diode voltage drop at max current - the drop over a short cable run is irrelevant (and its compensated for anyway) - so its down to absolute maximum ratings for self heating & temp and duty cycle which certainly isn't indefinite for max power.
Needs more thought but I'd consider it feasible. Wiring like this and separate rectifier/regulator packaging & cooling is much more expensive and more complex so of course it would never be done in volume production.
An interesting project idea - I think our alternators would run much much cooler with only a brush pack on the back. However lots of hassle and certainly much more expensive than a just a new uprated alternator... but potentially a better and more reliable solution (depending on how you build it...)
Alan
Our alternators only have 3 star phases - so I'd assume 3 phase wires @ ~6AWG (~2/3 total load current rms per phase).
Of course if you move the rectifiers you move the regulator too to avoid the unreaslistic (wrt battery) temperatures - so add one more for positive field @~12AWG
Target here is hot reliability with slightly uprated performance (more like 150A - than 200A) but mainly for much better idle voltage regulation. You'd need a positive side regulator with remote battery temperature sense in that case to maintain some "reasonable" temperature compensation.
Wire length here is short - given the rather large rectifier diode voltage drop at max current - the drop over a short cable run is irrelevant (and its compensated for anyway) - so its down to absolute maximum ratings for self heating & temp and duty cycle which certainly isn't indefinite for max power.
Needs more thought but I'd consider it feasible. Wiring like this and separate rectifier/regulator packaging & cooling is much more expensive and more complex so of course it would never be done in volume production.
An interesting project idea - I think our alternators would run much much cooler with only a brush pack on the back. However lots of hassle and certainly much more expensive than a just a new uprated alternator... but potentially a better and more reliable solution (depending on how you build it...
)Alan
11-05-2013, 11:58 AM
#22
Developer
Video Available
Here is a view of the 200-amp alternator installed and running on a 1989.
It also shows our Dual-Fan kit long enough that you can watch and hear (barely) it cycle on and off at idle.
It also shows our Dual-Fan kit long enough that you can watch and hear (barely) it cycle on and off at idle.
