High voltage
Good points about heat, but to evaluate whether any given unit is going to run hotter, the electric load is the driving force.
Yes the higher rated alternator may run hotter if both are being run at maximum for 100% of the time (duty cycle) and it doesn't have better heat sinks and cooling capacity.
Fortunately, thats not usually the situation.
Lets look at some typical situations......
charging circuit.
Thank you for acknowledging the heat load. And although you are correct with what is actually going on with alternator load requirements. And “yes” tractor trailers have a high usage load - upwards of 70amps with just amp load on lighting alone. but so much runs on the air system which lessens the electrical load.
Anyhow, I believe your correct BUT the reason we are chatting about the loads is because as we add electrical loads - in this case ignition, plus a big block in an abody... we are adding electrical fans, custom ignition, plus we all dislike dim head lamps, want more sounds to include power amps for the music and even in some cases adding ac, power locks and power windows, power seats, etc. So not to get off track with the original post about alternator usage and how upgrading the alternator is only part of the equation.
Also, please check your math as those amp loads you stated in the Mattax post above is not correct. Brake lamps are listed as 2.5 amps and so is turn signals. If a turn signal is 2.5amps then brakes lamps is 5amps (actually closer to 6amps due to they are run in series and heat loss across the wire. Also, night time driving includes running lamps all the way around, dash lamps center console lamps, aux gauges and lighting possibly other lighting the load can be upwards of 30+amps alone.
I appoligiese in advance for my detail but I was a Master Tech for GM in my earlier days and my specialties was automatic transmissions and electrical. Amp loads were calculated down to the 10th of an amp on cars because of weight and components (weight of over sized wiring or parts translated into fuel mileage and cost of building production cars. Smaller wire was a $0.02 per harness but across 100,000 vehicles was a big savings.) smaller alternators was also a fuel savings. Etc, etc.
All I will add is you need to look at your individual needs and decide what is best for your car. Stock /6 with all stock electrical keep it stock. Built street car needs more power and modified electrics and modified electrical needs. :)
Okay- I’m done. Off soap box.
