Our van, a 5.9l V8 360 engine, has a 65 Amp alternator. When stopping at a red light for example with the headlights on, I put the AC on low, otherwise I am starting to discharge the battery. Not much, and not for long, and recharge quick again once driving again, but still...
The engine and its accessories to run, they use about 35 Amps if I am not mistaken. So our 65 Amp alternator, at idle, just manages to produce that. But as I said before: with headlights on and/or AC, etc., the 65 amp alternator is no match when at idle. It does a great job when driving though, even at slow speeds. We will upgrade soon to a 100 amp alternator. At idle it will produce just enough for the engine, headlights, AC to operate without having to draw power directly from the battery only. (AC probably on low as well.)
Thought of a dual alternator, both 100 amps, but then again: dual belt? Weight and weight distribution of the alternators affecting the engine? Etc. So might just go with a single 100 amp alternator swap and live with that.
PD: On modern cars it is less pronounced as the computer regulates it pretty good, also reduces AC load automatically when idling, and similar things. It seems not to be an issue, but truth is they "suffer" from the same: not enough amps when idling. Its instrument needles just don´t show that trend as they (with their computer) know that it is just temporary and will get back to non-idle again soon. If not (after very long idle) they will show.
Our elder vans are just more... mechanical.
Last edited by Xplorer_Loco; June 18th 2019 8:49 am.