Your mechanic was right about the charging system. 12.8 volts is too low and is just a little above what a fully-charged battery will read with the engine off. The battery voltage with the engine running must be between 13.75 and 14.75 volts. Yours is still a fuzz low at 13.6 volts, but that will come up as the battery charges. It was also measured at idle, which is not representative of a good charging system, and it was measured "with loads on". All that proves is the new generator is able to supply most of the electrical needs of the car at idle. Generators are very inefficient at low speeds. All testing is normally done while raising engine speed to 2000 rpm, not at idle. The fact that your new generator was able to maintain 13.6 volts at idle under those conditions is commendable.
It is normal for the head lights to dim a little when you turn on a lot of stuff, especially the rear window defogger. Those draw a lot of current and load down the electrical system. The heater fan is another heavy load.
It is never acceptable for the ignition switch to get hot, but it is common among car owners who turn everything electrical on high without understanding the consequences. Much of that current has to go through the switch contacts and connector terminals. The slightest amount of resistance between those connections results in heat buildup, and that heat buildup promotes degraded connections and higher resistance. Just ask any Ford owner who has had their garage start on fire from overheated ignition switches.
Since ignition switches, like everything else today, are built cheaper and cheaper, the contacts can just barely handle the normal current they're expected to carry, with very little extra safety margin. In response, some manufacturers are using relays to turn on accessory circuits, and some of those relays are inside computer modules. Relays are electromechanical switches that use a very small current to turn on a much larger current. It is easy for the ignition switch to handle that small current, but there are still other circuits that get their current through the ignition switch.
What you should consider is not turning on all the accessories on high at the same time. I have 4-speed heater fans in all of my vehicles and it is very rare that I turn one on higher than the lowest speed. I put up with -25 degree days in winter, and even use the defroster on the lowest speed. Running it faster brings in more cold air which results in colder air being blown onto the windshield. Also, turn off all those systems before turning the ignition switch off. That will reduce the arcing on the switch contacts and will make it last longer. I've replaced a lot of melted ignition switches and very often when I climb into those cars and start the engine, I find wipers and heaters already turned on. That is very stressful to switches and electrical connectors.
Thursday, November 22nd, 2012 AT 12:02 AM