Hi today my alternator caught on fire.
I think we can agree that flames coming out of the alternator isn't exactly desirable. Some things can be a bit marginal, but actual flames coming from the alternator isn't usually a good sign.
I did get a new alternator and fitted today, but when I tested it had 16V on idle and 15.7 with lights and con on. My mondeo have a heated seats, factory fitted xenon lights, and so on.
After running for about 3mins it started smelling burn again and alternator is to hot to touch.
While those voltages are a bit high
- You can certainly get differences of 0.1 - 0.2 volts (possibly a little more), depending on where you measure and what you measure with
- Something like 15.5 volts can be a voltage that exists for a short period in a smart charge system
the degree of equipment fitted to your Mondy is essentially irrelevant, if those bits of equipment are turned off (and only of partial relevance when they are turned on). All Mondys of a given series (Mk IV, etc) have a fair amount of electrical equipment, and, as far as I know, the same capacity of alternator, etc, so the same thing should apply to all. The biggest individual loads are the heated screen, front and rear, so those are useful for testing what happens under load (and are fitted to all trim variants).
I think one of the possibilities for a fault is the feedback signal to the alternator. The 'traditional' alternator set-up uses the power lead from the alternator to the battery to measure the battery voltage (which has inaccuracies dependant on the current flowing). The more modern system has a separate feedback line, along which high currents do not flow, and so should be more accurate. However, if you have a fault on that line, it can cause faults that could not occur in the traditional system.
You have something like a three or four way connector to the alternator, and one of those lines ought to connect to the battery (there would be a separate, thicker wire for the high current path to the battery). If there is a series resistance (which you can measure with a meter, but you'll be best advised to take the battery out of the circuit to do it), then the voltage may go up. Also, if there was a parallel resistance to, eg, ground, that would also do it (also measurable with a meter, just about, with the battery out of circuit, depending on the other electrical equipment in the car; with the ignition off, the measured resistance ought to settle after a while - it is possible that it doesn't, though, if you have, eg, an ultracapacitor on the head unit supply).
Also, it would be a good idea to check that the connections to the battery are clean and secure, given that you are messing around with the battery terminals, because high and non-linear resistances there can cause weird problems, and make measurement difficult. If you have, say, 0.5 volts drop at a battery terminal, then the battery voltage is probably 0.5 volt, or more, different from what you measure it as, depending on exactly where you connect the DVM leads.