To everyone who took the time to reply, I really appreciate your input and suggestions. For those of you who are interested, here is an update on my decision:
1) The safety recall issue, which has to do with a faulty capacitor design, has caused about 286 out of the roughly 100,000 MME's sold to break down. They needed to be towed to the nearest Ford dealer and then the part had to be replaced. Ford has issued a software update. It seems like the software update does not necessarily prevent the problem, but it makes the car more driveable if a problem occurs (this is not a fact, just the theory and opinion of some MME owners on the MME forum). Instead of a "stop safely now" message, the car will reduce power and say "service soon". The actual fail rate of this part is around .2 percent of all MME's sold. It is suspected that any MME that has the car replaced is getting a new part that is more robust and a lot less prone to breaking down.
2) I could be wrong, but it seems like most of the MME's affected are earlier models. Of course, this could be due to the fact that these are the models with more mileage. But it could also be that the most recent MME's coming off the line have had improvements to reduce the possibility of a problem. This is something I am researching.
3) I ordered my MME back in 12-2021. So I locked in the price at the time of ordering. If I were to order the same car today, it would be $5K or so more. Plus, if I wait for a year or two, I will likely miss out on the $7,500 federal tax rebate.
4) I realize the used car market could cool with higher interest rates. But if the MME turns out to be problematic, I can just sell it. Given my pricing from 12-21 as well as the federal rebate, I would not really lose too much money. Unless MME resale values go down because of this recall issue.
5) This weekend, my wife and I test drove the Hyundai Ioniq 5 as well as the Kia EV6. While they are both solid cars, both my wife and I strongly preferred the EV6 over the Ioniq 5. However, we also both prefer the MME GTPE over either one of these alternatives.
We have not yet made a final decision and I am reading all of the helpful posts here. Thank you again!
Joe
@joebruin77: Got a minor syntax error for you to clean up.
I've been doing the reading and all. It's not a CAPACITOR, it's a CONTACTOR that's driving the Mach-E guys nuts. I know, I know: I'm a EE, so I get upset about this kind of thing.
A capacitor: Two conductors separated by a non-conductor. The Capacitance, in Farads, of a capacitor are (nominally) C = eps*A/d, where A is the area, d is the distance between the conductors, and eps is the permitivity and is equal to 8.854*10^(-7) * eps(r), where eps(r) is 1.0 for a vacuum or air and various other things, like 4.6 for epoxy circuit boards. A 100 microFarad capacitor is on the largish side. Used in AC circuits everywhere to pass AC signals and stop DC signals. Symbol:
. Picture of one:
A contactor is a Relay. Usually mechanical. Has contacts. Goes "click" when activated; goes "clunk" when it's a big one. Mechanical relays/contactors may have one set of contacts or many of them and are usually activated by a magnetic coil. That is, run some current though this coil, it makes a magnetic field, and attracts a (usually) spring loaded arm that does the "clunk" noise.
There's a bunch of specs with every part (what else is new) but the big ones with contactors are (a) how much current can it carry and (b) how much voltage can it withstand when it's open (as compared to shut). Itty bitty relays go down to milliamps. Nearly everybody who has a HVAC system of any kind has a Contactor in it that switches 220 VAC (minimum, we're not talking the industrial A/C plants) at somewhere between 20A and 100A. Those of you who have the Tesla Wall Connector have heard the one inside of that beast every time one starts charging the car: There's a notable "clunk" when it lets fly. Symbol:
Picture of one:
Notice the coil of wire at the bottom
.
The deal with contactors, and why Life Gets Difficult for Designers: Say you've got a closed contactor conducting hundreds of amperes. That means you've got two fancy looking blocks of metal with $DIETY's own strange metallurgy shoved up next to each other. Silver plating on top of nickel on top of copper, or gold plating on top of nickel on top of copper, or some weird alloy that I've never heard of, all with the idea of minimal heating with all that current passing through. The Really Big Guys can be a half-inch across or bigger.
But that's not all! Say that you want to
open that contactor. Given EV's, let's say that there's 300VDC hanging around. When one depowers the contactor, those two contacts start moving apart from each other. Let's say they're on their way, but they're only a millimeter apart. 300V across a millimeter means that one is going to Get an Arc. As in, Lightning Bolt Time. When a lightning bolt hits that fancy metallurgy, things tend to melt and vaporize. So the people who build contactors are Really Big on moving the contacts away from each other Really, Really, Fast, the faster the better, with the eventual air gap big enough to quench the arc.
As a natural result of this, the contacts tend to get pitted over time. And one's fancy metallurgy gets plated all over the place. There's various means to cut back on the arcing; snubbers, for one, where the energy that would go into arcing and destroying the contacts gets dumped through a capacitor (ha!) and a resistor, with a resistor absorbing the excess energy.
Those of you who are old enough to remember ICE distributors and (shudder) "points" might remember that the points in the distributor were replaced as part of a general auto tune up.. along with a small item named a, "condensor". That condensor was a combination capacitor and resistor in series and would attempt to keep the points (read: electrical contacts inside the distributor that basically supplied the energy to the spark plugs in a car) from getting too badly pitted over time. Just like with contactors.
From the sounds of it, the contacts in the contactor in the for Mach-E are getting welded to each other and Not Opening Up Any More. That happens when there's extensive pitting, high resistance, lots of heat as a result, and from there Bad Things Happen. Also sounds like it takes
time for it to happen; that is, the pitting is happening when the contactor de-energizes, each time the situation gets worse, and eventually it falls off the cliff and is Dead, Dead, Dead.
Or maybe it
is the snubber getting damaged. The snubber is a resistor and capacitor in series; the resistor is a couple of ohms, the capacitor is high impedance at, say, 60 Hz, but is nearly a dead short at, say, 100 kHz. Say one has one's furnance and turns it off. As the contacts open up, there's this big inductive kick from the furnace blower motor windings that try to keep the current going; it's a spike with a very fast rise time. Fast rise time spikes pass easily through that capacitor; the resistor then eats the motor winding energy and, ta-da, not much arcing at the contacts.
For this to work, the resistor is probably a couple of watt rating; and the capacitor has to have a voltage rating of, say for a house, a thousand volts or so. But if somebody put in a cheap cap that only had a rating of, say, 300V on a 240 VAC circuit, it might work for a while - but eventually the cap would break down. In that case, one ends up with (typically) one of two things: A capacitor turned into vapor, in which case it doesn't do its snubber work too well, or it turns into a short. Which would then mean that the couple ohm resistor that normally only dissipates the occasional spike would suddenly have 240 VAC across it when the contactor opens, which means that
the resistor would turn into vapor, or make a fire.
No question: Turning high-power systems on and off is not for the faint of heart. If I had to guess what happened with Ford, they
probably specified a decent part. Then, one puts oneself in the hands of one's suppliers. Some supplier trying to save on expensive metals (metallurgy again), or expensive, high quality capacitors could have easily sabotaged Ford's efforts.
