Guys and Gals?,
The reason I started this thread was/is that when I spoke with Ford's "recall service center" I was less than confident that the "battery harness" recall had been done let alone done correctly... The "fix" if it was done was at a dealer back east and before I acquired the FEH I also wanted to know if there was any programming done that was noticeable and hopefully an improvement.. Ford has been known to "flash" vehicles without informing it's clients... sometimes resulting in better performance sometimes not... I guess that would be with "mixed" results... Anyway, I guess I'll be befriending the Hybrid tech.,
next time I go to my dealer... I'm also going to call the folks down at 3Prong Power and see what I can find out...
Thanks again
Mike

 

Wow, nothing like personal attacks for disagreeing!

 

Yeah, maybe he should tell us how he REALLY feels...

 

Those of us that had the battery recall work done in Sept./Oct. 2007 reported on a "smoother" transition into EV after the work was done. This work did not include changing the battery chemisty but it did inlcude a software "flash" for the traction battery control module and the so called change in harness hardware.

 

What you gentlemen have forgotten is that in every binary system, or digital system, there is an A to D convertor if measurement of a quantitvative value is involved.

This is an analog to digital convertor. (For those of you that think the FEH computer can read battery SOC directly as a percentage, this might just be a news flash, but read on gentle soul.) This little unit converts an analog signal of some kind to a digital format the computer can use.

While it is true that the digital signal itself is precise, it is either "true" or "false," the accuracy of errors to be found in the operation come from the A to D process. Say it any way you want to, if you read amperage (or is this coulombs per unit of time?) you are really reading the voltage drop across a calibrated shunt. This is an analog signal. The conversion of this signal to a digital format involves a calibration error, or a ± percentage.

What you have forgotten to tell those you seek to influence with your half of the story is that the world is an analog place (and, yes Virginia, gravity is in fact analog). I acknowledge that when the program for the FEH trips and calls for engine start and charge it is likely at a SOC of 40% as read by whatever A to D mechanism Ford chose to use.

Do you have any idea why Ford chose to put the 40% you advertise into its sofware? Is there a perfomance or lifetime issue with the D-cells Ford chose to use?

But is battery SOC really 40%? Could some FEHs be really at a real world vlue of 38% and some at 42%. Did I miss something? Is there a little window on the battery pack that I can look in that reads SOC in Percents right from the battery?... Oh yeah, there are actually two battery modules, so maybe there are two windows.

The question you have conveniently ignored throughout this discussion is:
"How is this value measured" and "How accurate is that measurement?" You have, conveniently, chosen to focus on only the digital side of the issue. When you then make fun of someone that doesn't buy your argument since you left out the key part of it, you really show limited knowledge & lack of engineering experience.

Excessive and un-necessry accuracy may provide comfort and apparent wisdom to the uninitiated and ignorant but it leads to errors and mistakes. Do you really care whether your gas tank is at 19.757% or at 20.214%? Your A to D convertor in the gas tank is still a standard, wire wound, rheostat with a float on the end.

Current measurement is still done with a calibrated shunt and a milli-voltmeter. Even though water temperature is inferred from cylinder head temperature rather than observed directly, it is still measured as an analog signal from an RTD of some kind (That's Resistance Temperature Detector). This is a calibrated resistor having a known characteristic proportional to temperature that can then be converted to a digital ouput signal.

Rules of life: F=MA & "you can't push a rope." Or did you miss that in your engineering education. Yeah, I do believe in gravity.

This conversation has not been worth it. The only reason I have endured through the profound ignorance of how measurement signals are generated for the FEH computer is that you may have truly led those people astray who read these posts but do not otherwise participate.

I have been dealing in computers, A to D converters, and CAN busses for a significant chunk of my career. Until you understand how quantitative measurements are made, converted into a digital signal, and used by a computer, you will continue to mislead people.

Unfortunately, your demonstrated knowledge of how the FEH is designed, or its software implemented, is only Half-Vast.

 

I have ignored a lot of these posts (not meaning yours in particular), because it doesn't make any difference how it is measured - we are discussing how the SGII measures the values produced by the FEH monitoring systems. I think that only Ford would know the proprietary algorithms used to measure SOC and how it is converted. I would not be surprised if the SOC measurement varies over the lifetime of the battery, that is, that it represents 40% of whatever capacity the battery has at the current time.

But as I said in a previous post, there is not a lot of reported MPG losses from the various NiMH battery hybrid owners as their vehicles age, so it seems unlikely that it is fading too drastically, or else the manufacturers are managing to compensate for a weaker battery (which seems unlikely).

As to the world being analog, in general I agree, although I could make a case for the human brain POSSIBLY being digital, with the neurons either being turned on or off.

 

Man o man, when we get into neuron conductivity... (smile)

I frankly wouldn't expect the mpg to change much at all. The effect would be somewhat different. If the SOC measurement methodology is close to what I think, then the real effect, difficult to see easily from the drivers seat, is that of a shortened distance on a given charge.

The engine & computer will see a low discharge condition, charge the battery up, shutdown, then you would drive until the low limit is again reached, and then charge the battery back up. The engine, & computer, just wouldn't recognize the difference in distance "on the battery."

In order to detect this you would have to periodically do a test drive, at the same speed, and measure the distance from engine off to engine on. Since this number is already quite small, a 20% change in it won't really be noticeable to most.

In my case, at about 20-25 mph I can go a bit over one to two miles. If this were to change to 0.8 to 1.6 miles it would be almost un-noticeable in most driving.

By way of reference a lead-acid traction battery is considered at end of life at 80% capacity.

Detroit always allows for "field" experience when they put out something new, like the FEH. Ford as hedged their bets on battery life. If they hedged it right then we will see the same size battery show a longer & longer life as Ford gains experience. They will do this by widening the "percents" of low limit to high limit in subsequent FEH models.

Recall that Ford used to include a battery heater transformer in the block heater set up. They appear to have stopped that with either the 08 or 09 FEHs. I attribute that to an initial concern with whether the battery would have sufficient depth & capacity to start the engine in the coldest of situations.

Now that they have that history they deleted the heater transformer.

Take your FEH out for a test spin once a year or so and, at the same speed & on the same slope (if any), see how far it goes. I'd be interested in how it does.

 

I'm not sure I understand your reasoning. If the engine has to run more often to charge up the battery, then the MPG would automatically go down because you are burning more gas per mile...

 

There are only so many ways to measure a quantitative element and convert it to a digital signal. The software will respond as programmed, for example when the battery SOC reaches the low limit programmed: it will start the engine. (This next remark is not for you but for those folks claiming precision and exactness that they do not understand)...Duh.........

The question Ford has to solve is what is the absolute low limit it can stomach in the battery without failure and how do they then turn that number into a programmable number they will sign up to and put into software. Clearly the software number appears to be 40%.

But what we are interested in is what is the real SOC and what is the tolerance surrounding that number. The idea that it is exactly 40.00000% is nonsense.

The real, analog world just doesn't work that way. In reality, when you read a measuring device, even one that is computer driven, the reading is only as accurate as the money you are willing to put into the precision of that measuring device.

Somewhere there is a tolerance. My bet that it is ±2%, is a guess, but then I advertised it that way from the beginning.

This discussion has lost focus because some have chosen to focus on the supposed precision of the computer side of the issue. This is like saying when your alarm clock goes off at 6:00 am it must be 6:00 am exactly.

Of course it's close (if you set it right and it keeps reasonable time) but just because it triggered at "precisely 6:00 am" doesn't mean it's really 6:00 am (unless you spent the money to get one of those clocks that syncs with WWV), but of course it's likely pretty close.

Your question is fair, so don't take me strongly. I'm drawing on my experience with these kind of engineering things that I dealt with across a career and making inferences that seem to make sense. If people with different experience will put that up and put out their inferences we will get to a good answer. We'll see.

Some of the cheap shots, such as whether I believed in gravity, were simply uncalled for. Go out and do a somewhat controlled experiment on just how far your FEH will go an a charge. My reference is the oval loop around the Dulles Airport arrival area. Done while waiting to pick up someone.

See what you get.

 

I don't think I've ever tried to run the battery down to 40% (however that is measured!), because the FEH is ferocious about reclaiming the SOC, and the instant MPG is really dragged down. I regularly go on a flat surface for about 1/2 mile, generally losing about 5% SOC. But I've never measured it.

RE: Gravity. Are you familiar with the works of George MacDonald? I'm thinking of a story called "The Light Princess"...