That's a very good point! The OEM Ford GT is a "dumb" charger just blindly supplying 500mA, so it will work. But, smarter float chargers may not work as you accurately point out.Careful there. Most battery maintainers need to "see" a threshold battery voltage or they will shut down.
There is NO known cause of the gauge failures. One theory is electrical, another is corrosion of the fine needle movement with needle "stickiness" often being a predecessor to failure.You were VERY lucky you didn't lose a gage.
Way less than $200. Bluetooth OBDII reader from Amazon was under $20. Free Torque app on android phone (app lists compatible readers.)If I have had the battery disconnected, and need to go for a state inspection, I'll simply drive it for a while. Then I scan (under $200 scan tool) it to see if monitors are "ready". If not, keep driving (the misery). Doesn't take much, really.
I'm also an "analog designer"... I would assert that most of this is "old wives tale"... The primary reason is that virtually ALL electronics are on the "other side" of the ignition switch... There are some, but very few, things that are alive when the key is off, the OBDII memory being one. And there is really no reason for that given that the info COULD be stored in flash memory...I don't try to keep the memory alive. I guess results here prove me wrong, but battery chargers provide dirty voltage, without being tied to a battery to stabilize. This has the potential to ruin electronics. Some electronics specifically mention...do not use with battery charger..even WHEN connected to a battery. Also, when tying a small battery into the system, bad things can inadvertanty happen. So....unless keeping the memory alive is absolutely critical, the risk of damage is very costly.
I bet "Analogdesigner" has some thoughts on this, and probably has hooked an oscilloscope to a battery charger...any comments from "analogdesigner"?
Did you verify with an OBDII reader that the adaptives were retained?so battery replacement went very easily. Bought the Optima Redtop 25 at oreilly's auto parts for 91 bucks, had it in stock, put heavy blankets over the fenders, carefully removed the trunk lining, plugged in my 12 volt power source into the cigar lighter, removed the negative cable first, then the positive, rested the positive in the heavy blanket, unscrewed the battery clamp, pulled the battery up and out at an angle, pealed off the optima sticker, put a hair dryer on the ford gt battery sticker and pealed off, stuck the old sticker on the new battery and carefully reinstalled everything. Car fired up immediately with no glitches. Stuck the optima sticker on the old battery and got my 18 dollar core charge back.
Best thing is that the original battery lasted 14 years! (too bad the hood and hatch shocks do not!