RE; Prolific
I ran the gauge survey and got 30 repsonses; I also parsed every gauge thread and got 22 unique IDs that i PM'd, who voted.
I am not an actuary or electrical engineer; but a few things strike me
-30/4038 failures is very small
-75% of failures were using a non-OEM charger; 50% no charger at all
-the OEM charger runs at 500 mili-amps where as the Batt Tender runs at 750
One would need an eletrical engineer to review the wiring harness schematic to the gauge and the gauge internal components to decide if circuit is somehow unstable with certain variables (sometimes these are on web or buried in journals).
My uneducated take is a connection without constant current (usage) builds up coatings that hinder/amplify voltage regulation, and over time degrade sensitivity. Other culprits are static conductivity, feedback, and magnetism. In Vettes, for example low frequency magnetic fields around house gates /garage alarms were frying keyless entry systems.
Someone around here is qualified to look at this
Interesting fact as shared however the Battery Tender as used by a large number of folks is not the culprit; I share this so that folks with them do not panic or start calling Kendall. The differences between these two trickle charger examples are many however; the specific one that you addressed which is the maximum output of the charger does not reflect that which is being passed through to the battery at any given moment in time; in fact as the battery becomes fully charged the pass through voltage is minimal at best.
Now for the benefit of all; the gauge control module and the gauges are completely out of the loop while the key is removed the battery is being charged.
Empirical data would be nice however this is what I have been told; for example the speedometer uses a cool little very inexpensive integrated circuit (IC) and on those that have been this IC has been fried.
The belief by several that have looked that the gauges are that they are incapable of large voltage/amperage swings and when such it experienced one or more fail. It is also my understanding that when you turn the key on the attempt to hand shake with all of the gauges occurs and if one does not get a proper voltage signal it may simply not come to life which is why often times folks share that one gauge did not work however upon restarting the gal it comes back on line.
Could it be that the way that the gauges were wired allows them to experience the extreme draw when the gals are brought to life; maybe? One consideration discussed is to place a capacitor, a filter, or ? at the gauges thus reducing the voltage sweep; meaning create a constant voltage signal to the gauges regardless of the gal be started, the blower motor being activated, etc.
Now I agree that based on your collected data that the number of failures seems small however when one considers the in service time of these gals, the miles traveled, the number of mixed gauge failures, and then reassess the data as collected I would say that the failure rate would be by most standards; extreme.
All the best
Shadowman
