Anyone ever used or heard of E-cells?

30 years ago I worked for Ford Motor in the airbag group. We were investigating a component called the E-cell, which was an electro-chemical component that had an anode and a cathode separated by an electrolyte. The device could be used to time events over months or even years, by passing a known current through it. If in use, the circuit were hooked up with forward voltage, the device would slowly plate the anode. If current were reversed, the anode would unplate until all cathode material was removed, and the voltage would rise significantly. This could be detected and used to trigger an alarm.

Ford was considering using it to monitor how long someone drove their car with the fault light illuminated for the airbags. If there was a crash and the airbags failed to deploy, they could unplate the E-cell and tell the customer "we know you drove the car for three months with the fault light on".

They were never implemented, I don't remember the manufacturer, and I don't think they were ever really a production component. I have 5 samples, which may be the only ones left in the world.

Anyone else heard of them?

I have seen these things in the past.
They were used as elapsed time meters to give an indication of how long a piece of equipment had been in use.
Whether they are still used I do not know, I have not seen one for many years.

When i worked in a shipyard which built things like submarines.
Occasionally one of the test engineers would bring one of these things along and ask us to reset it to zero by applying a reverse current to make the red(?) line go back to the zero point.

Edit
I just did a bit of googling and found these:
https://aapt.scitation.org/doi/10.1119/1.1941803
**broken link removed**

JimB

That is right on track. The name Curtis Instrument rings a bell, and I remember elapsed time meters being one of their product lines, also the term coulometer. The samples I have are the discrete circuit elements themselves, which look like small axial lead caps.

Yes I've seen them in machine tools for run time indication.
They were in the form of a 1 1/4" fuse, I beleive they used electro osmosis.
Not seen or heard for a long time.

saw some of those in military equipment. looked like a tube filled with mercury, and a dark liquid gap in the middle. they were used for telling the user when to take the unit in for maintenance.. they were usually in equipment that led a quiet life. when there were extremes of temperature or vibration, they used the odometer style "hour meters".