I have a digital odometer for the first time, and I’ve been wondering something: is the odometer adversely affected by a dead car battery? Having a dead battery erase the mileage seems like it would be a serious design flaw, so I’m hoping that the battery isn’t responsible for “remembering” how many miles the car has traveled. Is there another battery, or fuse, that keeps track of this, or do I really need to worry about this when the time comes to replace the current battery? And if there is another battery or fuse keeping track, what happens if those die?
The mileage is written into non-volatile storage, usually some variant of Flash or EEPROM. I used to work for a semiconductor company that was trying to break into the Odo market. They had a really tough time getting their device to pass the very stringent lifetime / write cycle / temperature tests the auto manufacturers demanded.
So, no, it can retain the milage indefinitely without power.
That is interesting and good to know.
However, FYI, auto stores and online they sell a neat little gizmo that is basically just a 9V battery with some electronics that plugs into your cigar lighter if you have to replace a battery or have it disconnected for some reason in a shop.
It keeps enough current to maintain all your radio station settings, garage door opening settings and other stuff that otherwise you would have to program in all over again.
Here is one example
Exactly. Just like how a thumb drive/memory stick doesn’t need power.
On a related note (since the OP has been answered) computers do have a battery in them that provides enough power to keep the time/date/boot setup data intact whilst it is disconnected from the power.
Never mind I thought this was a question.