When I removed the AA batteries from my <relatively new> Garmin GPS,  all of my data was lost and the unit reset.

Why is this?  What happened?  What do I do?

A few years ago,  Garmin received a shipment of defective Lithium Batteries that were used in the memory backup system of a fairly large number of GPS receivers.  It is unknown exactly which units received these batteries.

If your unit should have this problem,  Garmin will replace the defective memory backup battery for you at no charge.  You should telephone Garmin Technical Support at 800-800-1020 (or Garmin UK if you are in Europe) for return instructions.  You may also contact Garmin Technical Support via Email.   Your dealer may also be persuaded to exchange your defective unit if it is new.

I took the batteries out of my GPS last year and when I turned it back on this year,  the memory battery alarm came on and I lost all my data.

Why is this?  What can I do?  Does this mean my memory backup battery is now defective?

In the first place,  you should NOT store your Garmin GPS without batteries.  (Excepting the newer models which use FLASH MEMORY and do not have a backup battery for memory retention.  The charge will supposedly last up to 3 months on the Lithium backup battery if the AA cells are removed.)  When you store your unit,  it should be with a fresh set of AA cells so as to maintain the backup battery and memory.  A fresh set of AA cells will usually keep memory "alive" for about 2 years if all is normal.

If you find yourself with this problem,  your memory battery is likely OK,  but has run down.  You should install fresh AA cells in your GPS and about a week later remove the batteries for a day and see if the memory data is still present when you put the batteries back in.  If the memory survives OK,  likely your memory battery is OK.  If not,  your unit should be returned to the factory for repair.

Joe Mehaffey