Replacing the memory battery in a Garmin GPS12xl

I have an old Garmin GPS12XL GPS handheld. Ages ago the memory battery expired and eventually I got around to replacing it. Instructions are not easy to find on the web so here is my take on it. You will need

A Panasonic VL1220 lithium battery
A toolkit for fiddly electronics work
A soldering iron (and soldering skills) for moderately small and awkward soldering but not as bad as surface-mount technology
A modicum of patience

I've encountered much worse repair work in the past. My source of the battery was CPC in the UK, where in 2009 a replacement battery cost £2.00.

Getting inside the case of the Garmin GPS12XL involves scraping the silicone sealant from the groove around the body. Amazingly this is the only mechanical fixing. On mine the top (furthest from the battery compartment) separated easily but the bottom was recalcitrant. I was worried that I'd missed a screw and would break the case but eventually teasing the two halves apart the case separated completely with no screws or clips anywhere. Once inside, the multiway plug that connects the PCB to the battery case and interface lead pulls out, it's just a press fit.

Next the PCB (circut board) has to come out. There are four very small cross-head screws that hold it to the front of the case. This requires either a tiny cross-head screwdriver and good eyesight or as in my case, a magnifying glass and the use of (yuck) a jewellers flat-head screwdriver and some luck. Then the PCB pulls out.

The old battery is soldered in and can be removed by applying a soldering iron to the non-component side of the PCB but beware - the replacement battery has different connectors. The side with the writing on the battery is ok. For the other side I had to prise the connector off the old battery with a screwdriver breaking the welds onto the battery case (not a nice job). Then the old battery unsoldered easily, the new one popped in and I soldered the old connector to the one from the new battery. It's probably fairly simple to unsolder the entire old battery and then put a small wire link rather than do the surgery I did on the old connector but that's not what I did at the time.

The battery is a tight fit in the case but with some slight bending I got mine inside again. As I write this I haven't resealed the case halves and the unit is working fine. Of course it has lost the setup and the waypoints I had previously stored but the the city database is still in there, including the annoying spelling of Petersborough for Peterborough.