Ensoniq SD-1 Battery replacement

Is the battery soldered in on all versions of the Ensoniq SD-1 synth? Or, did Ensoniq upgrade to a pop in & pop out battery holder when the unit was upgraded to 32 voices?

Ensoniq never used a battery holder on the SD-1 - it was always a solder-in battery with leads. A coin battery of the type used in a snap-in holder has a much lower amp-hour rating, and will not last nearly as long as the cylindrical yellow battery.