For R50 12V system with 2 x 6V batteries

L x W x H = 126 x 63 x 137 mm

Maintenance free battery:

- maintenance-free or sealed battery needs NO refilling of electrolyte.

- minimal spillage and sulfur formation.

However, a maintenance free battery is still a Lead Acid Battery and needs to be kept charged also during periodes when the motorcycle is not used.

All lead acid batteries; irrespective of whether being VRLA Flooded, Gel, AGM & conventional flooded types are quick to charge to 70% of capacity within 2 or 3 hours, but this technology requires another 9 to 10 hours to “float charge” after the initial charge. If users fail to float charge, lead acid battery-type capacity is dramatically reduced. All types have a memory in that every time a user charges to less than 100% charge, battery capacity is shortened.

https://en.wikipedia.org/wiki/VRLA_battery