I see that Bosch are offering their Rotak 37LI battery mower which has a '36V Li-Ion' battery. No trailing wire and less weight and maintenance than a petrol engine model. Do any of the battery experts (flecc?) have an opinion on whether this type of battery might last a few years? I suppose the problem would be the 4 -5 months the mower is not in use. A charge every month perhaps? Or run the motor for a while without mowing, just to give the battery some exercise?