How did you get that information? I haven't seen anywhere that a cycle (in this case 20% of a cycle) would do more damage than storage at a high SoC. There's nothing particularly special about any of the Shimano batteries.
Certainly for a few days it's hardly worth the effort but if storage is several weeks or months then getting charge to 70% would be a good idea for maximum battery health.
Gordon
My experience from owning 4 batteries (internal 504wh bt-e8035) and watching them all rapidly decline in health regardless of how I stored them. Three of the batteries were always stored at 40-60%, one of them I always charged to 100% after my rides. As you can see it does not seem to matter as they all declined in the same manner.
Battery 1 - Original Battery
90% health; 10 cycles
87% heath; 23 cycles (at 87% agreed to warranty)
85% health; 32 cycles
84% health; 38 cycles
82% health; 40 cycles
Battery 2 - New Battery Purchased as Second Battery
90% health; 10 cycles
87% health; 20 cycles (either at 90% or 87% Shimano agreed to warranty)
85% health; 30 cycles
Battery 3 - Warranty Batt (24) (4/23/2020)
91% health; 4 cycles and - only 20 days old (4/23/2020)
89% health; 11 cycles
87% health; 20 cycles (Shimano refused warranty says has to be 60% 10/6/2020)
84% health; 30 cycles (11/29/2020)
82% health; 40 cycles (1/8/2021)
Battery 4 - Warranty Batt (B0) (4/23/2020)
90% health; 11 cycles (Shimano said they wanted more degradation)
90% health; 14 cycles
87% health; 21 cycles (Shimano refused warranty says has to be 60% 10/6/2020)
85% health; 30 cycles (12/20/2020)
) mine`s currently sitting with a full charge but i`d like to reduce it to 60-80% while it`s not being used.
