As winter has came and I'm not using the motorcycle until the good weather will be back, I took the battery inside house and stored it at constant temperature and dry conditions.
Its level was 70% when I arrived home after last ride (2 weeks ago).
Should I still fully charge it every month (or two months) even if I don't use it? Or can keep it at the current charge level and recharge it to 100% in March/April before next use?
Lithium batteries are optimally stored around 60%. Storing them fulling charged stresses the cells and can reduce life. You're probably fine at 70%, just don't charge it any further.
Yes its good to have it around 50%. That is about 3,75- 3,85v per cell.
My battery sits at about 3.8v now.
A fully charged Super Soco battery usually is 100% and show 100% in the display when charged to 69,7 volt. I reality its about 90% charged and each cell stands at 4,1v. Maximum for ebike batteries in general is 4,2v and is the true 100% charge level state for li-ion batteries.
It is also very good to charge every other month or so because some BMS (brains) in bigger batteries draw electricity or when connected to your Super Soco and the alarm is active. That draws a small current of electricity. Many small streams adds upp to larger rivers.
The more worse factor is having the battery sitting in the sun and sunbathing rather than having it in the coldest place in your house. On flor lever 18-19C, basement or garage still close to 0C but not below preferably. A higher temperature affects life more in a battery than the charge level state.
How I use my battery.
I charge at work to whatever level I wish 100% or 80% in this example. Then I drive home and the battery reaches 60%. Then I drive to work and it reaches 40%. A few hours. The time it takes to charge to 80% I turn on the charger. Slow charge preferably for example a speed of 0,1-0,3C* to 80% and the cycle starts over.
* Charge rate 1C = 30A for a 30AH capacity battery. Super Soco charger 4A is about 0.13C charge rate
