Batteries & Charging
State of charge (SoC)
What is State of charge (SoC)?
How full a battery is right now, shown as a percentage or as bars on the display. It is an estimate made by the battery's electronics.
State of charge (SoC) is how full your e-bike battery is at this moment. When the display shows 60%, or 3 of 5 bars, that’s the state of charge. The battery’s electronics estimate it, so treat it as a good guide, not a lab measurement.
Why it matters for storage
Battery makers set a state of charge for long breaks. Bosch recommends 30 to 60%. Shimano’s manual for its STEPS batteries says about 70%. On a Bosch pack, 30 to 60% is 2 to 3 lit bars, according to Tern’s Bosch battery guide. Our winter battery storage guide compares the two and explains how to set the level.
Common confusion
A battery at 50% has not lost half its life. How much capacity a pack has kept over the years is its state of health, a separate number. And a reading that drops while the bike sits unused is usually self-discharge or a small standby drain, not damage.
Also known as: SoC
Related terms
- State of health How much of its original capacity a battery has kept, usually given as a percentage of what it held when new.
- Self-discharge The slow loss of charge inside a battery while it sits unused, caused by chemical reactions in the cells.
- Battery management system The electronics inside a battery pack that watch its cells and cut charging or power when temperature, current or charge level go outside safe limits.