The Battery Self-Discharge Calculator helps you estimate how much energy your eBike battery loses while stored and not in use.
Lithium-ion batteries naturally lose charge over time, even when disconnected from the bike.
This tool calculates the remaining battery percentage, watt-hours, and estimated loss based on storage duration and self-discharge rate.
What Is Battery Self-Discharge?
Self-discharge is the natural process where a battery slowly loses its stored energy without being connected to any device.
Lithium-ion eBike batteries typically lose 2%–4% per month, but this depends on:
- Battery chemistry (NCM, NCA, LFP)
- Temperature during storage
- Battery age and health
- Storage charge percentage
- Internal resistance and cell quality
Typical Monthly Self-Discharge
- NCM/NCA Li-ion: 2–4% per month
- LFP (LiFePO₄): 1–2% per month
- Old batteries: 4–7% per month
- Stored in hot places: 5–10% per month
Tip: Storing your battery at 40–60% charge in a cool room (15–25°C) reduces self-discharge dramatically.
How Self-Discharge Affects Your eBike
Self-discharge doesn’t normally damage a lithium battery, but if it continues for too long, the voltage can drop to dangerous levels.
When a battery reaches deep discharge (below 2.5–2.8V per cell), it may become permanently damaged.
Risks of Long-Term Storage Without Charging
- BMS cutoff: Battery becomes non-chargeable
- Permanent capacity loss: Irreversible degradation
- Cells drifting out of balance: Reduced performance
- Shortened lifespan: Faster aging
For long-term storage, it is recommended to recharge the battery every 30–60 days to maintain safe voltage levels.
Best Practices for Storing Your eBike Battery
- Store at 40–60% charge
- Keep temperature between 15–25°C
- Avoid leaving the battery fully charged for long periods
- Recharge slightly every 1–2 months
- Do not store in hot places like cars or near sunlight
- Disconnect battery from charger and controller during long-term storage
Following these recommendations can reduce self-discharge and extend the lifespan of your lithium-ion battery by years.
Frequently Asked Questions
Q: How much charge does a lithium eBike battery lose per month?
A: Usually 2–4% per month, depending on temperature, age, and chemistry.
Q: Do eBike batteries self-discharge faster in hot weather?
A: Yes. Heat accelerates internal chemical reactions, increasing self-discharge to 5–10% per month.
Q: Can self-discharge damage the battery?
A: If a battery remains unused for months and voltage drops too low, permanent damage can occur.
Q: How often should I recharge a stored battery?
A: Ideally every 30–60 days to prevent deep discharge.
Q: What storage level is best for lithium batteries?
A: The ideal storage charge is 40%–60%.
