What voltage should my battery sit at?
Voltage targets depend on the battery chemistry and how you plan to use it. In general, a healthy lead‑acid 12V battery sits around 12.6 volts when resting, while lithium‑ion packs have different per‑cell targets (about 3.7–3.85 volts per cell when stored) and a maximum of 4.2 volts per cell when charging. Always check the manufacturer’s specifications for your exact battery model.
How voltage targets differ by battery chemistry
The following overview covers common battery chemistries and typical voltage ranges used in everyday devices and vehicles. Numbers are general guidelines and can vary by design, temperature, and age.
Lead‑acid (12V, flooded or VRLA/AGM Gel)
- Resting/fully charged voltage: about 12.6–12.7 V.
- Discharged threshold: around 12.0 V or lower.
- Charging voltages: roughly 13.8–14.4 V during bulk/absorption; float/maintenance around 13.2–13.8 V.
- Temperature note: charging voltage is often temperature‑compensated (roughly −3 mV per cell per °C above 25°C).
Lithium‑ion (Li‑ion, common consumer packs)
- Nominal per‑cell voltage: ~3.6–3.7 V.
- Maximum charge per cell: 4.2 V.
- Storage/resting target per cell: about 3.7–3.85 V (roughly 3.7–3.8 V is common for long‑term storage).
- Pack examples: a 3‑cell pack ≈ 11.1 V nominal; a 4‑cell pack ≈ 14.8 V nominal when fully charged.
Lithium iron phosphate (LiFePO4)
- Nominal per‑cell voltage: ~3.2 V.
- Maximum charge per cell: typically 3.6–3.65 V.
- Storage/resting target per cell: around 3.3–3.4 V for longer life.
- Pack examples: 4S pack ≈ 12.8 V nominal when in use.
Nickel‑metal hydride (NiMH)
- Nominal per‑cell voltage: ~1.2 V.
- Fully charged per cell: around 1.4–1.5 V.
- Battery packs vary widely; voltage is less often used as a sole indicator of health compared with capacity and impedance.
The figures above are starting points. For any battery you own, always follow the exact voltage targets stated by the manufacturer and account for temperature and age when charging or storing.
Practical tips for measuring and maintaining the right voltage
To keep your battery operating near its recommended voltage, use these practical steps as a quick checklist.
- Check resting voltage with a reliable multimeter when the battery has been off load for several hours.
- Assess temperature before charging—higher temperatures require lower charging voltages (temperature compensation varies by chemistry).
- Use the appropriate charger or charging profile designed for your battery chemistry and capacity.
- Avoid holding Li‑ion packs at 4.2 V per cell for long periods; store at the recommended 3.7–3.85 V per cell if you won’t be using them for a while.
- For lead‑acid batteries, avoid extended overcharging and monitor electrolyte levels in flooded types; ensure vents are clean and seals intact.
Following these steps helps maximize life, safety, and performance by keeping voltages within safe, manufacturer‑recommended ranges.
Summary
Voltage targets vary by chemistry: lead‑acid 12V batteries typically sit around 12.6–12.7 V at rest and charge in the 13.8–14.4 V range (float around 13.2–13.8 V); Li‑ion cells commonly sit near 3.7–3.85 V per cell when stored and up to 4.2 V per cell when charging; LiFePO4 cells target about 3.2 V nominal with a maximum around 3.65 V and storage around 3.3–3.4 V. Always consult your battery’s manual for the exact numbers and adjust for temperature. Regular checks and proper charging practices extend life and maintain performance.
