State of charge and resting voltage
| Charge | Battery | Range in the charts | Per cell |
|---|---|---|---|
| 100 % | 16.70 V | 16.67–16.79 V | 4.18 V |
| 90 % | 16.26 V | 15.94–16.36 V | 4.06 V |
| 80 % | 15.93 V | 15.50–16.10 V | 3.98 V |
| 70 % | 15.69 V | 15.13–15.85 V | 3.92 V |
| 60 % | 15.43 V | 14.86–15.53 V | 3.86 V |
| 50 % | 15.20 V | 14.60–15.35 V | 3.80 V |
| 40 % | 15.11 V | 14.45–15.21 V | 3.78 V |
| 30 % | 15.05 V | 14.35–15.06 V | 3.76 V |
| 20 % | 14.87 V | 14.21–14.93 V | 3.72 V |
| 10 % | 14.68 V | 13.97–14.74 V | 3.67 V |
| 0 % | 13.40 V | 11.20–14.00 V | 3.35 V |
Resting voltage at 20–25 °C. Typical: median of four measured tables (Samsung SDI, Libre Solar, PineNote, Anbernic); range: all four. Readings taken hours after the last charge or discharge.
What to know
Li-ion cells don’t all follow the same curve: in the middle of the range the tables we used differ by about 0.75 V, so read the percentages as approximate. Above about 16.26 V the battery is nearly full; below about 14.68 V little is left.
Charging and limits
| Charge (absorption) | 16.80 V (4.20 V max per cell) |
|---|---|
| Float | none: the charger stops when the current falls |
| Discharge cut-off | 10.00 V under load (cell datasheets) |
| Storage | 15.20–15.40 V |
| Charging temperature | 0–45 °C |
From the datasheets and manuals in the sources: the datasheet of your battery or charger comes first.
Tips
On a pack, also measure each cell at the balance plug: one weak cell can hide behind a normal total.
To store Li-ion and LiPo for weeks, leave them at about 3.8–3.85 V per cell (Grepow’s storage charge), neither full nor empty.
Measure at the battery terminals with everything disconnected. A meter that is off by a hundredth of a volt per cell already matters on LiFePO4 and Li-ion.
Open in the calculator →Enter the voltage you measured and get the charge with its range.
Other batteries
12 V LiFePO4 battery (4S) 24 V LiFePO4 battery (8S) 48 V LiFePO4 battery (16S) LiFePO4 cell (3.2 V) 18650 / 1S LiPo cell (3.7 V) 2S Li-ion / LiPo (7.4 V) 3S Li-ion / LiPo (11.1 V) 6S LiPo (22.2 V) 36 V Li-ion battery (10S) 48 V Li-ion battery (13S) LiHV cell (4.35 V) 12 V AGM battery 12 V gel battery 12 V flooded lead-acid battery 6 V flooded lead-acid battery NiMH cell (1.2 V)
Frequently asked questions
What voltage is a 4S Li-ion or LiPo pack at 50 %?
About 15.20 V at rest; the charts we used range from 14.60 V to 15.35 V.
What voltage is a 4S Li-ion or LiPo pack at 100 %?
About 16.70 V at rest, hours after charging. While charging, the charger holds it at 16.80 V.
At what voltage is a 4S Li-ion or LiPo pack empty?
At rest, below about 14.68 V only about 10 % is left, and devices usually stop at about 13.40 V. Under load the cells are rated down to 10.00 V.
Sources: the makers’ charts and datasheets listed on the calculator page.