How to Read an E-bike Battery Label
A battery label tells you what the pack is, whether it was safety tested, and whether it is on a recall list. Here is each line decoded.
What each line means
| Line | Example | Meaning | Why it matters |
|---|---|---|---|
| Nominal voltage | 48V | Average working voltage. Sets which bikes it fits. | Must match your controller |
| Capacity | 14Ah | Charge the pack holds. | Bigger is more range at the same voltage |
| Energy | 672Wh | V × Ah. The number to compare batteries on. | Also decides shipping class (over 100 Wh is regulated) |
| Cell configuration | 13S4P | Series count × parallel count. 13S = 48V. 4P × 3.5Ah cells = 14Ah. | Rebuilders need this |
| Cell brand | Samsung 35E | Who made the cells inside. Name brands: Samsung, LG, Panasonic, Molicel. | No brand listed is a warning sign |
| Max discharge | 30A | BMS continuous current limit. | Must exceed your controller peak amps |
| Charge voltage | 54.6V | Full-charge voltage. Your charger must output exactly this. | 42V = 36V pack, 54.6V = 48V, 58.8V = 52V |
| Model number | RP-1304 | The identifier recalls and warnings use. | Search it on our recalls page |
| Safety marks | UL 2271, UN 38.3 | UL 2271: pack safety. UN 38.3: passed transport tests. EN 50604-1: EU equivalent. | Required for sale in NYC and California |
| Date or serial | 2023-08 / S/N | Production batch. Packs older than 5 years are near end of life. | Needed for warranty claims |
Series and parallel quick reference
Cell configuration to voltage and capacityAssumes 3.6V nominal cells. Capacity shown for 3.0 Ah (18650) and 5.0 Ah (21700) cells.
| Series | Voltage | 3 parallel | 4 parallel | Cells (3P / 4P) |
|---|---|---|---|---|
| 10S | 36V | 3P: 9 Ah / 15 Ah | 4P: 12 Ah / 20 Ah | 30 / 40 cells |
| 13S | 48V | 3P: 9 Ah / 15 Ah | 4P: 12 Ah / 20 Ah | 39 / 52 cells |
| 14S | 52V | 3P: 9 Ah / 15 Ah | 4P: 12 Ah / 20 Ah | 42 / 56 cells |
| 20S | 72V | 3P: 9 Ah / 15 Ah | 4P: 12 Ah / 20 Ah | 60 / 80 cells |
Frequently asked questions
My label has no UL mark. Is the battery unsafe?
Not necessarily, but it was not tested to UL 2271, and it cannot legally be sold new in New York City or California. Treat it with more caution: never charge unattended.
What does 13S4P mean?
13 groups of cells in series (13 × 3.6V = 48V nominal), each group made of 4 cells in parallel. With 3.5 Ah cells that is 14 Ah and 52 cells total.
Where is the model number on a Rad Power battery?
On the label on the underside of the pack. The CPSC-flagged models are RP-1304 and HL-RP-S1304.