Wh vs Ah vs V
Watt-hours (Wh) is the only number that tells you how much energy a battery holds. Amp-hours alone is meaningless without the voltage.
| Number | Meaning | Example | Use it to |
|---|---|---|---|
| Volts (V) | Electrical pressure. Set by how many cells are in series. | 36V = 10 cells in series, 48V = 13, 52V = 14 | Must match your motor controller |
| Amp-hours (Ah) | How much charge the pack holds at its voltage. | 14 Ah means 14 amps for one hour | Only comparable at the same voltage |
| Watt-hours (Wh) | Total energy. Volts × amp-hours. | 48V × 14 Ah = 672 Wh | Compare any two batteries with this |
Conversion table
| Voltage | Amp-hours | Watt-hours | Typical range |
|---|---|---|---|
| 36V | 10.4 Ah | 374 Wh | 19–31 mi |
| 36V | 14 Ah | 504 Wh | 25–42 mi |
| 48V | 10.4 Ah | 499 Wh | 25–42 mi |
| 48V | 14 Ah | 672 Wh | 34–56 mi |
| 48V | 17.5 Ah | 840 Wh | 42–70 mi |
| 48V | 20 Ah | 960 Wh | 48–80 mi |
| 52V | 14 Ah | 728 Wh | 36–61 mi |
| 52V | 20 Ah | 1040 Wh | 52–87 mi |
| 72V | 20 Ah | 1440 Wh | 72–120 mi |
| To get | Formula | Example |
|---|---|---|
| Wh | V × Ah | 48 × 14 = 672 Wh |
| Ah | Wh ÷ V | 672 ÷ 48 = 14 Ah |
| Range (mi) | Wh ÷ Wh per mile | 672 ÷ 15 = 45 mi |
| Charge time (h) | Ah ÷ charger A × 1.2 | 14 ÷ 2 × 1.2 = 8.4 h |
| Cells in series | V ÷ 3.6 (3.7) | 48 ÷ 3.7 = 13S |
| Cells in parallel | Ah ÷ cell Ah | 14 ÷ 3.5 = 4P |
The median e-bike battery in our index is 482 Wh. A pack labeled "48V 20Ah" (960 Wh) holds 43 percent more energy than a "48V 14Ah" (672 Wh) pack. A "36V 20Ah" pack (720 Wh) holds less than a "48V 17.5Ah" (840 Wh) one despite the bigger Ah number.
Frequently asked questions
Is a higher Ah battery always better?
Only at the same voltage. Compare watt-hours. A 52V 14Ah pack (728 Wh) beats a 48V 14Ah pack (672 Wh) and a 36V 20Ah pack (720 Wh) is in between.
Why does my 48V battery read 54V?
Nominal voltage is the average under load. A 13-cell 48V pack reads 54.6V fully charged and about 39V empty.
How many Wh do I need?
Multiply your longest ride in miles by 15 Wh (moderate assist) or 20 Wh (throttle, hills, heavy load). A 30-mile commute needs 450 to 600 Wh.