E-bike battery charge time
Charge time in hours is roughly amp-hours ÷ charger amps × 1.2. The 1.2 covers the slow constant-voltage finish in the last 15 percent.
Hours from empty to fullCharging from 20 percent takes about 80 percent of these times. Most stock chargers are 2A; fast chargers are 4A to 5A.
| Battery | 2A charger | 3A charger | 4A charger | 5A charger | 8A charger |
|---|---|---|---|---|---|
| 7.8 Ah | 4h 41m | 3h 07m | 2h 20m | 1h 52m | 1h 10m |
| 10 Ah | 6h 00m | 4h 00m | 3h 00m | 2h 24m | 1h 30m |
| 10.4 Ah | 6h 14m | 4h 10m | 3h 07m | 2h 30m | 1h 34m |
| 12.8 Ah | 7h 41m | 5h 07m | 3h 50m | 3h 04m | 1h 55m |
| 14 Ah | 8h 24m | 5h 36m | 4h 12m | 3h 22m | 2h 06m |
| 15 Ah | 9h 00m | 6h 00m | 4h 30m | 3h 36m | 2h 15m |
| 17.5 Ah | 10h 30m | 6h 60m | 5h 15m | 4h 12m | 2h 38m |
| 20 Ah | 12h 00m | 8h 00m | 6h 00m | 4h 48m | 3h 00m |
| 25 Ah | 15h 00m | 10h 00m | 7h 30m | 6h 00m | 3h 45m |
Charger voltage must match the pack
Charger output by pack voltage
| Pack | Series cells | Charger output |
|---|---|---|
| 24V | 7S | 29.4V |
| 36V | 10S | 42.0V |
| 48V | 13S | 54.6V |
| 52V | 14S | 58.8V |
| 60V | 16S | 67.2V |
| 72V | 20S | 84.0V |
Charger current and pack life
| Charger | Speed | Note |
|---|---|---|
| 2A | Slow | Best for cell life; stock on most bikes |
| 3–4A | Medium | Fine for packs 14 Ah and up (under 0.3C) |
| 5A+ | Fast | Only for 17.5 Ah+ packs with 21700 cells; heats smaller packs |
| Rule | 0.3C or less | Charger amps ÷ pack Ah ≤ 0.3 keeps heat low |
Frequently asked questions
How long does a 48V 14Ah battery take to charge?
About 8 hours 24 minutes with the stock 2A charger, 5 hours 36 minutes at 3A, or 3 hours 22 minutes at 5A.
Can I use a faster charger?
Yes if the output voltage matches exactly and the current stays at or below 0.3C (0.3 × pack Ah). A 5A charger is fine for a 20 Ah pack but hard on a 10 Ah pack.
Should I charge to 100 percent?
For daily use, stopping at 80 to 90 percent roughly doubles cycle life. Charge to 100 only before a long ride, and ride soon after.