2026-11-07
A charger label carries more useful information than most buyers expect. Three values explain nearly every question about charging speed, heat and pack life: output voltage, output current and the capacity of the pack being charged.
The three numbers that matter
Output voltage tells you which pack class the charger serves. Output current tells you how fast energy moves into the pack. Pack capacity, measured in Ah, tells you how much energy the pack holds. Charging problems usually appear when one of the three is outside the range the pack was designed for.
Input voltage matters too for Indian sites. A wide input range helps when supply voltage swings during peak load hours, which is common in industrial areas and smaller towns.
Estimating charge time
A simple estimate is capacity in Ah multiplied by 1.2, divided by charger output current. A 100Ah pack on a 15A charger works out to about 8 hours; a 40Ah pack on a 5A charger works out to about 9.6 hours. The 1.2 factor covers charging losses and the tapering current at the end of the cycle.
Real charge time also depends on how deeply the pack was discharged and on ambient temperature. A pack at 20 percent state of charge takes noticeably longer than one at 60 percent, and very hot afternoons slow the final stage on temperature-compensated chargers.
Why output current is sold in bands
Chargers are grouped by current band because the right value depends on pack capacity rather than on the vehicle. Our range runs from 2A to 35A: 2A to 8A suits 20Ah to 45Ah packs charged overnight at home, 12A to 18A covers the common 60Ah to 100Ah e-rickshaw packs, and 18A to 35A is aimed at fleets and small forklifts that need a fast turnaround.
Choosing one band higher than the pack requires will shorten charge time, but it also raises temperature and reduces cycle life. Choosing lower is safe and slow. For a dealer stocking mixed packs, two bands usually cover most of the demand.
Early signs of a mismatch
Watch for a cable or plug that becomes hot to the touch, a charger that never reaches its constant-voltage stage, a fan that runs continuously for the whole cycle, or a pack that stays warm long after charging ends. Any of these suggests the current, the voltage class or the pack condition is wrong, and the charger should be checked before the next charge.