Why do trains still use Ni-Cd batteries?
An electric train may take its energy from the line, but controls, communications, emergency functions and certain auxiliary systems must keep operating after a main supply failure. The battery is therefore part of the critical-power chain, not simply an energy-storage component.
Nickel-cadmium, or Ni-Cd, remains an established railway battery technology. In EKA System’s work with SAFT railway batteries, selection considers operating temperature, vibration, discharge characteristics, charging conditions and vehicle backup requirements together, as well as Ah capacity.
What is expected from a train battery?
Battery duties vary by application. Controls, safety functions, communications or onboard auxiliary loads may need support for a defined period after main power loss. Diesel vehicles may also require a short burst of high current for engine starting.
This environment differs from an ordinary standby-power application. The vehicle experiences continual vibration and temperature changes, yet the battery must deliver when needed. SAFT railway Ni-Cd solutions emphasise shock and vibration resistance, a broad operating-temperature range and product families for different power demands.
Why is Ni-Cd still selected?
Reliability in demanding conditions is a major reason. Ni-Cd technology is suitable for low-temperature operation and can be designed with robust construction for mechanically demanding industrial applications. High-power Ni-Cd batteries can serve short-duration, high-current duties such as engine starting.
These characteristics matter when a train is expected to operate for years in different climates and operating conditions. The objective is to select a predictable solution suited to its duty.
Should every train use Ni-Cd?
No. Railway battery selection follows project requirements. Voltage, load profile, autonomy, temperature, mechanical conditions, maintenance approach, weight and available space can all influence the choice of technology.
The answer to why an older technology remains in use is that critical systems depend on how reliably a technology fulfils its duty. Railway applications provide a clear example.