About chargers - High-frequency chargers
The input mains voltage is rectified and then converted into a high operating frequency (50kHz) by a high-frequency chopping circuit. This high-frequency input is then passed through a transformer and rectified to the correct DC voltage with only a negligible ripple. Because of this high frequency, the transformation can be done with a small ferrite transformer. This makes HF chargers suitable for all types of lead acid batteries.
High-frequency chargers have an efficiency of over 90%, which makes them very cost effective. Because an HF charger does not have a heavy transformer, its weight is generally a quarter to one fifth of that of a similar conventional charger. This allows for wall mounting, thus increasing floor space and safety.