De-noising the A24050-2 scoot mobile battery charger.
pa0nhc 20160323

Lead acid charging TIPs.

Manufacturer component data: http://batterymaximizer.com/mobility%20off-board%20chargers.htm

This charger was delivered with a Pride scoot mobile. This charger caused strong and wideband rattling radio interference, even when the battery was fully loaded or even disconnected.

When the charger was opened, some filter capacitors and a ground connection shown not to be installed as often is the case (to lower production costs).

        The cure :
The white seal on de side was cut, and the four rubber feet and screws removed. The underside of the PCB should be screened by an insulated metal plate.
A short connection wire (on the right side of the photo) was de-soldered from the screening plate, to make the plate removable.

On that side of the PCB, two mains filter capacitors (CY1 en CY2), and their connection to safety ground were missing. I soldered the wire, and two capacitors 3300pF/400V~ (or 630Vdc).

Also missing was a capacitor on the 24Vdc output. An elco of 470uF 35V (or higher) 105C (important as the charger can become hot) just fitted here.

At the underside of the PCB, also at the 24V output, was just enough place available for extra filter capacitors. At the input and the output of the green ring-core choke, film capacitors 100nF 63V were soldered.

After re-placing the metal screening plate, and re-soldering the short ground connecting wire, the cabinet was closed and the cables filtered.  The wide band noise was much less, and after a few meters distance at acceptable low level.