Retevis RT-3 Battery Eliminator Problems

 In the car, I enjoy using my hand held radios to listen to DMR and FM over local repeaters or via a pi-star hotspot that I have in the car. I use a battery eliminator instead of a battery, so that I always have full voltage at the hand held and removing the need to charge batteries.

These clip on to the back of your hand held in place of the battery pack. This one worked for years until it recently started to power the radio for the first 60s after plugging it in and then the voltage would drop out, come back, drop out, etc. repeatedly every second or so. Very annoying.

These are normally sealed units, designed to be thrown away after they stop working. However, with some force, they can be broken open along the plastic welded joint that holds the front half to the back half.

As we can see, the layout is made up of a buck converter to reduce the voltage from 12-24V down to the 8V that the radio requires.

The caps buffer and smooth the voltage as it enters into the radio. If the caps go bad then they can not buffer the 8V long enough for the next duty cycle of the buck converter and this is what was resulting in voltage coming and going. The replacement caps were fitted.

After repair, the battery eliminator worked perfectly. A perfectly smooth and constant 8V supply voltage again.