Replacing Motorola Batteries

Posted on Feb 7, 2014

These were about $60 a pair with charger and batteries, and have a three-bar battery gauge. With experimentation I found that if the voltage is greater than 4. 28V, all three bars light up. More than 3. 47V, two bars will light up. Below this latter voltage the radio chirps regularly, and only one bar will light up. After a few years use, we noticed

Replacing Motorola Batteries
Click here to download the full size of the above Circuit.

the batteries do not last longer than a few hours, so I wanted to replace them. A search on the web shows that the battery packs are about $12 each (plus shipping), and their capacity is still only 600mAh, so I decided to investigate a home-brew battery replacement for these units. I pealed back the sticker on one battery pack and discovered that the hidden elecronics are very simple and can be easily reproduced. One terminal of the charger connections connects to the negative terminal of the battery pack, and the other terminal connects to the positive terminal via a blocking diode. Insert the three batteries into the radio, and verify that it powers up. If it doesn`t you may have to bend the metal tabs out to meet the battery terminals. Remove the paper backing, on the tape, and fold the tab over so that the tape forms a `b` shape. The top arm of the `b` is not sticky on either side because you folded the tab over. The bottom belly of the `b` is sticky. Tape the bottom (belly) part of the `b` onto a corner of the paper substrate (top copper tab in the pictures below). Have the non-sticky top arm stick out of the edge. Insert the top arm of the `b` under the negative terminal of the battery. Since you folded the tab under, both sides of this leg are exposed copper and will make good contact with the battery and the radio terminal. Tape the 0. 75" square piece of copper tape in the opposite corner of the paper (see below)....

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