1 #+TITLE: Ham radio battery charger mod
2 #+author: Svjatoslav Agejenko
5 * (document settings) :noexport:
6 ** use dark style for TWBS-HTML exporter
7 #+HTML_HEAD: <link href="https://bootswatch.com/3/darkly/bootstrap.min.css" rel="stylesheet">
8 #+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
9 #+HTML_HEAD: <script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/js/bootstrap.min.js"></script>
10 #+HTML_HEAD: <style type="text/css">
11 #+HTML_HEAD: footer {background-color: #111 !important;}
12 #+HTML_HEAD: pre {background-color: #111; color: #ccc;}
16 + DISCLAIMER: I DO ELECTRONICS AND 3D DESIGN SOLELY AS A HOBBY. THERE
17 COULD BE ERRORS THAT CAN RESULT IN ALL KINDS OF DAMAGE. USE THESE
18 DESIGNS AT YOUR OWN RISK.
20 + This design is released under Creative Commons Zero (CC0) license.
24 - Homepage: https://svjatoslav.eu
25 - Email: [[mailto://svjatoslav@svjatoslav.eu][svjatoslav@svjatoslav.eu]]
30 - [[../../index.html][Other physical projects in this repository]]
31 - [[https://www.svjatoslav.eu/projects/][Other projects hosted at svjatoslav.eu]]
35 Warning: this project is quite hacky. It requires breaking original
36 charger to get required critical charger part. Instructions are not
37 very detailed. Only describe the overall idea. Do not attempt to
38 reproduce this unless you exactly know what you are doing.
43 I have Baofeng GT-STP and Baofeng UV-82 radios. Their batteries have
44 slightly different geometry, so chargers are physically not
45 compatible. Also each changer comes with its own power adapter to plug
46 into wall power socket. Electrically batteries are apparently
49 By building this battery charger I solved 2 issues:
50 + It can charge batteries for both radios. Is physically and
51 electrically compatible to both models.
52 + Wall adapter is no longer needed. Now it is powered by USB connector
57 Body ignores small physical differences between batteries and both can
62 Front side contains critical fragment of the original changer circuit
63 board to drive the actual battery charging.
67 Back side contains voltage upstep converter that is tuned to convert
68 5V USB input to 10V output that is required by the charger.
72 Voltage upstep converter can produce significant voltage
73 ripples/impulses that travel backwards to the power source and forward
74 to the changer. To reduce this effect, there are capacitors and
77 [[file:electrical.png]]
79 Front and back sides are connected by wiring at the bottom. Also there
80 are screws to hold original Baofeng charger pins/springs that connect
85 After assembly is complete, back, front and bottom parts are sealed
86 with lid: [[file:cover.png]]