4 <title>12V Lead-Acid battery changer and terminal</title>
5 <!-- 2020-03-21 Sat 00:35 -->
7 <meta name="viewport" content="width=device-width, initial-scale=1">
8 <meta name="generator" content="Org-mode">
9 <meta name="author" content="Svjatoslav Agejenko">
10 <link href="https://bootswatch.com/3/darkly/bootstrap.min.css" rel="stylesheet">
11 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
12 <script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.5/js/bootstrap.min.js"></script>
13 <style type="text/css">
14 footer {background-color: #111 !important;}
15 pre {background-color: #111; color: #ccc;}
17 <style type="text/css">
18 /* org mode styles on top of twbs */
35 background-color: #f5f5f5;
62 display: inline-block;
74 .bs-docs-sidebar.affix {
77 @media (min-width: 768px) {
83 /* All levels of nav */
84 .bs-docs-sidebar .nav > li > a {
91 .bs-docs-sidebar .nav > li > a:hover,
92 .bs-docs-sidebar .nav > li > a:focus {
95 text-decoration: none;
96 background-color: transparent;
97 border-left: 1px solid #A1283B;
99 .bs-docs-sidebar .nav > .active > a,
100 .bs-docs-sidebar .nav > .active:hover > a,
101 .bs-docs-sidebar .nav > .active:focus > a {
105 background-color: transparent;
106 border-left: 2px solid #A1283B;
109 /* Nav: second level (shown on .active) */
110 .bs-docs-sidebar .nav .nav {
111 display: none; /* Hide by default, but at >768px, show it */
112 padding-bottom: 10px;
114 .bs-docs-sidebar .nav .nav > li > a {
121 .bs-docs-sidebar .nav .nav > li > a:hover,
122 .bs-docs-sidebar .nav .nav > li > a:focus {
125 .bs-docs-sidebar .nav .nav > .active > a,
126 .bs-docs-sidebar .nav .nav > .active:hover > a,
127 .bs-docs-sidebar .nav .nav > .active:focus > a {
132 /* Nav: third level (shown on .active) */
133 .bs-docs-sidebar .nav .nav .nav {
134 padding-bottom: 10px;
136 .bs-docs-sidebar .nav .nav .nav > li > a {
143 .bs-docs-sidebar .nav .nav .nav > li > a:hover,
144 .bs-docs-sidebar .nav .nav .nav > li > a:focus {
147 .bs-docs-sidebar .nav .nav .nav > .active > a,
148 .bs-docs-sidebar .nav .nav .nav > .active:hover > a,
149 .bs-docs-sidebar .nav .nav .nav > .active:focus > a {
154 /* Show and affix the side nav when space allows it */
155 @media (min-width: 992px) {
156 .bs-docs-sidebar .nav > .active > ul {
159 /* Widen the fixed sidebar */
160 .bs-docs-sidebar.affix,
161 .bs-docs-sidebar.affix-bottom {
164 .bs-docs-sidebar.affix {
165 position: fixed; /* Undo the static from mobile first approach */
168 .bs-docs-sidebar.affix-bottom {
169 position: absolute; /* Undo the static from mobile first approach */
171 .bs-docs-sidebar.affix .bs-docs-sidenav,.bs-docs-sidebar.affix-bottom .bs-docs-sidenav {
176 @media (min-width: 1200px) {
177 /* Widen the fixed sidebar again */
178 .bs-docs-sidebar.affix-bottom,
179 .bs-docs-sidebar.affix {
184 <script type="text/javascript">
188 $('.bs-docs-sidebar li').first().addClass('active');
190 $(document.body).scrollspy({target: '.bs-docs-sidebar'});
192 $('.bs-docs-sidebar').affix();
197 <div id="content" class="container">
198 <div class="row"><div class="col-md-9"><h1 class="title">12V Lead-Acid battery changer and terminal</h1>
200 <div id="outline-container-sec-1" class="outline-2">
201 <h2 id="sec-1"><span class="section-number-2">1</span> General</h2>
202 <div class="outline-text-2" id="text-1">
204 <li>DISCLAIMER: I DO ELECTRONICS AND 3D DESIGN SOLELY AS A HOBBY. THERE
205 COULD BE ERRORS THAT CAN RESULT IN ALL KINDS OF DAMAGE. USE THESE
206 DESIGNS AT YOUR OWN RISK.
209 <li>This design is released under Creative Commons Zero (CC0) license.
214 <li>Svjatoslav Agejenko
216 <li>Homepage: <a href="https://svjatoslav.eu">https://svjatoslav.eu</a>
218 <li>Email: <a href="mailto://svjatoslav@svjatoslav.eu">svjatoslav@svjatoslav.eu</a>
225 <li><a href="../../index.html">Other physical projects in this repository</a>
227 <li><a href="https://www.svjatoslav.eu/projects/">Other projects hosted at svjatoslav.eu</a>
235 <div id="outline-container-sec-2" class="outline-2">
236 <h2 id="sec-2"><span class="section-number-2">2</span> Project description</h2>
237 <div class="outline-text-2" id="text-2">
240 <p><img src="make.png" class="img-responsive" alt="make.png">
246 <p><img src="make,%202.png" class="img-responsive" alt="make,%202.png">
251 Simple charger and terminal (front-end) for 12V lead-acid battery.
255 Idea is to distribute power from rechargeable 12V battery to various
256 appliances (soldering iron, radio transmitters, etc..) while also
257 providing use-charging in the background.
261 Single on/off button disconnects battery and up-step voltage source
262 from front panel terminal connectors.
266 <a href="https://www.amazon.de/gp/product/B07G4KWV6S/ref=ppx_yo_dt_b_asin_title_o08_s01?ie=UTF8&psc=1">Tecnoiot MT3608</a> voltage up-step is used. 3V DC external power supply
267 is used to feed voltage up-step. Up-step is tuned to ~14.4 V.
272 <p><img src="schematic.png" class="img-responsive" alt="schematic.png">
277 Current design is rather of blog (experience sharing) value. It has
278 quite some drawbacks:
282 <li>Warning: Circuit has dangerous instability. Requires low voltage
283 ~3V but relatively high current external power supply. Using
284 higher voltage but low current power supply could easily lead to
285 situation where step-up generated load pushes power supply output
286 voltage down too much. This leads to too much power being lost
287 within power supply and easily leads to power supply overheating!
290 <li>There is no dedicated current limiter. 3V external power supply
291 and up-step are acting as current limiters.
294 <li>While RCA connectors do work as DC power connectors, but are not
295 intended to be used this way and are not very reliable.
298 <li>Voltage up-step provided output is not very clean. Extra capacitors
299 and induction coils could be added to remove high frequency noise in
303 <li>Metallic and shielded body would be helpful to reduce
304 electromagnetic/radio noise generated by step-up.
310 <div id="outline-container-sec-3" class="outline-2">
311 <h2 id="sec-3"><span class="section-number-2">3</span> Body</h2>
312 <div class="outline-text-2" id="text-3">
315 <p><img src="body.png" class="img-responsive" alt="body.png">
321 <p><img src="cover.png" class="img-responsive" alt="cover.png">
329 <li><a href="body%20and%20cover.FCStd">body and cover FreeCAD file</a>
331 <li><a href="body.stl">body in STL format</a>
333 <li><a href="cover.stl">cover in STL format</a>
340 </div><div class="col-md-3"><nav id="table-of-contents">
341 <div id="text-table-of-contents" class="bs-docs-sidebar">
343 <li><a href="#sec-1">1. General</a></li>
344 <li><a href="#sec-2">2. Project description</a></li>
345 <li><a href="#sec-3">3. Body</a></li>
350 <footer id="postamble" class="">
351 <div><p class="author">Author: Svjatoslav Agejenko</p>
352 <p class="date">Created: 2020-03-21 Sat 00:35</p>
353 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 26.1 (<a href="http://orgmode.org">Org-mode</a> 9.1.9)</p>