12V Lead-Acid battery changer and terminal

Battery charger and dual power supply unit

1 General

@@ -209,10 +209,10 @@ DESIGNS AT YOUR OWN RISK.

This design is released under Creative Commons Zero (CC0) license.

Author: +

Authors:

Svjatoslav Agejenko -

Homepage: https://svjatoslav.eu
Email: svjatoslav@svjatoslav.eu @@ -220,6 +220,11 @@ DESIGNS AT YOUR OWN RISK.

Valeria Agejenko +

See also:

Other physical projects in this repository @@ -235,121 +240,440 @@ DESIGNS AT YOUR OWN RISK.
2 Project description
+
+I needed dual voltage power supply for my lab that runs on mains +electricity (wall power) and slowly charges attached 12V Lead-Acid +battery. Lead-acid battery in turn provides high current when needed +as well as power in portable situations or when mains electricity is +not available. +
+

+
+Power supply provides about 13 Volts and 5 Volts simultaneously. +
+ +
+!!!WARNING!!! I use USB-A connectors for power output, but IT IS NOT +COMPATIBLE WITH USB DEVICES AND POSSIBLY WITH EXISTING USB CABLES. +
+ +
+Normal USB devices and cables should not be plugged in! It would +damage device/cable and likely power supply. +
+ +
+I found USB-A connectors to be easily available, cheap, reliable and +functional, so I re-purposed connector for my own needs but I'm using +totally incompatible electrical wiring. +
+
-
+

-Simple charger and terminal (front-end) for 12V lead-acid battery. +As seen, it has dual voltage output. Additionally one wire is +dedicated to data transmission and can be used with 1-wire +protocol. Power supply simply passively links all data wires together +but does not participate in communication.

-Idea is to distribute power from rechargeable 12V battery to various -appliances (soldering iron, radio transmitters, etc..) while also -providing use-charging in the background. +Power supply uses 3D printed body with lots of holes, for fanless +cooling.
+ +
+
+
+
+
-Single on/off button disconnects battery and up-step voltage source -from front panel terminal connectors. +Various modules are realized on top of prototype PCBs that slide into +dedicated rails within the body.
+ +
+
+
+
+
-Tecnoiot MT3608 voltage up-step is used. 3V DC external power supply -is used to feed voltage up-step. Up-step is tuned to ~14.4 V. +Like this:

-
+

-Current design is rather of blog (experience sharing) value. It has -quite some drawbacks: +When cover is closed, it blocks PCB movement:
-
- Warning: Circuit has dangerous instability. Requires low voltage -~3V but relatively high current external power supply. Using -higher voltage but low current power supply could easily lead to -situation where step-up generated load pushes power supply output -voltage down too much. This leads to too much power being lost -within power supply and easily leads to power supply overheating! -
- There is no dedicated current limiter. 3V external power supply -and up-step are acting as current limiters. -
- While RCA connectors do work as DC power connectors, but are not -intended to be used this way and are not very reliable. -
- Voltage up-step provided output is not very clean. Extra capacitors -and induction coils could be added to remove high frequency noise in -the voltage. -
- Metallic and shielded body would be helpful to reduce -electromagnetic/radio noise generated by step-up. +
  +
  +
  +
  + +
  +Download: +
  +
  - Body STL file +
  - Big cover STL file +
  - Small dummy cover on top, STL file +
  - Body and covers FreeCAD project
-
3 Body
+
3 Transformer and AC to DC converter

+
+This is where high voltage from mains electricity enters the system. +
+ +
+Schematic: + +
+ +
+For safety I kept high voltage section as minimal as possible. That +is, wall plug runs straight into transformer. Also I used UV hardening +glue for extra safety and isolation on PCB. +
+ +
+Power on/off switch operates on already reduced voltage of about 30 +volts. Power switch is located on indicator panel. +
+
-
+

+
+DC current of about 30 volts is then routed to Main board. +
+
-
+

+
+Single sided prototype PCB is used. +
+
+
+ +
+
4 Main board
+
+
+This is logically main board because it appears to be central hub that +connects all components. It also houses 2 adjustable DC-DC Step Down +voltage converters. +
+ + +
+
+
+
+ +
+High-level schematic of entire device: + +
+ +
+As seen from schematic, ~30 volts DC from transformer board is routed +into first step-down converter that reduces it to about 15V. Reduced +voltage is then directed to Current limiter circuit. Current limiter +loses about 2 volts. Now we have current and voltage limited power at +about 13 volts. This power is used to charge connected 12V Lead-Acid +battery. Also the same power is routed to connector terminal to be +consumed by connected devices. +
+ +
+As seen from this schematic, device is not meant to provide high +current for long periods of time. Instead it gets comparatively +limited current to charge the battery and feed devices with low +current requirements. Occasional current spikes are backed up by +battery that stays in use-changing mode. +
+ +
+Also about 13V output voltage is approximate and depends on connected +battery charge level. +
+ +
+Second Step-Down converter reduces voltage even further to quite +precisely 5V DC. This resulting voltage is also routed to connector +terminal. +
+ +
+Both 13V and 5V lines are also routed to indicator panel for +monitoring. +
+ +
+There is single on/off switch. In off position, it disconnects battery +and transformer from the system effectively powering everything down. +
+ +
+On schematic above, some wires are annotated with numbers from 1 +to 13. This corresponds to output pins on the board. +
+ + +
+
+
+
+
+
+
+
5 Current limiter
+
+
+Schematic: + +
+ +
+Simple LM317 based current limiter is used. I used 4.7 ohm +resistor. It provides about 265 milliamps of current. See calculator. +
+ + +
+
+
+
+ +
+Thermal paste below and UV hardening glue on top is used to attach +LM317 to the heatsink. There is also jumper-like solution on top +right. This is handy to attach multimeter tap to verify/monitor +current during initial device calibration. +
+ +
+If attached battery is really empty, significant voltage drop can +occur in LM317. Heatsink is needed to dissipate that power. +
+ + +
+
+
+
+ +
+Note: resistor gets hot to. +
+
+
+ +
+
6 Indicator panel
+
+ +
+
+
+
+ +
+Basically 2 digital DC voltmeters and main on/off switch. +
+ + +
+
+
+
+ +
+Download: +
+ + +
+
+
+
- Download: -
  - body and cover FreeCAD file +
  - STL file
  - body in STL format -
  - cover in STL format +
  - FreeCAD project
  +
+
+ +
+
7 Connector terminal
+
+
+Schematic: + +
+ +
+As seen above, most of the USB connectors are used to deliver dual +power output and 1-wire data connectivity, except one on the bottom +right. This is used to attach 12V battery. Some capacitors are thrown +in as well to stabilize against smaller current spikes. +
+ +
+Electrically schematic is realized using smaller prototype PCBs. +
+ + +
+
+
+
+ + +
+Those PCBs are wired to central small PCB that acts as a hub: +
+ + +
+
+
+
+ +
+PCBs are held together by being sandwiched between front panel: +
+ + +
+
+
+
+ +
+and smaller back-end plate: +
+ + +
+
+
+
+ +
+Result: +
+ + +
+
+
+
+ + +
+Download: +
+
- front panel STL +
- back panel STL +
- FreeCAD project
+ +
+
8 Calibration
+
+
+Since device uses adjustable step-down modules, these need to be +calibrated to provide correct output voltage. It is important that +battery receives proper charging voltage otherwise either no charging +occurs or battery starts gassing out and gets destroyed. +
+ +
+See here for more details: https://www.powerstream.com/SLA.htm +
+ +
+ +
+Happy building! :) +
+
+

diff --git a/power/12V Lead-Acid battery changer and terminal/index.org b/power/12V Lead-Acid battery changer and terminal/index.org index c625858..7a14868 100644 --- a/power/12V Lead-Acid battery changer and terminal/index.org +++ b/power/12V Lead-Acid battery changer and terminal/index.org @@ -1,4 +1,4 @@ -#+TITLE: 12V Lead-Acid battery changer and terminal +#+TITLE: Battery charger and dual power supply unit #+AUTHOR: Svjatoslav Agejenko #+LANGUAGE: en @@ -19,65 +19,234 @@ + This design is released under Creative Commons Zero (CC0) license. -+ Author: ++ Authors: - Svjatoslav Agejenko - - Homepage: https://svjatoslav.eu - - Email: [[mailto://svjatoslav@svjatoslav.eu][svjatoslav@svjatoslav.eu]] + - Homepage: https://svjatoslav.eu + - Email: [[mailto://svjatoslav@svjatoslav.eu][svjatoslav@svjatoslav.eu]] + + - Valeria Agejenko + See also: - [[../../index.html][Other physical projects in this repository]] - [[https://www.svjatoslav.eu/projects/][Other projects hosted at svjatoslav.eu]] * Project description +I needed dual voltage power supply for my lab that runs on mains +electricity (wall power) and slowly charges attached 12V Lead-Acid +battery. Lead-acid battery in turn provides high current when needed +as well as power in portable situations or when mains electricity is +not available. + [[file:make.png]] +Power supply provides about 13 Volts and 5 Volts simultaneously. + +!!!WARNING!!! I use USB-A connectors for power output, but IT IS NOT +COMPATIBLE WITH USB DEVICES AND POSSIBLY WITH EXISTING USB CABLES. + +Normal USB devices and cables should not be plugged in! It would +damage device/cable and likely power supply. + +I found USB-A connectors to be easily available, cheap, reliable and +functional, so I re-purposed connector for my own needs but I'm using +totally incompatible electrical wiring. + +[[file:connector%20terminal/USB%20hack.png]] + +As seen, it has dual voltage output. Additionally one wire is +dedicated to data transmission and can be used with [[https://en.wikipedia.org/wiki/1-Wire][1-wire]] +protocol. Power supply simply passively links all data wires together +but does not participate in communication. + +Power supply uses 3D printed body with lots of holes, for fanless +cooling. + +[[file:body%20and%20covers/body,%201.png]] + +Various modules are realized on top of prototype PCBs that slide into +dedicated rails within the body. + +[[file:body%20and%20covers/body,%202.png]] + +Like this: + [[file:make,%202.png]] -Simple charger and terminal (front-end) for 12V lead-acid battery. +When cover is closed, it blocks PCB movement: + +[[file:body%20and%20covers/cover.png]] + +There is still some empty space inside, so why not add dummy cover on +top that can be replaced later with add-on functionality/expansion +board/terminal :) + +[[file:body%20and%20covers/cover%20cover.png]] + +Download: ++ [[file:body%20and%20covers/body.stl][Body STL file]] ++ [[file:body%20and%20covers/cover.stl][Big cover STL file]] ++ [[file:body%20and%20covers/cover%20cover.stl][Small dummy cover on top, STL file]] ++ [[file:body%20and%20covers/body%20and%20covers.FCStd][Body and covers FreeCAD project]] + +* Transformer and AC to DC converter + +This is where high voltage from mains electricity enters the system. + +Schematic: +[[file:transformer%20and%20AC%20DC%20converter%20board/schematic.png]] + +For safety I kept high voltage section as minimal as possible. That +is, wall plug runs straight into transformer. Also I used [[https://www.amazon.de/gp/product/B07VGQKM3G/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1][UV hardening +glue]] for extra safety and isolation on PCB. + +Power on/off switch operates on already reduced voltage of about 30 +volts. Power switch is located on [[id:c9a69490-f920-4a31-b32e-b101bfc3d01b][indicator panel]]. + +[[file:transformer%20and%20AC%20DC%20converter%20board/make,%201.png]] + +DC current of about 30 volts is then routed to [[id:65d68227-4bf2-4c4f-b4d3-c390bc6a9c34][Main board]]. + +[[file:transformer%20and%20AC%20DC%20converter%20board/make,%202.png]] + +[[https://www.amazon.de/gp/product/B07RLQH5TR/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1][Single sided prototype PCB is used]]. + +* Main board +:PROPERTIES: +:ID: 65d68227-4bf2-4c4f-b4d3-c390bc6a9c34 +:END: + +This is logically main board because it appears to be central hub that +connects all components. It also houses 2 [[https://www.amazon.de/gp/product/B072MQYJ93/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1][adjustable DC-DC Step Down +voltage converters]]. + +[[file:main%20board/main%20board,%201.png]] + +High-level schematic of entire device: +[[file:main%20board/schematic.png]] + +As seen from schematic, ~30 volts DC from transformer board is routed +into first step-down converter that reduces it to about 15V. Reduced +voltage is then directed to [[id:afc22d23-9bc4-421c-9cac-e0ce34bd36bc][Current limiter circuit]]. Current limiter +loses about 2 volts. Now we have current and voltage limited power at +about 13 volts. This power is used to charge connected 12V Lead-Acid +battery. Also the same power is routed to [[id:e33940bd-652f-4ec0-b53b-1c03e16941c8][connector terminal]] to be +consumed by connected devices. + +As seen from this schematic, device is not meant to provide high +current for long periods of time. Instead it gets comparatively +limited current to charge the battery and feed devices with low +current requirements. Occasional current spikes are backed up by +battery that stays in use-changing mode. + +Also about 13V output voltage is approximate and depends on connected +battery charge level. + +Second Step-Down converter reduces voltage even further to quite +precisely 5V DC. This resulting voltage is also routed to [[id:e33940bd-652f-4ec0-b53b-1c03e16941c8][connector +terminal]]. + +Both 13V and 5V lines are also routed to [[id:c9a69490-f920-4a31-b32e-b101bfc3d01b][indicator panel]] for +monitoring. + +There is single on/off switch. In off position, it disconnects battery +and transformer from the system effectively powering everything down. + +On schematic above, some wires are annotated with numbers from 1 +to 13. This corresponds to output pins on the board. + +[[file:main%20board/main%20board,%202.png]] +* Current limiter +:PROPERTIES: +:ID: afc22d23-9bc4-421c-9cac-e0ce34bd36bc +:END: + +Schematic: +[[file:current%20limiter/schematic.png]] + +Simple LM317 based current limiter is used. I used 4.7 ohm +resistor. It provides about 265 milliamps of current. See [[http://www.reuk.co.uk/wordpress/electric-circuit/lm317-current-calculator/][calculator]]. + +[[file:current%20limiter/current%20limiter,%201.png]] + +Thermal paste below and UV hardening glue on top is used to attach +LM317 to the heatsink. There is also jumper-like solution on top +right. This is handy to attach multimeter tap to verify/monitor +current during initial device calibration. + +If attached battery is really empty, significant voltage drop can +occur in LM317. Heatsink is needed to dissipate that power. + +[[file:current%20limiter/current%20limiter,%202.png]] + +Note: resistor gets hot to. + +* Indicator panel +:PROPERTIES: +:ID: c9a69490-f920-4a31-b32e-b101bfc3d01b +:END: + +[[file:indicator%20panel/indicator%20panel,%201.png]] + +Basically 2 digital DC voltmeters and main on/off switch. + +[[file:indicator%20panel/indicator%20panel,%202.png]] + +Download: + +[[file:indicator%20panel/indicator%20panel.png]] + ++ [[file:indicator%20panel/indicator%20panel.stl][STL file]] ++ [[file:indicator%20panel/indicator%20panel.FCStd][FreeCAD project]] + +* Connector terminal +:PROPERTIES: +:ID: e33940bd-652f-4ec0-b53b-1c03e16941c8 +:END: + +Schematic: +[[file:connector%20terminal/schematic.png]] + +As seen above, most of the USB connectors are used to deliver dual +power output and 1-wire data connectivity, except one on the bottom +right. This is used to attach 12V battery. Some capacitors are thrown +in as well to stabilize against smaller current spikes. + +Electrically schematic is realized using smaller prototype PCBs. + +[[file:connector%20terminal/make,%201.png]] + -Idea is to distribute power from rechargeable 12V battery to various -appliances (soldering iron, radio transmitters, etc..) while also -providing use-charging in the background. +Those PCBs are wired to central small PCB that acts as a hub: -Single on/off button disconnects battery and up-step voltage source -from front panel terminal connectors. +[[file:connector%20terminal/make,%202.png]] -[[https://www.amazon.de/gp/product/B07G4KWV6S/ref=ppx_yo_dt_b_asin_title_o08_s01?ie=UTF8&psc=1][Tecnoiot MT3608]] voltage up-step is used. 3V DC external power supply -is used to feed voltage up-step. Up-step is tuned to ~14.4 V. +PCBs are held together by being sandwiched between front panel: -[[file:schematic.png]] +[[file:connector%20terminal/front%20panel.png]] -Current design is rather of blog (experience sharing) value. It has -quite some drawbacks: +and smaller back-end plate: -- Warning: Circuit has dangerous instability. Requires low voltage - ~3V but relatively high current external power supply. Using - higher voltage but low current power supply could easily lead to - situation where step-up generated load pushes power supply output - voltage down too much. This leads to too much power being lost - within power supply and easily leads to power supply overheating! +[[file:connector%20terminal/back%20panel.png]] -- There is no dedicated current limiter. 3V external power supply - and up-step are acting as current limiters. +Result: -- While RCA connectors do work as DC power connectors, but are not - intended to be used this way and are not very reliable. +[[file:connector%20terminal/make,%203.png]] -- Voltage up-step provided output is not very clean. Extra capacitors - and induction coils could be added to remove high frequency noise in - the voltage. -- Metallic and shielded body would be helpful to reduce - electromagnetic/radio noise generated by step-up. +Download: ++ [[file:connector%20terminal/front%20panel.stl][front panel STL]] ++ [[file:connector%20terminal/back%20panel.stl][back panel STL]] ++ [[file:connector%20terminal/connector%20terminal.FCStd][FreeCAD project]] -* Body +* Calibration -[[file:body.png]] +Since device uses adjustable step-down modules, these need to be +calibrated to provide correct output voltage. It is important that +battery receives proper charging voltage otherwise either no charging +occurs or battery starts gassing out and gets destroyed. -[[file:cover.png]] +See here for more details: https://www.powerstream.com/SLA.htm +----- -+ Download: - + [[file:body%20and%20cover.FCStd][body and cover FreeCAD file]] - + [[file:body.stl][body in STL format]] - + [[file:cover.stl][cover in STL format]] +Happy building! :) diff --git a/power/12V Lead-Acid battery changer and terminal/indicator panel/indicator panel, 1.png b/power/12V Lead-Acid battery changer and terminal/indicator panel/indicator panel, 1.png new file mode 100644 index 0000000..2b40b73 Binary files /dev/null and b/power/12V Lead-Acid battery changer and terminal/indicator panel/indicator panel, 1.png differ diff --git a/power/12V Lead-Acid battery changer and terminal/indicator panel/indicator panel, 2.png b/power/12V Lead-Acid battery changer and terminal/indicator panel/indicator panel, 2.png new file mode 100644 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2.7 Radio

12V Lead-Acid battery changer and terminal

Battery charger and dual power supply unit

1 General

2 Project description

3 Body

3 Transformer and AC to DC converter

4 Main board

5 Current limiter

6 Indicator panel

7 Connector terminal

8 Calibration