SwitchDoc Labs SolarMax Lead Acid User manual

SolarMax Lead Acid Assembly and Testing Guide
December 2019
Version 1.4
For powering solar systems such as systems based on the
Raspberry Pi, Arduino and ESP32/ESP8266
and the SwitchDoc Labs System
Version 1.4 December 2019

Table of Contents
Errata 1.............................................................................................................................
What is SolarMAX Lead Acid? 2........................................................................................
SolarMAX Specifications 3...............................................................................................
What is in the SolarMax Lead Acid Kit? 4.........................................................................
What Else is Required for the SolarMax Lead Acid Kit? 4.................................................
SolarMax Lead Part Identification 6.................................................................................
Step by Step Assembly 8...................................................................................................
Wiring the SolarMax Lead Acid 13....................................................................................
Solar Panel Wiring 13.................................................................................................................
Grove Wiring Table 16................................................................................................................
Jumper Wiring 21......................................................................................................................
USB Cable Wiring 23..................................................................................................................
Lead Acid Battery Wiring 24......................................................................................................
Connect your 12 V Lead Acid Battery 27.....................................................................................
Finally 29...................................................................................................................................
Testing Your SolarMAX Lead Acid System 30...................................................................
Testing With SkyWeather 30......................................................................................................
Testing with a Raspberry Pi (without SkyWeather) 31................................................................
Installing Your SolarMAX Lead Acid System 32................................................................
The Science and Education Goals Behind SolarMax 33.....................................................
Support 33........................................................................................................................
Disclaimer 34...................................................................................................................
Version 1.4 December 2019

Errata
Version 1.3 - Removed single jumper pin from LIPOBATIN to 5V. Added Grove cable from Arduino Mini Pro
LP to USB PowerCentral Enable/Control port to implement hysteresis during low power conditions. See
article on www.switchdoc.com
Version 1.4 - Removed step W8 - Not needed
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Version 1.4 December 2019

What is SolarMAX Lead Acid?
SolarMAX Lead Acid is a SwitchDoc Labs designed system to charge Lead Acid batteries from 18V Solar
panels in order to provide more power to small computer systems. SolarMAX is designed to collect and return
data about the solar panel system to the powered (or other) computer via a LoRa link. SolarMAX collects and
transmits the following data every 30 seconds:
• Battery Voltage
• Battery Current
• Solar Panel Voltage
• Solar Panel Current
• Load Voltage
• Load Current
It also supplies the following about inside the SolarMAX box:
• Inbox Temperature
• Inbox Humidity
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Version 1.4 December 2019

SolarMAX uses a 433MHz LoRa module which can transmit up to 2 kilometers or further with larger antennas
and uses very little power.
This is a perfect system for powering SkyWeather and other small computer systems.
SolarMAX Specifications
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Version 1.4 December 2019
Table 1-1
Solar Max
LeadAcid
Solar Max
LeadAcid
Minimum
Nominal
Maximum
Solar Panel
Voltage
15V
18V
18V
Solar Panel Voltage
Solar Panel VOC
25V
Solar Panel VOC
5V Load Current
5A
5V Load Current
Solar Charging
Current
4A
Solar Charging
Current
Battery Type
12V Lead Acid
Battery Type
Size of Battery
Large
Size of Battery
Cost of Battery
Low
Cost of Battery
Available Output
Voltages
5V, 12V
Available Output
Voltages

What is in the SolarMax Lead Acid Kit?
• High Current INA3221 with Terminals
• Solar Charger for 12V Lead Acid Batteries
• USB PowerCentral
• Dual WatchDog Timer
• 16MHz Mini Pro LP
• 6 Port I2C Hub
• HDC1080 Temp Hum
• LoRa 433MHz Radio
• LoRa 433MHz Radio
• MC4 Plus Female (and Pin)
• MC4 Minus Male (and Pin)
• USB Weatherproof Plug
• Short USB Cable Type A - Type A
• 20cm Grove Cables - 7 Cables
• Grove Connector to Female Pin Headers - 1 Cable
• Single Wire Female to Female Jumper - 2 Wires
What Else is Required for the SolarMax Lead Acid Kit?
12 V Lead Acid battery - We recommend >= 20000mAh - https://amzn.to/2qGCVd8 (This battery fits
PERFECTLY in the Bud Enclosure below)
M2 Nylon Hex Thread Assortment - https://shop.switchdoc.com/products/140pcs-box-m2-nylon-hex-
thread-assortment-kit
Solid Core Hookup Wire 22 Gauge - https://amzn.to/3202Ppa
Bud Enclosure NBB-22241 Style B - 6-25/32” x 10-23/32” x 6-25/32” - https://amzn.to/2zk8B8R
Spade Quick Connect Crimp Cold-Pressed Terminals (for 12V Battery) - https://amzn.to/2OgxqLm
You can buy all the above from SwitchDoc Labs as the SolarMAX Weather Proofing Kit.
100W 12V Solar Panel with MC4 Connectors - https://amzn.to/2rjjmYi (VOC 21.6V Max Power 17.4V)
Optional
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Version 1.4 December 2019

Solar Panel Crimping tools for MC4 (optional) - https://amzn.to/2U6IN9J
Tools
Soldering Iron
Straight blade Small Screwdriver
Crosspoint Small Screwdriver
Super Glue
Silicon Caulking
Wire cutter
Wire stripper
Pliers
Drill
Drill Bits for:
1” holes
2/3” holes
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Version 1.4 December 2019

SolarMax Lead Part Identification
•Part A - MC4 Minus Male (and Pin)
• Part B -MC4 Plus Female (and Pin)
• Part C -High Current INA3221 with Terminals
• Part D -Solar Charger for 12V Lead Acid Batteries
• Part E - USB PowerCentral
• Part F - USB Weatherproof Plug
• Part G - Short USB Cable Type A - Type A
• Part H - Identical LoRa 433MHz Radio (one for SolarMax)
• Part H - Identical LoRa 433MHz Radio (one for receiving Computer)
• Part I - 16MHz Mini Pro LP
• Part J - HDC1080 Temp Hum
• Part K - 6 Port I2C Hub
• Part L - Dual WatchDog Timer
Cables
• 20cm Grove Cables - 6 Cables
• Grove Connector to Female Pin Headers - 1 Cable
• Single Wire Female to Female Jumper - 2 Wires
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Version 1.4 December 2019

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Version 1.4 December 2019

Note: Part C (High Current INA3221) will look like the picture below:
Step by Step Assembly
Step 1) Drill two 2/3” holes in the upper left side of the lower part of the Bud Box. (See Part A and Part B
location on pictures above)
Step 2) Drill 3 1” holes in the front of the lower part of the box. Separate the holes by at least 2 inches, center
to center. (Two vent holes and one hole for the Part F- USB Weatherproof Plug.
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Version 1.4 December 2019