Raspberry Pi Experiment 12: More Solar Power + A2D Converter for Battery Voltage Reports

Reviewed by Editor: Jack Allison

Experiment Goal:

To enable the following features:
– Increase current by adding of additional solar panels
– Reading and reporting of battery voltage so that the value may be tracked over time

Components:

Raspberry Pi Model A+
EDIMAX Wi-Fi Adatper (EW-7811Un)
– (2x) WN-11 1W 5V 180mA Solar Power Panel, 99 x 69mm (from “Move Power”).
– (2x) SS34 diodes (from “Move Power”)
– (1x) ADC Pi V2.2 8-channel A2D converter fro www.abelectronics.co.uk for reading the battery voltages
– (1x) Empty chocolate box of medium size form Ferrero Rocher

Rechargeable batteries (connected in parallel):
– (8x)  rechargeable batteries AA 1.2V 3000 mAh
– (4x) New Sun-PL653494 7.4 V 1800mAh batteries (from “Move Power”)
– (3x) Unknown rechargeable batteries (from “Move Power”)

Experiment Description:

One more “Move Power” device was disassembled for spare parts (solar panel, diode, batteries and charging circuit). While specifying that it provides 30000 mAh, when taken apart, actually contains four 1800 mAh  batteries. In previous case of disassembling of such a device these were three batteries of unknown capacity. In addition, some batteries were detached from what should have been the battery array (batteries soldered in parallel to each other). As a result, I had to recreate the battery arrays.

20150109_14314520150110_104102 20150109_14494220150109_14495920150109_14514820150109_162736???????????????????????????????

I have attached all battery arrays in parallel, creating one bigger battery array.

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All this was connected to the solar array

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To allow battery voltage reporting, an A2D converter was added after soldering on appropriate pins. Also additional wires were added from the battery to the ADC Channel1 for voltage sensing.

I have tried to keep everything detachable for better maintainability

20150110_07071620150110_084922 20150110_084358     IMG_0244

Finally we have standalone box (larger than before) that should:

– recharge itself if there is no direct sunlight shining on and its solar panels

–  keep RPi alive overnight

– report battery voltage through Wi-Fy via Multicast  messages

20150110_09025320150110_08533920150110_08511220150110_08551720150110_09001020150110_081845 20150110_084306


SW Description:

See ADC related code samples, including data reader and data logger.


References:

Using I2C with Raspberry PI
Enabling I2C port at RPi

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