1Charger

What if the solar panels were covered with a black t-shirt ?

While I made some improvements on the display circuit I noticed a 70mA charge current with the solar panels completely covered  with a black t-shirt. This is more than enough for the watt-meter circuit which only require 7.5mA. The light intensity were like 400-500 W/m².

Today I've charged during rain and used OpenLog to record data. The charger captured 2Ah during 10 hours charging. I've made a utility for managing plotly files easily. It's called log2plotly and it automatically adds date and time to all measurements, it also allows for manipulation of custom measurements such as GA1A12S202. I've not yet figured out how to calibrate and use the light sensor reliable. During this measurement I left it fully exposed to the rain ( which might explain some strange values ). I'll include log2plotly with source code (upcoming ver 0.95).

An example of charging a LiFePO4 8Ah battery with 2 solar panels in parallel ( total area 6.4 dm².. a size like an open dvd-case). The light intensity is measured with GA1A12S202 ( just a rough esitmate ). The approximate conversion of Lux for the SUN is 0.000079 W/dm² per lux. The GA1A12S202 has a dynamic range of 3 to 55,000 lux. Values above 4.35 W/dm² are unreliable.

Note, all measurements are available in Plotly fork and edit

( I leave it to the reader to guess when my Windows decided to take a nap...I've ordered an OpenLog ;-)

It is very easy to make a charge curves with multicharger....

Update the following defines in mcharger.c ( and then make and flash ;-)

#define SOFTWARE_UART

Plotly works best with a date specified which also makes it easier to keep track of charge curves and allow comparison with weather stations. I started using a hard coded date and later made a utility called log2plotly.

Connect a usb to serial 3.3V to PA7 and GND and start Tera Term ( or other simple serial devices like OpenLog, ESP8266, HC-05 Bluetooth ). Then choose a log-file. When charging is complete, import file to Plotly.

1. fast charging 8Ah LiFePO4 curve (no electron left behind ;-)

2. fast charging A123 2Ah curve