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Sample board out of the oven


#1

Solar powered IoT anyone?


#2

Nice! Little 5-10 watter?


#3

Solar panel is 5.5v 0.5W


#4

Nice :slight_smile:. What charging and LiPo-protection ICs do you use? :thinking:
I thought about building something similar :slight_smile: (just for fun, nothing commercial).


#5

You charging a battery with that or just running it straight off of it?

Tell us more! :slight_smile:


#6

@trent1098s @glx

Yes the panel is charging the Lipo via a TI BQ24232

The BQ24232 has a power path circuit so if there is an input power source which on this board is Solar or USB then the BQ24232 will charge the Lipo and power the board so the Lipo will only be used if there is no input power source or if it needs to supply more mA than the input can supply. This means that the Lipo is not being constantly discharged/charged.


#7

Ah cool :slight_smile:. I’m currently playing around with a MCP73831, but that doesn’t have the DPM-feature, so it doesn’t really work with a solar-cell. I’ll try to pair it up with a S-8261 to prevent over-discharging of the LiPo.


#8

I just built a solar set up for my ganoe (aluminum canoe with a flat back for a motor) that uses a 100 W panel to charge a 12 V battery powering a trolling motor. Solar power is SOOOOO much fun.


#9

Until it gets cloudy or dark


#10

Which is never in Florida… If it rains, its the equivalent of a tropical storm lasting 30 mins then blazing hot again with twice the humidity. The deep cycle battery we use can power the motor a solid 6+ hours with 700 lb load on the canoe without being charged as well.


#11

So i slapped a Lora Bee on top for and placed it near a window for testing yesterday.

Lipo is 1000mah and the board reads it’s onboard temp sensor and sends Temp, Lipo voltage and RTC every minute and then the STM goes to sleep. The Lora module is not put to sleep and so draws ~3ma while idle. Putting the Lora module and the STM to sleep would drop current down to the uA’s while sleeping.

So overnight the battery drop 0.07v and was topped back up very quickly once the sun came out the play.

So with putting both the uC and the Lora module to sleep you could use a pretty small lipo and solar panel.


#12

out of interest, how are you measuring LiPo batt voltage?


#13

Voltage divider and analog pin.


#14

so more wasted mA’s :wink:


#15

Yup - but uA’s not mA’s :stuck_out_tongue_winking_eye:


#16

over time tho, it all adds up :slight_smile:


#17

Hence the solar panel and solder pads to disable it :grin:


#18

Did you code with NetMF or TinyCLR or something else? :blush:


#19

Currently running NETMF 4.4 but can do the same with TinyCLR