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Charging's gone

Finally the sun has arrived to Stockholm and my kit charges nicely. But once the sun’s down, my battery capacity takes a nosedive.

What can I do?

For us up North, the kit will not survive for long unless the solar cell charges as much as possible.
Can I buy a larger battery (

A alternative is to ditch the solar cell & battery and instead go with a 220-transformer.
Any thoughts?

Hi @MaxHeadroom!

I am glad to read that the sun arrived. I went last christmas there and we miss the daystar.

Anyway, I have been testing a couple of kits attached to solar panels for the last weeks here in Barcelona and the sun was enough powerful to maintain the kits alive from one day to the other (and these panels were not being hit for more than 2 or 3 hours!).

It is true that two cloudy days in a row with clouds (or with not sun at all), caused the shutdown of the kits but if your battery reaches the 100% after the solar panel being hit by the sun during the day, it should be enough charge to keep your device alive (at least) until the next day.

Can you send me your kit’s URL so I can check out the graphics!?

I would not ditch the the solar cell & battery yet. Using a larger battery could be a solution. Also changing the connection and posting intervals of your kit, but if you want to still connecting and sending data every minute this is not a good option.

In any case, try to expose your solar panel as much time as possible to the sun and check out the values of the solar panel/battery during the day.

I look forward to hearing from you.

All the best.

Here you go:

Me thinks its a combination of many faults.
First the battery drops like a rock once the sun is out.
Secondly, the webpage (smart also seem to display the values wrong.
Otherwise, why would the solar panel go from displaying 4% to 19 (no value) to 4.3 Volts (probably).

Right now I have to turn the kit off during nighttime.
At the moment I leaning towards the battery I posted on earlier + a Adafruit solar charger.

Its less than 60 dollars, but might help the smart citizen-kit afloat.


What did the graphics tell you?

Hi @MaxHeadroom,

Sorry for the late response. I hope you are ok.

Regarding the graphics, the solar panel’s highest peak that I can see in the last week is 15.3V (that % sign needs to be changed). If you check any of the kits I am testing with a solar panel attached (i.e.: or, you can see that everyday for the last week they have been around 20V to full sun.

Your measures are not clear. Can you send me pictures of your set up!? Where is your solar panel located!? I have got mines on the roof. Are the connections correctly done!?

A bigger battery will not be helpful if you have not enough power to charge it

FYI: we will upload the new firmware (v0.9) that improves the SCK’s power consumption to these kits on the roof tomorrow or Tuesday.

I look forward to hearing from you.


The charge circuit in the system limit current to battery to about 350-400 mA - and shuts down charge on big temperature changes (like coming from night to day) to try and protect the battery. What that means is it will never charge completely with the current chip on board…

For more information see the datasheet of the chip.