Intro
A while ago I set out to build a solar lamp that can work all the time, especially in the dark winter months. After a while I realized that there is already some version of it in my home. So now it’s time for part 3
SOLVINDEN skeleton, new insides
Step 1 – beef up the solar panels: 2 pieces of 6V 133mA each
Step 2 – assemble the led head
Step 3 – wire it up for simplicity: the battery is charged through a diode, while the LED is permanently connected with 112Ω resistor.
Step 4 – the batteries fit satisfyingly perfect in the base
Step 5 – profit: the lamp working during a winter day, while the normal SOLVIDEN is already depleted in the background
How does it work?
Just like the build in Part 2, this lamp will be lit a lot more time, but the light intensity will depend on the battery state. So during winter nights it will provide less light than during summer nights when batteries are going to be full most days.
How to monitor it?
Throughout building this I have been thinking about how to monitor this to see if it really works. The initial idea was to use a wireless sensor node and report battery status, but after a while i decided this is the project where i am looking for 80% results with 20% of the effort. This is why, there is no electronics to switch the LED off during the day and why i will only monitor it by human sight. If this concept works, I should be able to see the lamp lit during dark mornings of winter. If that is a common sight, then this is successful.
So will report back on this later.
How about cost?
The original Solvinden lamp which cost 8 EUR now. Compared to this, we need to add: 6 EUR for batteries, but remove 1 EUR for the original battery, 2.8 EUR for the solar panels. So if Ikea build this, it might cost 16 EUR, about double. Possibly, their high volume scaling will have a smaller impact and they might be able to sell this version for slightly less than that. This is significantly more than the original lamp, but i think there is a market for such a lamp. I specifically prefer the idea of a lamp that works all the time, but less bright during winter time, as opposed to running at constant intensity but for fewer hours during winter time.