Instructables

Solar Walkway Lights Solar Panel Replacement

Picture of Solar Walkway Lights Solar Panel Replacement
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I recently put in a series of solar powered walkway lights in front of my house. They're equipped with a fairly powerful LED, and correspondingly have a large solar panel (compared to other solar powered walkway lights). I've found that these lights work really well when they are exposed to direct sunlight for a significant portion of the day, but when they are partly or completely shaded, they only charge enough to run for an hour or two after sunset. To fix this problem, I decided to replace the stock solar panel with a larger one. The original solar panel provides 5V to the charger circuit which in turn charges the 3.7V LiFePo4 battery that powers the LED at night. The charger circuit also switches the direction of current flow through the battery; when there is enough sunlight hitting the solar panel that its output voltage is sufficient to charge the battery, the circuit charges the battery. When the solar panel's voltage falls low enough, the charger circuit switches the battery to powering the LED. There is a certain amount of hysteresis built into the system so that the light doesn't flicker on and off when the power level is right around the cutoff/turn on point. Because the circuit requires a solar panel that nominally provides 5V in full sunlight, this is the kind of panel that must be used. I bought my replacement solar panels from a store on eBay that sells them for about $4. This adds about 50% to the total cost of the walkway light, but vastly improves its function. replacing the original solar panel with a larger one enables is to charge in less light, which in turn lets the walkway light fully charge even when placed in a fairly shady location. For the walkway light right in front of my front door, I used a larger 2.5W solar panel to let it charge even though it is completely shaded by a large bush right next to it. This is the walkway light shown below that has a larger solar panel attached to the top.
 
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bruce210 months ago
Hi Vlorbschnat,
Great project. Where did you buy the walkway lights?. I need a strong led unit and 3.6v lights are impossible to obtain in my locality. I live in Australia "down under"..
Your help will be greatly appreciated. Best regards, Bruce Owen.
Vlorbschnat (author)  bruce210 months ago
I bought them from Lowes Hardware. If they don't have similar walkway lights in hardware stores there, you could try buying them online. I found some walkway lights on Amazon.com that are a different style but seem to have similar power specs: http://www.amazon.com/Moonrays-91762-Solar-Powered-Bronze-4-Pack/dp/B004IEBBKW/ref=sr_1_1?s=lamps-light&ie=UTF8&qid=1380446165&sr=1-1&keywords=solar+walkway+lights+6x .
bruce2 Vlorbschnat10 months ago
Many thanks for your help. Lowes hardware are represented in Australia in association with Woolworths and trading under the name of Masters Hardware.
If anybody is also chasing these lights, the brand is Portfolio Model 00956.