My first post here and new to the community.
I’m looking to build/buy a small solar panel that will charge a battery during the day. At dusk the battery will then power a flicker LED until dawn. I’ll need 12-16 of these “systems” to install in jack o lantern that will line a long driveway (actually attached to trees about 5’ up). The jack o lanterns are made from styrofoam and sealed for outdoor use. These will be outside for the month of October. The LED I’‘ve chosen is from Prop and Scenery lights (Flame Effects Prism Light kit — Prop and Scenery Lights) I have tried hacking similar setups from Amazon (walkway lights) but they all have the solar panel/battery/LED mouned in a single package. I want to have the solar panel mounted off to the side of the tree about 1-2’ away from the jack o lantern. I can weather proof the setup easy enough. I need help in getting all the pieces put together.
Any help would be appreciated.
Unfortunately I can’t think of a cheap/easy way to do what you’re looking to do.
What you’d need is:
- 1 - A solar panel.
- 2 - A charge controller to charge the battery from the solar panel.
- 3 - A 12 volt battery OR a lower voltage battery and some sort of 12 volt boost circuit.
- 4 - A dusk/dawn switch.
Sparkfun has some of the components you’d need but not everything and you’d need to make everything work together.
For a charge controller, Sparkfun has the sunny buddy but they don’t currently carry a solar cell that would work with it.
For battery, if you’re using the sunny buddy I’d use one of these batteries.
To boost the batteries 3.7ish volts to 12, I don’t see anything that Sparkfun carries but you could find something online.
Sparkfun doesn’t carry a dusk dawn switch either, you might be able to locate that online as well.
You do have plenty of time, and you’re going to want time to test whatever setup you’re able to build.
There’s not too much demand for what you’re looking for sadly and it’s doable to build but it would be pricey to build one let alone 12 of them. Personally, I’d hack an existing solar yard light by removing it’s included LED and replacing it with a “ficker flame” type LED, it would be a lot easier and less expensive but if you have the time and money, a 12 volt custom setup would probably be more versatile and you might be able to reuse it on other projects.
Looking at the flickering lights they seem to consume less power at +9Vdc so I would aim for that voltage input.
For the solar charger my preference is the BQ boards from Adafruit.
Then add a boost from Pololu.
The battery is going to be tricky. A quick calculation shows that a 2Ah may give you close to a day (under 24hrs) of juice. If you are only turning these things on for a few hours at night that gives you maybe 4-5 days of going juice; but if you are doing dusk-dawn that could be anywhere from 8-10hrs (and this is on a non-cloudy day) you may have 2 days at best. So I would aim for higher than 2Ah just to give you more leeway.
The panel then has to be able to “charge” at least half of that in one good day; so something like a 2W (or higher) panel.
These little “systems” are going to get expensive. And this doesn’t include the dusk-dawn control.
Solar Charger → Adafruit bq25185 USB / DC / Solar Lithium Ion/Polymer charger : ID 6091 : Adafruit Industries, Unique & fun DIY electronics and kits or Adafruit Universal USB / DC / Solar Lithium Ion/Polymer charger [bq24074] : ID 4755 : Adafruit Industries, Unique & fun DIY electronics and kits
Boost Converter → Pololu - 9V Step-Up Voltage Regulator U3V16F9 or Pololu - 9V Step-Up Voltage Regulator U3V40F9
Battery → Lithium Ion Battery Pack - 3.7V 4400mAh : ID 354 : Adafruit Industries, Unique & fun DIY electronics and kits or Lithium Ion Cylindrical Battery - 3.7v 2200mAh : ID 1781 : Adafruit Industries, Unique & fun DIY electronics and kits or Lithium Ion Battery - 2Ah
Solar Panel → 6V 2W Solar Panel - ETFE [Voltaic P126] : ID 5366 : Adafruit Industries, Unique & fun DIY electronics and kits
As an alternate (cheaper) option; you could try to just run NiCd or NiMh directly from a solar panel and a few transistors. But that will require to design everything yourself.
Even cheaper would be to hack a bunch of Walmart $5-10 solar garden lights and use that.
Cool project, though it could get expensive (for the 12-14 units).
[edit: Sorry, I see you went down this path already. Still may be good to revisit; perhaps considering getting a bigger panel to feed several of these and wire that - just a thought.]
I would seriously consider hacking one of these:
Mainstays Solar Powered Black Tapered LED Path Light, 5 Lumens (6 Count) - Walmart.com
Agree, I’d certainly start with those. They’ll probably need some help in the battery/solar area but the controller portion seems to be just what you’re looking for and, heck, the price can’t be beat.
How far apart are the luminaries? I’d give serious consideration to wiring if it’s at all possible. Having one power supply & controller will save enormous effort during dev and likely be massively more reliable over time (provided you don’t shred the wires with the mower, lol). They’ll also be able to turn on and off in unison which I suspect will bedevil a dozen independent dawn/dusk decisions.
A third option is independent power (solar & batt for each Jack) but centrally toggled. If you decide to go to the trouble of designing your own independent lights, you might as well make them wireless remote controlled to synchronize toggling or even animate dancing driveway Jacks. Sparkfun offers these nifty radio modems which I think could be readily adapted to your project: Light Switch XBee | Digi International
You might ask where ever those crazy Christmas light house folks hang out. They probably have some product ideas ready to go.
Thanks for the detailed reply. I do have solar panels that have built in dusk/dawn switch so this might get me there.
Great details and I appreciate the calculation input. I’m quickly learning all the subtle details needing to make this work.