Using solar garden lights
- Thread starter Andy1967
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Andrew Cowan
Senior Member
Stan (manuka) has done lots on that subject. I'll try and find some stuff for you - otherwise wait for him.
A
Edit: http://www.picaxeforum.co.uk/showthread.php?t=10392&highlight=solar+light
A
Edit: http://www.picaxeforum.co.uk/showthread.php?t=10392&highlight=solar+light
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There seems to be three options for powering a PICAXE - running from the PV cell, running from the rechargeable battery or running from the LED. All of which have their pro's and con's and possible limitations; PV only works when light is present, battery may be too low a voltage and PICAXE current may extend charging time, LED may be pulsed rather than steady output.
There also seems to be three types of solar lights - Original with lots of transistors, IC with light sensor, IC which uses PV as light sensor - plus two and one battery types. The ones I picked up in my local PoundLand store have a very tiny rechargeable battery, about 1cm in length, but I've no idea of the rating.
Given they are often so cheap they are ideal candidates for 'try it and see' experimenting.
There also seems to be three types of solar lights - Original with lots of transistors, IC with light sensor, IC which uses PV as light sensor - plus two and one battery types. The ones I picked up in my local PoundLand store have a very tiny rechargeable battery, about 1cm in length, but I've no idea of the rating.
Given they are often so cheap they are ideal candidates for 'try it and see' experimenting.
Well answered guys- it really boils down to what you want the PICAXE to do. Naturally seasonal solar variations arise too. This is not that much of an issue in sunny mid winter NZ, where we've just had our balmiest August ever, but possibly extemely significant in the likes of overcast & low sun angle wintery UK.
Typical backyard setups are feasible with lots of SLEEP time (drawing hence µA level currents under BOD) & ~once a minute 10mA draw to flash LEDs/run a 433 MHz TX. But you want more service? With lamps so cheap, consider just removing the 2V PVs & wiring say 3 in series across 3 NiCds to run a PICAXE directly.
Perhaps the best circuitry insights are those of Colin Mitchell at "Talking Electronics" => http://www.talkingelectronics.com/te_interactive_index.html Such classic bipolar solar lamp circuitry (as below) is slowly being replaced here in NZ by a 4 leg ZE002 IC. Stan.
Typical backyard setups are feasible with lots of SLEEP time (drawing hence µA level currents under BOD) & ~once a minute 10mA draw to flash LEDs/run a 433 MHz TX. But you want more service? With lamps so cheap, consider just removing the 2V PVs & wiring say 3 in series across 3 NiCds to run a PICAXE directly.
Perhaps the best circuitry insights are those of Colin Mitchell at "Talking Electronics" => http://www.talkingelectronics.com/te_interactive_index.html Such classic bipolar solar lamp circuitry (as below) is slowly being replaced here in NZ by a 4 leg ZE002 IC. Stan.
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Check Andrew's PICAXE PV insights => http://picasaweb.google.com/picaxe/SolarPowerPICAXE#
As for "cheap" garden lights, like most things electronic, the general public here in S.A. are taken for a REAL ride ! "Cheap" garden light from big "GAME" department store cost me ZAR 59.00 and provided 0.5V at micro Amps ?!. Then 2 x 12V @ 3mA PV's from Mantech cost me ZAR 32.00 ! Easy choice for me, NO MORE "cheap" garden lights, the trannies and/or IC's will be cheap enough and then I'll have something that probably works a whole lot sweeter with current to spare for charging batteries at the same time. Just my thoughts on it.
BeanieBots
Moderator
Probably just a geographical thing manie.
In the UK, they can be obtained so cheap that it's often worth it for the LED alone!
In the UK, they can be obtained so cheap that it's often worth it for the LED alone!
Re Dippy, this circuit is a fairly well regulated 5V one
http://www.talkingelectronics.com/projects/PowerSupply5vSolar/PowerSupply5vSolar.html
I modified it to a regulated version here
http://drvernacula.topcities.com/315_mhz_solar_powered_radio_rptr.htm
Though subsequently I've moved to 12V SLA batteries and off the shelf charge controllers http://www.futurlec.com/Solar_Charge_Controller.shtml and standard 36 cell panels eg 10W as making homemade panels takes a long time and I got a bit greedy and needed 30mA instead of picaxe microamps (sleeping). Also I use simple switchers LM2575 for the 5V regulation.
Another problem with solar lights is they use epoxy to pot the solar cells and the epoxy goes cloudy and brittle after a few years in the sun. Wheras larger panels tend to use glass.
http://www.talkingelectronics.com/projects/PowerSupply5vSolar/PowerSupply5vSolar.html
I modified it to a regulated version here
http://drvernacula.topcities.com/315_mhz_solar_powered_radio_rptr.htm
Though subsequently I've moved to 12V SLA batteries and off the shelf charge controllers http://www.futurlec.com/Solar_Charge_Controller.shtml and standard 36 cell panels eg 10W as making homemade panels takes a long time and I got a bit greedy and needed 30mA instead of picaxe microamps (sleeping). Also I use simple switchers LM2575 for the 5V regulation.
Another problem with solar lights is they use epoxy to pot the solar cells and the epoxy goes cloudy and brittle after a few years in the sun. Wheras larger panels tend to use glass.
Cheap solar lights do seem to be getting less reliable, possibly because they are too cheap to test without pushing cost up and one of lower quality or dead is something a punter will tolerate.
As to low PV voltage and/or current, apart from being faulty, they are designed to do the job they do, not anything else. Repurposing unknown components 'on the cheap' has always been a hit and miss affair.
As to low PV voltage and/or current, apart from being faulty, they are designed to do the job they do, not anything else. Repurposing unknown components 'on the cheap' has always been a hit and miss affair.