Solar power

[Jonsey]

I have a solar panel out of an old garden light, could I be able to mod the external transmitter so that is runs off solar during the day and batteries at night.
I still have the PCB off the light its one of them ones where it charges the battery during the day, then uses the battery at night. I have attached a multimeter to the panel and on an overcast day it reads between 2.79 and 2.84v, and if I hold it up to
a 100w halogen light bulb it reads between 3.81 and 4.75 depending on how far away from the bulb it is, can this be done??



Dave

[hans]

first you should measure what the output of the battery is(i see there is only one)if it is around 3 volts then that is ok.
you could replace it by 2 nihms of 1.2 v,if that is not sufficiant then you would have to take 3,that gives 3.6v ,
having that and the high load of the solarpanel which can give 4.75v it would be wise to use a 3 volt regulator(made with a lm 317 i thought,if the input is high enough for it) between them and the weather unit to protect it.

but honestly i think it would only prolong the live of the batteries en they go flat anyway(due to their own discharge and cold temp),maybe sooner than regular batteries.

[Jonsey]

first you should measure what the output of the battery is(i see there is only one)if it is around 3 volts then that is ok.
you could replace it by 2 nihms of 1.2 v,if that is not sufficiant then you would have to take 3,that gives 3.6v ,
having that and the high load of the solarpanel which can give 4.75v it would be wise to use a 3 volt regulator(made with a lm 317 i thought,if the input is high enough for it) between them and the weather unit to protect it.

but honestly i think it would only prolong the live of the batteries en they go flat anyway(due to their own discharge and cold temp),maybe sooner than regular batteries.

Thanks for the reply hans, so do yoy think there won't be much point in messing around with it, for at best little gain?

Dave

[hans]

your solarlamp doesn,t have that much energy to give,each part added will cost some milliamps.
how about something like this?
http://www.thebackshed.com/Windmill/assemblyMini1.asp

that has more output so it is more easy to regulate,it is only to charge so it doesn't matter that wind is irregular.
high wind is buffered by a voltregulator,low/no wind it won't charge