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Thread: Offgrid solar lighting - battery & PIR

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  1. #1
    Automated Home Guru jpdw's Avatar
    Join Date
    Oct 2007

    Default Offgrid solar lighting - battery & PIR


    Not really "Automated"/smart home related, but this place has all the most knowledgable people...

    I've recently been involved with setting up a solar lighting kit for an off-grid toilet at our local allotment. The kit consisted of a 25w panel, charge controller, 12v bulb (CFL!!) and assorted fittings (cable, switch, conduit etc). Note - no battery and in a hurry I had to make do with whatever I could source from the nearest maplin.

    It works quite well so far in the 2 months so far.

    However, on a few occasions we've found that people have left the light switched on and run the battery down. As the toilet cubicle is basically a windowless wooden hut, this is a problem!

    So I'd like to enhance the system by putting in a PIR - so the light goes out once the occupier has! But any PIR would need to have low 'standby' current draw to ensure that doesn't become the thing that drains the battery!

    Does anyone have a recommendation or done something similar?

    Second question is about the battery ... the kit didn't include a battery and we needed it up and running quick and all I could get from maplin was a lead acid like this one. Given it's going to be getting 6-14 hours trickle charge per day and occasional drain for 5-10 mins at a time, is this the right battery technology or should I seek out something better?

    Thanks in advance.

  2. #2
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    North Lancashire


    as an alternative to PIR, how about a micro-switch or reed-relay on the door & some sort of toggle or timer relay ?

  3. #3
    Automated Home Guru jpdw's Avatar
    Join Date
    Oct 2007


    I like it. Times out after someones been in the 'too long' (whatever the timer is set to, but with a button for people to turn it back on again), or times out when the door gets opened.

    Background power consumption would be zero - which is probably 23hrs of the day....

    Thanks... Something for me to work on...

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