# Off grid light in small shed

#### azaxev

##### New Member
I am looking for a way to install light in a shed, approx 6m2.

Have 5m 2W/m LED strip that will be stapled to rafters, they are exposed.

For the battery, I am thinking convenient Ryobi set of **broken link removed** that sells here rather inexpensively. Battery would be pernamently in charger, stepped down to 12V for LED strip.

Charger's DC adapter would be removed and replaced with solar panel + boost regulator.

Expecting one inconvenience, charger is too fast, charging 36Wh battery in 40min, that is 54W, so solar panel would need to be about that size as well, which seems rather ineffective, since the battery can be topped during entire daylight I would prefer if it took 4-6hrs to recharge that battery. Not sure how difficult would it be to fiddle with chargers internals to slow it down.

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#### Diver300

##### Well-Known Member
You need to find what is used to charge the battery. Your link doesn't work for me.

The power tool chargers that I have generally don't have separate mains adaptors and chargers. There may be a charge control IC that can be made to reduce its charge rate. Some charge ICs are happy to be fed from a low current supply, and they will just let the battery charge as fast as the available current will charge it until the battery is full.

#### Pommie

##### Well-Known Member
It might be much simpler if you use a 12V SLA (sealed lead acid) battery. Note, your LEDs are going to take ~830mA so to last 12 hours would require a (12x0.8) 10Ah battery - however, a 20Ah would be better as you never want to fully discharge a lead acid battery. Also, your 18V 2Ah battery only contains 36W of energy so assuming 100% efficiency it will last ~3.5 hours. A single 12V LED downlight only uses 6W and will (probably) be much brighter than your strip lights.

Mike.

#### azaxev

##### New Member
You need to find what is used to charge the battery. Your link doesn't work for me.

The power tool chargers that I have generally don't have separate mains adaptors and chargers. There may be a charge control IC that can be made to reduce its charge rate. Some charge ICs are happy to be fed from a low current supply, and they will just let the battery charge as fast as the available current will charge it until the battery is full.

Thanks, that is great to know about chargers. This one seems to have external wall adapter.

It might be much simpler if you use a 12V SLA (sealed lead acid) battery. Note, your LEDs are going to take ~830mA so to last 12 hours would require a (12x0.8) 10Ah battery - however, a 20Ah would be better as you never want to fully discharge a lead acid battery. Also, your 18V 2Ah battery only contains 36W of energy so assuming 100% efficiency it will last ~3.5 hours. A single 12V LED downlight only uses 6W and will (probably) be much brighter than your strip lights.

Mike.

I really do not need that much from it, the shed is used as storage, nobody ever stays there longer than 5 minutes.

Also considered SLA battery and I would be fine with even 1Ah one but they are not that much more cost effective. The small ones cost $1-$2/Wh here and I could not find any on the second hand website within 30km radius. Power tools batteries have become uniquitous, often come on promotion for less than \$1/Wh or in BOGOF deals. I own a small Ryobi, Dewalt battery powered tool lineup, several chargers and battery packs. Tools and batteries are also heavily traded on second hand markets.

#### Pommie

##### Well-Known Member
Is a battery charger available that can be powered from 12V I.E. a car lighter socket.

Mike.

#### azaxev

##### New Member
Thanks to all.

Ended up using 12V/18AH SLA I had left from different project, it is a bit overkill but very shallow cycling will keep it alive for longer. 18V voltage would have been too many needless conversions.

Got 30W polycrystaline solar panel from AliExpress but it only qualifies as 10W - active area is 38x16cm=608cm2, polycrystaline efficiency 15% so this panel should be marketed as 9-10W. Today we had a nice winter unclouded sun at noon I measured VOC=14.5V and ISC<0.15A, which seems bad. Panel is at 60deg facing south. Had to build a weatherproof backing/junction box for it, because it was just a flimsy piece of plastic and we get some strong winds here. 10W should be fine for this purpose but for same price could have had Coleman 10W panel from CanadianTire, that comes with aluminum frame, tempered glass. Next project I will know.

Still need to do proper connections, attach the solar panel and cleanup, but light works well. There is full 5m strip installed on 3x 1.8m light bars.

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