OutdoorKing Repair Forum Forums General Discussion Forum Off Topics Who's good with electrics?

I've got 2x old car batteries that still have some life left. One was getting to be noticeably slow cranking (barely starting), the other still fine but didn't instill me with confidence for much longer.

So bit the bullet when I saw them for 25% off.

Anyway, I was about to take them for recycling when it was suggested to me that I might use them in the sheds to power lights.

Here's where my question lies
I am planning on getting these https://www.ebay.com.au/itm/221921754180 and using 2x in each shed.


My queries are:
At 7200 lumens each, am I going to burn my eyeballs out in a 3x3 shed?

At 18w each, how long will it take to kill the battery (I won't run them empty as they aren't deep cycle)

What gauge wire do I use? Is 3mm (10a max) wire enough, or will they likely take more?

Note, I will use alligator clips to connect to batteries when in use as I don't want to leave them connected and potentially burn down the shed

Thanks

I ran a setup as you described in a shed many years ago. I ran it off a brand new truck battery and had a large solar panel on the roof. It worked okay but was a bit limited, as the lights would go out suddenly as the battery drained. You'd probably be better off buying a brand new truck battery which will give you the amp hours that you will require, as old car batteries will probably not hold a charge for long enough. You will probably need some heavy duty solar panels and a controller to prevent your batteries getting cooked in very sunny weather in summer. Generally you need heavy, thick wire for anything on the battery side, but on the other side of the controller you will only need light wires to run things like lights. Best advice would be to visit your local solar power shop and they will be able to fit you up with what you need and calculate things like charge times and amp hours. Back when I did this solar stuff was fairly cheap, but could be expensive these days. I'm not sure as I have not done anything with solar for like 15 years. Might be an idea to shop around a bit. Good luck with your project.

Hi Tyler,
main thing is to put an inline fuse in the positive wire, that will stop any potential problem. 18 watt will give you light, just depends on if you are wanting to work at night using the light and for how long you want the light on. Next problem is the solar won't keep the battery up if you want the light on for any time. I have a lot of 12 volt stuff going on in my house, 5 smoke detectors, 3 CO2 detectors, a house number light out the front, a clock in the kitchen, high water alarm downstairs and a 12 volt submersible pump which only activate if we loose power and it is raining. I think the solar panel is 150 watt which could keep the battery charged during summer but as soon as winter hits I have a trickle charger on for 4 hours a day. I also have volt meters in the family room so I can see exactly what is going on with the batteries at a glance. I also have 2 newish batteries with combined 110 ah capacity
So in answer to your question it all depends on your usage and you are most likely going to need a 240v trickle charger to keep the battery up so it might end up being not worth it

G'day Tyler ,Vm and Norm,

I'm not sure if car batteries would be worth using these days for lights in a shed , for around $10 more you can
get the complete solar kit with 3 lights .

With a 3 meter shed I usually just use a rechargeable torch /work light.

It just depends how much light you want and for how long you want light for.

Cheers
Max.

Thanks guys

I don't think I will go the solar route. One shed is in 70% shade and the other is a couple metres away, so would have to run cabling between them

I haven't had good luck with solar anyway.

Really, all I need is a few hours of light per week - they are storage sheds not work sheds

Normally use a led worklight and its not bad, but some fixed lights on the roof would be nice.

Am thinking of getting one of these as its all there and harder to bugger up, see how it works. At least this way I have the option of returning it

https://www.anacondastores.com/camp...2-bar-camping-light-kit/BP90174206-black

Here's what I use in the 3m x 3m shed. It's a AA battery (3) operated detector light and it illuminates the shed well enough as soon as you walk in. I got mine through global shop direct but have seen the same under another brand at SCA. Only irritating aspect is shutting down when you're doing something. You can either switch from auto to on or wave your arm toward it to trigger it again.

I use rechargeable NiMH cells.

Yep, starting to think its easier to stick with my torches. Bought eiger lantern/spotlights in 2017 and still going. were $40 each back then (found the receipt the other day when looking for a misplaced tax deduction receipt haha). have saved many $$$ on d size batteries

There's several unpowered sheds on our rural property and I use the $5 head torches with 3 AAAs if poking around in them after dark or out walking the dogs. If needing serious lighting for say, doing repairs to a pump or loading a trailer my Ozito led work light on a 4 Ah battery can last all night and light up a large shed.

I also use one of these for lighting up specific areas. This one fell and cracked but still works. I bought a couple from Ikea quite a few years ago. You can stick them on any metal surface. You just push on the lens.
Worked quite well on it's own but the detector light with it's ring of LEDs does a better job of overall lighting of the interior and I use this as a handy mobile light within the shed itself.

And not one person asked how I run all my various items with different voltages all from a 12 volt supply.

You must use inverters and various adapters.

Hi MF,
I just use adjustable bucks before each smokie or clock and adjust it to the voltage each item requires. Mostly brought about because I got sick of my wife climbing up on a kitchen stool to shut up a smoke detector in the middle of the night. And my dog is terrified of the smokie beeping. Takes me hours to settle him down if he hears one

Hi NormK, never heard of bucks.

Hi Tyler,

18W Led at 12V supply will draw 1.5A Max. Rule of thumb, the size of wire handling current must be double of the rated current means you use a wire can handle at least 3Amps. For a single LED is normally rated at 30mA to 50mA. On the link you supplied, it indicates 36 LEDs for this light means each LED is rated to 18W/36 which is equal to 0.5W. So the rated current in each Led is equal to 0.5W/12 which is equal to 41.6mA which is correct within the 30mA-50mA.

How long you can run the light for a new 12V car battery.?Most car batteries has at least 300Ah means you devide 300Ah by 1.5A whis is equal to 200hrs of continuous usage. What is you use a dimmer control in series to reduce the current by half means the hours will be doubled to 400hrs continuous usage.

With the used battery with reduced charging capacity let's say only 50Ah means you can the light continuous with dimmer control for roughly 67hrs. If you use only 2hrs a day means 67/2 is roughly 30days before you charge the battery.

Make sure you use an inline fuse rated just above the light maximum rated current (let's say 2A fast blow fuse). Use an inline switch between the fuse and dimming control so you can leave the alligator clamps connected to the battery.

You have lots of options for charging, using solar or mains trickle charging.

Cheers,
CM

These are the bucks I used MF, once I adjusted them to the voltage I required I put them in a small black box to keep them free of dust.
https://www.ebay.com.au/itm/293547520422?

Hi NormK and MF,

Buck converter is a type of switched mode power supply topology. There are many topology used in SMPS e.g. boost, flyback, buck-boost depends on power conversion. I have similar buck converter on hand that I can try. I knew this particular buck converter doesn't step up the voltage. Boost converter is the one which could step up the input voltage. I will test this buck converter if we can adjust the output voltage down. For example if I supply it with 12V input, I will check if I could adjust the output from 1.3V up to 12V +2.5% regulation. As I mentioned about dimmer, this buck converter will do the job if we can adjust the output voltage down to half or 6V. The maximum output current anyway is good enough for the 18W bar lamp which is 2Amps.

Cheers,
CM

Hi CM and MF,
I have 10 of these bucks working around the house and so far have never had a problem with them. The lowest I have gone is 1.5 volts and that is to replace items that use a AA battery. Just set it up with 12 volt in and with a multimeter on the outlet side turn the screw anti clockwise till you get it down to the voltage you require. One thing that did surprise me was how much they pulled the 60 ah battery down overnight

Interesting Norm, I was wondering what you were doing. I was figuring some sort of inverter as well.
Might have to investigate one.

Carbymaster, thanks for the detailed info. The battery that is still pretty solid was a 70ah, the other one I think was only a 60ah to start with.

Will be interesting to see how they go so I will report back when I do it.

Hi NormK,

You must ran all 10 bucks in one battery but still battery shouldn't drain overnight. Check how how much total current drawn using a multimeter in series with the battery set at 10A.

Hi Tyler,

To know the total hours the battery will last is you devide the Ah by total current of the load. For example, your load draws 1.5A at 12V supply and your battery is 60Ah, so 60Ah/1.5A is equal to 40hours.

Hi CM,
It isn't draining the battery too much but when I got the battery it came with a warning not to drop it lower than 11.7v so I try to keep it above that. I will have to see if the solar panel will be able to keep up during summer. I also have a solar light over the front door that I want to connect to the 12volt system because during winter that light goes flat before midnight