12V DC Garage lights

[paulca]

So hopefully this will be an easy one, but you guys always surprise me with insight, ideas and things I didn't think of.

The garage lights in the new house are basically shot to hell.  Looks like it was DIY wired to have 3 x 2m fluorescent lights switched in the kitchen.  None of these work anymore.

My plan, as I have a small hobby solar system already out there is to put 2 x 12V LED wide angle spot lights in place of each fluorescent lamp, making 6 12V LEDs in total.  If these are something like IKEA MR-16 bulbs at around 5 watts each, that's 30W and ~3A.

I can reused the existing 1.5mm twin and earth wiring.  The idea I have is to mount a box on the wall with a 2.5mm barrel jack socket.  (or just a hanging 2.5mm barrel socket on a cable). This will allow any 12V wall wart to power the lights should the solar battery be dead or should I sell the house and take the solar with me.

From this box A 10A fuse will protect the battery and wiring from shorts.  I will run the + over to a normal household pull cord at the door and the switch + back to the lights in parallel.  The normal main pull cord should have no trouble switching 3A DC.

I don't expect the garage lights will be used more than 5 or 10 minutes a day and I think my small solar system (50W with 100Ah) will surfice.

Now you get to tell me, "What could possibly go wrong!"

[paulca]

Well... anyway, thanks for the help, but these turned out just fine.

Shut off the lights breaker, measured no voltage in the garage lights.  Cut the feed cable, nothing happened.  Later I found the RDC had tripped due to neutral to earth leak.

Moved the lighting end of the feed over to my pull cord switch.  Wago clipped the GNDs and put the + through the pull cord.  I know it's an AC 10A pull cord, but the lights only pull about 3A max, so I figure it will be fine switching DC.

From the pull cord I re-used the previous lighting 1.5mm twin and earth, to get to each beam where the lights previously were.  Added a wire across each so I could put a light at either end.  Lots of wago clips

So the feed comes from a 100A marine battery, solar charged via a 10A EPEver MPPT, through a boat switch panel, so there is a light master and a 5A fuse.  That goes to the pull cord.

Surprisingly it all works.  The downside is it's a bit ugly, but it's a garage!  If I forget to turn them off the battery will last nearly a week.

Also the LEDs claimed to be 5W each, but.. in reality they only pull about 3 tops.  However I half expected this and the thing I was most interested in where the enclosures/brackets and I can later wire sockets in them and replace the bulbs with MR16s of my choice.

[james_s]

I didn't even see the thread.

The problems that come to mind are voltage drop at 12V depending on the length of the wire could be significant. Also a lot of those Chinese LEDs are nowhere near the power they claim to be. Some of the COB types seem to be ok though.

[paulca]

I didn't even see the thread.

The problems that come to mind are voltage drop at 12V depending on the length of the wire could be significant. Also a lot of those Chinese LEDs are nowhere near the power they claim to be. Some of the COB types seem to be ok though.

The cable used is 1.5mm solid core and total length to the furthest light is around 5 meters.  I don't see any noticable brightness drop between the closest and furthest light, but I haven't measured the voltage at the furthest point.

Yes the COB LEDs are nowhere near their stated 5W which should pull 30W for all 6 lights, circa 2.5A, but they only pull half of that from the battery.  As I mentioned I can, if I want put an MR16 holder in the light enclosures and open myself up to a much wider choice of 12V bulbs.