Technical LED fuse help

[bowman99]

I'm fitting 4 sets of 12V LEDS in my car footwells, on their own circuit because using the cab light doesn't make for easily putting in an independent switch.

I'm trying to work out what fuse I need but I have no idea how to work out how many amps the circuit is using.

Technical bits: 2 sets of 5050 SMD LEDS (18 bulbs Per strip)
2 sets of 3528 SMD LEDS (15 bulbs Per strip)
Running 12v off the car battery , in a parallel circuit.

(the LEDS don't tell me What amp or watt they are using anywhere)

What fuse would I need (if anyone can work it out for me) or if not please just help me work it out ? im so lost at the moment with this.

Thank you in advance!

If I've missed anything out that you need to know let me know.

(also wasn't sure if this belongs in technical or styling so i apologise in advance)

 

[g8rpi]

<SNIP>

I'm trying to work out what fuse I need but I have no idea how to work out how many amps the circuit is using.

Technical bits: 2 sets of 5050 SMD LEDS (18 bulbs Per strip)
2 sets of 3528 SMD LEDS (15 bulbs Per strip)
Running 12v off the car battery , in a parallel circuit.
<SNIP>
What fuse would I need (if anyone can work it out for me) or if not please just help me work it out ? im so lost at the moment with this.

Thank you in advance!
<SNIP>

Hi,
The fuse is mainly to protect the wiring, not the load (LEDs). A 1A (Black ATO) fuse would be adequte for the load but is not a scommon size. A 2A (grey) would be OK too. Use 1mm /20AWG or thicker wire. If the LED strips have thin wires keep them short and protected from damage .

Robert G8RPI.

 

[bowman99]

Thank you!!!! I shall do some hunting for one appreciate the help and pictures up when I'm done

 

[Ziggy122]

Id piggy back fuse off the cigarette lighter socket....
Id stick a 1amp fuse in too
Leds draw very very little current

If you connected a amp.meter in series itd tell you the amperage (well the millamp draw)

By using the cigarette fuse its a switched feed so the leds cant be left on an drain ur battery

Ziggy

 

[nitramtpr]

As Ziggy says, get yourself a piggy back fuse holder, something like these:

https://www.ebay.co.uk/itm/4-x-piggy-back-fuse-add-a-circuit-standard-blade-fuse-holder/112399216997

Then you can run the positive feed to a switch and then onto the LED strips.

According to the specs for a roll of 5050 SMDs they use 5 amps for 300 LEDs so 4 strips of 18 are going to be only around 1.2amps.

I've fitted LED footwell LED strips with the power coming off the interior light, works a treat and why have an independent switch, just have them come on with the light, easy peasy

 

[g8rpi]

As Ziggy says, get yourself a piggy back fuse holder, something like these:

https://www.ebay.co.uk/itm/4-x-piggy-back-fuse-add-a-circuit-standard-blade-fuse-holder/112399216997

Then you can run the positive feed to a switch and then onto the LED strips.

According to the specs for a roll of 5050 SMDs they use 5 amps for 300 LEDs so 4 strips of 18 are going to be only around 1.2amps.

I've fitted LED footwell LED strips with the power coming off the interior light, works a treat and why have an independent switch, just have them come on with the light, easy peasy

Hi, Only half are 5050 LEDs hence 1A should be OK. Need to be careful about connecting to existing lights on newer cars. They are often switched electronically so the extra load can trip a fault indication or even cause damage over time.


Robert G8RPI.

 

[nitramtpr]

Hi, Only half are 5050 LEDs hence 1A should be OK. Need to be careful about connecting to existing lights on newer cars. They are often switched electronically so the extra load can trip a fault indication or even cause damage over time.


Robert G8RPI.

I was worried about my footwell LEDs as I wired them direct off the interior light, my MK2 is a B with CANBUS so the interior light isn't a normal straight on off feed, as I've only got 18 LEDs in total (2 strips of 9) they work a treat. I've also swapped the festoon bulb for a LED one, this will have reduced the wattage so I'm pretty sure the new LED festoon and two strips are less wattage that the old normal festoon bulb!

 

[Michael Dranfield]

Hi, Only half are 5050 LEDs hence 1A should be OK. Need to be careful about connecting to existing lights on newer cars. They are often switched electronically so the extra load can trip a fault indication or even cause damage over time.


Robert G8RPI.

Good point but easily sorted by using the existing lighting circuit to operate a relay so the extra draw from the lighting circuit would be reduced to just tens of milliamps ,don't forget to include a diode across the relay coil to clip the back EMF.