amps help plz

[zoaman]

i always forget this one can somebody remind me.
if i have 12v and 3 1.2 leds wired in series will that be 3.6amp draw.
or if wired in paralel will this be 3.6 amp draw

[beale]

I wouldn't of thought an LED would draw 1.2A ?
If you wire in series it reduces the voltage as it has to pass through the resistance of each LED, in parallel the voltage stages the same to the positive pin on Each

[fidspeed]

seris circuit 1.2 A draw (if one LED fails all LED go out
parallel circuit 3.6 A (if one LED fails others will stay on )

http://www.bbc.co.uk/bitesize/ks3/science/energy_electricity_forces/electric_current_voltage/revision/4/

see if link works explantion for beginners in electrics

regards dave

[beale]

A 12v 5mm LED is 120mW or 0.12W
0.12/12v=0.01A
As Fidspeeds link shows the lamps in a series circuit will be dimmer as the voltage reduces to each lamp
If you have 12v LED's run them in parallel otherwise use 5v LED's

[fidspeed]

thanks Mr. Beale I was going on OPs figures

but thinking about it now with the prompt they would be fairly heavy duty LED !!!

regards dave

[zoaman]

ok should have gave more info
i bought 4 x 1m led strips(should have been 1 x5m but that another story)
according to description each 1m draws 12v and 1.2a 14.4w
so i bought a psu that has arious outputs(9.5,12,15,18 ect)witha max output of 3.5amp 64w
when i used the 12v the led got hot(50degree) and u could see them from the moon
so i lower the volts on the psu to 9.5(checked with a meter and is 10.2v)
so as i wanted them for under my caravan i wanted them cool and didnt worry to much about the brightness(plenty of light still even at 10.2v)
so run them
1m x parralell
2 x 1m in series and then run parralel to the first one.so running 3 altogether
when i check the amp draw it was only 0.92a.so i run another in parallel and the total draw of amps was 1.12a
so either the seller has the draw of 1.2a per meter wrong or am i checking something wrong.or is it because im running them at just 10.2v and not 12v
amps where checked with a multimeter thru the 10a non fused side.
+thru multimeter to - leds
is this still ok the run them with less volts and run cooler
als the leds then run at ambient temps and was checked for 2 hours

[beale]

You won't get a true reading even on most Fluke meters , it will be low anyway but their figures are potential so you need to wire in gauge to suit their est pot.