XSeries-forum

If you have to put in load resistors to stop OBC warnings is that defeating the object of fitting for less power consumption and only leaves the reason as cosmetic. How much difference in consumption is there between a 12v 21w bulb and an LED with 50w 6ohm resistor (seems to be the normal resistor thats sold)?

50W is the maximum power that the resistor can cope with before melting.  One reason that size is used is that it can be chosen for a whole range of different LEDs and is an easy size (physically) to work with.  That makes it easier for a supplier as they can order them in bucket loads.  The actual power going through it will depend upon the rating of each LED in the replacement lamp itself.

Larger resistors also don't get as hot....another complication that has to be included in the designs.

Technically you only need a resistor rated for each complete LED lamp unit plus about 20%, but that can result in components that need soldering in and are harder to use by the average 'modder'.

Power (W) = Supply Voltage (12V) X Current drawn (in Amps)

Most purchased LED,s that you can buy are Canbus friendly, the resistance only needs to be enough to simulate an unlit bulb, as the car checks all bulbs to make sure there is a resistance equivalent to a normal unlit bulb.
Most fit LED bulbs for the looks over energy efficiency.

I just got some canbus friendly indicator and reverse LEDs. The indicators flash way to fast and the reverse bring on an OBC warning. As you said Horizon, I want to keep them cos they look nicer so will just get the pack of 4 resistors they're only £6
As ever X5Sport thanks for filling in one of the many empty boxes in my head.