Re: Need resistor help please (35w x 12v)

Locu wrote:
I just presented this question to xenondepot.com, I guess a leading
supplier of headlights in the US. Their response is:

Hello Sir,
We do not sell this however you need to purchase 2 x 15ohm resistors ( 1 per side).

Their calculation seems to be way off from ours, any ideas?

This assumes that the load sensors in the ciruitry will "sense" that
headlights are installed with 15ohm loads which could very well be true
as it comes from xenondepot. With a 15 ohm resistor and the vehicle
voltage around 14V, Ohms law tells us this resistor needs to be rated
at over 13W.

Watts = Volts^2 / Ohms 13.066 = 14^2 / 15

You can order 15 Ohm / 25 Watt rated resistors from Mouser.com for
$2.18 US. Part # is 71-HL25-06Z-15. You will need 2 of these, 1 for
each headlight.
http://www.mouser.com/index.cfm?handler=displayproduct&lstdispproductid=193771&e_categoryid=359&e_pcodeid=71046

If you go this route, make sure you order the correct resistance. If
you put that part # into Mouser's part search, their first few results
will be the incorrect ones as they show the 150 Ohm and 15k Ohm
resistors first.

If you want to experiment a little, you can try going to any electronic
store around you like a radioshack and picking up a few 1.5k resistors
either 1/4 or 1/2 watt will do as you will be only passing .13 watts
through them at 14V. These come in packs of 5 or so from Radioshack
for 99 cents. It is quite possible that your sensors will see even
this small of a load as a working light. If this doesnt work then your
only out a buck and I would suggest going with the 15 Ohm resistors.

--Brian

.

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