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running 2 sets of spotties on 1 relay
Posted: Mon Jul 13, 2009 5:31 pm
by 83-mud-lux
i got a set of rectangle spotties on the headboard of the lux and just got another set of round ones but they didnt come with a relay.
im going to put them on the same switch but im not sure if i can run them through the same relay..also less wiring to do..help would be much appreciated thanks..smiley..
Posted: Mon Jul 13, 2009 5:43 pm
by ausoops
a 12v30A relay costs about $10, do it right, you will destroy your wiring and existing relay if you try to double up on the one circuit.
Posted: Mon Jul 13, 2009 6:28 pm
by bru21
Watts = volts x amps.
assume 1 light is 100 watts
2 lights is 200 watts
4 lights are 400 watts
now divide the energy needed in watts (400) by the voltage supplied - (use the lower voltage to be safe ie 12v not 13.6 running voltage)
400 / 12
=33.33 Amps
Therefore assuming the relay is the limiting factor
a 30A relay (at 12v) would be too small.
a 40A relay would be adequate.
You need to see also if the wiring can handle it etc..
V = IR etc or Narva site etc
http://en.wikipedia.org/wiki/Ohm%27s_law
http://www.howstuffworks.com/question501.htm
Posted: Mon Jul 13, 2009 7:17 pm
by 83-mud-lux
thanks bru21.
all to technical for me but i got eventually haha.
i will get a 40amp relay tomorrow.yea its pretty good wiring set-up i got..
Posted: Mon Jul 13, 2009 8:54 pm
by bru21
make sure the relay holder is rated to 40 also, it will die if its not. Also I always choose a s/h ford relay over a narva etc as you cannot match oem quality
Posted: Mon Jul 13, 2009 9:10 pm
by DamTriton
Globes can draw about 50% more amps on startup (1-2 secs). Two 30 amp relays would be better as you will only have 2 lights out if you blow fuses or a relay sh*ts itself. Cheaper in the longrun and easier to purchase and replace out in the sticks.
Posted: Mon Jul 13, 2009 9:22 pm
by chimpboy
DAMKIA wrote:Globes can draw about 50% more amps on startup (1-2 secs). Two 30 amp relays would be better as you will only have 2 lights out if you blow fuses or a relay sh*ts itself. Cheaper in the longrun and easier to purchase and replace out in the sticks.
I agree, I would rather run two 30A relays than one 40A relay.
It is hardly any more work to install.
Posted: Mon Jul 13, 2009 9:24 pm
by T_Diesel
I woud wire each set on a 30A relay and fuse each relay individually. Better off doing it properly first up to avoid any hassles down the track.