dual optics 5 amp fuse blowing

[jakm15]

hi, just fitted some dual optics and tried adding the 5 amp fuse you need but when the lights are on it just blows it, ive added a 10amp one instead and they work fine, the wires dont get hot.

any ideas to sort this?

 

[fraserd007]

my opinion but i wouldnt leave the 10amp one in if they were originally designed to run on a 5, i dont know alot about them but there is obviously a prob with them to keep blowing the 5

 

[jakm15]

my opinion but i wouldnt leave the 10amp one in if they were originally designed to run on a 5, i dont know alot about them but there is obviously a prob with them to keep blowing the 5

ill check all the wiring and make sure all connections are ok, im not 100% on the 5 amp, it does say it in the guide but could be wrong.

 

[aliengravy]

just work it out
what wattage bulbs have they got in them?
55watts or 130watts?

How many bulbs have to be on to pop the bulb?
whats the total wattage?

 

[jakm15]

just work it out
what wattage bulbs have they got in them?
55watts or 130watts?

How many bulbs have to be on to pop the bulb?
whats the total wattage?

done a gcse in electronics i should have thought of that, well when its on full beam which the fuse is for there are 2x55w 2x60w and 2x5w = 180W. but only 110w for the main sooo

to work out the fuse size ive done (55w+55w)/12v=9.16

so it looks like a 10amp

also in the guide it says RED 5 AMP, but im sure 5 amp is orange and 10 amp is red

 

[aliengravy]

you need a 10amp fuse then!! simples!! 55Watt bulbs are standard! you can get up to 130watt but they are show bulbs!

im doing electronic and electrical eng at uni every now and again it comes in usefull

 

[Ian]

I swapped mine from a 5 to a 10amp as my 5amp fuse blew pal, seemed to sort mine out. Had to replace the bulbs as well as nothing was working.

 

[aliengravy]

should think wiring would be rated to 30 odd amps anyway, if not more

I ran 130's in mine and they where fine, 260/12 = 21.6!!

 

[Dink]

remember mind that the electrical system in a car will be at nearer 14v with the engine running
so it will pull even more current then

 

[jakm15]

thanks for the help, ill leave the 10amp in. , going to wire my front fogs up next when i get chance.

 

[aliengravy]

remember mind that the electrical system in a car will be at nearer 14v with the engine running
so it will pull even more current then

HA HA HA

If your going to post on a forum, post something factual!!

260/14 = 18.57amps

that's less current!!

Worst case scenario is engine off, full lights on, so voltage circa 12.7V!

 

[Dink]

umm i think you find the resistance of the lamp will always be the same so you apply a higher voltage you will get increased current

ffs you cannot have learned much on your uni course

 

[aliengravy]

umm i think you find the resistance of the lamp will always be the same so you apply a higher voltage you will get increased current

ffs you cannot have learned much on your uni course

Resistance will change with the temperature! (hence a bulb pops!)
Power(w)=VoltsXAmps
Power/Volts = Amps
260/12 = 21.67
260/14= 18.57

Nothing to do with resistance mate!

V= I X R
R = V/I
12/21.67 = 0.5537
14/18.57=0.7539

change in resistance is negligible! Almost the same! temperature of filament will differ slightly causing variation! lil error in rounding!

when we are talking about resistances this small the length of wire and internal resistance of the battery will come into play!

maybe again for you?
P/I^2 = R
260/21.67^2=0.55ohms
260/18.57^2=0.75ohms

 

[Dink]

yes but the power of the lamp is at 12v it's output will be higher at 14v

so I = P/V
I=55/12
I= 4.58A at 12v

R=V/I
R=12/4.58
R=2.62 ohms is lamp resistance

so apply 14v to 2.62 ohms

I=14/2.62
I=5.34A at 14v

 

[aliengravy]

If the bulb rating is stated at 12V then you a right....... +or- variations in bulb resistance!

 

[Dink]

yes but they are 130w @12v

thats how they are tested.

if resistance doesn't matter that means i could put 12v into a 230v lamp and still get the same brightness as with 230v?

 

[aliengravy]

Yes ok i admit your right! I got owned! and i got my f**king analogue electronics exam in the morning all on this s**t lol

 

[Dink]

no worries mate i get simple things like this mixed up sometimes tbh lol

 

[aliengravy]

im tired, and i been doing fricken equations all day, polar form and rectangular form of what we just doing! Gunna fail tomoz i know it lol!!