Discussion
I’m thinking that this is potentially a good subforum to ask this question:
I’m planning on replacing a few standard dashboard 12v bulbs with conventional 5mm LEDs. What got me thinking was that the wires to the existing bulbs are quite heavy gauge whereas the wires on the 12-18v LEDs that I have are very lightweight. So before just soldering then in I’ve developed the concern that the currents possibly involved might be too much?
Thanks.
I’m planning on replacing a few standard dashboard 12v bulbs with conventional 5mm LEDs. What got me thinking was that the wires to the existing bulbs are quite heavy gauge whereas the wires on the 12-18v LEDs that I have are very lightweight. So before just soldering then in I’ve developed the concern that the currents possibly involved might be too much?
Thanks.
As long as you're using 12v LED's the wires supplied on the LED will be more than enough for any current the diode will draw, they are self limiting so if you stick one straight across a couple of thick battery cables & a battery with almost limitless amps available, it will still draw only the tiny amount of mA it normally would.
The current drawn depends on the component in use.
A filament bulb draws much more current than an LED so the wiring for a bulb may have needed to be heavier duty but the LED will only draw the current it needs to operate. No more.
As a side note make sure the LED's are suitable for automotive use. With the engine running a normal charging system runs at around 14.4v and some 12v LED's cannot take the extra voltage.
A filament bulb draws much more current than an LED so the wiring for a bulb may have needed to be heavier duty but the LED will only draw the current it needs to operate. No more.
As a side note make sure the LED's are suitable for automotive use. With the engine running a normal charging system runs at around 14.4v and some 12v LED's cannot take the extra voltage.
They'll be fine.
LEDs rated for use on higher voltages (like your '12-18v') include a 'current limiting diode' - essentially a jfet current source - and so regardless of the nominal or effective local supply voltage, the actual LED die only gets fed the tiny 5-20mA it requires. [the led itself likely only drops about 3v for a 'white' LED, by the way - there's more in the 5mm package than just the LED die.]
So yes, the supplied wires will be tiny.
NOTE this also means that the LED replacements will likely not 'dim' with the dashboard lighting adjuster if the car in question has one!
- they'll stay at constant brightness over a very wide voltage range, likely from about 4-5v up to whatever they can take (20+ V easily, even for nominally 12v parts, again, thanks to that onboard current limiting)
LEDs rated for use on higher voltages (like your '12-18v') include a 'current limiting diode' - essentially a jfet current source - and so regardless of the nominal or effective local supply voltage, the actual LED die only gets fed the tiny 5-20mA it requires. [the led itself likely only drops about 3v for a 'white' LED, by the way - there's more in the 5mm package than just the LED die.]
So yes, the supplied wires will be tiny.
NOTE this also means that the LED replacements will likely not 'dim' with the dashboard lighting adjuster if the car in question has one!
- they'll stay at constant brightness over a very wide voltage range, likely from about 4-5v up to whatever they can take (20+ V easily, even for nominally 12v parts, again, thanks to that onboard current limiting)
Edited by Huff on Thursday 5th March 19:36
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