resistor for led

i am an idiot wrote: If you have a 12volt LED, you should not need a resistor.

thats what i thought, but i can't explain why they are blowing out. Any thoughts on my diagram? does everything look proper? even considering the draw on 12-15A draw by the pump?

Maybe it's a reverse-polarity spike causing the damage (albeit unusual). Try a reverse biased diode across the LED - eg - something like an 1N4004 (1A 400V) with its Kathode (line end) towards the +12V and other end (Anode) to GND in parallel with LED (whether the LED itself or the LED with inbuilt resistor).

would a bad ground on the led cause the damage? i would think a bad ground would only cause it to intermitantly work. oldspark, thanks for the tip.

For bulbs - yes - intermittents are probably the biggest cause of failure (when people say it's a short - they mean intermittent (think about it)) - other than vibration/shock or poor quality. Though it's a possibility, it's unlikely for LEDs - ie, no thermal shock; LEDs are often switched at very high frequencies. Reverse polarity (through inductive spikes) is more probably, but it's worth ensuring a good ground anyhow.

i am an idiot wrote: If you have a 12volt LED, you should not need a resistor.

For a minute there you had me wondering. LOL!

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