led/mah question.

[ShaolinDrunkard]

Hey guys, another seemingly stupid question but here goes.

You cant overload something with Mah can you? Heres a for instance:

Say you have an led that needs 3v, 20ma... and you have a battery thats 3v 1000ma, it should work fine as long as it has enough mah, right?

heres what I'm trying to do. I'm trying to run a bunch of 12v led bulbs that were meant for automotive use (12vdc) off a 12vdc wall supply. What I want to make sure of is that I can get a wall supply with a very high mah rating and not have to worry about putting different amounts of bulbs in there. Basically as long as I have enough Mah to run the bulbs, it doesnt matter if the number is much more than I need right? Not sure if I made myself clear but anyways, thanks ahead of time.

[Kurt_]

Well, mAh is the capacity. mA is the current used.

In the case of LED's, you need to restrict the current flow or they'll burn out quickly.

[ShaolinDrunkard]

Well, heres exactly what I want to do. I want to take a bunch(probably at least 15) Led cluster bulbs that were meant for a car and require require 12v and use a 12v wall adapter to power them, but I have no way of knowing the current draw that they will take. So I figured I'd get an adapter with a high Mah current capacity. But since you say that the current must be limited, now I am at a loss as to how to figure this out. I contacted the manufaturer of the bulbs and they cant offer me the current draw of each one, also I might use two different types of 12v bulbs on the same project, so that complicates things even more. I know using resitors isnt an exact science, but still, I would have no idea how many or what Ohm resistor to use.

[Kurt_]

Use a multimeter in series to measure the current draw of the LEDs.

As for the resistor,

http://home.cogeco.ca/~rpaisley4/LEDcalc.html

If that doesn't tickle your fancy, search Google for "LED resistor calculator." There's many of those thingies out there.

[superdeformed]

If the LED assemblies are made as direct replacements for car bulbs, and I'd imagine they are since they run off of 12V, then they will already have resistors built into the assembly, and all you have to worry about is providing them with enough power. The packaging should tell you the power rating of each bulb (in watts) and from that you divide it by 12 (the rated voltage) to get the current draw in amps. After that, you just need to decide how many you think you will want to power at the same time and pick an adapter with an appropriate current rating, which will be measured in milliamps or amps. Milliamp hours (mAh) is a rating of capacity used for batteries, not how much current something can actually supply.

[ShaolinDrunkard]

Thanks guys.