Understanding MR16 LED lamps

Hi everyone,

Ive had an account here, but I havent been on much. I don't have a whole lot of experience in this hobby. It's more of one of those things where I am not really interested in it until I need to build something, which isn't that often.

For example recently I put ten NiMH cells in series 1.2v x 10 = 12 volts. Put an mr16 led in a waterproof casing. Put them in a tube and made a handheld light waterproof light for wading in salt water. See what I mean? I love fishing. That's why I built it. Not because I'm a huge led hobbyist. But necessity is the mother of learning/invention.

So those batteries said 5000maH on the side. Which is probably overrate, but not really my concern. They last a very long time.

What I am wondering is, don't those MR16's that say they run on 12v, dont those bulbs really operate on the 3-4v range and have some kind of electronics to step the voltage down?

And if that is the case, I know in my old electronics classes 15 years ago, that when you use a transformer, voltage up, current down. Current Up, voltage down. But obviously these don't have an iron core transformer in them. They are converting 12v dc to some smaller voltage if I am not mistaken.

So this is the question.
Assuming source is 12v at 5aH.
Assuming the voltage was regulated down to 3v ( factor of 4) internally in these MR16 bulbs.

does that increase the aH rating by a factor of 4 ?

Thanks in advance

These led's do use about 3.7 volts. So in order to provide the proper voltage they have special electronics to step down the voltage, this is called a regulator. There's different kinds some are a linear regulator and simply act like a variable resistor and will simply drop the voltage by converting it to heat. Not good when you're talking dissipating 8 volts at upwards of one amp. There's also another one that acts more like your computer's power supply it's called a buck regulator. They actually do have a sort of transformer in them, it's a ferrite cored inductor and it's tiny, less than a 1/4 inch high. It switches the current really fast in it so it can convert it down and uses fancy electronics to regulate power. If you have a buck circuit it will increase your runtime by approximately 4 times.

But another way to increase efficiency is to not have to convert to such a different voltage. That's why you often see these MR16's with 3 led's 3x3.7v=11.1v That's almost a perfect match for 12 volts so it doesn't need to convert to a really low voltage. This enhances efficiency nicely by matching the running voltage with the power supply voltage.

qwertyydude said:

These led's do use about 3.7 volts. So in order to provide the proper voltage they have special electronics to step down the voltage, this is called a regulator. There's different kinds some are a linear regulator and simply act like a variable resistor and will simply drop the voltage by converting it to heat. Not good when you're talking dissipating 8 volts at upwards of one amp. There's also another one that acts more like your computer's power supply it's called a buck regulator. They actually do have a sort of transformer in them, it's a ferrite cored inductor and it's tiny, less than a 1/4 inch high. It switches the current really fast in it so it can convert it down and uses fancy electronics to regulate power. If you have a buck circuit it will increase your runtime by approximately 4 times.

But another way to increase efficiency is to not have to convert to such a different voltage. That's why you often see these MR16's with 3 led's 3x3.7v=11.1v That's almost a perfect match for 12 volts so it doesn't need to convert to a really low voltage. This enhances efficiency nicely by matching the running voltage with the power supply voltage.

Click to expand...

ohh,that makes a lot of sense. The ones I have are 3x3 watts supposedly. so yeah, if they were hooked up in series, I guess they would use that 12v input quite nicely. I guess I just assumed they were internally wired in parallel and taking the 12v and reducing it to 3.7.