Power usage lights vs. fans

[OldManMirage]

I was on the boat today working on my electrical system and using my ammeter to test various components to see what they were drawing.

I was very surprised to see that my LED lights consumed about twice as much power than my cabin fans. The fans pulled about .5 amps each and the lights closer to a full amp.

I never looked at the specs for either but I would have expected the opposite.

Just found it an interesting discovery.

[dougweibel]

Good quality 12 volt fans using surprisingly little power.

1 amp sounds somewhat high for a single LED light. LEDs are typically between 75% and 90% more efficient than incandescent so 1 amp at 12 volts translates to 48 to 120 watts of incandescent lighting. For a single LED lamp I'd expect less than half an amp but the amount of light and efficiently of the LED definitely could push you up to an amp.

[tenchiki]

To be very picky, LED light fixtures (and replacement bulbs) are electronic devices, not electrical; they have a power supply to convert from 12/24/120v to ballpark 1-2V for the actual LED. There are some really poor LED power supplies out there. I was once on a boat where the "LED" light fixture was hotter than the incandescent one. I assume that it drew more power, too! That must have been one terrible power supply design!

[OldManMirage]

Originally Posted by tenchiki

To be very picky, LED light fixtures (and replacement bulbs) are electronic devices, not electrical;

That is definitely very picky.

And I should mention that the fixtures are dual LED type, so it was 2 bulbs running as I was checking. So that sounds about right.

And they are (gasp!) RV type fixtures, not bonafide (read cost 3X as much) marine ones. So there's that too.

But they work, I'm not going to be changing them anytime soon.

[GordMay]

I would expect a typical Double LED Light Fixture [20+ LEDs, 250 - 285 lumen output, roughly equivalent to 20-25 Watt Incandescent] will draw about 260 mA [>1/4 A] of current, consuming about 3.1 Watts of power, @ 9-14.5 VDC.

[sailorboy1]

I found that for the most part my fans and LED lights used so little power it was hard to determine

[Baronkrak]

Originally Posted by GordMay

…consuming about 3.1 Watts of power...

Really?

[wholybee]

Originally Posted by GordMay

I would expect a typical Double LED Light Fixture [20+ LEDs, 250 - 285 lumen output, roughly equivalent to 20-25 Watt Incandescent] will draw about 260 mA [>1/4 A] of current, consuming about 3.1 Watts of power, @ 9-14.5 VDC.

Originally Posted by Baronkrak

Really?

Absolutely. On my boat, most LED cabin lights (inexpensive from WM use only 20mA. The brightest about 750mA. That 750mA fixture is a Marine Beam 19" dual tube to replace dual fluorescent tubes with 120 individual LEDs. It is crazy bright and could be used to light a large outdoor space. When cooking I want my galley BRIGHT.

250mA is right in the middle where most good LED's fixtures should be

I don't think there is any difference between "RV" and "Marine" fixtures. I doubt there is even a price difference.

[Baronkrak]

Originally Posted by wholybee

Absolutely...

So how much power will be left after 1 hour of use?

[silvercreek]

One thing I noticed is that LED lightstrips, consisting of dozens or even hundreds of individual LEDs, draw a shocking amount of power. On our vessel, which uses these lightstrips in the ceiling, under the cabinets, and along the floor, the lights can consume over 10A alone.

[Nicholson58]

Originally Posted by tenchiki

To be very picky, LED light fixtures (and replacement bulbs) are electronic devices, not electrical; they have a power supply to convert from 12/24/120v to ballpark 1-2V for the actual LED. There are some really poor LED power supplies out there. I was once on a boat where the "LED" light fixture was hotter than the incandescent one. I assume that it drew more power, too! That must have been one terrible power supply design!

Cheap, especially automotive replacements, use various simple converters to achieve the proper forward current. Linear and buck resisters consume most of the savings you thought you would get with LED. Search out only PWM, pulse width modulation. Within limits, LEDs tolerate higher voltage than design. What is important is the forward current. This is controlled by switching the current on and off at high frequency and modulating the ratio of on vs off time. The resultant current is regulated no mater the input voltage. PWM bulbs will permit variable input voltage. For marine use that might be 9 to 32 for example. This system has no wasteful resistor circuit and consumes the least power. Good PWM bulbs also have a rectifier input bridge so polarity is not an issue. I had extremely good PWM bulbs that could be installed in an AC 110 volt socket. The rectifier switched the AC to DC and the PWM controlled the current. I have 60 PWM replacements in our ceiling fixtures and the total current draw is too small to worry about.

Marketers of these among others are: IMTRA, Marine Beam. Watch out for all automotive bulbs and even many chandeliers including We$t Marine carry bulbs labeled 12 volts. These are not PWM.

https://store.marinebeam.com/led-replacement-bulbs/

If you happen to have the marine DC fluorescent fixtures Marine Beam has LED strip festoons as replacements. They are bright and fantastic.

BTW, they also sell great fixtures and Navigation replacements. In the Caribbean, it’s easy to spot aftermarket LED anchor and navigation lights. They are far brighter than IC.

[leecea]

Originally Posted by Baronkrak

So how much power will be left after 1 hour of use?

Even a small battery could have 50 amp-hours available before the battery was too low. In the example it was stated that the lamp consumed 1/4 amp. If you ran that for 1 hour you'd use 1/4 of an amp-hour, which is negligible.

You're likely to be using a lot more power for other things.

[Baronkrak]

Originally Posted by leecea

In the example it was stated that the lamp consumed 1/4 amp.

At what voltage?

[CarinaPDX]

Stay far away from RV LED fixtures. A friend with a nice, relatively new travel trailer was having trouble with his lights. It turns out that the fixtures had LED clusters in them that were driven by series current limiting resistors, which are energy wasters but also lacked voltage regulation - which makes them vulnerable to higher voltages. His fixture was an old design, as many RV fixtures are, and it had sockets for incandescent bulbs, so replacing the clusters with proper regulated ones was easy. While RV products can be both useful and cheap, don't count on marine quality.

Greg

[Nicholson58]

Originally Posted by CarinaPDX

Stay far away from RV LED fixtures. A friend with a nice, relatively new travel trailer was having trouble with his lights. It turns out that the fixtures had LED clusters in them that were driven by series current limiting resistors, which are energy wasters but also lacked voltage regulation - which makes them vulnerable to higher voltages. His fixture was an old design, as many RV fixtures are, and it had sockets for incandescent bulbs, so replacing the clusters with proper regulated ones was easy. While RV products can be both useful and cheap, don't count on marine quality.

Greg

Totally correct! Please read my post above somewhere. I describe this in detail for anyone who would like to understand the technology. Find links to marine type units using PWM current regulation.