Switch Panel Power Consumption!

[samaki]

Hello,

I thought I was being smart last year when I duplicated or replaced most of the lighting (navigation and domestic) on my old sailing cat with LEDs ... until I decided to fit new switch panels as well - this was in order to keep as many circuits as possible separately switched (twelve in all). However, since I wanted to have light indicators on the switch panels to show which circuits were turned on, I now realise that these indicator lights would possibly use up more power than I was saving by using LEDs!

This indeed seems to be the case with a switch panel which I tested. Each indicator light appears to be using about 180mA (they are very bright) - more than most of the LED 'bulb' clusters which are on the interior/domestic lighting circuits!

Is there any answer to this problem since it appears that with a 12V switch panel, even if the indicator lights were LEDs, they might require more than the nominal 40mA in order to make them compatible with a 12V system?

If indeed the light indicators are using 180mA for each switch, then if six or more were on whilst sailing or at anchor then then more than 1A would be required just to power the light indicators on the switchboard.

Presumably, switch indicator lights could be neon - do these use even more current. Any ideas much appreciated.

I am very pleased with the low current requirements of my new LED lights but now I need a way of showing which circuits are on in the dark without using too much electricity! Many thanks.

[Landlubber]

samaki,

Many LED lights run on 12VDC using a 560 ohm resistor. I would be very easy to have a separate circuit for all the idiot lights, and a simple switch to turn them off when not required, such as night time in bed at anchor.

[samaki]

Thanks very much 'Landlubber' - I had been thinking that this might be necessary and wondering how I could do it (I can solder but am not an electronics buff)! First, I have to determine if the switch indicators are in fact LEDs (difficult to see what's inside through the red plastic filter). They look like they might be a single LED but they are very bright which makes me a bit suspiciious - they could be small bulbs - hence the 180mA per switch!

[Ratch]

If the indicator is pulling 180mA and you cannot get to the globe to change it then I think it would be safe to assume they are neon.

Leds are the best choice for a low power consumption indication light and there are ways you can reduce that even further. For example you could use a 1k resistor so you can see it at night but not during the day or if you are really ambitious a light sensor to auto dim the LEDs at night. Another idea is an oscillator that switches the led on/off fast so that it looks constant but draws half the power because it is off half the time plus whatever the oscillator draws.

Oscillators and light sensors are beginners circuits so you should be able pick them up as kits from your local electronics store.

I goggled this and it looks like a good write up on how to wire LEDs http://www.bpesolutions.com/ledcalculator.html

[samaki]

Thanks very much 'Ratch' for those suggestions - things are coming together now! I have spoken to two other sailors on the phone and have received other ideas on fixes which I shall briefly state for others who might be interested or wish to comment upon.

1. I did some measurements and calculations which indicated that the power required to drive the indicator lights was between 2.16W and 2.25W! So this is important to me when I'm at sea at night - thats more than most of the LED light clusters I'm using in the boat.

2. Someone suggested that since the negative bus bar on the switch panels are just to light up the indicator lights they could be switched on as when required eg off at sea and on when alongside with shore power connected up.

3. Panels could be drilled and LEDs inserted which bypass some or all of the existing lights. This sound a lot more difficult and time consuming, however, I should like to use the two new panels I have bought if possible therefor a fix like this would be good if I could do it myself.

4. Maybe I should have a low power panel for use with circuits used mainly at sea and another panel for when connected to shore power.

I'm still open to more ideas and indeed if anyone can recommend decent panels (do not need to be waterproof) with low power LED indicators that are not too expensive!

Thanks again.