Voltage divider circuit??

[llldks]

On my 53MY, my 32 volt anchor light and white running lights are relatively dim. Ideally I would like to convert them to LEDs but haven't found 32 volt LEDS. Does anyone have a source?

I stumbled across a site which described a "voltage dividing circuit" which looks like 2 resistors in series with the load parallel with the second resistor. Using the calculator on the site, 32 volts to a 10 ohm resistor in series with a 6 ohm resistor would give 12 volts to a load (12volt led) wired in parallel to the 6 ohm resistor.

Are there reasons for not doing this for each light??

Thanks, Larry

 

[SEVEN]

I used those in both engine rooms and added 12 volt LED strip lights. I tapped into 32 volt existing lights and stepped down to 12 volt. FYI you need to keep the 32 volt lights in place. If you remove them from the socket it will not work.

 

[SEVEN]

Here is what I used.

 

[llldks]

Is the necessity for the old bulb being in the old socket to complete the negative circuit return to the 36v batteries? If so, could I splice it out? I wouldn’t be able to fit two light sockets within the fixture.

Thanks

 

[SEVEN]

I believe it is but never checked that out. All I know is if the bulb blows or I remove it l, the LED will not power up.

 

[Photolomy]

Two resistors in series is a voltage divider, but they are not used to supply power. They are generally used in very low current situations to change signal voltages.

In your example, 10 ohm + 6 ohm would give a total resistance of 16 ohm, and 32/16 = 2 amps of current. And then 2*10 = 20 volts, and 2*6 = 12 volts.

However, that changes once you add the light across the 6 ohm resistor because now it is in parallel with the 6 ohm resistor and the total resistance of that part will be less than 6 ohms. Assuming you figure out what the 6 ohm resistor should be such that it plus the light ends up to be 6 ohms total, the second issue is power. 2 amps at 32 volts is 64 watts of power, and 40 of those watts are being consumed (and wasted) by the 10 ohm resistor (20 volts x 2 amps), leaving you with 24 watts for the light. As you can see, this is super inefficient as a power supply.

Also, the resistors you generally see are 1/4 watt resistors. A 40 watt resistor is much more robust (because of heat).

Resistor voltage dividers are not used for power supplies. They are used for very low current signaling applications. For example, to change 32 volts to 12 volts I would use a 10k and 6k resistor. Note, 1000's of ohms. The total current in such a circuit is only 32 / 16000 = 2 milliamps. Too small to drive a light, but more than adequate to drive a measurement or the input to some device that requires a 12 volt "signal" rather than 32 volt.

Buck converters are the choice for low voltage DC to DC voltage step downs.

 

[Photolomy]

Regarding lights in parallel versus in series. If you want to use the original light switch to power your light, without much modification, then you wire it in series with the old light, but the issue then is if the old light burns out, your light will not work. I ran into a similar issue with my TV in the master. I wanted to use the 120v that the ceiling lights used, because the light switch was right where I wanted to put the TV. But that switch is actually only one side of the circuit. For current to be flowing, the switch (and the light) have to be on. A power receptacle on the other hand doesn't have this issue, because both sides of the circuit are wired to a power receptacle.

So, to have the single (original) ER switch power two lights in parallel (so that if one is out the other stays on), you simply need to tap one side of your 12 volt buck converter + light into the wire going to the original engine room light, and run a second wire from your 12v light to a ground, which by the way is just on the other side of the original light. Now your light is in parallel, not in series.

 

[davidwigler]

Here is what I used.

I used a similar buck converter. Installed it in the DC panel after the navigation breaker and then replaced the nav, anchor and running light bulbs with LEDs. Works great.

 

[llldks]

Will explore the buck converter for my application. Thanks for the help-larry

 

[Westfield 11]

Norman lights has 32v LED anchor lamps for $6.50. P/N LED-3KDC-38v, plug and play. They have lots of other lamps too, just call them directly.

 

[Westfield 11]

Sorry, that’s Norman Lamps, not Norman Lights.