6 Volt fixtures - 12 Volt battery

[madjack]

Hmmm... Sometimes the best answer is just so obvious we overlook it?

Like a $ 0.20 resistor?

Bad Boys Ravish Only Young Girls But Violet Gives Willingly...or something rather similar....................

[bdosborn]

Hmmm... Sometimes the best answer is just so obvious we overlook it?

Like a $ 0.20 resistor?

Bad Boys Ravish Only Young Girls But Violet Gives Willingly...or something rather similar....................

Bad Booze Rots Our Young Guts But Vodka Goes Well.


Bruce

[bdosborn]

Hmmm... Sometimes the best answer is just so obvious we overlook it?

Like a $ 0.20 resistor?

A simple voltage divider circuit will work but there's better solutions. The problem with the divider circuit is that LEDs are *very* sensitive to voltage. So what's the starting voltage you divide? Its going to vary from 12V to 14.3V, depending on the battery charger you use. I biased some LEDS for my truck at 12.7V and they burned out really fast when the truck was running and the voltage was at 14.4V. I biased them for 14.4V and they weren't very bright. The voltage circuit I posted a link to will give you a steady voltage, no matter how the input varies, so you get the most life and brightness out of the LED.
Bruce

[Podunkfla]

Hmmm... Sometimes the best answer is just so obvious we overlook it?

Like a $ 0.20 resistor?

A simple voltage divider circuit will work but there's better solutions. The problem with the divider circuit is that LEDs are *very* sensitive to voltage. So what's the starting voltage you divide? Its going to vary from 12V to 14.3V, depending on the battery charger you use. I biased some LEDS for my truck at 12.7V and they burned out really fast when the truck was running and the voltage was at 14.4V. I biased them for 14.4V and they weren't very bright. The voltage circuit I posted a link to will give you a steady voltage, no matter how the input varies, so you get the most life and brightness out of the LED.
Bruce

Yep... That's why I suggested just using the auto LED bulbs they make to replace 1157's with. I use them on motorcycles a lot... and the turn signals wouldn't work right because the resistance was so low. They sell a simple voltage stablizer for bikes for about 15 bucks that works great... It would work fine for a tear too. I'll try to find the link where I bought mine.

This outfit has lots of LED stuff... Kindy pricy tho... You can usually find the same stuff on ebay for a lot less. Good place to see what's available though... http://www.customdynamics.com/

[bdosborn]

I'll try to find the link where I bought mine.

I'd like that. I'm having an issue with the LEDs in my reading lights. They're not lasting as long as I would like so I was going to put a voltage regulator in. I wouldn't mind buying one instead of building one.
Bruce

[Podunkfla]

I'll try to find the link where I bought mine.

I'd like that. I'm having an issue with the LEDs in my reading lights. They're not lasting as long as I would like so I was going to put a voltage regulator in. I wouldn't mind buying one instead of building one.
Bruce

I checked my files... and the guy I got my LED module from isn't listed on ebay any more? I'll keep noodling around though.

[Gerald_G]

A simple voltage divider circuit will work but there's better solutions. The problem with the divider circuit is that LEDs are *very* sensitive to voltage. So what's the starting voltage you divide? Its going to vary from 12V to 14.3V, depending on the battery charger you use. I biased some LEDS for my truck at 12.7V and they burned out really fast when the truck was running and the voltage was at 14.4V. I biased them for 14.4V and they weren't very bright. The voltage circuit I posted a link to will give you a steady voltage, no matter how the input varies, so you get the most life and brightness out of the LED.
Bruce

Thanks for the circuit diagram Bruce. That's exactly the kind of input I was looking for. I did not want to build a resistor divider, becuase I also did not want to simply waste the power converted to heat that a resister basically does. Looks like the 317 curcuit should be efficient.

All that said, I was at my RV repair place Fri, and my friend at the place, showed me some new old stock reading fixtures that were too good, and too good of a deal to pass up. They take 1156 or 1141 bulbs, which mean I can simply put in the LED bulbs as suggested above.

I wired them in and mounted them tonight.

Pics provided (of course).

Gerald

[GreatPumpkin]

I realize a couple things...
1) This is a very old thread
2) There is a simple (alternate) solution

Disclaimer - Yes, I have tried the search function - hence the old thread...

But, here goes anyways

I acquired some pretty neat "eyeball" lamps by removing them from some commercial emergency lights.

I plan on utilizing the swivel "eyes" from the units. I've already disassembled them, so I know they will work how/where (placement) I want them to. I am placing them in an overhead shelf for lighting the interior of my tear, and the swivel function will make it nice to direct them and also be able to use it as a reading light.

The bulbs are MR16C rated 6V 5W.

Can I easily convert my 12V to 6V to power these lights? or, Will they run on 12V without doing anything else to them, or will that just burn out the bulbs?

The simple alternate solution would be to just change the bulb to a 12V. The MR16 is a pretty common bulb and available in a wide assortment of voltages (and price! ) I've found 12V versions for as much as $12 each, to $12.95 for 12 on Amazon. That is for a 12V 35W version. So that would be just under 3 amps per bulb, which brings me to the second half of my question:

I'm running these on 16G stranded wire (part# 151600 http://www.gocsc.com/pdf/CCcableMC_NS.pdf ) The run is only about 8' so there would be very minimal voltage drop. There will be nothing else on this particular circuit. Research indicates a wide range of "facts" or opinions on the amperage a 16 gauge will safely run - ranging from 18-24amps quoted (10' run) which is well over what I plan on putting on it.

Am I within safe parameters with this combo?

KISS principle says just buy new bulbs, but I have acquired a lot of these 6V bulbs (free!), so KISS also says use them if I can without making it too comlicated...

Your thoughts?

[Leon]

If you wire them in series you can run the 6v bulbs on 12v but both will be on or off at the same time. Otherwise change the bulbs to 12v.

[Shadow Catcher]

Like a $ 0.20 resistor?

Which does away with the value of the LED in power consumption.
There are 12V puck lights e.g. http://www.vintagetrailersupply.com/12V ... ts-816.htm

Or http://www.cabelas.com/cabelas/en/templ ... stid=69501 for ~10$

Or do what I did and find fixtures that take a standard bulb and switch

[Leon]

Maybe I read it wrong but he said he has MR16C bulbs which are not LED.

[eamarquardt]

Using two six volt batteries in series to get 12 volts is common practice but for otimum life they should be subjected to the same loads and charging. If you tap into the circuit to get six volts and run them down unequally, charge them with a single twelve volt charger, they will be charged unequally (as the same current will be going through all cells) and one may be undercharged and the other overcharged.

Here's a site that details how to add a resistor to the circuit to limit the current and ensure that each LED gets the proper voltage:

http://white-leds.co.uk/led-wiring-guide.htm

You could measure the current your fixture uses when on batteries (a small digital meter would work) and calculate how much resistance to add with Resistance=Voltage(6 Volts)/Current. Then multiply the Current and Voltage to get the wattage rating of the resistor you'll need. Typically a 1/4 watt resistor will suffice for single series circuits.

Cheers,

Gus

[GreatPumpkin]

Yes, I have MR16 bulbs, NOT LED's.
Resistors were previously mentioned, but you're losing the excess energy thru heat loss correct?
I know that wiring two 6V batteries in series will produce 12V, but am I understanding correctly that wiring two 6V lights in series will work on 12V?
All things considered, I guess just replacing the bulbs will be the best way to go. I've already started the shelf and light install. Tested the lights out on the small 6V batteries that came in the Emergency lights. Two of these swivel light heads light up the trailer fine. I think I may end up with 3 - One pointing up to light the entire trailer, and two pointing downward for reading lights. I'll get a picture posted soon