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Running LED Bulbs in Series

Can't seem to find an answer on this one......

I have a Delco-Light 32 volt plant and several boxes of antique 32 bulbs....swell. The only problem is that once they burn out, modern replacements are kind of expensive so I'm looking to upgrade to LED bulbs instead. Longer life and insignificant current draw.......except 32 volt LED's are expensive too!

Now, there are 12 volt LED's available for RV's with a standard Edison base that are affordable. An old trick among the 32 volt crowd is to run three 12 volt incandescent bulbs in series, in order to demonstrate their light plant. But........would the same stunt work with LED bulbs?

I'm just not sure on this one, as a standard incandescents makes a dandy current limiter. But would an LED perform the same way?
 

PLCtech

Registered
Re: Running LED bulbs in series........

I'm not a light plant expert. I would think an LED driver of the 10-30V input wouldn't care what voltage it received from your light plant. But it wouldn't have the resistive properties to affect the current. You may need a resistor.
 

Vanman

Subscriber
Last Subscription Date
06/10/2020
Re: Running LED bulbs in series........

I don't think I would consider LEDs to be an "upgrade". :brows: I think three 12 volt bulbs in series is perfect. They'll look great, and last a long time.
 

I like oldstuff

Registered
Last Subscription Date
11/09/2015
In a word, no.

Incandescents are merely a wire that's heated.
LED's are a diode and each one requires a hot and a ground. They won't work in series.

So get some old school wire types and have fun with your toy. Automotive headlights, tail light bulbs or whatever. Hook em in series and have at it.
 

pegasuspinto

Registered
LED's work fine in series, it's how the new LED light bulbs are made.

The 120vac lights usually have a small switching power supply and multiple strings of LED lamps in series. Because it's a switching supply, they will work on AC or DC and often they will work on much lower voltages then designed.
 
Just got back to the forum right now........and in the meantime, got myself an education on LED circuitry. I found out that a DIMMABLE LED will work...sometimes. Depends on the brand, and since I can't see buying several different brands to see which one works I'll just stick with my incandescents.

Thank you for the replies and advice!
 

Tracy T

Subscriber
Last Subscription Date
07/16/2019
I dont know exactly what you are looking for, but they make 12 vdc bulbs that have the same base as a household lamp. think portable droplight, you can get them at just about any auto parts store.
 

gnucklehead

Subscriber
Last Subscription Date
07/13/2019
3 x 12V automotive LED's in series should work just fine on 32V, as long as you get the polarity right :shrug:

If not, two might work without an additional resistor (or other current limiting device). Depends on how they are made, will handle a wider range than you might think.
 
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waterloo123

Sponsor
Last Subscription Date
02/08/2020
Can't seem to find an answer on this one......

I have a Delco-Light 32 volt plant and several boxes of antique 32 bulbs....swell. The only problem is that once they burn out, modern replacements are kind of expensive so I'm looking to upgrade to LED bulbs instead. Longer life and insignificant current draw.......except 32 volt LED's are expensive too!

Now, there are 12 volt LED's available for RV's with a standard Edison base that are affordable. An old trick among the 32 volt crowd is to run three 12 volt incandescent bulbs in series, in order to demonstrate their light plant. But........would the same stunt work with LED bulbs?

I'm just not sure on this one, as a standard incandescents makes a dandy current limiter. But would an LED perform the same way?
Place a series resistor with it for safety, as to not burn up your LEDs. I think you'll find each assembly has a dropping resistor in it already though, so you should be able to series them.
 

waterloo123

Sponsor
Last Subscription Date
02/08/2020
In a word, no.

Incandescents are merely a wire that's heated.
LED's are a diode and each one requires a hot and a ground. They won't work in series.

So get some old school wire types and have fun with your toy. Automotive headlights, tail light bulbs or whatever. Hook em in series and have at it.
Look at current flow and get back to me on that!!! They may be diodes, but + to - in series does work. Learned that in 3rd grade.
 

Radiomike

Registered
LEDs can be run in series, lots of mains bulbs do this but they use an electronic driver. I have done it to run some white LEDs from a 12 volt supply with a simple series resistor. It is possible to buy 5 and 10W SMD leds and put them in a old bulb
. Ebay has lots of the SMD chips. This is an interesting Wiki article on LED "filament" bulbs, these are run in series. and a tear down of a cheap filament bulb.
 

Vanman

Subscriber
Last Subscription Date
06/10/2020
I would think that the potential problem would arise if the LED bulbs have drivers in them that would attempt to keep the power output to the lamp’s LED constant across varying supply voltage.

So if you had such lamps in series, as soon as one tries to take a little more current, the voltage across it will drop, and it’ll take more current. Meanwhile, the other one in the series circuit will see a higher voltage, and so will take less current. Obviously not stable!

So while individual LEDs can certainly be operated in series, actual LED bulbs may not work in series.

Keith
 
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Radiomike

Registered
So the cheap type with just a series resistor would be the best choice. Unfortunatly there is no easy way to tell until you try or strip them down.
 

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