dropping voltages

[mattysupra]

Hi, i would like to check im correct here as been a fair few years since i left school.


If i have 24v supply (dc) and i wire 2x 12v bulbs together they will be fine?

so i take the positive from battery and wire to positive on light. The negative on light i take to positive on the other light and then its negative back to battery? is that correct?

wiring in series i think its called??

 

[Iggifer]

you can wire them in series if you want to but I'd wire them in parallel personally (depends on the purpose though)

Parallel

Series

 

[Taylortwocities]

Yes.
But the problem with wiring lights in series is that
1. they both go out if one lamp fails
2. the wattage of the lamps need to be the same or the voltage across one lamp will be more and the other will be less than your 12v target.

Better to get 24v lamps and wire them in parallel.


Curses, too slow

 

[Iggifer]

Curses, too slow

 

[ban-all-sheds]

you can wire them in series if you want to but I'd wire them in parallel personally

You'd connect a 12v lamp to a 24v supply?

Not the best of ideas.

 

[ban-all-sheds]

This has reminded me - I never did do this:

//www.diynot.com/forums/electrics/im-tempted.298317/

I should measure the cold resistance before I try though...

 

[mattysupra]

you can wire them in series if you want to but I'd wire them in parallel personally (depends on the purpose though)

Parallel

Series

i cant wire them parallel can i ? they are 12volt bulbs with a 24volt supply?

 

[mattysupra]

Bit more info of why im thinking of doing this.


Its a 20 year old boat with 20 year old fittings but the fitting are like new condition. Some of the bulbs have gone and i have had a look around for replacement bulbs but they don't seem to be available any more in u.k. I found some in America but they want £115 per bulb !

So i either change the whole fitting and bulb which i have found fittings for £12 quid with a bulb but they are smaller fittings. I cant find fittings the same size which is also a issue.

Also i would prefer LED bulbs as they are a lot cooler than the halogen bulbs and take less power i understand? The power bit im not over worried about but as i have a small child that can reach the light fittings when he is stood on the bed i don't want him burning himself on the halogen bulbs.

Hence i have found LED bulbs that fit the original fittings but they are 12v .

Does that make sence?

 

[Iggifer]

i cant wire them parallel can i ? they are 12volt bulbs with a 24volt supply?

Yea the detail I missed off that TTC did include was to swap them for 24v lamps

 

[ericmark]

There are droppers to change from 24 volt to 12 volt sold in the main to run a CB in a wagon cab. However I remember as a 6 year old sticking two 6 volt bulbs across my model train track and when one failed I replaced it with a bulb of a different wattage which caused it to blow.

I don't know what the bulb base is but I did a google for "24 volt BA22d bulb" and got ebay bus bulb 36W 24V at £2.95. I do think the problem is often finding the right phrase to use in google. Also referred to as Railway bulbs.

I was quite surprised at what I found even reversing beepers built into LED bulbs for use with trailers clearly you don't want it beeping at you but think it unlikely the 24 v bulb is no longer made.

Tell us more I am sure some one on here will point you to a bulb at reasonable cost.

 

[bernardgreen]

This company may be able to help. They do a range of LED lamps with a wide imput range of 10 to 30 volts

http://www.boatlamps.co.uk/contents/en-uk/d66.html

worth a browse around.

 

[mattysupra]

the bulbs are made by osram. I have left the bulb at work so not sure here but they are i think 20watts with the same pins on the back as 12 volt downlighters. They are downlighters but with a strange black cap that covers the bulb.

I will see if i can find them again.

 

[mattysupra]

just been searching ebay and i think i have found the same bulb but MUCH cheaper than i found before.

Again from USA but around £15 a bulb and £27 postage i think it was. Still a lot of money for a bulb.

Anyone know a LED replacement for these - http://www.ebay.co.uk/itm/Osram-419...371?pt=LH_DefaultDomain_0&hash=item4d0a996b13


Also now i have a part number from the ebay listing i found as cheap as £6.99 so im happy with that.

but would still prefer a led replacement if anyone knows of one?

 

[Iggifer]

not LED but cheaper than £6.99

http://www.cp-lighting.co.uk/M107-41930SP-24V-20W-AR48

 

[securespark]

International lamps worth a shufty.