12v led bulbs will not work ... why?

[djw]

I have 4 identical 12v led bulbs, that are 15d type ie both contacts are on the base. They are cheapies from ebay .... Hong Kong.

Each one blows the fuse when I connect them and spark. I have connected them directly to a separate12v supply, they just spark on contact.

Am I doing something wrong? I have connected the contacts the opposite way .....same result.

Any ideas before I bin them!

 

[elton]

Perhaps they require an external resistor or a current controlled power supply?

 

[lw395]

Sounds like they are faulty.

 

[Capt. Clueless]

I had a not too dissimilar problem yesterday when re-wiring my boat & fitting new 12V LED strip as the old lights would not work. Luckily, I had my trusty multi tester with me to trace back a problem. It wasn't that they sparked, it was just that they just would not work (and the original lights didn't either). The previous owner had cocked up the wiring. However in your case, you appear to have power. Presuming that you are putting in new "bulbs" (or lamps as they should be termed..bulbs you put in the garden. I had that beaten into me some time ago), you must have taken the old lamps out of the fitting? What were the originals you took out? Can you post pics of the old & the new?

 

[JumbleDuck]

I have 4 identical 12v led bulbs, that are 15d type ie both contacts are on the base. They are cheapies from ebay .... Hong Kong.

Each one blows the fuse when I connect them and spark. I have connected them directly to a separate12v supply, they just spark on contact.

Am I doing something wrong?

Yes. Buying cheapies from Hong Kong.

Yours helpfully, JumbleDuck

PS My guess is that they are actually 15S's with the two base contacts wired together. Try one base and the side ...

 

[djw]

The led bulbs look this http://www.ebay.com/itm/2X-Xenon-Wh...RV-Car-LED-Light-Bulb-1142-1076-/400931207469

With the twin contacts on base. The old one is from the cabin lights. It is about the same size but not led and works, so I know the wiring is ok.

 

[elton]

The led bulbs look this http://www.ebay.com/itm/2X-Xenon-Wh...RV-Car-LED-Light-Bulb-1142-1076-/400931207469

With the twin contacts on base. The old one is from the cabin lights. It is about the same size but not led and works, so I know the wiring is ok.

Does the old one have two contacts in the base? Does the socket have two contacts in the base?

If not, that could point to the problem.

 

[ghostlymoron]

I've got one that looks like that. Bought as an anchor light. It didn't work in my two contact lamp holder but did if I connected positive to BOTH bottom pips and negative to the side.

 

[prv]

My guess is that they are actually 15S's with the two base contacts wired together. Try one base and the side ...

That certainly fits the observed facts. By applying 12v across the base, you're simply short-circuiting your supply.

Pete

 

[djw]

The 2 contacts on the base are the same as on the old bulb.

I am going to connect one wire to the side and one to the base and see what happens .... it certainly makes sense!

 

[CJU]

I had a not too dissimilar problem yesterday when re-wiring my boat & fitting new 12V LED strip as the old lights would not work. Luckily, I had my trusty multi tester with me to trace back a problem. It wasn't that they sparked, it was just that they just would not work (and the original lights didn't either). The previous owner had cocked up the wiring. However in your case, you appear to have power. Presuming that you are putting in new "bulbs" (or lamps as they should be termed..bulbs you put in the garden. I had that beaten into me some time ago), you must have taken the old lamps out of the fitting? What were the originals you took out? Can you post pics of the old & the new?

So did I 'lamps glow, bulbs grow' must be ex GPO.

 

[djw]

Yes, they work. Positive on base, negative on side! Certainly not what I was expecting ....

Unfortunatelt that is not what I need because of the bulb holder. I need one contact on base negative and the other positive.

Any idea what these are called? Can any one send me a link to any please?

 

[JumbleDuck]

Yes, they work. Positive on base, negative on side! Certainly not what I was expecting ....

Unfortunatelt that is not what I need because of the bulb holder. I need one contact on base negative and the other positive.

Any idea what these are called? Can any one send me a link to any please?

What you need are 15D (15mm diameter, Double contact on base) and what you have been sent, as I guessed - preen, preen - are 15S (15mm diameter, Single contact on base) internally, but with two connected contacts on the base.

What you do now is go to www.boatlamps.co.uk and buy the right thing from a helpful forumite. I am only a customer, but a happy and repeat one.

If the pins are level it's http://www.boatlamps.co.uk/contents/en-uk/d182.html and if they are staggered it's http://www.boatlamps.co.uk/contents/en-uk/d183.html

 

[VicS]

Wot JD sez.

I was going to post a link to this page which compares the types of base http://www.boatlamps.co.uk/contents/en-uk/d181.html

 

[djw]

Thanks all .... I will get the right one now

 

[Aeolus]

Out of curiosity, is there a rational reason for a far-eastern factory to produce lamps that look like 15D but are wired as 15S?

 

[JumbleDuck]

Out of curiosity, is there a rational reason for a far-eastern factory to produce lamps that look like 15D but are wired as 15S?

General fiendishness, I imagine.

 

[Adrian Jones]

Out of curiosity, is there a rational reason for a far-eastern factory to produce lamps that look like 15D but are wired as 15S?

I think there is a simple answer, the lamps are designed for use in a vehicle combined tail brake light. The lamp will have two light level outputs with each level activated by connection of 12v +ive to the bottom contacts. The -ive is connected to the lamp cap case.

Regards

 

[ghostlymoron]

You can get 15Ds off eBay if you shop around and ask the right questions. Boatlamps have a good reputation but are a lot more expensive.