Car lamp bases / LED replacement?

I was going though some stuff last night and came across an old Sealey

12V lead light a mate (who had his own car repair garage) gave me, like this:

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After testing that it works, I cleaned it up, fitted a new lead (it had been cut short) and crock clips and noted the lamp was a frosted incandescent type, 12V/24W.

I have actually used it when working on the car at his and liked it because it has a very strong clip and a strong ball joint thing so could be pointed where you want (and stayed there).

So, whilst it is all up and working, I think I'd like to look for an LED lamp replacement, basically to save power but am having difficulty pinning down what that might be.

It's a 15mm diameter, non-offset pin, twin contact (<that's the bit that seems to make it more complicated), bayonet lamp and I'd like an LED that has 'all round' illumination like the original incandescent lamp, so you get a nice general light, rather than a beam.

I think I have found a suitable lamp:

LED Lamp S8 BAY15D (MCS8Y15D16NS30DCW) ... but they seem quite expensive and often from

... but if I knew how to accurately describe that particular base, it might help me pin it down?

Is it a P21W / R335 as that doesn't seem to help or is there a more common name for them please?

Cheers, T i m

Reply to
T i m
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If you need a better price, pump that part number into Google. I know in the past, those LED replacement bulbs had ridiculous pricing. Try a local auto parts store, and check the "ricer aisle" for LED bulbs like that.

The datasheet I got for your part number, isn't exactly very good. But that's all I can find for it.

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- the LED might overheat, if there is a globe cover over the whole assembly. For the number of service hours this application will receive, it won't matter.

- the light output might not be uniform with respect to direction. More light from the side than the end. In a car light assembly, the reflector and diffuser fix this.

- the lamps with LED filament chains might be no more robust than an incandescent, when you drop your inspection light. The product above appears to use discrete LEDs which are likely sitting on a flat substrate.

A proper datasheet for a product like that, should stretch to about 30 pages in the PDF.

Paul

Reply to
Paul

Sounds like a standard car SBC. Although more commonly single contact as with a indicator bulb. Twin contacts usually twin filament.

They've probably done that to force you to buy spare bulbs from them, rather than 2 for a quid at Halfords. Although cars are now 19w rather than the older 21w - 24w not common.

Much older cars sometimes did have two contact SBC single filament bulbs. But LED replacements for them not common, I'd guess.

Possible to remove the base from your old bulb and fit a suitable led cluster to that? Or change the bulb holder?

Reply to
Dave Plowman (News
<snip>

<snip>

I looked though this one:

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But it still wasn't clear if there was a code that described that base (with two connectors and one filament) exactly?

Yeah, I did that but didn't find anything (other than the one I linked to) and as you say, often quite expensive. Well, I found one that was affordable but the P&P from the USA wasn't. ;-(

Trying to avoid bricks-n-mortar places atm (but I would normal do as you suggest). ;-)

Noted.

I was thinking that most 'car lamps' are running in a similar sized enclosure?

Hopefully.

No, that was one of the 'worries', compared with the frosted incandescent 'globe' that is in there now.

That shouldn't be a problem (and might even be an advantage), given there is a basic reflector in there.

This one has a reflector (of sorts) but no diffuser, relying on the lamp in the std design.

Agreed.

Well, I just need to know a few bits of info and you would have thought 'fundamental' points, re how it was wired might be a one of them? ;-)

Something that has since come to mind though ... a 'what if' ... ;-)

The lamp holder is fairly substantial metal (not needed as such as the connection is just via the base connections) and on an even more substantial metal disk that sits in a groove in the clamshell 'handle'.

The two contacts to the lamp base are made by nicely engineered screw terminals ... so, if I was to use an easier-to-find dual filament lamp (say a stop tail) then I could re-wire the unit so that the ground is on the lamp base (as normal by drilling and tapping for a small machine screw or a small nut / bolt though the flange with a pear-shaped-tag) and re-wire the lamp holder to give the 5W on all the time (when connected to 12V) and then the 21W on (as well) when it's turned on at the rocker switch.

Or ... replace the SPST switch with a SPCO, so I can swap between lamp sides (21/5W), if that might make the lamp last longer if both 'sides' aren't on at once (you would normally only have the side lights on continuously and the stop occasionally) or if I can get a SPCO with centre off, have a filament on each side of the switch and could also turn it off with the switch (a bit like a dual heat hot air gun)?

You could go further and mount some SM LEDS / Cree modules directly to the disk but I'd like to keep it as standard as possible. ;-)

Cheers, T i m

Reply to
T i m
<snip>

Possibly. ;-)

No, I'd not seen one before?

Ok.

Well, as I've replied to Paul since, I had a 'what if' along those lines and assuming the pin spacing / orientation is 'stock'. for something more common, I could re-wire it so that the base is earth and then could feed the two filaments as you might with a stop / tail.

So it's just a matter or finding a suitable (LEDS facing straight out and sideways) LED lamp and giving it a go.

Would you think running stop / rail together would impact the life span much Dave?

Cheers, T i m

p.s. I'm thinking with a LED lamp, this could be an inspection light and a general purpose emergency light that could be attached to one of my several 12V LA batteries. ;-)

Reply to
T i m

B15d, aka BAY15d, as in

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and there the spec drawing of the base.

Thomas Prufer

Reply to
Thomas Prufer

Assuming the holder makes it possible to wire to the base. It could be plastic (or a brass sleeve in plastic)

Most car replacements are like that, as the original tungsten made use of a crude reflector.

Interesting point. Things like rear fogs can use a 19 watt SBC, and they could be on for quite a time, rather than stop lights, etc. You'd expect a tail light to have a good life.

Reply to
Dave Plowman (News

It's possible the two pins are (+) and the shell is (-). You have to current steer, or current share, or do something with the two pins, to drive the chains of LEDs and give a pleasing light pattern.

One mystery with some of this stuff, is what is the semiconductor other than the LEDs and resistors for ?

The only thing I could figure, was a zero-bias FET as a constant current source. But that never makes sense because these zero bias FETS, the current flow was way too low for usage with LED arrays. You can do zero bias FETS with a single LED, as that's enough for a pleasing light level with a cheap T-1 3/4 LED.

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Your lamp product appears to have a 10V (four white LED) to 30V range. I don't know how that's possible, while at the same time claiming to be consuming 5W for the lamp function. If there was any sort of current limiting linear function in there, it would be getting hot.

The 16 LEDs could be split as four groups of four LEDs. And the four LEDs in a group, could have 10V across them. OK, now, how do we connect those four chains of LEDs together ? Four chains in parallel ? Or some other arrangement ? And operating off a car battery, that's not really a well regulated source as such. If you were to jam the field winding, the automotive bus voltage goes up to 18V. So any LED lamp has to withstand at least 18V. The other specs for automotive situations involve pulse patterns (load dumps) at much higher voltages.

If the lamp was larger, we could assume there was an SMPS in the base. That would solve a lot of problems.

Paul

Reply to
Paul

I thought that was the case but it doesn't seem to specify the number of connections?

The picture seems to suggest there is only one central connector?

Thanks for that but again, I'm not sure if the diagram is indicating there are one or two connections on the bottom, as the view is from a direction that would mask the second connector behind the first?

This is why I was unsure if there was a formal designation for this base and wiring (two connections, one filament and not using the metal of the cap as a (ground) connector).

eg, The layout of this is more like a mains powered bayonet lamp

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I might be able to get a single element lamp to make contact with either / both of the two contacts or if I use a twin element lamp, run them individually or in parallel.

Cheers, T i m

Reply to
T i m
<snip>

No, it's very (in comparison with most car lamp holders) substantial metal Dave:

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I have seen some that seem to just face back but unless the LED's were

*very* wide angle, it might work more like a spotlight.

Ah, good point.

Agreed ... just that there seem to be LED lights and LED lights ...

Cheers, T i m

Reply to
T i m

Which is a BA15d

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I assume the relevant fitting.

If you google "BA15d 12V LED" the first hit:

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You will have a selection of spots/lights. One I looked at worked from

10v-30v DC.

But I suspect I'm in your killfile?

Reply to
Fredxx

B15d is bayonet, 15 mm, double B15s is bayonet, 15 mm, single (t triple, q uadruple, , p penta/five)

A is for automotive, Y yellow (though this rule seems often ignored).

And BAY15d may have different-height pins, with two base contacts and case for ground, for double-filament automotive lights that need a single mounting orientation (brake & running light, I think is one...)

Thomas Prufer

Reply to
Thomas Prufer

There are offset pins (height wise) for the older stop/tail bulb. And then a different offset (not 180 spaced) came in for others - like amber flasher bulbs.

Reply to
Dave Plowman (News

Why is is that cars always seem to use the dual-filament bulbs for tail/brake, with a separate bulb for rear fog lights? Given that tail and fog lights serve the same purpose, of defining the presence and width of the vehicle as seen from behind, it would be better if clusters were designed to have tail/fog on the dual-filament bulb and a separate light for brake.

Reply to
NY

Ah, thanks for the explanation Thomas. ;-)

;-)

Ok.

Understood. As mentioned in my OP, the pins aren't offset (in either orientation) but I don't know if there is also a height standard / range for the non-offset pins?

At least that gives me a bit more info to search for options.

Cheers, T i m

Reply to
T i m

At a guess, tail and brake are older and more standard. Rear Fog are comparatively modern and therefore an extra.

Reply to
charles

There also seems to be 1156 and 1157 that is supposed to refer to the pin orientation but getting all that to line up Bay15D 1156 (< supposedly non offset pins) and a single filament wired across both terminals and not terminal to base *and* with the LEDS facing all ways and at a reasonable wattage / light output, seems quite an ask. ;-)

I may have found such on ebay and I've asked for confirmation of fit in general, wiring and wattage.

It sorta suggests it's polarized and if it is I can stick a blocking diode in there or bridge (single diode less lossy), in case I or someone connects it up backwards.

Cheers, T i m

Reply to
T i m

Probably history, as cars had stop lights well before rear fogs. But not all did as you say anyway - not even all Lucas.

Reply to
Dave Plowman (News

If a car bulb, it will already be protected against reverse connection.

Reply to
Dave Plowman (News

They might now but at one time a single fog light was allowed. The rear light clusters having that single fog on the (off?) side and the reversing light in the same position on the (near?) side.

Reply to
Dave Liquorice

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