RUMCars Forum
General Category => Unusual Microcar Discussion => Topic started by: plas man on August 15, 2015, 03:45:06 PM
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question to all , do LED's stand up to indicator use with constant flashing ?
Reason I ask is the local £ world as some 12 led , 12 volt bulbs 50mm round , the type you put into the ceiling . and with a bit of modification it would fit a Lucas light unit , or use as running lights .
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Have just my band mate, an electrician, and he says LEDs are NOT good for repeated flashes. Shame!
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Is that why they don't use them for flashing Christmas decorations?
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I reckon I have seen plenty of flashing LED Christmas lights, but have no idea how long they last! Perhaps they have a particular type of LED, or perhaps some extra components or circuitry. I do have some flashing LEDs in my bass guitar, but probably not bright enough for indicators.
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Funny ive been playing around with LEDs a lot resently , reason is to bring the power drain down so the charging of the battery is better , I've got a relay that works really well with low led current, I can make you some circuit boards up that you screw straight in to your lights if you like
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I'd take what that electrician said about flashing led's being no good with a very large pinch of salt. They work perfectly well being strobed.
What you can't do is use them in standard indicator circuits with a bi metallic electro mechanical flasher. This is owing to low current the LED's draw from the supply not permitting the unit to work as it should. So you either need to use parallel resistors, which nixes the advantage of the low current draw, or fit an electronic flasher.
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That's probably what Sparky was on about and what I hinted at... a bit more circuitry!
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There's no need to go modifying household units: you can now buy, quite cheaply, many kinds of automotive LED bulbs which will fit straight into the sockets on the car, and put up with vibration etc.
To save on current, I've changed over most* bulbs on both my Bonds, some years ago, and have not yet had to replace a bulb. The reduction in current required has been dramatic.
*The headlamps I've not changed for LED, as I could find only bulbs with multiple LEDs in a large cluster - not able to replicate the "point source" of the filament, and therefore giving a hopelessly unfocussed spread, rather than a beam.
One Bond owner, though, recently showed me some single-LED headlamp units which he'd fitted to his 6V car. One upward-facing LED comes on for "dip" (the beam heading downward after being reflected), while a second, downward-facing, LED also comes on for "main". The lights looked bright, but I'm waiting to see how well they work at night.
LEDs make good indicators, as they come on (and go off) very much faster than an incandescent filament heats up and cools down. This gives a starker, more noticeable flash. (In brake lights, the quarter-second difference is worth 11 feet at 30 mph - perhaps the difference between the following car pulling up behind you, or inside your boot!) However, because the LEDs take so much less current, it's not enough to trigger the correct flashing rhythm in traditional flasher untis. If you move over to LED flashers, you also need to change the flasher unit for an LED-compatible one.
Addendum: Oops, I see that AndyL made that last point while I was typing!
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To give you some idea of longevity of LED's. We fit them in railway signals, they've been in over ten years now, and they're on 24/7 in fairly harsh conditions. Relatively few failures and no replacements. When we still used filament lamps, relamping was common, even with 12 weekly maintenance intervals.
In a car, you should expect them to last for a lifetime and possibly beyond.
LED's are about five to seven times more efficient than filament lamps, so you will save some juice.
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With regards to headlamp LED units. There are a variety on the market now, and as they're mainly from China, they're not terribly expensive. Couple of points to bear in mind, the output of these units tends to be fairly hot, so the wattage saving over incandescents isn't huge, if that is what you're after. The output is obviously much better however.
Another point is focusing, the units I've seen tend to use large LED chips, so I'm wondering if that is likely to give you more dazzle. At best that could give you an MOT failure, and at worst get your collar felt.
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AndyL, Not sure with what you say about them running Hot, incandescents tend to run very hot too! I have found them to be slightly cooler when I have used them!
If you think about it nearly all high end cars these days have LED, and they are drifting down the prices as these things do. They have lots of subtle benefits, like they can be lots smaller than an incandescent bulb, so you can place them into things like trafficators to give that subtle bit of extra change that the person in a modern car will see your intentions!
My regular car has been converted over, and several classics I have had recently have been converted as lighting issues are found, I find them much more stable.
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I find it ironic that LED lighting was at first exclusively London buses, then on large expensive cars, all with plenty of space for their powerful alternators!
It is only recently that LEDs are moving down to cheap small cars, where large alternators are more of a problem, and now even to classics, the very cars whose dynamos are best suited to the lower power demand of LEDs!
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They're more expensive than incandescents, at least the up front purchase is. Gradually they're levelling out, and eventually they will become cheaper I think.
When I say they run 'hot' I mean they are powerful LED's, they tend to be about 20-35 watt draw, not far away from the low powered incandescents used in micro cars. This is why I went down the route of growing my own, I found 4-6 watts was sufficient to obtain the same level of light output as the original 36-42 watt BPF lamps. However obtained a 64-72 watt reduction in power required. With the rest of the lamps adapted to LED, the overall saving was about 100 watts.
The dynastart will be working at less than 25% of its rated capacity.
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Always nice to have plenty of "spare" capacity because you never know when you might be grateful of it, especially in classics!
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In my case I was aiming to free up capacity for electronic fuel injection.
This means a pump and wideband lambda sensor. the two combined can draw up to about 45 watts, although that reduces to about half that amount once the lambda sensor has warmed up (they have a built in heater which draws most of the current).
I figured with a standard system a flat battery and night running would almost certainly drain the battery, so I looked at LED's.
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Good idea. I reckon that modifcations are best when they are reversible to original condition. Show Cars are best in original condition, but those that are driven regularly can be made far more pleasant and dependable with a few modern conveniences!
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On the subject of running hot, some LED headlamp conversions now have a fan so that the heat sink on the power supply can be minimised.
But I think once we're talking LED power supplies, we are talking of the devil's work - indeed I put my chair is on a rubber mat just to look at photos like the one below.
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I went for passive heatsinks on mine, however obviously much lower wattage than the commercial units, plus I have quite a lot of room in the Isetta teardrop headlight housings for the larger area
Many installations can be quite tight, so an active heatsink is sometimes desirable.
Power supplies are relatively straightforward for LED's. If you have to drop a lot of voltage at high current then switch mode supplies are best, and cheap on ebay. For lower current linear regulators are inexpensive and rugged. Most of the LED units have current limiting built into them, so just plug and play.
The efi will all be pretty much bolt on, so the car can be put back to standard easily and quickly. The areas where a bit of modification is necessary, is increased wiring for the sensors, plus a bung has to be welded into the exhaust manifold for the lambda sensor. The sensor wiring can be run as an independent loom.
I like to drive cars once they're roadworthy, so sitting round in a field polishing the underside of a floor pan does not throw my switch.
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What you can't do is use them in standard indicator circuits with a bi metallic electro mechanical flasher. This is owing to low current the LED's draw from the supply not permitting the unit to work as it should. So you either need to use parallel resistors, which nixes the advantage of the low current draw, or fit an electronic flasher.
thanks for the vast number reply's guys , as for the flasher unit the one I fitted to my Bond in the 1960's is of mechanical operation ( clock work in other words ) so should have no problem with bi=metal strip warm up . instead there is a set of contact points like the Lucas type .
That aside I have forked out a couple of quid and going to do some experimenting - on the bench , whilst looking thru' the box's for suitable ''scrap'' ( older ones that's still nice and shiny ) light's to play with .
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If it's relay based then should work fine.
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I know you have to make a bit of heat to make light, and vice versa. Ro much heat starts to sound inefficient. So when we are talking about to much heat I assume that once you reach the sort of light needed as a headlight the heat produced is taking out the unit creating the light, unless its cooled.
I like the answer, add a motor, using extra power. It starts to not be a simple solution to a problem. Still its all interesting stuff and research continues. Can only be good.
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The best power LED's tend to be about 60% efficient. So for say a 6 watt LED, 3.6 watts is going to be produced in heat. This is much better efficiency than a few years ago, and it's improving gradually year on year. The cooler you can keep your LED the better the efficiency.
Now bear in mind most power LED dies are very small components, e.g 3-5mm across, then you require a fairly good heatsink to keep the component within its rated temperature spec.
The most difficult aspect is ensuring the heat spreads out adequately from such a small area to a much larger area.
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Back to the subject of home-made conversions: do take the required colour into account.
The old-fashioned incandescent bulbs produced light in a broad range of colours, adding to "white". This meant that there would be plenty of light left, when filtered by a red rear lamp lens, or an amber indicator lens.
A "white" LED, though, produces only a few particular frequencies, usually quite strongly blue. If there's very little amber or red in there, not much light at all will get through the coloured lens. For indicators and rear lamps, you need to start with amber and red LEDs.
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Very good point Dave!
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this topic is getting interesting , but tomorrow I will visit the local motor factor and see if they sell replacement bulb's in led format , will let you know the results , once again thanks for all information given .
the £ shop lights will fit nicely under the pelmet on the model railroad , and there is a 12 volt suppy at hand :)
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tomorrow I will visit the local motor factor and see if they sell replacement bulb's in led format
I've found that most motor factors, Halfords, etc don't stock them (and I've wondered whether it's because all automotive lights are supposed to carry a European code, or something ...)
They're readily sold at classic car shows, though, and of course on eBay.
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I've found that most motor factors, Halfords, etc don't stock them....
Well, it looks like they don't stock them. If you gave yourself six good sprays from a can of aerosol acne, lowered your trousers sufficiently to display your chosen brand of underwear and then asked to see the stock 'under the counter', you'd have them at once.
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I've found that most motor factors, Halfords, etc don't stock them....
Well, it looks like they don't stock them. If you gave yourself six good sprays from a can of aerosol acne, lowered your trousers sufficiently to display your chosen brand of underwear and then asked to see the stock 'under the counter', you'd have them at once.
Good heavens. You mean I should go in without my monocle?
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Most of the customers I see at the local Halfrauds are middle aged men going their to get batteries, wipers or headlamp bulbs replaced. You see some little lass struggling out with a battery as big as herself, with some burly looking bloke standing by the side of his motor with his arms folded. Comical.
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well no luck at the local motor factors , the high street shops selling numerous types of bulb , now maybe we should stock up on the present day bulb for our family car use just in case , as the long livery of LED's might make the humble bulb unobtainable ?
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You mean I should go in without my monocle?
Leaving off the cravat and plus fours may help as well.
My comment was based on my belief that the vast majority of LED bulbs are fitted by those who consider the colour temperature to be really fashionable, particularly amongst the fraternity in McDonalds' car parks, where very few plus fours are seen.
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I've been playing around with a couple of LEDs , this is an example of 3 extra bright LEDs
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Showing A brake light but meant to be for indicators
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Take it that you are aware that automotive lights have to achieve a stated level of lumens - not sure what these values are though.
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Low wattage tungsten filament lamps produce about 10-12 lumens per watt, and that's when they're new and in tip top condition. As they age and the envelopes black-up, that efficiency drops further.
Most running lamps tend to be about 6 watts, with brake and indicator lights at 21 watts. LED running lights operate at about 1 watt, with brake and indicator lights operating at about 3 watts.
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Take it that you are aware that automotive lights have to achieve a stated level of lumens - not sure what these values are though.
I'm guessing that this is for newer vehicles? I know that my 1951 Bond was originally fitted with one rear lamp (sharing its glow between the red rear lens and lighting the number plate) that had a bulb of 3W. And the lens pointed more upward than backward!
I took it for MoT, when I first got it in 2009 - still with no indicators, no brakelight, and no dip to the headlamps. I showed the guy the original circuit diagram, and he passed it.
(And no, it isn't like that now: for my own safety, it has three tail lamps, a brake light, and flashers.)
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My bro does normal car mots and I just asked him about lights , he said there's nothing to actually test the light amount really part from beam angle in head lights , if they look about right they won't be questioned, I will give it ago see what happens
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That was based on my Isetta and my mini. Clearly the Bond had a very low wattage lamp. So you can get away with low power LEDs.
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If an array saying Go Away, or something similar, used the same as standard rear lights, I think I would be happy. Rig up a photo electric cell so that it automates to come on when one of the dazzlers turns up. I think my bud is right. Its time to get tinted specs to drive at night to cut down on the dazzle.
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I know that my 1951 Bond was originally fitted with one rear lamp (sharing its glow between the red rear lens and lighting the number plate) that had a bulb of 3W. And the lens pointed more upward than backward!
as light travel's in straight lines this should make no difference to the sharing of the glow , however human eyes might be drawn towards the brighter part - in this case the number plate , like walking into the cinema from the daylight your eyes become focus on the screen .
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If you're aiming to reproduce the luminence of a 3 watt led with normal 3 or 5mm, I would look at putting in about eight LED's.
Three LED's is too few IMO.
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I thought this may be of interest. I found these tonight, and they appear to be fairly new- BPF fitting LED for dip and main beam. Standard swap around, dead easy to fit. Not terribly cheap at about £48 for a pair, but if you need those spare watts....
http://www.dynamoregulatorconversions.com/led-headlamp-bulbs-shop.php