JohnN
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| posted on 9/6/05 at 09:44 PM |
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LED's and ballast resistors
Anybody had problems using LED indicators with an associated load ballast?
Without the wattage of a 21 watt bulb, the relay doesn't flash properly, so a 21 watt load is needed in parallel to the LED
I could have used a dummy bulb to make the flasher relay see the correct (21 watt) load, but chose to use a load ballast - only it doesn't work
(although it was made for the job) - I assumed it would just be a 7 Ohm 21 watt resistor, but its supposed to be a bit cleverer than that ...
Anybody know the detail of these things, there was a rumour that they need to be matched to the make of LED.
The LED's are LUXVISION and the Ballast is DURITE
Oh - yes, the LED does flash correctly if I wire a normal bulb in parallel with it
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omega 24 v6
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| posted on 9/6/05 at 10:05 PM |
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I'm pretty sure all the dummy loads we fit at work are in parrallel as well i.e. one end to live and one end to earth. Although we work with 24
volt systems i will check the load size in the morning and see if i can get any more info for you.
Other than this there is an issue in that the light led unit can fail,, and as you have a dummy load you will not be aware that it has failed as the
flasher unit speed will not alter. This could be a potential sva fail as there is a requirement for an audible or visible bulb fail but i don't
think they're uo to speed on led's yet so you could be lucky. They are great things though and defo the future way to go with a bulb life
of 100,000 hrs.
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shortie
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| posted on 9/6/05 at 10:13 PM |
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Hi John,
I have LED indicators and ballast resistors from S-V-C. There is a wiring diagram on my website http://www.dewweb.co.uk/indyblade showing where they
are fitted (in parallel). They just act as another load to slow the flash rate down.
One thing that is worth noting is when the charge on my battery was low they DO NOT slow the rate correctly so before you start ripping any wires
apart fully charge the battery.
I found this out the hard way by un-taping a load of wiring only to find that as a last resort I thought 'it can't be but I'll give
it a go anyway' and charged the battery oernight. Walked in the next morning and bingo, all worked perfectly.
This was after even having a conversation with SVC who said it should make no difference.
One thing I found which might help you diagnose whether it's the same problem is that I noticed when I put the lights on for instance they
flashed quicker and I worked out that this was because the lights were taking more load from the battery and hence making it worse.
Don't ask me why they are effected by battery charge but I know they are!
HTH,
Rich.
[Edited on 9/6/05 by shortie]
[Edited on 9/6/05 by shortie]
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mookaloid
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| posted on 9/6/05 at 10:14 PM |
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I had a similar problem with mine. The resistor kind ot assumes that you have a 21w bulb at the front and a side repeater whatever rating that is.
Mine wouldn't work properly and eventually I discovered that the front indicators I was using off some chinese motorbike only had 10 w bulbs or
something.
I changed the bulbs for 21w items and it all worked fine.
HTH
Mark
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mkblade
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| posted on 9/6/05 at 10:43 PM |
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i have all led lights on my mk aprt from the front had same problem as you wouldnt flash just stay on . i got the relay that puts resistance in the
indicators from premer wiring .you will have to give him the make of your lamps as the relays arnt all the same
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Kissy
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| posted on 10/6/05 at 06:20 AM |
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I just put a couple of bulbs in parallel and hid them under-bonnet with black heatshrink over the glasses.
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splitrivet
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| posted on 10/6/05 at 10:12 AM |
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Stick a 50 watt wirewound 3.9 ohm resistors in parrallel with each side ie between each sides indicator feed and earth,this will give you the required
load.
So you'll need 2 off maplin part no X3R9 £1.99 each.
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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Hellfire
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| posted on 10/6/05 at 02:50 PM |
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Rather than mess with loading, wouldn't it be simpler to purchase an electronic switching relay as an alternative for the current bi-metal strip
type?
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JohnN
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| posted on 10/6/05 at 08:52 PM |
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Thanks for all the advice chaps.
Hellfire, if the switching device was a direct replacement for the flasher unit, I'd have got one, but I was lead to believe it was a bigger
jobby. The thought of paying more (£25?), and having to remove the scuttle to get better access to the existing relays stopped me doing this.
(moral of the story, test the electrics while its still easily accessible)
Durite advised that they could NOT confirm that their ballast unit would work with any LED unit, other than their own.
S-V-C say they have sold loads with no problems, and will take mine back & refund - thanks S-V-C, very fair.
I think sourcing the big resistor from Maplin seems the simplest solution - thanks Bob.
JohnN
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Hellfire
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| posted on 10/6/05 at 09:44 PM |
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The electronic one isnt a replacement, it's an alternative  It is more expensive but if you're using LED's you've already
forked out for them anyway! If your ballast bulb goes you're f*****d anyway's... I think the resistor jobby is the best bet.
Have you thought of using a warning buzzer to add a little load? Mind you it may not be enough.... we've put some on to warn us whe indicators
are left on. Not that you can hear them above 40! 
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blueshift
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| posted on 11/6/05 at 11:17 AM |
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I'm confused. why a 3.9 ohm resistor instead of a 7 ohm one? by my calculations 6.86 ohms would give you 21 watts at 12 volts (ignoring the
power of the LED array).
It's been a while but I didn't think my electronics knowledge was that rusty.
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splitrivet
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| posted on 11/6/05 at 09:19 PM |
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You'd use 2, 1 per side youd use 7 ohm if you were fitting 4, 1 per bulb.
Cheers,
Bob
[Edited on 11/6/05 by splitrivet]
[Edited on 11/6/05 by splitrivet]
I used to be a Werewolf but I'm alright nowwoooooooooooooo
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blueshift
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| posted on 12/6/05 at 08:17 PM |
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oh right. I see now.. total power 42 watts?
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