LED Indicator Strips and Resistors

Yes the total load is 21Watt doubled up so comes to 42 Watt. I wrongly thought they were 5Watt but only the side lights are 5Watt.

With regards to the flasher unit replacement for a new electronic one, the thing against it is that often on modern vehicles this flasher unit comes with built in electronics for feedback to the ECU or EMU. These feedbacks range from bulb breakage or missing to time indicator on. In the case of a motorcycle it also includes lean angle and yards moved till switched off automatically. These features mean that replacement is hard and if possible very expensive. Cheaper to load the system up with a load resistor.

Thanks you made me look again and find my answer. The resistor will help with my problems.

Oh I didn't know they had extras on them these days...

I seem to remember that most cars indicator bulbs were about 21 to 23 watts which together with the side indicators gives about 50 watts loading.

I suppose if the power is there and its not going to make a major problem using it then as you say it will be easier to just waste the power into a resistor or possibly into heated gloves???

John

Hmmmmm, now there is an idea!

What is the wattage of those heated grips? We have to look that up and see if I can somehow divert that loss. Thanks again for another good idea.

http://www.4-motorcycles.co.uk/acatalog/Heated_Grips.html

That looks to be exactly right to me. Maybe need to also have them on me toes though to get the right amount when just in the "on" position

Might just give this a go some time before next winter.

Hey, not only is this 'thinking outside the box', this is saying 'there's a box?'! Love it!

Case, recommend you well-document the wiring diagram once you get it figured out. Looks to me like it will be just complicated enough to never be able to recall 'where that wire goes' in about 2 year's time...

Yes it will.

The reason they are staying on is that the flasher unit that you have needs the current to operate correctly. No (or should I say -far less) current = no flash.

Or you need to design a flasher unit that works independent of the current taken, a simple 555 circuit should be able to do that for you.....

555 circuit???? Sorry but that is just a little short of the real deal 666 circuit

Sorry but I have to decline as only the best is good enough for me and my hog

I have ordered the 50 watt resistors from e-bay late last nite and I am eagerly awaiting.

The heated handgrips will have to wait as I have decided that if you have heated handgrips, you need heated toes as well and where do you draw the line. Heated crotch pocket?

That would be nice but no thanks

Hmmmm that reminds me of a time 30 years ago, when I was riding home on my trusty motorbike in winter and I suddenly realised that certain parts of my anatomy were numb from the cold....

I stopped and for several minutes at the side of the road I was jumping up and down massaging myself to get some feeling back... Luckily nobody reported me

John

Incandescent bulbs have a hot/cold resistance ratio of about 10/1. This means that that when they are operated from a voltage source, the cold current is about 10 times the hot current. The flasher designers know this and design the flasher to flash at the desired rate under average current draw. Your LED lamps exhibit constant current drain and provide a different loading profile to the flasher.

Ok bought the little gold beauties but they do not work....at all.

Yet when I introduce even the one normal bulb (21Watt), it blinks fine.

Anyone any ideas here?

'gold beauties'... are these the power resistors? are they supposed to dissipate 50 watts at whatever the voltage is on a Harley (12volts? so therefore about 3 ohms each resistor).

But the indicators work with a 21 watt bulb?

John.

Ok , I had not measured the ohms yet but they are 9.6 ohm each????

This would make for 115 Watt which clearly would be too high. Why would somebody sell these for this purpose?? I am even more confused and perplexed now.

The 2 led indicators work correctly when I introduce 1 of 21Watt normal bulb in addition to the 2 leds.

This makes me question a normally used concept in DC motor braking with power resistors. These big gold coloured resistors are always rated in Watts but that has to be dependend on Voltage or not? DC motors voltage varies anyway so how does this work?

Sorry I stray off the important issue here but still........

9.6 ohms they're no good, you want at least 5 ohms or less...

The 21 watt bulb is taking almost 2 amps and the resistors are only taking just over one amp = 14 watts...

If you need to dissipate 48 watts you need a resistance of 3 ohms...

You've been sold the wrong ones by the sound of it...

John.

I think you are right. I will take it up with this e-bay dealer right now. Good thing is he has reasonable feedback so he might want to keep that.

I is still confused about this load business.

The bulb heats up and its resistance changes or not?

If so , how is a steady load resistor ever going to fool the blinker unit?

Do not worry, two in parallel should do it for you!

Try using 2 resistors in parallel....

Woahh, I must live in a parallel world already. I just saw your post double, as in parallel with itself.

I will try right now but don't see how it would work in this setup.

It will halve the resistance and double the current, which should be close enough to make the blinker unit think its a 21 watt lamp!!

Shoot me down dead right now, that works although they flash a bit on the fast side. Nothing I could not live with mind you.

Thanks andy, that is solved for most of the way. So the resulting resistance is now just over 4.8 Ohms and reducing that further down to near 3ish would correct the flash rate altogether?

Why can't I just get a 3 ohm resistor from work and fit that? Does it have to be a load resistor, seems very big for this job and more expensive as well?

I think the flash rate would be slowed if you could slightly increase the resistance.....my calculations tell me that you actually need a 6.8 ohm resistor in fact.....to simulate a single 21 watt bulb. Halve that for two 21 watt bulbs.....

Experiment a little and see what makes the flash rate correct (from memory between 60 pm and 120 pm)

I did not see mentioned the resistance in Ohms, could you remind me please?

I have just ordered a pair of extra resistors and will live with the faster blinking for as long as I can stand it. That means probably as long as the temporary repair has hold out in my bathroom, just over 3 years and still counting

You know you speak to an engineer if the emergency repair is better than the real deal to begin with.

Shore do!!

Case491, just seen the problems...

the resistors may be rated for 50 watts but its the resistance volts and amps that count...

As you need at least 21 watts to operate the indicators you will need a resistance to give 21 watts power dissipation.

So P = V x I = 12 x I > I = 21/12 ≈ 2 amps

With the resistors you have of 10 ohms the power is...

P= V x I = V²/R = 144/10 = 14 watts which apparently isn't enough.

The resistors you have should have been less than 6 ohms each to work, I would have a moan with the ebay seller!!

John.

I have and he claims to have sold these for a while and apparently all worked fine so he asks what is different about my flasher unit???

I don't care enough to be honest, it will cost me another £6 including postage and it is sorted than. Will get myself an aluminium plate from work to mount them on and cover them with plastidip and they will sit in the lids of my panniers.

Thanks for all of your help and any of the others as well. Sure made sense of it all in the end with our combined thinking prowess

Ummmmmmmm.....dumb question here. The bulbs were replaced with LED strips; what is the maximum current they will take before exploding. The discussion is about getting the current back up to the level that would caused the thermal timer to operate to cause a flash. I presume they are in series with the LEDs if they were with the bulbs. Please don't beat me; I'm just a normal nitwit!

I don't see why we would beat you, valid question IMHO.

The current has dropped due to the much lower power rating of the LED strips. The resistors are parallel to the strips so the strips will not see more current, the resistor will see the additional required to make the flasher unit trip on and off again.

Hope this is clear (and right)

Can that be right? If the LED strips are in parallel with the resistors, when the LEDs are forward biased the resistance will be considerably less than the 50 ohm resistors; oh yeah........there goes the flash. Once.

Case 491 is right Kyoto.

The leds have an inbuilt resistor to operate off the 12 volt supply... tha additional resistor is needed in parallel to increase the supply current to operate the bimetallic flasher as per normal.

John

Roger that.

I'm a little late into this one but can provide some clarification on intended operation of flasher units.

They are designed to flash at "the prescribed rate" when the correct load is in the circuit. They sense the apparent current flow (and thus apparent resistance). They are REQUIRED BY LAW to flash at a different rate if there is significant change in the load (like a bulb blows) so that the driver can notice this and be warned to make repairs.

The flasher/indicator lamps are regarded as a safety device on the car/bike/truck and are expected to operate correctly.

The symptom described (Staying on) is the flasher behaving exactly as expected. For the really low load that the LEDs would represent, a "constant" signal is not unexpected. (Sorry for the double negative but there's other options that could also have happened.)

Now here's a return question.

If one lamp is removed from the circuit, does the "tell-tale" feature still function?

If not, then what are the implications? Is your compliance plate for the bike still relevant? Would the bike manufacturer regard this modification as maintaining their responsibility? What about insurance?