LEDs and current draw

[breakdirt916]

do LED's reduce the current draw on the electrical system?

I'm looking to install heated grips (~3 amps), and I read that motorcycle alternators only put out ~10-11 amps, so I don't think my 16 year old bike will like the extra current draw. So considering that my battery is only a year old, and my turn signals and brake lights noticeably dims my lights, can I save up some current, by swapping in LED bulbs?

I know they use less power in general, but does that mean their resistance is less, and more current flows through the electrical system? Or are the designed to match the resistance of an incandescent bulb, thus using the same amount of current and providing no relief on the electrical system?

Thanks

[DuncanMoto]

Much less draw.
In fact most of the time you'll need to put resiters in line or change out your flasher relay.
Do yourself a favor and get bright some LED flasher stalks. Just the bulbs are not ussually that bright.

What do you have for a bike again?
Some older bikes have alternators and put out more power than you think.

Also I may have some stalks left over for cheap. I'll check today and let you know.

[stoinkythepig]

I have not been impressed with LED replacement bulbs in brake/tailight applications that were originally designed for incandescant bulbs. They are harder to see from angles other than straight on. Incandescent bulb taillight assemblies utilize a parabolic reflector that does not work with the LED bulbs that I have seen.

I would not sweat the 3 amps. I suspect your charging system is providing plenty of juice when you are cruising and that you only see the dimming when at idle when the bike is likely draining the battery, evon though it's running. I also suspect you have 10-11 amps of juice above and beyond what you need to run the bike. I routinely run 10+ amps of heated gear on my bike with no issues at all.

[NeverlosT]

I just replaced my blinkers with LED systems, not just bulb replacements. But to trick the bike ECU to not think that your blinker is out (since the current draw is far less) you have to put a resistor in parallel with your blinker, which brings your current draw back to stock (like 2 amps to my surprise!). So not any "power savings" there. They are bright as hell though.

I've never had heated grips so I dont know how they work. Is it just a resistive load in the grip that heats up?

[BluGixxer]

Just a little somthin I've learned,
Incondesent bulbs can project 360 degrees
LED's differ from one to another depending on how they are made. Some only project 30 or even 70 degrees, the more it broadcast its lite, the weaker it is.
The leds themselves work on around 2 1/2 to 3 volts and .023 millamps, even the really bright one don't use that much power. They are just made to different standards.
If you really want to reduce amp draw , get an electronic flasher that doesn't work of of currant draw, and get the best LED's you can .
And I'm thinking that replacement bulbs won't be as bright as replaceing the whole turn signal. A new turn signal should have the LED's positioned so the lite is projected in the correct direction, not just straight ahead.

[breakdirt916]

bike is a 1995 FZR600

Ted - I don't mind getting stalks instead of bulb replacements; let me know if you have any, but you'd have to ship since I'm currently in CA. And pics?

so, if you're putting a resistor to match the current usage of an incandescent bulb, then LED bulbs don't put any less strain on the electrical system?

but if I install a flasher suited for LEDs, I can run them and save current?

and when you guys say they don't work as well in brake/tail combinations, do you mean the SMD type LEDs?



the SMD LED's are flat, and are mounted on the sides to provide illumination from all angles; similar to an incandescent bulb. But while it's good in theory, is it good in practice?

[Rossco]

The SMD's like the ones pictured above, should work just fine.

It's those cheapos that you get at Most auto-parts stores that are all one direction, and generally suck.

like these ones, avoid them like the plague.

[breakdirt916]

ok, this is my plan:
1.) LED turn signals won't offer me any power savings because I need a load equalizer to make sure the signals don't flash too quickly; and since I can't get a plug-and-play electronic flasher anyways (and I'd have to figure out which pins go where with an after market electronic flasher), I'm not too interested in that route
2.) the brake/tail light bulbs and gauge lights, however, can offer power savings, because they don't have anything to do with the flasher

so, here's my current order from www.superbrightleds.com:
-2 x 1157 rear tail/brake SMD-style LED's; this is where my power savings will come from since load balancing resistors are not required.

the SMD (surface mount design) style LED's provide a more uniform light output to better eliminate the "spot" LED illumination found on the ones pictured by Rossco

-4x194 style wedge bulbs for the gauges

hopefully the SMD style provides even illumination on the 4 cluster gauge lighting

-2xload resistors for the rear turn signals if I ever decide to buy rear LED turn signal stalks...and instead of cutting into the OEM wires (I hate doing this since my bike stays outside and can build corrosion), I'll just splice into to the afttermarket turn signal wires

The rear brake lights (27Wx2) alone will total 54 watts, which will more than cover any additional power consumption by the heated grips (with even more power savings coming from the running light and gauge lights/total = extra 11 watts)...so, while I don't anticipate much extra strain by the grip heaters, I'll play it safe with the power savings of these bulbs.

Anyone have any recommendations on some bright stalks?

[breakdirt916]

ok, the tail/brake lights are installed

At night, the light output is comparable with the incandescent bulbs, based on the SMD-style, and the horizontal-pointing layout. I feared that they would be really directional, but they are not. The dispersion might be a little bit less, but the power draw is substantially lower, and I don't notice any dimming when I tapped my brakes.

incandescent bulb:


LED bulb:




I thought LED's were either on or off, but for some reason, having the bike on (and running the voltage a little higher) makes the LED's a little bit brighter.

The LED's passed bulb the nighttime test, so by tomorrow I'll see how they fare during the day.

[nhbubba]

LED output is dependent on the amount of current provided, to a point. Since V=IR, and your R is fixed, your I will increase with V. So the more voltage, the more current, the brighter the output.

Too much forward current and you exceed the If max of the LED and release the magic blue smoke and light output will fall to zero!


Did you measure the current draw before and after? I thought those plug-n-play setups had resistors in them to jack up the load, keep the flasher circuits and light out warning bits happy.

[breakdirt916]

hmm, I didn't think it changed output, but so be it

I didn't measure any current draw, and I'm not worried since these are the brake/tail lights, and there are no flasher's in the circuit that need to be made happy

[NobodySpecific]

Did you measure the current draw before and after? I thought those plug-n-play setups had resistors in them to jack up the load, keep the flasher circuits and light out warning bits happy.

Your bike has light out warnings?

[nhbubba]

Yes. My flashers blink extra fast when one is out. That's supposed to warn me.

Your point is taken though. No, my cheapo Suzi does not. But some (ie euro bikes) do, don't they?

[NobodySpecific]

Yes. My flashers blink extra fast when one is out. That's supposed to warn me.

Your point is taken though. No, my cheapo Suzi does not. But some (ie euro bikes) do, don't they?

I have no idea, I would guess BMW might, but any bike that has a light out warning light would likely have a good enough charging system that the power savings isn't important. I noticed an improvement in my grips and vest when I changed everything over to LED on my XT, so I don't believe that a load resistor is common on any of the LEDs from that site (same place I bought mine). I could be wrong though.

[drop]

I have no idea, I would guess BMW might, but any bike that has a light out warning light would likely have a good enough charging system that the power savings isn't important. I noticed an improvement in my grips and vest when I changed everything over to LED on my XT, so I don't believe that a load resistor is common on any of the LEDs from that site (same place I bought mine). I could be wrong though.

bmw does - mine monitors the 3 headlight bulbs, city light, tail/brake light, and turn signals.

[breakdirt916]

okay...2 years later and the grips lay dormant in my closet

why not just run a relay to power the grips directly off the battery?

that way the relay (which won't suck too much current from the running light), will switch the grips off when the bike is off

[stoinkythepig]

okay...2 years later and the grips lay dormant in my closet

why not just run a relay to power the grips directly off the battery?

that way the relay (which won't suck too much current from the running light), will switch the grips off when the bike is off

That's what I do.

[Kurlon]

okay...2 years later and the grips lay dormant in my closet

why not just run a relay to power the grips directly off the battery?

that way the relay (which won't suck too much current from the running light), will switch the grips off when the bike is off

That won't solve a lack of current issue though, if the bike puts out 10A, and you're drawing 12A, your battery is discharging even with the bike running. All the relay does is give you a nice low voltage drop line to the battery vs tapping off the skinnier, older wiring in your harness.

[stoinkythepig]

That won't solve a lack of current issue though, if the bike puts out 10A, and you're drawing 12A, your battery is discharging even with the bike running. All the relay does is give you a nice low voltage drop line to the battery vs tapping off the skinnier, older wiring in your harness.

He already addressed that with LEDs.

[ZX-12R]

why not just run a relay to power the grips directly off the battery?
that way the relay (which won't suck too much current from the running light), will switch the grips off when the bike is off

Just make sure both sides of your relay (coil and contacts) are connected to the switched side of your power distribution block. You don't want a "failed-on" condition to wreck your battery when you shut the bike off.

[Dave603]

Just make sure both sides of your relay (coil and contacts) are connected to the switched side of your power distribution block. You don't want a "failed-on" condition to wreck your battery when you shut the bike off.

as long as its not a solid state relay it should fail open

[breakdirt916]

I'll double check the wiring here after I follow the diagram...but I was thinking about using a simple, 5-pin bosch type relay like this:

http://www.parts-express.com/pe/psho...30-073&scqty=1



and Josh - the rear running lights run ~8w x 2 = 16W, plus I swapped out 3 speedo cluster 2.7w bulbs with SMD LED's as well...total saving is around ~24W, and the grips are probably going to use 24-36W, so I'll likely only add (assuming it is a 3A draw, and not 2A) 1A to the bike's electricals...the clymer doesn't say what the alternator output is, but the battery "capacity" is 12V/12A hour...so maybe it means it's a 12 A system? if so, 1 A hopefully won't drain battery while I'm riding with the grips on

[ZX-12R]

as long as its not a solid state relay it should fail open

"Should" is a condition a safe design doesn't rely on.

[ZX-12R]

but the battery "capacity" is 12V/12A hour...so maybe it means it's a 12 A system? if so, 1 A hopefully won't drain battery while I'm riding with the grips on

Ampere-hour is a measure of electric charge and tells you the capacity of your battery. A 12Ah battery in an ideal world can deliver 12 Amps for 1 hour, 6 Amps for 2 hours, 1 Amp for 12 hours, etc., etc. Unfortunately it doesn't give you any insight into the capacity of your charging system.

[jasnmar]

Quit guessing.

Get a battery bug. If you are pulling to much shut down the heaters for a while. Let the battery recharge. Turn the heaters back on when charged.