This really doesn't have anything to do with trailers, but I just bought a whole bunch of LED bulbs from superbrightleds.com. My question is, will I have to mess with my flasher? I know on cars, they don't work good! But, I've talked to other truckers, and they said that it works just fine! The trailers I haul don't have LED's in them, so that should be OK. But, I'm wondering since they have no draw, will my turn signals work OK? I'm just replacing the bulbs-I'm not replacing the whole light assembly, with something from like Iowa 80. I don't know if those assemblies have some sort of voltage increase, that would make the flasher work better?
John
I converted my truck and trailer to all LED's including the dash lights and everything works fine. Even if you had to put a load resistor in, you would only have to put it at one light position on the truck and just make sure it put enough load on the flasher to make it flash....But you won't have to do that because these days the more modern LED Brake, Turn, Tali lights have a load resistor in them from the factory.
LEDs draw 1/10th the current as regular bulbs.
The resistors are because each individual LED only needs 1.5 volts, but they need to operate on a 12 volt system. Rather than have a bunch of little 8 LED circuits wired in series, and then all those circuits wired parallel, it's easier just to put a 3 cent resistor in there to drop the voltage and wire all of the LEDs in parallel to common buses.
The resistors have nothing to do with the turn signal flashers.
If you have an electronic turn signal flasher, your turn signals will blink at the same rate regardless if you have LEDs or regular bulbs, add trailer lights to the circuit, or have one burnt out.
On older vehicles with electro-mechanical turn signal flashers, having a burnt out turn signal will make the other one not flash at all. If you convert to LEDs, they won't flash at all. If you add a trailer with regular bulbs, they'll blink faster.
The older style turn signal flashers are designed to have the amp load from two bulbs going through them. The front and rear bulbs (regular bulbs) typically draw 4.5 amps each.
The current goes through a bi-metallic strip that heats up. (a tiny strip made of two dissimilar metals with different expansion rates) As it heats up, one side expands faster than the other side, making it bend away from a contact in the middle. When that happens, it breaks the circuit, the strip cools down very rapidly, it straightens out, and the two contacts come back together, closing the circuit. The process is then repeated, over and over and over as "Blinker Boy" is going down the road for 10 miles
.
Contrary to popular belief, there is no "blinker fluid" involved in the process.
If you screw with the amp load going through that bi-metallic strip, it will affect the flash rate. More amps will make it heat up & break the circuit quicker, but the "off" time will remain the same. If you have 3 bulbs on the circuit because you've added the amp load of incandescent trailer lights, you'll have 13.5 amps going through and they'll blink so fast the "on" time will be so short the bulbs won't even have time to reach full brightness. If a bulb is burnt out, there will only be 4.5 amps going through that strip and it won't heat up at all and the light will remain on steady. The same thing will happen if you have LED bulbs that don't use as much current.
Most cars & pickups these days use electronic turn signal flashers. The electronic ones do not use the bi-metallic strip & therefore the amp load doesn't affect the blink rate.
You can upgrade to an electronic flasher in 10 seconds, for about $20-30. It's as simple as replacing a fuse. Actually easier, because you don't need needle-nose pliers to pull the old one out like you do with a fuse.
I've upgraded my two old pickups to electronic flashers so trailer lights won't affect the blink rate.