Additional Turn signal draw

[agentfox1942]

Does anyone know if I install an auxiliary set of turn signals on my '05 1600 classic will the flasher be strong enough to flash all six lights? The new ones are the small halogen silver bullets. Specs say they draw 4 amps, but I come up with less than 3 with a 30 watt bulb (watts = volts x amps 30/12=2.5)
Thanks

[MFolks]

The flash rate may increase if the flasher is stock. The newer electronic ones are supposed to compensate for LED's and regular bulbs. Give it a try,the only thing I think will happen is shorter flasher life with more lamps.

[StarGate]

I'd check to make sure the wiring is rated to handle the total new amp load also.

[agentfox1942]

All good points. Thanks

[turbochardged]

it will change the flashing rate, also check wire load. Add front and rear amps that's your total load on the flasher, if you add a extra light then you have to compensate by replacing one of the original bulbs with a smaller amp bulb to make up the difference. It's ok if your not exact (off by an amp)

[RichLockyer]

I think they'll be fine.
The stock bulbs are 21w, and the circuit is a 10a circuit.
I believe the circuit also powers the brake light (another 21w), so you have a total of 3 bulbs at 63 watts with front and rear, another 10 watts for the 2 front running lights and another 5 for the taillight brings you to 78 watts.
That'll total 108 watts, which is still only about 7.7 amps (at 14v, not 12)... you're below 80% of the fuse/circuit rating.

I know for a fact that you can run 110 watts off of the 10 amp accessory circuit.

[agentfox1942]

Why is it 14volts and not 12 volts? I know my volt meter shows 14-14.5 volts but the bulb is rated at 12 volts. Do I always use the output voltage instead of the draw?

[Alizard]

Originally Posted by MFolks

The flash rate may increase if the flasher is stock.

Actually, it will flash slower because the bimetallic strip will get a lot hotter, takes longer to cool and come back to reconnect the current.

It may destroy the stock flasher but I do believe auto stores sell "heavy duty" flashers rated at maybe 5A or more to use with trailers which also require additional turn signal lights to be run by the flasher.

[Alizard]

Originally Posted by turbochardged

it will change the flashing rate, also check wire load. Add front and rear amps that's your total load on the flasher, if you add a extra light then you have to compensate by replacing one of the original bulbs with a smaller amp bulb to make up the difference. It's ok if your not exact (off by an amp)

Good idea. Superbrightleds.com makes "drop in" 3W LED's that replace the 1034/1157 type bulbs and use very little current (but are still bright). Install one of those in a turn signal location. Since the turn signals are in parallel, the stock flasher will operate correctly seeing a load of two standard bulbs and one LED in parallel.

[Alizard]

Originally Posted by agentfox1942

Why is it 14volts and not 12 volts? I know my volt meter shows 14-14.5 volts but the bulb is rated at 12 volts. Do I always use the output voltage instead of the draw?

If the bulb's wattage (power draw) is specified for 12V, you use 12V to calculate the load current it draws. FYI, at 14V, the bulb will draw about 16% more current than at 12V.

Watts = Volts x Amps

Amps = Watts / Volts

If the bulb's power (Watts) is specified for 14V, you calculate the current using that voltage.

The wiring and fuses are rated in Amps, they don't care about voltage.

[RichLockyer]

I believe the bulbs are rated for 14v, since that is the nominal operating voltage of motor vehicles.

NAPA and Phillips both show their 1157 bulbs as being 12.8/14v... not really clear, but the difference is significant. A 100 watt bulb rated at 12.8v would draw a touch over 109 watts at 14v.

Only way to know for sure would be to put an ammeter on a bulb.

[Alizard]

My FSM says the bulbs are:

12V: 23W/8W (turn signal filament/running light filament)

That would mean at 14V, the Wattage would be: 31W/11W

[RichLockyer]

Put an ammeter on it... that's the only way to know for sure.