6v vs 12 volt issues

[Skulldigger]

I have been collecting a lot of 6 volt lights and sirens. They tend to be easier to buy (less competition) and they also tend to be the older ones. Ran into an interesting issue I had not thought about.

Trying to wire up my new 6volt 184, I am having trouble getting enough amps to it. 4 - 35 watt bulbs plus the motor is drawing quite a few amps. 6 volts apparently require more amps than 12 volt does.

Watts / Voltage = Amps.

SO
A 35 w bulb running on 12 volts pulls 2.91 amps.
A 35 w bulb running on 6 volts pulls 5.83 amps.

Therefore

A 4 bulb 12volt 184 only needs 11.6 amps just for the lights.
A 4 bulb 6 volt 184 needs a whopping 23.33 amps just for the lights.

Trying now to figure out how much amperage the motor needs because 30 amps, which is the most I can give it is having trouble powering the lights and the motor. At this point I am probably going to have to wire up the motor and lights separately to keep the amperage down and get plenty of power.

 

[shues]

If I were in your position, I would purchase a 6-volt battery. You could purchase a large automotive battery if you choose, or you could purchase something smaller like small security-light battery and use it in concert with your 6-volt power supply.

 

[Sparky_911]

Im in no way an electrical engineer and am sure someone will flog me for suggesting this........

You could run it on a 12v power supply if you install an in line adjustable voltage regulator (think similar to a model train set). Allow the volts to come up a bit to compensate for amp consumption. I would think 8-9vdc shouldn't(?) wreck the motor or bulbs if you're just running it for 5-10 minutes at a time.

Easiest solution would be to find a 6v battery and charger. Use the battery to run it and keep it charged up.

 

[kerry4951]

I use those 12 volt to 6 volt ( 30 amp) "step down" converters on all my 6 volt lights. I run them off of a 12 volt 30 amp Pyramid power supply and it works fine.

https://www.ebay.com/itm/WaterProof...=item239e111e32:g:PIcAAOSwofxUdJ2v:rk:11:pf:0

 

[Skulldigger]

I use those 12 volt to 6 volt ( 30 amp) "step down" converters

I have a 12v to 6v stepdown 30amps, but 30 amps is about maxing out. That's my problem. Can't find any stepdowns over 30 amps. What I am thinking of is two 20 amp step downs one connected to motor and one connected to the lights. Essentially that gives me plenty of power for both.

If I were in your position, I would purchase a 6-volt battery.

I've thought about the battery option, but how often am I going to run it vs how long will the batter last just sitting.

 

[kerry4951]

I hear ya. Come to think of it Im not sure if I tried running a 4 bulb with motor on a 30 amp 6V converter. The things I run work fine on those converters but then Im not pulling that many amps like you are.

 

[Skulldigger]

Im not sure if I tried running a 4 bulb with motor on a 30 amp 6V converter.

First time for me. I have some two bulbs, mostly smaller sirens. I can spin a 5-1/2" siren with no issue with a 30 amp, but it's just a single motor. I think my issue is four of those nearly 6 amp bulbs.
Something else I might try is going to 25 watt bulbs. That would drop my amps by almost 7 amps. Inside display should not matter too much.