Another electrical question

[LUDELVR]

Alright electrical gurus, I have another question about using the wall's 110 ac to lower led lights but this time I'm wondering how to use the wall's power through a 12vdc power source plug with 500 ma to power those battery powered led lights.

I have those battery powered, push on and off emergency lights that use 3 aaa batteries and want to use the wall to power them instead of batteries. I've hooked up 4 of their little lights and powered it to the wall socket and it works but I don't want to leave it until I know it's sound.

Can someone tell me the formula for calculating the total power/wattage of these 4 lights? I'm assuming it's 3x1.5 per light so there 4.5 volts per light and then 4 of those lights and I'm using that 12 volt source.

[rx7_turbo2]

I'm not sure I can figure out what it is you're doing? You can buy LED strips for like $30 off Amazon in you're choice of 120v or 12v.

In regards to you're question. Yes a AAA battery is 1.5v. However the required voltage of each light depends on how the batteries of each light are wired (Series v Parallel). My guess is they're wired in series in which case yes the requirement of each light is 4.5 volts. So have you wired the actual lights in series or parallel? If you wired them in parallel you're powering lights rated for 4.5v with 12v, it's low voltage so probably not gonna catch fire but they might not last long. In terms of wattage what's the current draw? Is the wattage not stamped on the lights themselves?

Power=Current x Voltage

[RealJimmyJames]

I have never seen 120V LED strips, I always see that they need a transformer. Am I wrong, or do some just have a small transformer integrated with them?

[chathamf]

Originally posted by RealJimmyJames
I have never seen 120V LED strips, I always see that they need a transformer. Am I wrong, or do some just have a small transformer integrated with them?

They have built in step down transformers. Same sort of thing as a cell phone charger.

[rx7_turbo2]

Originally posted by RealJimmyJames
I have never seen 120V LED strips, I always see that they need a transformer. Am I wrong, or do some just have a small transformer integrated with them?

http://www.amazon.ca/gp/product/B009S1CDV6?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

[LUDELVR]

Originally posted by rx7_turbo2
I'm not sure I can figure out what it is you're doing? You can buy LED strips for like $30 off Amazon in you're choice of 120v or 12v.

In regards to you're question. Yes a AAA battery is 1.5v. However the required voltage of each light depends on how the batteries of each light are wired (Series v Parallel). My guess is they're wired in series in which case yes the requirement of each light is 4.5 volts. So have you wired the actual lights in series or parallel? If you wired them in parallel you're powering lights rated for 4.5v with 12v, it's low voltage so probably not gonna catch fire but they might not last long. In terms of wattage what's the current draw? Is the wattage not stamped on the lights themselves?

Power=Current x Voltage

Sorry, I'm kind of typing this on the go and on my phone.

They are wired on parallel, all 4 lights. I'm using an old power source from my other project and it's rated at 12VDC at 500 mamps. It powered 4 puck lights at 80 mamps each.

The battery powered lights have 5 LEDs on them each and are a lot less bright but yes, you're correct and they do not have the power output or any info on them. I just gauged that they were less powerful from their light output.

I'm just wondering what the result would be if the power voltage of the battery powered lights (total) was less than 12 volts (like 4.5) and it were running off a 12volt power source like I'm doing now.

[LUDELVR]

These are the lights I'm using

lights (http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=261376103433&category=3201&pm=1&ds=0&t=1453655278323)

I'm using these just because I had a whole heap of them.

[rx7_turbo2]

Originally posted by LUDELVR
I'm just wondering what the result would be if the power voltage of the battery powered lights (total) was less than 12 volts (like 4.5) and it were running off a 12volt power source like I'm doing now.

Well generally speaking it's not a good idea to apply a higher than rated voltage to a device. I mean would you try and power you're car with 24v instead of 12v? Like I said though they probably won't catch fire they just won't last as long. Who knows though maybe they'll last forever. If it was my setup? I wouldn't do it.

[LUDELVR]

So what would the total number of volts that would be going through these 4 lights? I'm trying to recall the equation and see if it applies here. Would it remain at 4.5 since that's what it is for one light or do I multiply that 4.5 by 4 and get 18 volts because it's wired in parallel? Am I doing the maths right or am I way off here?

[rx7_turbo2]

Originally posted by LUDELVR
So what would the total number of volts that would be going through these 4 lights? I'm trying to recall the equation and see if it applies here. Would it remain at 4.5 since that's what it is for one light or do I multiply that 4.5 by 4 and get 18 volts because it's wired in parallel? Am I doing the maths right or am I way off here?

Way off. 12v is what's being applied to each light when their rated voltage is likely 4.5v. The current through each light because they're run in parallel is not a concern since its determined by the light itself in just that branch of the circuit. Because we don't know the power consumption of each unit you'd have to use a meter to determine current draw and use that to calculate total power. Your power supply is 500mA and it likely has an internal fuse, which you haven't blown so we can assume the total current draw is less than 500mA.

Like I said though the only real issue is that your powering lights rated for 4.5v with 12v.

Maybe this will help

http://tinkernow.com/wp-content/uploads/2014/12/water-tank.jpg

[LUDELVR]

Originally posted by rx7_turbo2


Way off. 12v is what's being applied to each light when their rated voltage is likely 4.5v. The current through each light because they're run in parallel is not a concern since its determined by the light itself in just that branch of the circuit. Because we don't know the power consumption of each unit you'd have to use a meter to determine current draw and use that to calculate total power. Your power supply is 500mA and it likely has an internal fuse, which you haven't blown so we can assume the total current draw is less than 500mA.

Like I said though the only real issue is that your powering lights rated for 4.5v with 12v.

Maybe this will help

http://tinkernow.com/wp-content/uploads/2014/12/water-tank.jpg

That makes perfect sense and thanks for the illustration...how'd you know I was a visual learner?!

I watched a video of guys using a voltage regulator to drop the 12 volts down to a lower voltage so I guess I could do that yeah?

Also, would another option be to simply use a plug that has a lower voltage rating but still high amperage?

Finally, would the only downside to using the 12 volt power supply on the 4.5 volt lights be that tje lights would burn out quicker? Is there an immediate fire hazard?

Cheers for the quick replies and help. Totally appreciate it!

[rx7_turbo2]

Originally posted by LUDELVR


That makes perfect sense and thanks for the illustration...how'd you know I was a visual learner?!

I watched a video of guys using a voltage regulator to drop the 12 volts down to a lower voltage so I guess I could do that yeah?

Also, would another option be to simply use a plug that has a lower voltage rating but still high amperage?

Finally, would the only downside to using the 12 volt power supply on the 4.5 volt lights be that tje lights would burn out quicker? Is there an immediate fire hazard?

Cheers for the quick replies and help. Totally appreciate it!

No worries. The whole voltage v current thing gets lots of people. That illustration isn't entirely correct but it helps understand the basic concept.

Yes your goal should be to match the voltage and current rating of your power supply with the voltage and current rating of your lights.

So, we're making an assumption your normally battery powered lights are rated for 4.5v, remember it's possible although not likely they're wired and rated for 1.5v. And we're also assuming your current power supply rated at 500mA has an internal fuse which hasn't blown so your total current draw is below 500mA.

You should be looking for a power supply rated for 4.5v and 500mA. Most small cell phone type charges would be close. 5v or there abouts and 500mA+.

We're making a lot of assumptions, and doing it this way seems like a lot of trouble when you can buy a trip of LED's you know are rated for 12v for pretty cheap.

Dangerous? No guarantees, will they catch fire? Honestly I wouldn't think so, but iyou're kind of "jerry rigging" stuff likely made in China together so......