Electrical question(s)

[ftpiercecracker1]

1#

 

What is the difference between a 12v and a 24v motor? As in the internal structure/configuration/wiring. A 12v ran on 24v will double its output, but will burn up in just a few short minutes. At least that's what happened to my trolling motor yesterday. 

I have had zero success trying to find the answer doing a regular internet search.

 

 

2#

 

LEDs. They are super efficient, use minimal power and generate almost no waste heat energy.

 

From what ive seen LEDs must have resistors. In my mind resistors are simply energy sponges that take in enegery and disperse it as heat, therby dropping the outgoing voltage to whatever is specified.

 

What is the point of using a super efficient LED if you have to burn off all the excess energy anyway?

 

Isnt there a way to step down the volatage/power without having to consume some of it in the form if heat through resistors? Its seems like such a brutish way of metering electricity, just like how the incandescent bulb creates light. Its a shorted connection that can withstand the temperature. Using brute force to generate so much heat that it glows white hot.

 

It would seem to me that there would be a different way of metering electricity. 

 

Like pouring a glass of juice, you only pour what you need (power going to device) and the rest stays in the jug (battery)

 

Right now it seems like you hold the cup over the sink and pour out the whole jug to fill a tiny cup. Once the cup is full the rest has to be poured down the drain (resistor consuming energy) because we can't stop the flow of juice. I made a pun.

 

 

Electricity is my absolute favorite subject, but its so gosh darn mystifying. 

[Dzimm]

Well as far as the LED question, the device will only use the amount of energy it requires, this is often called "Draw".  This draw will be in reference to how many amps the device pulls to be used.  It is the amperage of the device that drains the battery/uses the power, not the voltage.  

 

You are referring to voltage in your question.  A single LED bulb is usually rated between 1-3volts depending on color and other factors.  They have a safe range depending on the LED and as you experienced with your trolling motor, higher voltage just makes the LED brighter (motor spin faster). All the resistors in the circuit are doing is knocking down the voltage to a safe level for the LEDs, the amount of "waste" created in this process is incredibly small and has little to no effect on power consumption.  

 

This all assumes a well designed circuit, in a poorly designed circuit it could cause all kinds of problems with power consumption.

 

This is why LEDs are so much more efficient, they have very little to no waste of power, and they have such a small amperage draw.  A typical incandescent bulb draws more amperage and creates a lot of heat, which means it creates a lot of waste.

[derf]

An electric motor is rated for a certain voltage and amperage.  If you double the voltage, you're likely to double the amperage everything else being equal.

 

When you double the amperage, you overload the wiring inside the motor that wasn't designed to take that much current.  When you do that, things get hot and melt.  Bye bye electric motor.

 

As far as LEDs, there is the voltage for the LED being a factor.  Again, too many volts will burn out something that can't handle it.  Resistors are a convenient way to bring that voltage down.  And sure, there is a little heat.  But an LED has high resistance naturally so it's always a low current circuit.    And like Dzimm says, the waste heat coming off the resistor is trivial.  It's way less than an incandescent bulb generates. 

 

One other thing you may find is an LED turn signal bulb.  Trouble is, with the low draw of an LED circuit, you don't get enough current through the the standard flasher so it won't trigger and the light will stay solidly lit.  The right way to fix that is with an LED specific flasher module.  But you can also wire a resistor in parallel to the LED bulb that will cause it to draw enough power to trip the flasher.  Given the ease of finding LED flasher modules, the parallel resistor is more of a "redneck engineering" solution.  But it does work.

[Zambeezy]

4 hours ago, ftpiercecracker1 said:

What is the difference between a 12v and a 24v motor

About 12v 

[ftpiercecracker1]

 

10 hours ago, Dzimm said:

You are referring to voltage in your question.  A single LED bulb is usually rated between 1-3volts depending on color and other factors.  They have a safe range depending on the LED and as you experienced with your trolling motor, higher voltage just makes the LED brighter (motor spin faster). All the resistors in the circuit are doing is knocking down the voltage to a safe level for the LEDs, the amount of "waste" created in this process is incredibly small and has little to no effect on power consumption.  

 

Resistors control volts specifically? I thought volts and amps have a direct correlation. You can't change one without effecting the other.

 

 

10 hours ago, Dzimm said:

This all assumes a well designed circuit, in a poorly designed circuit it could cause all kinds of problems with power consumption.

 

What is an example of a well/poor designed circuit? How can a simple single LED circuit be screwed up poorly designed? Two wires, power source, device, done.

 

 

 

 

 

 

9 hours ago, derf said:

An electric motor is rated for a certain voltage and amperage.  If you double the voltage, you're likely to double the amperage everything else being equal.

 

When you double the amperage, you overload the wiring inside the motor that wasn't designed to take that much current.  When you do that, things get hot and melt.  Bye bye electric motor.

 

 

Does that mean 24v motors are just physically larger than 12v motors? There is no difference in the internal wiring configuration? 

 

This is what i really want to get to the root of. Really wish i had a 24v motor here so i could tear it apart for myself.

 

 

 

 

 

9 hours ago, derf said:

As far as LEDs, there is the voltage for the LED being a factor.  Again, too many volts will burn out something that can't handle it.  Resistors are a convenient way to bring that voltage down.  And sure, there is a little heat.  But an LED has high resistance naturally so it's always a low current circuit.    And like Dzimm says, the waste heat coming off the resistor is trivial.  It's way less than an incandescent bulb generates. 

 

 

Why volts? I thought excessive amps is what causes things to go boom.

[Dzimm]

7 hours ago, ftpiercecracker1 said:

Resistors control volts specifically? I thought volts and amps have a direct correlation. You can't change one without effecting the other.

Yes and no.  How resistance affects the current and voltage of a circuit is one of the most difficult things to understand about electricity and something I cannot explain in any short way, something youd have to read into to understand fully. 

 

I know it goes against what the math would tell you but for simplicity's sake, think of it as the current will remain unchanged and the voltage will drop across the resistor because the draw from the LED doesn't change, the battery doesn't push current, the device pulls it, and the resistor only cares about bringing down the voltage on its way.  Think of it as a speed bump, the speed bump is a resistor, your car is the amperage, and your speed is the voltage.  Your car remains unchanged on the other side but the speed bump caused you to slow to down.  

 

7 hours ago, ftpiercecracker1 said:

 

What is an example of a well/poor designed circuit? How can a simple single LED circuit be screwed up poorly designed? Two wires, power source, device, done.

In a single LED circuit one could use an improperly sized resistor.  Too much resistance increases waste and causes a dimmer light, too little resistance reduces the lifespan of an LED.  It's a balancing act and the more devices added to the circuit, the more chances someone has to make poor choices for the design.  You'd be surprised at how much you can change on a low voltage circuit or how many ways you could build it to accomplish a single task, but there are definitely wrong ways to do it.

 

7 hours ago, ftpiercecracker1 said:

Why volts? I thought excessive amps is what causes things to go boom.

The device itself pulls the amount of amps it needs, this is the "draw".  The voltage is what kills electronics.  The amps is what will kill a human.

[Ωhm]

On 4/27/2020 at 10:47 AM, ftpiercecracker1 said:

What is the difference between a 12v and a 24v motor?

Wattage rating.

 

On 4/27/2020 at 10:47 AM, ftpiercecracker1 said:

A 12v ran on 24v will double its output, but will burn up in just a few short minutes.

Doubling the voltage, doubles the amperage, since the resistance stays the same. Back to wattage rating.

[ftpiercecracker1]

3 hours ago, Dzimm said:

Yes and no.  How resistance affects the current and voltage of a circuit is one of the most difficult things to understand about electricity and something I cannot explain in any short way, something youd have to read into to understand fully. 

 

I know it goes against what the math would tell you but for simplicity's sake, think of it as the current will remain unchanged and the voltage will drop across the resistor because the draw from the LED doesn't change, the battery doesn't push current, the device pulls it, and the resistor only cares about bringing down the voltage on its way.  Think of it as a speed bump, the speed bump is a resistor, your car is the amperage, and your speed is the voltage.  Your car remains unchanged on the other side but the speed bump caused you to slow to down.  

 

In a single LED circuit one could use an improperly sized resistor.  Too much resistance increases waste and causes a dimmer light, too little resistance reduces the lifespan of an LED.  It's a balancing act and the more devices added to the circuit, the more chances someone has to make poor choices for the design.  You'd be surprised at how much you can change on a low voltage circuit or how many ways you could build it to accomplish a single task, but there are definitely wrong ways to do it.

 

The device itself pulls the amount of amps it needs, this is the "draw".  The voltage is what kills electronics.  The amps is what will kill a human.

 

I feel like i actually understand. 🙂

 

Why do LED light bars need giant heat sinks?

 

 

 

 

 

1 hour ago, Ωhm said:

Wattage rating.

 

Doubling the voltage, doubles the amperage, since the resistance stays the same. Back to wattage rating.

 

 

That still doesnt explain the physical difference that allows one motor to operate at 24 and another at 12.

 

 

 

If i wanted to convert a 12v motor to run on 24 or 36 or 42 etc what has to change about thr motor physically? Because obviously whatever is inside a 12v motor can't handle 24v coursing through it.

 

How is a 24v motor wired such that it does not burn up?

 

Thank you for sharing your knowledge. 

 

[Dzimm]

16 minutes ago, ftpiercecracker1 said:

Why do LED light bars need giant heat sinks?

In reality, they don't need them as much as you'd think but they sure do make the housings look cool!  With that many LEDs in a small case you will have some heat produced from the circuitry and some designs may need some form of heat sink for the LED driver circuitry.  

[Ωhm]

52 minutes ago, ftpiercecracker1 said:

If i wanted to convert a 12v motor to run on 24 or 36 or 42 etc what has to change about thr motor physically? Because obviously whatever is inside a 12v motor can't handle 24v coursing through it.

 

How is a 24v motor wired such that it does not burn up?

Internally you would need, lower gauge wires, in order to handle the increase in current flow. This would apply to everything;  Armature, Commutator, Brushes, Field Coil. If you want a bigger burger (12vdc to 24vdc), you need more beef.

[derf]

1 hour ago, ftpiercecracker1 said:

If i wanted to convert a 12v motor to run on 24 or 36 or 42 etc what has to change about thr motor physically? Because obviously whatever is inside a 12v motor can't handle 24v coursing through it.

 

How is a 24v motor wired such that it does not burn up?

 

Think of it like taking a street car and turning it into a drag car.

 

Double the horsepower in your engine and what happens?  You start breaking things.  Cast cranks don't hold up.  Cast connecting arms fail.  Pistons start behaving badly.  Transmission internals won't like it.  Even the transmission case can come apart if it's a light duty transmission to start with.  U-Joints don't live as long.  The driveshaft can twist.  The axle shafts can snap.  The ring and pinion start chucking teeth.  You can spin axle tubes.

 

Same thing with electricity.  Double the power and things not designed to take that much power give out.  A lot of what fails in an electrical system tends to be because of the excessive heat generated.  But the same concept applies.  Bigger power needs stronger parts.

[Minuit]

4 hours ago, ftpiercecracker1 said:

Why do LED light bars need giant heat sinks?

Damn forum ate a long and math-filled post that I was about ready to submit.

 

The first result I found for a Jeep light bar claimed a 320W draw across 32 chips. I didn't care to look up the chips they used, but a typical LED chip is somewhere around 40% efficient. That means about 60% of the energy you put into it comes out as heat and 40% as light.

 

That means that 40% efficient light bar is still dissipating 192 watts of heat. That's quite a bit, especially considering that each of these 32 chips is about the size of the head of a small nail, and the individual silicon tracks inside of the chip that make the magic happen are way smaller than that. We're talking microscopic here. Semiconductors can handle quite high temperatures, but you still want to keep them below a certain temperature. The larger your heat sink, the more ability it has to remove heat from the LED chips and dissipate it either through radiation or convection into the atmosphere. I'm sure there's a "make it look big, black, and mean" factor in there somewhere, but high power LEDs still dissipate a whole lot of heat and need fairly substantial heat sinks to be reliable. Sometimes, you'll even see forced-air cooling in LED lighting. It's somewhat common for LED replacement headlight bulbs to have fans in them.

 

Still, it could be worse. We could be in the dark ages of incandescent lighting still. They're just heating elements we overdrive until they glow bright enough to light something up. Their efficiencies are in the low single digits. You can get over 150 lumens per watt out of a good LED, but maybe 16 lumens per watt out of the best incandescent bulb.

[fiatslug87]

6 minutes ago, Minuit said:

Still, it could be worse. We could be in the dark ages of incandescent lighting still. They're just heating elements we overdrive until they glow bright enough to light something up. Their efficiencies are in the low single digits. You can get over 150 lumens per watt out of a good LED, but maybe 16 lumens per watt out of the best incandescent bulb.

 

Yeah, but this still looks better on our old MJs. (400 watts, don't know about lumens)

[derf]

There are some options out there for lights with the old school classic look but they are LED based.  That's what I'm looking into for my MJ builds.

[Minuit]

2 hours ago, fiatslug87 said:

 

Yeah, but this still looks better on our old MJs. (400 watts, don't know about lumens)

No argument from me

 

For what it's worth, my MJs contain absolutely no LED-based lighting in any way. Because hot and inefficient is how it's SUPPOSED to be, damnit!

[ftpiercecracker1]

8 hours ago, Dzimm said:

In reality, they don't need them as much as you'd think but they sure do make the housings look cool!  With that many LEDs in a small case you will have some heat produced from the circuitry and some designs may need some form of heat sink for the LED driver circuitry.  

 

 

What is the function of an LED driver?

 

 

 

2 hours ago, Minuit said:

No argument from me

 

For what it's worth, my MJs contain absolutely no LED-based lighting in any way. Because hot and inefficient is how it's SUPPOSED to be, damnit!

 

🤣

 

 

 

 

8 hours ago, derf said:

 

 Same thing with electricity.  Double the power and things not designed to take that much power give out.  A lot of what fails in an electrical system tends to be because of the excessive heat generated.  But the same concept applies.  Bigger power needs stronger parts.

 

So high voltage motors can't be small and the only difference is physical size? Like wire guage and what not?

 

 

[Dzimm]

2 hours ago, ftpiercecracker1 said:

 

What is the function of an LED driver?

LEDs run on DC and are low voltage.  The driver will step down the voltage, stabilize it, and to get the power within the specs of the LED.  If the main power supply was AC, the driver would also convert it to DC for the LED.

[Minuit]

And if conditions are right, that "LED driver" could be as simple as a single resistor, the value of which would be calculated based on the LED's current and voltage requirements.

[ftpiercecracker1]

41 minutes ago, Dzimm said:

LEDs run on DC and are low voltage.  The driver will step down the voltage, stabilize it, and to get the power within the specs of the LED.  If the main power supply was AC, the driver would also convert it to DC for the LED.

 

 

Its like the hydra. Every answer i get inspires two or more questions. 🤪

 

To spare you all from my unending stream of questions perhaps you could suggest some recommended reading? Not so much "black wire hot, white wire nutral, bare wire is ground", but electron flow, terminology and there meanings, formulas, history of formulas. Applied electrical theory? 

 

 

Is anyone here an actual EE?

 

On a scale of 1-10 how well do we understand electricity?  10 its our b***h, 1 we're its b***h.

[Minuit]

As for qualifications, I'm not an EE but I did complete the early parts of an EE degree as part of my ME degree. Circuit analysis I and II, lab equipment (that started a long and expensive fascination with vintage test gear), a terrible class on control theory, some very basic digital logic, a 5 minute tutorial on soldering, that kind of thing. Or to put it another way, a lot of surface level knowledge that isn't terribly useful on its own. I learned a hell of a lot more once I actually started doing it.

 

The Art of Electronics is the most frequently recommended electronics book I've seen. It's a university level textbook though, not sure if you're wanting to go that deep. Look at some reviews and the table of contents to see if it's what you're looking for.

 

As for our level of understanding, I'd give it an 8 or 9. We know pretty well what's going on with it, but we are almost to the point now where we are almost out of "room" to make transistors smaller. If there is a way around that, that'll be the next big breakthrough I think. It's not quite like magnetism - the only thing that really stuck with me in my electromagnetism class from school is that "we really have no idea how the @#$% this works" - at least, not in a way that you could explain to a sophomore that doesn't already have a strong background in physics.

[derf]

I'm more of a computer guy than an EE but I do low level systems software.  Embedded control systems and the like.  I've been at it for a few decades, working in the trenches with other engineers bringing systems to life and have picked up a few things.

 

That being said, I defer to the real experts for a lot of the detailed information.

[Dzimm]

My high school offered a few electronics classes and I had some in college as well when I was going for Mechanical Engineering but I never finished it.  I got the basics in school and continued my education on my own as I frequently dabble in electronics, specifically low voltage DC stuff.  I have scratch built many small circuits for projects, most notably the electronics for Ghostbusters proton packs and proton wands with all the actual light functions from the first movie just for fun.   I enjoy electronics and have thought about making it a career multiple times but just couldn't bring myself to pursue it any further than a hobby.

 

The best resource for information is Google and YouTube.  You can find the answer to any question you have, just start looking into a topic that interests you or you have a question on and soon you'll be absorbing all kinds of information and start piecing things together into a larger understanding of the topic.  I'm not an expert on any topic, I just have spent so much time absorbing information in all kinds of topics that I have a good base of information and will seek out information on anything I want or need to know that I don't.