Are you trying to hide the power source while exposing the solar cell?

 

1) i would like them to run for 8 hrs, it can also be a rechargeable battery like in smart watches.
2) the space i have for them is 10mm× 2'' long x 3mm thick.

 

1) i would like them to run for 8 hrs, it can also be a rechargeable battery like in smart watches.
2) the space i have for them is 10mm× 2'' long x 3mm thick.

The limits of chemistry and physics prevent you from doing this. It's simply impossible with the constraints you've set. There is no magic that can violate the laws of physics that prevent you from doing more work than the energy you have available.

No fancy circuit, no clever hook up, nothing. It's just like asking to fly by flapping your arms—not going to happen.

 

What is it you are doing with these fans?

What is the actual goal of your project? What purpose is the project trying to accomplish?

Leaving that aside for now, the information you are giving now is a bit different than what you gave originally in terms of the fan specs. Originally you said that the fans were 3 V, 0.28 amp fans. Now you are saying they are 0.28 W fans. Since you appear to be reading the latest directly from the fans, I'll assume this is the correct info. This is a big difference. 0.28 amps means that it draws (under some specified load) 0.28 A of current which, at 3 V, means that it is consuming about 0.84 W of power, since power is the product of the voltage across a device and the current through it. But if it is rated to draw 0.28 W at 3 V, that means that the current draw is only about 93 mA, or just one-third of what it did before.

The third fan is more problematic. Under its spec'ed load it should draw about 3.7 W /8 V = 0.46 A, but that's at 8 V. I don't know how well it will work, or what it will draw, if you only apply 3 V to it.

Do you actually have these fans?

Can you connect them up to two batteries in series (preferably two AA cells or larger) and see if they will do what you need them to do powered that way? If the answer is yes, then we can proceed. If the answer is no, then we need to take a step back and look at a fundamentally different approach.

What is it you are doing with these fans?

What is the actual goal of your project? What purpose is the project trying to accomplish?

Leaving that aside for now, the information you are giving now is a bit different than what you gave originally in terms of the fan specs. Originally you said that the fans were 3 V, 0.28 amp fans. Now you are saying they are 0.28 W fans. Since you appear to be reading the latest directly from the fans, I'll assume this is the correct info. This is a big difference. 0.28 amps means that it draws (under some specified load) 0.28 A of current which, at 3 V, means that it is consuming about 0.84 W of power, since power is the product of the voltage across a device and the current through it. But if it is rated to draw 0.28 W at 3 V, that means that the current draw is only about 93 mA, or just one-third of what it did before.

The third fan is more problematic. Under its spec'ed load it should draw about 3.7 W /8 V = 0.46 A, but that's at 8 V. I don't know how well it will work, or what it will draw, if you only apply 3 V to it.

Do you actually have these fans?

Can you connect them up to two batteries in series (preferably two AA cells or larger) and see if they will do what you need them to do powered that way? If the answer is yes, then we can proceed. If the answer is no, then we need to take a step back and look at a fundamentally different approach.

Hello, yes i do have these fans, they are made by sunon, its there smallest fans 9×9×3 mm, I jus want the to work without burning up lol. I did solder them to the circuit board on a smartwatch just to se it would work but it didnt.lol. it did run on 2 aa bateries but really slowly.

 

The limits of chemistry and physics prevent you from doing this. It's simply impossible with the constraints you've set. There is no magic that can violate the laws of physics that prevent you from doing more work than the energy you have available.

No fancy circuit, no clever hook up, nothing. It's just like asking to fly by flapping your arms—not going to happen.

Ok, thank you

 

Datasheet

2.0-3.5Vdc
92mA

Getting out my bar napkin...

At 235mAh for rating for Energizer CR2032 you can run this fan for 2.55 Hr (not at steady speed though). These are the numbers for a single fan, single CR2032 and BEST CASE.

Figure out what you want to scale to get your 8 hours and go from there.

 

1) i would like them to run for 8 hrs, it can also be a rechargeable battery like in smart watches.
2) the space i have for them is 10mm× 2'' long x 3mm thick.

So let's look at some basic values.

The volume you have available is 1 cm x 5 cm x 0.3 cm = 1.5 cc.

Let's use the 0.28 W for two fans and MrSoftware's 1.4 W estimate for the other. That's basically 2 W of power for 8 hours, or 16 Wh. That means you need an energy density of well in excess of 10,000 Wh/liter.

The Lithium manganese dioxide cells you seem intent on using have energy densities in the 300 to 700 Wh/l and the highest energy density I've been able to find is less than 1700 Wh/l for zinc-air.

So your idea is a complete nonstarter by about an order of magnitude.

Back to square one.

Again -- what is the purpose of the project. I have a hard time believing that the goal of this project is to run these three fans for eight hour off of a couple of coin cell batteries.

Why are there fans involved at all?

Why eight hours? Forget about what you would LIKE -- tell us what is NEEDED.

 

Datasheet

2.0-3.5Vdc
92mA

Getting out my bar napkin...

At 235mAh for rating for Energizer CR2032 you can run this fan for 2.55 Hr (not at steady speed though). These are the numbers for a single fan, single CR2032 and BEST CASE.

Figure out what you want to scale to get your 8 hours and go from there.

Thank you!

 

1) i would like them to run for 8 hrs, it can also be a rechargeable battery like in smart watches.
2) the space i have for them is 10mm× 2'' long x 3mm thick.

Watts and amps...
Inches and millimeters...

How is anyone to make sense of this?

 

Watts and amps...
Inches and millimeters...

How is anyone to make sense of this?

Worked for the Hubbell space telescope :/

 

Worked for the Hubbell space telescope :/

I know this sounds impossible, but how can a smart watch last 8 hrs and it can do all kinds of things from powering the lcd screen to powering every thing on its pcb board.its also all inside a tiny thin watch. Sorry for making people upset with my insane question's. Thank you all for your hep

 

I know this sounds impossible, but how can a smart watch last 8 hrs and it can do all kinds of things from powering the lcd screen to powering every thing on its pcb board.its also all inside a tiny thin watch. Sorry for making people upset with my insane question's. Thank you all for your hep

Simply, because it requires MUCH less power to operate.

Let’s say you have a small car and a large truck and each only has one gallon in their tanks.

If the small car can drive 20 miles, how come the truck can only go 5 miles?

 

I know this sounds impossible, but how can a smart watch last 8 hrs and it can do all kinds of things from powering the lcd screen to powering every thing on its pcb board.its also all inside a tiny thin watch. Sorry for making people upset with my insane question's. Thank you all for your hep

The smart watch spends a LARGE amount of time sleeping. And when it does wake up, it's not drawing anywhere near 90mA. You want to stay awake for 8 hours straight AND run 90+mA. Let me turn off that fan 90% of the time and operate in the uA range and I can make the bestest longest running fan (that doesn't blow) in the world.

 

I know this sounds impossible, but how can a smart watch last 8 hrs and it can do all kinds of things from powering the lcd screen to powering every thing on its pcb board.its also all inside a tiny thin watch. Sorry for making people upset with my insane question's. Thank you all for your hep

Smart watches don’t attempt to violate the laws of physics.

Anything you want to power needs a certain amount of energy over time. The energy in a cell can be roughly understood as a special sort of tank for electricity. It contains a finite and specific amount, and can deliver it at a particular rate which affects how much it can deliver over time.

The cell-tank is filled with chemicals that provide the electrical current. The nature of that chemistry determines how much energy will fit in a tank of a given size. A cell-tank full of carbon and zinc will contain a lot less energy than one full of lithium and aluminum. It’s a matter of physical laws. You can’t game it.

Even at the highest energy densities, the most compact cell-tanks, you can’t do what you are demanding. A smart watch does very little work compared to a fan. The watch consumes orders of magnitude less energy than the fan, for various reasons. In the end, physics says no.

 

Simply, because it requires MUCH less power to operate.

Let’s say you have a small car and a large truck and each only has one gallon in their tanks.

If the small car can drive 20 miles, how come the truck can only go 5 miles?

Smart watches don’t attempt to violate the laws of physics.

Anything you want to power needs a certain amount of energy over time. The energy in a cell can be roughly understood as a special sort of tank for electricity. It contains a finite and specific amount, and can deliver it at a particular rate which affects how much it can deliver over time.

The cell-tank is filled with chemicals that provide the electrical current. The nature of that chemistry determines how much energy will fit in a tank of a given size. A cell-tank full of carbon and zinc will contain a lot less energy than one full of lithium and aluminum. It’s a matter of physical laws. You can’t game it.

Even at the highest energy densities, the most compact cell-tanks, you can’t do what you are demanding. A smart watch does very little work compared to a fan. The watch consumes orders of magnitude less energy than the fan, for various reasons. In the end, physics says no.

Ok thank you!

 

I know this sounds impossible, but how can a smart watch last 8 hrs and it can do all kinds of things from powering the lcd screen to powering every thing on its pcb board.its also all inside a tiny thin watch. Sorry for making people upset with my insane question's. Thank you all for your hep

Because it is specifically designed using technologies that use extremely low power. In many devices, the current draw is so low that it is below the self-discharge rate, meaning that if you took two brand new sets of batteries and put one in the device and the other on a shelf and came back a year or two later, you would have a hard time determining, from state of charge, which set of batteries was which.

But use the light on a digital wristwatch very often and you will notice a significant decrease in how long the battery lasts.

 

So you cannot fit the battery that you need, in the space that you have. If you wish to continue with the solar option, please answer:

(1) How much room do you have for solar cells
(2) What is the lowest percentage of sunlight that the fans need to run in
(3) What is your solar panel budget

 

So you cannot fit the battery that you need, in the space that you have. If you wish to continue with the solar option, please answer:

(1) How much room do you have for solar cells
(2) What is the lowest percentage of sunlight that the fans need to run in
(3) What is your solar panel budget

Room for cells is - 10mm width x 2" in length× 3mm depth.
No budget and it will be used 90% outdoors

 

OK so your next task is to find a solar cell that fits within your size constraints, that can deliver at a bare minimum 2W of power, in your minimum acceptable level of light. Keep in mind that you may actually need more than 2W if you need to add parts to control the voltage (those parts are not 100% efficient), but see if you can find anything that will give you at least 2W and that fits your size and light constraints.

 

OK so your next task is to find a solar cell that fits within your size constraints, that can deliver at a bare minimum 2W of power, in your minimum acceptable level of light. Keep in mind that you may actually need more than 2W if you need to add parts to control the voltage (those parts are not 100% efficient), but see if you can find anything that will give you at least 2W and that fits your size and light constraints.

Great info, thanks