Playing with NOKIA BATTERIES! 9v??

[radiokid]

Hey guys, gals, chimps and baracudas!

Hey does somebody know how I can use the various Nokia batteries, instead of a 9v battery, in other non-mobile related purposes?
The power output of the device will be: Output Power: 200mW

Please I will be very grateful to someone WHO KNOWS WHAT THEY ARE DOING to help me out cos I dont want a battery to blow up on me! :cry:


Jamie!

[Musicb0ffin]

Hey, To get 9v, you have 2 options. You could use 3 batts or so in series to provide around 9v, or you could built a basic step up circuit. The first solution would give you 9v at 900mAh or whatevere the current output is, which would keep your machine running for a repectable amount of time. The downside is you have 3 batts to charge when they are flat. The 2nd solution requires you to do a bit of maths and a small magnet. The formula for a transformer is somthing like voltage 1/turns on 1 = voltage 2 / turns on 2. Im sure anyone else doing physics can correct me if thats wrong... That means the voltage going in (3.7v), divided by the number of turns on that side of the magnet will equal the output voltage divided by the number of turns on that side of the magnet. To get your 9v, you just need a ratio of around 1:3 for the number of turns. I know i haven';t explained this very well, and if you are unfamiliar with transformers, you might have some difficulty building one up from my instructions. Still, hope i've helped a bit. Any q's, i'll try to answer.

[FU_Too]

Hey, To get 9v, you have 2 options. You could use 3 batts or so in series to provide around 9v, or you could built a basic step up circuit. The first solution would give you 9v at 900mAh or whatevere the current output is, which would keep your machine running for a repectable amount of time. The downside is you have 3 batts to charge when they are flat. The 2nd solution requires you to do a bit of maths and a small magnet. The formula for a transformer is somthing like voltage 1/turns on 1 = voltage 2 / turns on 2. Im sure anyone else doing physics can correct me if thats wrong... That means the voltage going in (3.7v), divided by the number of turns on that side of the magnet will equal the output voltage divided by the number of turns on that side of the magnet. To get your 9v, you just need a ratio of around 1:3 for the number of turns. I know i haven';t explained this very well, and if you are unfamiliar with transformers, you might have some difficulty building one up from my instructions. Still, hope i've helped a bit. Any q's, i'll try to answer.well I not into physics but I thought a transformer needs ac voltage to work as stepup or stepdown so its not as simple as you say. maybe a voltage converter is more appropriate. Also 3 nokia batteries would add upto 11volts as each one is 3.7volts :) I could be wrong :rolleyes:

[radiokid]

Hey thanks for the replys,

With what I am constructing I will only be using one Nokia battery. I know theres a way to do this...only how?? I dont think it will be nessacary to use multiple batteries to acheive the voltage but I feel acheiving the: 200 mW output would be more crucial??

But safety is the #1 concern, so its got to be safe (i dont want overheating or battery guts all over me!) :cry:

Jamie!

[FU_Too]

Hey thanks for the replys,

With what I am constructing I will only be using one Nokia battery. I know theres a way to do this...only how?? I dont think it will be nessacary to use multiple batteries to acheive the voltage but I feel acheiving the: 200 mW output would be more crucial??

But safety is the #1 concern, so its got to be safe (i dont want overheating or battery guts all over me!) :cry:

Jamie!Its unlikely you'll get a battery to explode from discharging as its the wrong charging that could cause the battery to explode or get hot. I know there are voltage converters (semiconductors) that can turn 1.5v up to 5volts but not sure about the current rating you'll need. I also remember something about current to voltage ratio. Something like 200mA at 9v device would be 600mA at 3v (but as I say I'm not sure) :-?

[deviat0r]

Its unlikely you'll get a battery to explode from discharging as its the wrong charging that could cause the battery to explode or get hot. I know there are voltage converters (semiconductors) that can turn 1.5v up to 5volts but not sure about the current rating you'll need. I also remember something about current to voltage ratio. Something like 200mA at 9v device would be 600mA at 3v (but as I say I'm not sure) :-?


OK,

Yes, transformers are DC blocking. Which means the transformer is not really an option. As converting it to AC, then stepping up then back to DC is efficency drain.

As for the current.....

the formula is one of the following depending on what (sorry no punn intended!) is missing......

If missing Amps
Amps=Watts/Volts

If missing watts
Watts=AmpsXVolts

If missing volts
Volts=Watts/Amps

So if we take our 200ma, or for this case it would be .2 X 9volts = 1.8 Watts

Then 1.8 watts / 3.6 volts = 500ma

So what we have is a 3.6 volt batery giving out 500ma. ALthough there are other factors, like efficency. A step up device will never be 100% efficent, it is most likely to be between 50-80%.

This makes me think realistically 200ma @ 9v is going to need 3.6 volts at up 1 amp! Thats an awful lot of current coming from a small battery. Although the battery shouldn't explode, it won't last long!

I hope this helps and doesn;t make the matter worse.

Dave

[deviat0r]

ok,

UPDATE

http://www.xs4all.nl/~odu/dcdc.html

Shows a simple circuit, you'll need to work the maths out, but that ain't too hard.

If you want something a bit easier to make try this......
http://www.rowan.sensation.net.au/electronics/stepup.html

Dave

[FU_Too]

OK,

Yes, transformers are DC blocking. Which means the transformer is not really an option. As converting it to AC, then stepping up then back to DC is efficency drain.

As for the current.....

the formula is one of the following depending on what (sorry no punn intended!) is missing......

If missing Amps
Amps=Watts/Volts

If missing watts
Watts=AmpsXVolts

If missing volts
Volts=Watts/Amps

So if we take our 200ma, or for this case it would be .2 X 9volts = 1.8 Watts

Then 1.8 watts / 3.6 volts = 500ma

So what we have is a 3.6 volt batery giving out 500ma. ALthough there are other factors, like efficency. A step up device will never be 100% efficent, it is most likely to be between 50-80%.

This makes me think realistically 200ma @ 9v is going to need 3.6 volts at up 1 amp! Thats an awful lot of current coming from a small battery. Although the battery shouldn't explode, it won't last long!

I hope this helps and doesn;t make the matter worse.

DaveWell I wasnt far out, but just got a Question? Where did you get the 1 amp from as you'd worked out it would draw 500mA, is this to take account of reserve or initial surge? Just curious. ;)

[Musicb0ffin]

well I not into physics but I thought a transformer needs ac voltage to work as stepup or stepdown so its not as simple as you say. maybe a voltage converter is more appropriate. Also 3 nokia batteries would add upto 11volts as each one is 3.7volts :) I could be wrong :rolleyes:

Yeah, you got a point there mate... oops... :) Its been a while since i've done any major electonics modding so im a bit rusty on the ins and out, and now it's been pointed it out, stepping up doesn't seem to be a good idea. Oh well, sorry my idea wasn't any good.

[danwood76]

About DC and transformers,
if you switch the DC on and Off at regular intervals ie with an oscilator circuit you can simulate voltage shifts like in AC so you can effectively run a transformer with a battery and wo or three small components

about transformers, the calculation for the vin and vout of a transformer is:#

NP = VP
NS VS

so the ratio between the first and second coil is directly linked to the ration between the in and output voltages

hope this helps,
Danny