Battery question

Amp34 said:
A small handheld fan (9v) says it uses 200mA and 200mW.
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Those figures cant be right.

If you have a current draw of 200mA at 9volts then the power consumption is as follows (roughly).

P=V.I = 9x200x10-3 = 1.8 watts

or if you work off 9 volts and 200mW

then the current would be

I=P/V = 200x10-3/9 = 22mA


Fog
 
I didnt think of that, thats what it says in the manual. :confused: Its a single unit with all the things built into a sortof case, It must have some resistors etc on the IC unless the manual is wrong.

Anyway only one way to find out. :p
 
Foghorn Leghorn said:
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See, that's the same things that I ran into trying to calcualte the vital stats for this setup. I guess that amp32 is right, the only good way to know is to try it.

Amp, I hope that nothing about this it really vital or irreplacable. Just bite the bullet and run them wires in series. Tell us how it goes. :)

/BTW I ask that you excuse any craziness in this post die to extreme drunkenness on the part of the poster.
 
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Its not a particularily expensive or important piece so ill have a go and see what happens. I may put the batteries in parallel though as in series it will definitly blow. ;)
 
Umm. In parallel it will blow becasue the volatage will be 18v. IOn series wit will be 12v with increased current. Run it in series; red to black, red to black.
 
Billy MUST be very drunk. ;) He's mixing up his terms.

Hooking the bateries up in parallel like you originally suggested will only double the run time of the fan. Nothing more.

"+" to "+", "-" to "-", and then run the fan as normal.

It's the whole premise of the battery bank for the renewable energy project I'm working on.

It's also basic electronics.

<----- Electronics technician.

And yes, there is no way the thing can run on 9VDC and get both 200mA and 200mW. One or the other, the maths don't add up for both.

Watts = Current X Voltage

Voltage = Current x Resistance

Or, to use proper terms:
P = I x E
E = I X R

So, 200mW cannot equal 200mA times 9 volts. Just doesn't work......
 
BillytheImpaler said:
Umm. In parallel it will blow becasue the volatage will be 18v. IOn series wit will be 12v with increased current. Run it in series; red to black, red to black.
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!!

Heehee, where did the 12V come from? I'm hoping you've already realised that's wrong ;-)
 
Just a quick question in a similar vein, what is the max amperage and wattage of a single pp3? I've looked everywhere but cant find any information on the subject.

And yes i did realise Billy was rather, shall we say, out of it ;)
 
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