Battery question

Amp34

Amp34

Amp34

Caporegime
Joined
25 Jul 2005
Posts
28,851
Location
Canada
If I attached two 9V batteries together in parallel (ie the two red wires together and the two black wires together) would that mean anything running off this would have twice the life of just a single battery, say instead of 4 hours 8 instead? Would it cause any problems such as too much wattage or amperage?

I would then just connect the positive and negative wires from the device to the joins where i connected the two batteries together?
 
Amp34 said:
If I attached two 9V batteries together in parallel (ie the two red wires together and the two black wires together) would that mean anything running off this would have twice the life of just a single battery, say instead of 4 hours 8 instead? Would it cause any problems such as too much wattage or amperage?

I would then just connect the positive and negative wires from the device to the joins where i connected the two batteries together?
Click to expand...

iirc in parallel will run twice aslong, but in series twice as much voltage.

KaHn
 
Chronos-X said:
I think you'd get 18v. For the same reason appliances that use 6v AC will use 4x 1.5v batteries. Could be wrong, though.
Click to expand...
You are wrong. Running red to black to red to black (series) will get you double the voltage. Using the method the OP proposed, he'd get double the current for the same resistance.

V=IR
 
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Chronos-X said:
I think you'd get 18v. For the same reason appliances that use 6v AC will use 4x 1.5v batteries. Could be wrong, though.
Click to expand...

6 volt ac will not run of 4 1.5 batteries for the simple reason, batteries are DC current.

KaHn
 
i thought if you connect 2 volt batteries in parallel in a circuit one tries to go against the other? (Opposing loops)

But then again the last time i did A-level physics was nearly 2 years ago so i could be horribly wrong :/
 
Heofz said:
i thought if you connect 2 volt batteries in parallel in a circuit one tries to go against the other? (Opposing loops)

But then again the last time i did A-level physics was nearly 2 years ago so i could be horribly wrong :/
Click to expand...


Glad you realised it instead of us.

KaHn
 
Well I think you should be good to go. You should end up with the capability to flow about 800 mAh with it. If you think it's breaking or is unhappy with the increase in current, kill it. I think it'll be fine.

Now that I've said that and bumped this thread, somebody smarter than I will coma along and n00bify me. Please do if I'm missing something. ;)
 
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Lol thanks for that, I was just wondering as your previous post sounded like ther may be a problem. :)
 
To do it properly you'd install a resistor in series with the rest of it. that would cut down the current to less dangerous levels. However, I'm not sure thow to beasure the resistance of the motor when it's on. The specs of the motor will chenge when it's running becasue of back EMF.
 
Putting your two 9v volt batteries in parrallel will just give you twice the capacity. the motor will not pull any more current than if you are just using one battery so there is no need for a current limiting resistor (putting a resistor in series would also reduce the speed of your fan due to the volts drop across it).

Fog
 
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