Lvangundy

Does anyone know how to wire two 9V batteries in parallel ?

I have a device that uses 300milliamps of power on 9V. Normally it plugs into an AC power plug with a DC adapter but I made a plug so that I can use it portably with a 9V battery. Only problem is the power last only a short while.

Anyone know how to wire two batteries together so the power lasts longer?

I just read that doing this decrases battery life in a staggered way - quote -

"You can also wire two 9V batteries in parallel to get 9V for longer play time, but I won't suggest that because of the staggered effect. You see, current will flow only from the battery with more charge (not 4.5V from each), so you'll be getting something staggered like 9V from A, then 9V from B, 8.9V from A, 8.9V from B, 8.8V from A, 8.8V from B...and so on. It is not 9V all the way and by the time both batteries get low, you'll just get a longer period of undesired low wattage. "

Lvangundy

Would it be like this?

fast400

Put a diode (.7v or lower) between them. With the way you have it when one battery degrades lower than the other it will look like a load the the opposite battery. Using a diode between them will auction the power source based on its capacity.

Lvangundy

I see.

I'm not an electronics guru, so does any plain diode work? If I walked into an electronics store and asked for a .7 volt or lower diode would whatever they came out with work? Does the diode go on the positive or neagtive side - or both?

Also another question -

Most 9V batteries only supply 150ma and the device says 300ma. I couldn't find a 300ma 9v battery. Would wiring them in parallel give me the 300ma? Or would serial do this, but supply 18V ? (which would kill the device right?)

vj604

wiring two pbatteries in parallel will give you 9v total with 2 times the current of each battery. this is a viable option to double your current but you wont get any sort of longer life no matter how many batteries you put in parallel. to do that you will need a bigger battery.

i dont see how putting a diode in between is going to tell the device which batter to use. Diodes serve the function of allowing current to flow in one direction. the primary application of a diode is as a rectifier, or in any area where negative voltage is not permissible, where the diode is wired in shunt with the device.

hope you figure something out.

TimDimman

Hmmm...

Adding a diode will give you a V drop of .7V...??? Operating at 8.3V not 9V correct? The diode is not needed.

Tim