Batteries are specified by its charge capacity, or C-rating.

For example, a common 9V battery might be rated at 600 mAh.
This means that such 9V battery might be expected to last for 1 hour while delivering 600 mA.

Use the C-rating as a guide only since this can change with current load, temperature and variation in chemistry (and increasing battery internal resistance). Moreover, you can expect the run-time to be lower when you increase the current drawn. For example, a battery supplying a load at 10C will not run for 1/10 hour (6 mins) but somewhat less than 1/10 hour.

 

As

Papabravo... I am learning..as I stated in original?, is this even a logical ?, apparently not. Yes, garbage in/garbage out. I have been fed garbage and am trying to learn the correct answer, which brought me to this forum.

LynneMarie.. I was not speaking to you with my reply, but rather the poster who asked you the question. Maybe I should have said "you don't have the answer yet".

 

Hi,

I elected not to bring up the complexities of the change in apparent ampere hour rating with current draw so that the OP could get a basic idea how batteries worked before progressing to the more exact (if we can even call it that) calculation. This would allow her to grasp the basic concepts first, then more ahead when she felt comfortable with that.

But i cant ignore the question about the different manufacturers and how their batteries compare.
I've read about basic tests done with different brand batteries, and i saw quite a spread in run times. It was almost hard to believe, at least until i bought a wireless refrigerator monitor where you place the measurement unit inside the fridge and the receiver outside where you can read the temperature inside. The transmitter and receiver BOTH needed batteries because neither plugged into the wall, and they required two AA batteries each.
After a couple years of running various brand batteries, i found that the Radio Shack brand lasted a lot longer than the other name brands in the transmitter. That was pretty amazing. I dont know why but they must be better batteries. The difference was at least 50 percent more run time, so that works out to about three months over the other brands two months (2 x AA alkaline).
I have since then switched to a home brewed version that allows the two batteries to last for almost 2 years, but that was only after going through a bunch of batteries with the purchased wireless unit.

 

Thankyou everyone for the info. I feel I have a greater understanding now, from the simple basics to various batteries and how they may perform under various circumstances. I have been reading on the subject, and along with everyone's input think my op (maybe awkwardly wordered) was answered...yes, different batteries though rated same mah, same volt or wattage, same load and resistance can perform differently under the same circumstances.

 

Yes that makes sense. I am beginning to understand better now. When I stated watts... I meant the battery was capable of running watts vs volts at a given 'setting'. The amp of the battery would be the same, with a 'variable' setting on the voltage or wattage. I think my question was rather naive after reading more of currents and circuits, etc. thank!

I've never seen a battery that I can set the voltage or wattage on.

What, exactly, are you working with?

 

Thankyou everyone for the info. I feel I have a greater understanding now, from the simple basics to various batteries and how they may perform under various circumstances. I have been reading on the subject, and along with everyone's input think my op (maybe awkwardly wordered) was answered...yes, different batteries though rated same mah, same volt or wattage, same load and resistance can perform differently under the same circumstances.

I originally didn't see all the replies you've received, so my first reply was a bit dated.

One thing that hasn't been pointed out, but has been alluded to, is that two batteries of the same voltage will not always output the same current when applied to the same load. A good case in point would be a 12V battery made up of putting 4 3V coin cells in series. Try to start your car with that. Most people would have no expectation that it would work. But we start our cars all the time with a 12V battery. So what's the difference? It's internal resistance. All real batteries have an internal resistance which, while very complicated in how it comes about, look as if (to a first order approximation, anyway) a resistor in series with an ideal voltage source. The resistance of those coin cells is so high that most of the voltage is dropped across the internal resistance by the time you are drawing a few dozen milliamps, while the internal resistance of the car battery is so low that you haven't dropped very much across it even when it is supplying a few hundred amps.

 

I originally didn't see all the replies you've received, so my first reply was a bit dated.

One thing that hasn't been pointed out, but has been alluded to, is that two batteries of the same voltage will not always output the same current when applied to the same load. A good case in point would be a 12V battery made up of putting 4 3V coin cells in series. Try to start your car with that. Most people would have no expectation that it would work. But we start our cars all the time with a 12V battery. So what's the difference? It's internal resistance. All real batteries have an internal resistance which, while very complicated in how it comes about, look as if (to a first order approximation, anyway) a resistor in series with an ideal voltage source. The resistance of those coin cells is so high that most of the voltage is dropped across the internal resistance by the time you are drawing a few dozen milliamps, while the internal resistance of the car battery is so low that you haven't dropped very much across it even when it is supplying a few hundred amps.

The op was made due to an arguement I was having with someone using a battery for a personal vaporizer, commonly referred to as an e-cig. They now have batteries with variable voltage or wattage settings, whichever you prefer to use. It got me into looking more at circuits, currents etc as I had just a very basic understanding.
Your example of grouping batteries to gain a certain voltage is very interesting and brings into play the resistance factor which is very important in these devices, as the resistance is a variabke the user changes in the part of the device that creates the vapor. There are many people using these devices now with little to no understanding of how they work, but user variables are commonly changed. I wanted to become a bit more educated about the workings of these devices. Again, thanks everyone!

 

People using devices they don't understand is certainly nothing new. How many people have the faintest idea how a television or computer works? Or the remote control for their TV? The same can be said for mechanical systems, too. How many people understand how the brakes on their car work, let alone the engine? Inquiring into how any of it works is a pretty rare quality -- good to see that you have it.

 

People using devices they don't understand is certainly nothing new. How many people have the faintest idea how a television or computer works? Or the remote control for their TV? The same can be said for mechanical systems, too. How many people understand how the brakes on their car work, let alone the engine? Inquiring into how any of it works is a pretty rare quality -- good to see that you have it.

Thankyou! I have always been curious and when discussing something like to know the facts. Cars, remotes... Haha I never discuss the inner workings. There seem to be alot of people however that claim they know what they are doing with these devices that only have knowledge of flicking a lighter at the end of a stick tobacco. It's a bit more complicated than that and as I said, just curious. Also I have always puzzled over how electricity, batteries, circuits, etc work. Thanks all for patience with a newbie!