Popriv,

Here's a basic but easy way to remember volts vs. Milli-Amps with a battery: think of it as a gas tank with an outlet hole in it.

As your power needs increase, you need more fuel which means a bigger hole in the tank to get more fuel out of it. Hence the outlet hole equates to the voltage of the battery pack. More power desired means a larger fuel requirement (larger fuel line, or hole in the fuel tank), so the higher the voltage needs to be.

The capacity of that fuel tank is measured not in gallons, but Milli-Amps. The higher the Milli-Amp capacity is equates to a larger gas tank - more fuel in the tank means the further you get before you have to fill it back up.

One other thing to think of is the C-rating of the battery if you're going to use a high-power draw system. That equates to how fast the fuel can flow from the tank, or battery. The higher the C-rating, the faster you can empty the tank. The lower the C-rating, you can't empty the tank as fast without causing damage to the battery. This is where you have to use a Watt Meter and start figuring mathematically how fast you're going to drain the battery to determine if you're going to exceed the C-rating or not. Exceeding the C-rating will eventually damage the battery due to excessive heat. Unless you're flying high-performance on the edge, you probably won't have to worry about exceed the C-rating of the battery for normal activities.

So basically in your case, the higher capacity battery at the same voltage will be safe as long as you maintain your CG and the plane doesn't get too heavy to affect the flying characteristics. You're just adding a larger fuel tank.

Hogflyer