for Model Aircraft Radio Control Systems
When I first entered the hobby and for a long time afterward, I had no idea
Milliamp Hour (mAh) is, how to figure out what capacity battery I
needed for any given application or how many flights it was good for.
I do not think anything confused me more than batteries. In fact, I
still do not fully understand it, so take that into consideration while you
If you really want a thorough understanding of batteries, then you will have
to look elsewhere. This page will cover the basics as I understand and
what I have gotten by with.
The scary thing is that there is no formula to determine battery size.
There is a good reason for that. I am talking about onboard batteries
Milliamps (mA) are the capacity of the battery. One mA = 1/1,000 of an
Think of mAh as a fuel tank. More milliamp hours = bigger tank (more
Think of Volts as the octane rating of the fuel. More volts =
If you have a 600 mAh battery and you think you need more capacity then
changing from a 4.8 volt pack to one having 6.0 volts is the wrong answer. Get a pack
having a higher mAh rating instead — an 800 mAh pack,
Skull and Crossbones !!!
Higher voltage reduces the lifespan
of the servos. Additionally, some equipment can not use voltages
above 4.8 volts.
Always check that the receiver and servos are
rated for a given battery voltage before plugging them in.
All reputable manufacturers publish this information
in their literature and on their websites.
If you want your servos to move faster or have more
power and you do not want to buy faster or more powerful servos, that is the
time to step up the voltage.
Milliamp Hours is the milliamp draw a battery can sustain for an hour (in
theory) before the voltage drops to an useable number. For example, a
600 mAh battery can sustain a 600 mA draw for one hour. In theory,
this means it can sustain a 1,200 mA draw for 30 minutes or a 300 mA draw
for 2 hours.
The actual relationship is not linear, however, due to other factors such as
internal resistance of the battery. What this means is that as you
load the batteries more, the voltage will drop off faster. In the
above example, a battery may only be capable of providing 1,200 mA for15 -20
minutes rather than the 30 minutes you might expect.