Batteries are currently the weakest part of our hobby. Fly long enough and you will loose a plane due to a battery or switch.
Great strides have been made in recent years, which have left a lot of us totally confused. Your choices are Nickel Cadmium,
Nickel Metal Hydride, Lithium ion, and Lithium Polymer. The NiCad’s are very reliable, but also very heavy. The NiMhd’s
are slightly lighter. The Li-ions are light, but are really short lived and have limited burst power. The Li-poly’s
are very light and just about perfect, but require extreme vigilance to prevent catastrophic failures.
NiMhd’s are lighter than NiCad’s and can use the same charger - which is a plus. NiCads are heavy, but if you
maintain them they can last a decade or more. You don’t need a regulator with these packs, which is also a plus.
The Germans have completely crossed over to the Li-poly batteries for their flight packs. We have been slower to transition
in the US, as they have gotten a bad rep by guys that don’t pay attention to what they are doing. They are the lightest
available and have very high amperage ratings. Personally, I would only use them if I can remove them from the plane for charging.
If you over charge them by accident, they can cause a fire that is difficult to put out. They have soft wrappers, so you must
be cautious to keep them away from sharp equipment and exhaust heat. They will not last more than a year, but they are the
most potent setup you can get.
The best all-round performance battery is the Li-ion. They come in a classic AA case with 2800 mah as the capacity at the
time I am writing this. Just 2 years ago 2000 mah was the highest rating, so you can see how fast they are progressing with
these batteries. They are light and fairly durable, and charge in about 4 hours from fully discharged. They will normally
last a little over a year if you take care of them. Leave the switch on overnight, and they are ruined, though. Their main
down side is they do not release their power as fast as the other battery types, so you have to use a larger size battery
pack to ensure you have enough burst power.
So, if you are anal about the details, the Li-poly’s are the way to go. For the average Joe, I would recommend the
Li-Ions. Leave the other types for the sport flyers.
If you are new to these batteries, you should be aware of a few things. First, you need a special charger. Do not try to
use any chargers not specifically set up for Li-Ions AND the number of cells you are using. If you over charge just once (by
not setting up your charger properly), the packs are ruined. There is also a slight chance the cells will explode if severely
overcharged. If you run the batteries down to nothing, just once, they will be ruined. Cycling the batteries is not required,
and not recommended. If your pack is still working after 14 months, you are lucky, as that is about the maximum they last.
Which brings up a VERY important point…you have to check these batteries after each flight to make sure they are still
in good shape. They usually signal the end of their lifespan by rapidly reducing their rating. In other words, the pack that
used to give you 12 flights may only be good for a couple. If you are not vigilent, you could get caught airborne when they
finally play taps.
For 25% planes or smaller, just use a single battery. You don’t have the room and can’t afford the weight of
two packs. Run dual cells with a single regulator to bring the voltage back down to 6 volts.
For 35% planes, always run 2 battery packs and switches. Use two cell packs and two regulators. You need to electrically
tie the packs together after the switches, but before the regulators. This ensures the packs will discharge at the same rate,
and the regulators will share the load.
For 40% planes, run at least 2 packs and switches. Use a regulator for every 4 servos. If you choose Li-ions, I recommend
using 6 cell packs to raise the voltage to 10.8 volts, or even 8 cell packs for 14.4 volts. This will keep the supply voltage
from dropping below 6 volts if there is a large demand in flight. Once again, electrically tie the batteries together after
the switches but before the regulators.