Batteries for radio controlled models

Your Reviewer

My Credentials
So who's doing this reviewing then?

Well I've been building and flying or driving radio controlled models for over 40 years and during that time I like to think I've built up a reasonable amount of knowledge.

I'm also a qualified electronics engineer who has worked in radio frequency, analog, digital systems and software for more than three decades. In fact I designed and built my first RC set back in 1969.

For the past nine years I've also been involved in the design and manufacture of some rather sophisticated engine technology and UAV flight control systems.

So, chances are I've been there, done that and have a huge pile of tee shirts to prove it.

Right now I'm heavily into 3D flying and enjoy all aspects of the RC hobby. I may be old but I don't feel it.

In the Pipeline

Here's just a little bit of what's to come on this site...

RC explained: Demystifying terms such as PCM, PPM dual conversion, single conversion, full-range etc., this feature will explain it all.

Cheap Chinese Engines: Just how good are those cheap Chinese glow and gas engines that sell for half the price of their "brand-name" equivalent? I put several to the test.

Build your own radio gear?: Back in the old days, building your own RC gear was not uncommon and now the arrival of 2.4GHz has made it practical again.

Nickel Cadmium (NiCad) Batteries

STANDARD EQUIPMENT FOR YEARS

Nicads have been around for a very long time and were the only option for many RC applications for decades. These days however, they have largely been replaced by more advanced technologies. However, there are still places where nicad batteries can hold their own.

Nicad Pro's:

low internal resistance (high-currents)
low self-discharge
less affected by low temperatures than some

Nicad Con's:

heavier/bulkier than other battery technologies
suffer from memory/voltage-depression
environmentally unfriendly

A word about memory

One of the biggest problems that affects nicad batteries is something often referred to as "memory".

This is more accurately refered to as voltage-depression and occurs when a battery is repeatedly charged but only partially discharged. Over time, the battery appears to lose capacity to the point that only a small percentage of its rated energy storage is still useable.

The only way to recove the lost storage is by cycling the battery through a series of deeper discharge and recharge operations until its capacity is restored.

If you don't have a charger that will allow you to perform these capacit-restoring charge/discharge cycles then avoid recharging your nicads when they're only partially discharged -- or allow your batteries to discharge until they're nearly flat at least once every dozen charges.

When to use

Nicads continue to be used for both transmitter and receiver packs although with the advances in other battery technologies and growing environmental concerns, most manufacturers are now providing more modern options.

Despite the development of hi-capacity and hi-current lithium polymer (LiPo) batteries, some electric fliers still prefer to use Nicads as a power source on extremely fast models where weight is less of an issue than the ability to safely deliver extremely high currents.

Howver, it is pretty hard to recommend Nicad batteries for general use these days. As you'll find out as you read on, new technologies have largely left Nicads in the dust.

Next: Nickel Metal Hydride batteries (NiMH)
Plus: Lithium Polymer batteries (LiPo)
Plus: Lithium Iron Phosphate and A123 (LiFePO4)