CHOOSING A CHARGER
Now that you’re set up with batteries, let’s talk chargers. First and foremost, make certain that you get a NIMH charger if you have NIMH batteries, and a Lipo charger if you have Lipo batteries. It is vitally important to get that right. If you use both types of batteries, there are chargers that can be set for either battery type. If you go that route, be sure to set the charger for the correct battery type before you hit the “start” button. As for charger features to look for, the most important (after determining “Is it the right type for my battery?”) is amperage. The higher the charger’s amp output, the faster it can charge your pack. The math is easy: just divide battery capacity by charger output. Let’s say you have a 5-amp charger and a 6000mah battery. 6000 milliamp-hours equals 6 amphours. Divide 6 by 5, and you get charge time in hours: 6 ÷ 5 = 1.2 hours. The higher the amp rate, the quicker the charge time.
HOW MANY AMPS?
Now, we know what you’re thinking: “If more amps is better, why not get a 30A charger and blast that battery full in just five minutes?” That makes sense math-wise, and serious racers do exactly that. However, they also retire their batteries after 30-40 runs, while the rest of us would rather get 300-400 runs out of our batteries. Charging at lower amperages will extend your batteries’ lives— that means more recharges before the pack no longer performs well enough to be worth keeping. For maximum life, charge Lipo packs at the same rate as their capacity. For example, if you have a 4000mah Lipo battery, charge it at 4A. If you have a 5500mah battery, charge it at 5.5A. And so on—just take the battery capacity and divide by 1000. In the lingo of battery charging, this is known as charging at a rate of “1C,” or “capacity multiplied by one.” If you want to speed things up, charging at higher rates up to “2C” (twice the battery’s capacity; for example, 8A for a 4000mah pack) is fine, but do most of your charging at a lower rate whenever you can.