Tips on Batteries for Your Radio Controlled Boats

Today's radio controlled boats usually most often use nickel-cadmium (Ni-Cd) batteries to power the engine because of their ability to discharge energy rapidly. Older-style batteries could hold more power, but because it took longer to release their energy, they produced lower horsepower and thus lower slower speeds. In addition, people prefer Ni-Cd batteries because of their rapid quick recharge rate and reasonable inexpensive price.

Battery Basics

Individual batteries are called cells and Ni-Cd cells each produce about 1.2 volts. By joining 6 cells together, your battery pack has 7.2 volts (6 cells x 1.2 volts). You can increase the voltage by adding more cells, but eventually the weight gain will offset the increased power. You have to find the best combination for each boat.

Electrical current is measured in amps and the capacity of a cell is rated in amp hours. Most Ni-Cd batteries used in radio controlled boats have a capacity of 1.4 amp hours, which is usually written as 1400 milliamp hours, or 1400 mAh. The batteries will last longer with a low discharge rate and will run out quicker if the rate is higher. The amount of power delivered to your boat's engine is calculated by multiplying the total voltage (determined by the number of cells) and the current draw in amps. Most ready-to-run (RTR) boats consume between 10 and 20 amps, so the run time is about 4-8 minutes. This is a sweet spot for the beginner because the batteries won't overheat the motor or the speed control.

To make the boat run faster, you can either increase the amperage or the voltage. Generally, it's a good idea to add cells (voltage) and keep the amps at a moderate level to prevent overheating.

Choosing the Right Battery Type for You

Ni-Cd batteries are classified as SC, SCR and SCRC. The SCs are what you'll generally get with a basic RTR boat. For beginners they're a good choice because they last a long time and don't cost much.

SCR cells discharge their power faster than SCs, creating generating more horsepower and therefore faster boats. They can also be recharged many multiple times a day, so if you have several battery packs in rotation you can run your boat indefinitely.

SCRC cells can put out 1700 mAh, so they can run longer and produce more energy. However, you must be careful not to overheat them. Another drawback weakness is they will only take 2 or 3 recharges per day, so most hobbyists only use them for special occasions, or not at all.

Charging Your Batteries

There are several types of battery chargers to choose from. A timed charger will automatically turn off when the time you set has expired. So if you charge a flat battery at 5 amps, it will take 17 minutes to fully charge. The problems arise if a cell wasn't completely discharged before recharging. This can lead to overheating, the leading cause of battery failure.

A peak-detector charger, on the other hand, will turn itself off when it detects that the battery has received a full charge. These are very convenient, and unlikely to overcharge a battery. The main problem with some of these chargers is the possibility of turning off too soon. If you suspect this is the case, wait a few minutes and turn it back on. If it shuts off within a minute or so, the pack was fully charged. If not, this second run will do the trick.

Overheating is a cell's worst enemy, so always be sure it's cool before charging or being placed back in your boat.

You will always obtain the best long-term performance from your battery pack if you make sure it is completely drained before recharging. Some chargers have a discharge function, but if not, you can attach the pack to a small lightbulb (like an car's turn signal light) until it goes dark. That way you'll always get the full charge to your pack.

After digesting all this information, you should be able to maximize your batteries' ability to power your remote controlled boat. Now go out and have fun!