This short post is a basic guide to batteries that you might use in your model boat.
There are two different batteries that may be needed in a model boat:
These will normally be Nickel Metal Hydride (NiMH) battery packs rated at 600mAHr capacity or greater, and usually nominally 4.8 volts. Some people use 6 volt packs to obtain greater power from the servos, if you intend to use a 6volt pack, first check the voltage rating of all other components.
While batteries in a battery holder can be used, it is more reliable to use a ready made NiMH pack, as battery holders tend to corrode in the damp atmosphere inside a model boat.
These may be NiMH, Lead Acid, or Lithium Polymer (LiPo), as I have never used LiPo’s you will need to speak to your local model shop for guidance on this type of battery.
Lead Acid batteries are cheaper than NiMH, but are more bulky and heavier. If space and weight are a problem, use NiMH batteries.
The voltage rating is decided by that of the drive motors, and the capacity by how much current the motors draw, and how long a sailing session you envisage.
For lead acid batteries, 6volt and 12 volt sizes are commonly used.
For NiMH, 6, 7.2, 8.4, 9.6 and 12 volt sizes are used. The most common is 7.2 volts, therefore select the capacity by how much current the motors draw, and how long a sailing session you envisage.
It is a very good idea to fit a fuse into the power circuit of an electrically powered boat. This should be placed in the positive line as close to the battery as is convenient. (Remember you may have to replace the fuse some day.) Select a fuse rated at about 1.3 times the stall current of the motor.
Fuses will not protect the electronic components, they will only protect the wiring, and should help prevent your model from catching fire.
Blade fuses can be connected in-line using crimp receptacles.
When deciding the layout of you installation, think about the balance of the boat. Locate heavy items, such as the batteries, as low down as possible, and in the middle of the boat. Remember that electrical things require servicing, and so keep everything accessible. Everything you put in may also have to be taken out some day. Use stainless steel bolts and screws as they are less likely to corrode.
Mount the receiver away from the drive motor and from any wires that carry high currents. Mount it as high as convenient to help keep it dry.
Try to route the wires so as to keep things as tidy as possible. When making joints, ensure that no part is left bare. Insulate joints with “Heatshrink” tubing or tape.
Velcro is very useful for holding items in place.
**This is a brief guide and I recommend that you talk with your local model shop or model boat club for more detailed assistance.**