We have a new boat. It has a 7.2v 1800 mah battery. If we get a 5000mah I know it will last longer but how much heavier will it be and will this make the boat slower?
I have been told I won't have this problem with lipo battery's? What are these and will they also increase speed as well as lasting longer per charge? Cheers guys
Very simply, they are a new technology (Lithium Polymer) battery. They can store a lot of electricity, they are very light, and they have a very small internal resistance, so they can put out very high currents. They are much in use for electric planes.
They have some drawbacks. Each cell in a Lipo provides about 4 volts, but it mustn't be drained below about 3 volts. So running duration has to be tightly controlled. Lipo use is usually (though not necessarily) associated with brushless motors, which can make use of the phenomenal current flow a lipo can provide. So brushless ESCs often contain a voltage detection circuit which will shut down the motor when about 3 volts per cell is reached. Not too bad for planes - bit iffy for boats....
Lipos need special chargers called 'balancing chargers'. The charging process can be dangerous, because of the high energies involved. Lipos are very light, have softer sides than 'normal' batteries and so are easily damaged by denting. Such damage may cause a lipo to catch fire and burn fiercely.
You can see a selection of batteries and associated kit here:
http://www.giantcod.co.uk/lipo-battery-c-1.html?max=50
