To stop batteries from moving around, which could cause damage to their
terminals and connections, or cause them to spill corrosive liquids over the boat,
they must be securely fixed.

A source of ignition, like batteries, must be kept away from potential fuel sources
to reduce the possibility of fire or explosion. So, batteries can be kept in the
engine room, but they must never be under or next to a petrol or LPG tank,
cylinder, stopcock, pipe or filter. It's a good idea to keep your boat's batteries at
least half a metre (around 18ins) away from any petrol or LPG equipment.

If your batteries are kept in confined spaces in compartments it's essential that
the build-up of flammable hydrogen gas is prevented. To achieve this, battery
compartments must be properly ventilated.

To prevent sparks being created by metal objects or tools touching the top of
batteries, which could act as an ignition source and start a fire or explosion, the
positive and negative terminals of all batteries must have insulated covers in
place. Some batteries don't have individually covered terminals, and traditional
batteries have exposed connectors between the cells - in these cases you
must cover the whole top surface of the battery. Covering batteries will also
reduce the likelihood of electrical sparks caused by touching the terminals with
a metallic object. [3.1]