The type of cell that the bank is constructed of makes a difference and you didn't specify which type. The most common types are flooded lead acid cells and flooded Nicad. Both are used for emergency lighting and diesel starting. A couple basic things to remember when working around battery banks regardless of type.
Always follow the manufacturers instructions for isolating the bank from the charger/inverter/engine control systems before starting work. Remember that a connection that is loose will cause a tremendous arc if one of the previously mentioned devices attemps to energize,it doesn't matter if it's a charge or a discharge cycle.
Never use any device that will create a spark or flame unless you have evacuated every cell and are sure that no load or charging is taking place that can create explosive gases.
Ventilate the area before doing any load tests to make sure any gas that is generated is removed.Cover any adjacent cell and intercell connectors before starting work. I like to use a welders blanket as it insulates well and is tough enough for service work.
Before removing any connections verify that no current is flowing. Some of these systems have DC voltages as high as 240 volts on a string so use your gloves, these strings unlike an AC derived voltage cannot be locked out.
Make sure to lock out all equipment either feeding or fed from this bank. If you have a series parallel string remember to look over the installation to be sure where your connections are.
Before reenergizing the equipment do a double or triple check on the tightness and correctness of any work done.All cells are marked with + and - so make sure you get them installed properly.
I hope this helps with your service work I couldn't possibly cover all bases but these the basic. Just remember to work safe as you may be dealing with a lot of energy. Glasses gloves shields and insulated tools.
