Fire Pump Engine Start Battery Replacement

This article covers the requirements for the routine servicing requirements of batteries that are used for engine start applications for fire pumpsets, also known as compression ignition (diesel) driven pumpset(s).

For fire pump (electric or compression ignition (diesel) driven) there are TWO types of batteries used.  These are;

• Control Batteries; and
• Engine Start Batteries (also known as starter batteries).

Fire Pumpset - Control Batteries
A control battery can be found on an electric driven fire pump-set AND and a compression ignition (diesel) driven pumpset.  In simple terms a control battery is a type of stationary battery used to provide a source of stored energy necessary to operate the pump controller for a fire pump-set.

Fire Pumpset - Engine Start Batteries1
An engine start battery (or starter battery) conversely is a type of battery used for the rapid release of energy (current) measured in Ampere necessary for motor start applications. A engine start battery will have a capacity rating measured in Cold Cranking Amps ("CCA") or Marine Cranking Amps (MCA").

Dual Use (Control & Engine Start Batteries)¹
Modern fire pump-sets are typically fitted with batteries which are generally configured with a primary and secondary battery arrangement where both batteries (engine start and control batteries) can be used for the engine start application. In this case the battery used must be an engine start battery with a CCA rating.

• 1

  Australian Standard AS 2149—2003 Starter batteries — Lead acid, covers the requirements for lead-acid batteries with a nominal voltage of 12 V, used primarily as a power source for the starting of internal combustion engines.

Electric Fire Water Pump

An electric fire water pump is fitted with standby batteries in the event there is a mains power failure that enables the status of the pump including the "mains power fail" alarm signal to operate.  When installing batteries for an electric fire water pump, the battery must be a "standby battery".

Diesel Fire Water Pump

For diesel fire water pumps, the pump is fitted with a dual set of batteries;

• Primary Battery (12 volt systems) or Batteries (24 volt systems); and
• Secondary Battery or batteries.

A diesel fire water pump is fitted with two sets of batteries that in most circumstances operate as the motor start battery and the standby battery.  Where the primary motor start batteries fail, the secondary (backup) batteries are engaged.

Table 3.4.3 of Australian Standard AS 1851:2012  provides two different criteria for batteries used for fire pump-sets as follows;

1. Engine start batteries
   REPLACE all engine-starting batteries after a maximum of 2 years service, irrespective of condition. Record date of replacement on the new battery and the date the batteries were replaced in the service record.
2. Control batteries
   When the battery has not been replaced in the previous two years, verify the battery condition by carrying out a battery discharge test in accordance with Appendix F of the Standard.

Engine Start Batteries

Most modern fire pumps have a primary battery (12v systems) or two batteries (2 x 12v batteries in series to combine to make a 24v battery system) used for engine start applications.

These same systems will typically have a secondary (backup) battery or batteries that in their normal condition will serve as the control batteries but in an emergency situation may also be used as an engine start battery.

In this case all batteries MUST be replaced every two years irrespective of condition.

Control Batteries

It is more common to see an electric fire pump fitted with a single battery (control battery) that is used as a form of stationary battery. In this case, where the battery has not been replaced in the previous two years, a competent technician should carry out a battery discharge test in accordance with Appendix F of the Standard to verify its condition.

A flooded (wet) cell engine start battery is a type of rechargeable battery where the cell plates within a battery are submerged in an electrolyte that is a liquid (typically dissolved aqueous sulfuric acid).

Compared to modern rechargeable batteries, lead–acid batteries have relatively low energy density. Despite this, their ability to supply high surge currents means that the cells have a relatively large power-to-weight ratio. These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required by starter motors.Lead–acid battery. (2022, October 7). In Wikipedia https://en.wikipedia.org/wiki/Lead–acid_battery

By measuring the specific gravity of the electrolyte it is relatively simple to determine the start of charge of a flooded (wet) cell battery. Some modern flooded (wet) cell batteries include a simple hydrometer using colored floating balls of differing density.

Where a compression-ignition driven fire water pump is fitted with a flooded (wet) cell battery, then the Standard (AS1851:2012 A1) required the following routine service activities;

1. CHECK monitor and engine start batteries and enclosures for corrosion, physical damage and secure mounting;
2. REMOVE any corrosion from battery terminals as required;
3. TEST the float charge voltage of both the monitor and engine start batteries and record result;
4. CHECK electrolyte levels and top up with distilled water as necessary;
5. CHECK warning signage and rating (battery capacity) signage (where required).
6. CHECK battery capacity or cold cranking amperage is appropriate.

To ensure the batteries are maintained in an optional condition of 25°C (77°F). Operating at higher temperatures will reduce cycle life due to cell degradation, and cooler will prolong cycle life, however, low temperatures will reduce available battery capacity.

An engine start battery is rated in Cold Cranking Amps or ("CCA") and it is the measure of how much energy (current) a battery can deliver for 30 seconds at −18° Celsius or 0° Fahrenheit while maintaining a voltage above 7.2 volts.

Determining the correct CCA rating for a battery must take into consideration a range of factors including starter motor current requirements, engine size connected loads and ambient temperature.

To help people working in the fire industry, we have developed a rule of thumb for selecting the  battery capacity (Cold Cranking Amps) for most typical engine start applications;

Notes:

• Ambient Temperature: These recommendations assume moderate conditions. Lower temperatures (e.g., below 0°C) typically require higher CCA ratings.
• Diesel vs. Petrol: Diesel engines, especially in larger sizes, may require slightly higher CCAs due to higher compression ratios.
• System Load: Any auxiliary loads or increased starter demands should also be factored in when choosing a battery.

For precise selection, check the engine or starter motor manufacturer’s specifications.