Safety Alert ,Preventing battery explosions

Guidance about preventing explosions from starter batteries fitted on back-up diesel
engine systems (powering emergency generators, fire booster pumps etc) in buildings.

There have been a number of battery explosions recently,
involving automotive starter batteries fitted to back-up
(emergency) diesel engine systems.
Fortunately no-one has been injured from these incidents.
However such explosions have the potential to inflict serious
injuries, such as permanent blindness, and can be the cause of
building fires.
Investigations by WorkSafe indicate the explosions were not
related to an accident or a by-product of maintenance
processes at the time of the explosions. The explosions have
typically occurred several months after the battery was
In each instance, the batteries involved were the larger
automotive ‘maintenance free’ type with no provisions for
periodic topping up with water of the electrolyte (internal acid
fluid), and of a size typically fitted to heavy duty trucks,
agricultural plant etc.
‘Maintenance free’ is a misused description for starter
batteries. Even where batteries do not require periodic water
additions, maintenance requirements still extend to charging,
cleaning battery tops, periodic re-tightening of battery
connections, testing to confirm the working condition of the
battery etc.
According to the Australian Battery Industry Association
(ABIA), this type of automotive battery is designed for starting,
lighting and ignition (SLI) duties in vehicles where battery state
of charge is maintained by the vehicle alternator but only
during times when the engine is running.
In such applications, charge received from the alternator is
offset with partial discharges from repeat starting, ‘engine off
lights on’ periods etc.
ABIA advises automotive type batteries are not designed for
applications that involve continuous float (trickle) charge as is
almost always the case in diesel engine powered back-up
When subjected to constant charging, the usual benign end of
working life and failure modes experienced by automotive type
batteries on trucks etc are replaced by an increased risk of
explosion due to internal changes in the battery, largely related
to placing such batteries under continuous charging.

WorkSafe investigations and consultation with industry
sources shows that:
• ‘maintenance free’ automotive type batteries that cannot be
periodically topped up with water, in conjunction with
constant float charging, are not suitable for standby diesel
engine starting applications
• operating starting batteries at temperatures above 25ºC will
lead to higher water loss and shorter service life. The higher
the temperature, the greater the rate of water loss and
shorter the service life
• ‘maintenance free’ automotive type batteries that cannot be
periodically topped up with water in conjunction with
constant float charging can produce explosions with the
associated potential of injury to anyone present and the risk
of fire.
Control measures for starter battery solutions in backup diesel engine applications involving constant float
• avoid using automotive type ‘maintenance free’ batteries
that have no provisions for periodic top-ups with water and/
or monitoring of liquid levels in all cells for back-up diesel
engine systems involving constant float charging
• use stationary type batteries in back-up diesel engine
applications. Stationary battery formats are custom
designed for constant charge applications and all ‘vented’
formats provide for visual monitoring of the electrolyte level
• use constant voltage chargers. When operated at the
recommended charging voltage, they maintain the battery at
or near full capacity and provide automatic replenishment of
charge following a discharge
• if valve regulated lead acid batteries (VRLA) are utilised in
applications where average temperatures will be regularly
above 25ºC, charger voltage output control should have
temperature compensation provision in accordance with the
battery manufacturer recommendations
• wherever possible, the starter battery should be located in
the coolest position available
• any worker undertaking battery maintenance or working in
the near vicinity of a battery or batteries should at the very
least, wear eye protection at all times.

Information and training
Ensure service operators are informed and trained for:
• carrying out all battery manufacturer recommended
maintenance, including checking and maintaining electrolyte
levels in batteries where applicable
• identifying installations involving automotive type
‘maintenance free’ batteries or that are otherwise unsafe,
and instigating a replacement program with correct battery
and/or electrical systems
• avoidance of ignition sources (sparks, flame etc) when
working near batteries
• regularly checking the condition of the battery for physical
damage or deterioration
• dealing with battery damage should acid leakage occur or
explode the battery
• wearing of appropriate personal protective equipment
Note: For the purpose of this Alert:
– ‘Automotive batteries’ are batteries used for passenger
cars, commercial and industrial vehicles for normal use,
commercial and industrial vehicles for severe use, and are
batteries for use in deep-cycling applications (eg marine use,
taxis and coaches) – as detailed in the scope of the latest
edition of AS2149 Starter batteries-lead acid.
– ‘Stationary batteries’ are batteries that are designed for
service in a fixed location (ie not habitually moved from place
to place) and are permanently connected to the load and to
the DC power supply – as detailed in the scope of the latest
editions of AS4029 (AS4029.1, AS4029.2, AS4029.3)
Stationary batteries – lead acid and AS3731.(AS3731.1 and
AS3731.2) Stationary batteries – nickel cadmium.
More information
The Australian Battery Industry Association ( is the
representative body for manufacturers, importers, distributors
and wholesalers of automotive type batteries throughout
Australia. Membership is responsible for approximately 95 per
cent of automotive battery sales.