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Causes of
Vehicle Battery failure
Battery at end of service life :
During its natural cycle
material is transferred through electrolyte from one plate to another in each cell of the battery, this causes degradation
until the cell fails. The battery can also fail due to internal short circuit. Most batteries are stamped with a date code
and have an expected lifespan.
Self discharge:
A battery loses a percentage of charge even when disconnected
.A battery will generally become weaker as it ages.
Low electrolyte level :
The electrolyte is the medium
through which the electrons pass during the battery cycle. Low electrolyte can cause premature failure. A cracked battery
casing can allow electrolyte to leak causing advanced corrosion to surrounding structures.
Severe cold temperature can
freeze battery electrolyte.
Poor connections:
Loose or corroded battery terminals or defective wiring cause
high resistance resulting in either the battery not being charged properly or not being able to deliver its current when required.
Sulphate around battery terminals leads to poor connection.
Severely corroded battery clamps should be renewed.
Current
drain:
Each time a vehicle electrical consumer is switched on eg, lights, current flows from the vehicle battery
and causes it to discharge. Faulty components can cause the battery to drain unintentionally ,examples are wiring shorts, defective
diodes, etc.
Charging system failure:
If the battery is not being recharged as the vehicle is operated it
will gradually drain until breakdown occurs. Charging system failure can be caused by a faulty battery, faulty alternator,
incorrect voltage regulator setting, defective wiring, loose connections.
Frequent short journeys can result in a vehicle battery becoming discharged due to insufficient recharge time following heavy
discharge by vehicle starter motor.
For more information on battery charging systems see our Alternator page
OverCycling of the Vehicle Battery
Every time a battery is discharged ,its plates expand and contract resulting in excess material being released and deposited
at the bottom of the battery casing.This will eventually build up and cause a short circuit and premature failure.
The most common causes are :
Incorrect battery for application.
Vehicle electrics fault (eg diesel glow plugs relay stuck on)
Taxi or multi-drop vehicle use.
Starter battery used for leisure application.
Some batteries are
manufactured for this type of operation by fitment of glass wool between plate separators which holds active material in place to be absorbed back on to the plates when the battery is recharged.
Overcharging of the vehicle battery:
When a vehicle is engine is running , it is the alternator which supplies power to recharge the battery. A failure in the
alternator voltage regulation circuit can cause excess voltage to be applied to the battery. This causes decomposition of
active material forming the battery plates , and also loss of electrolyte. It is often first noticed by a smell of 'rotten
eggs' (hydrogen sulphide) , or by
vehicle bulbs continuously failing.
Battery fitting guidelines:
Safety first
Safety procedures should be undertaken when storing , charging, fitting and removing vehicle batteries. Dangers assosciated
with vehicle batteries include Battery Acids and Explosive gases. Eye protection and gloves should be worn during battery
handling and fitting. Batteries should only be charged in a well ventilated area. Refer to http://www.hse.gov.uk/pubns/indg139.htm
for further guidance.
Fitting a vehicle battery incorrectly can damage or destroy a vehicles electrical system.
Be Prepared :
Have the radio
code available and take note of any special
procedures recommended by the vehicle
manufacturer.
Use a memory saver device to prevent loss of computer memories if possible.
Disconnection of vehicle batteries
can result in memory loss from some computerised vehicle systems
for example body control modules.
Use the correct specification of battery
recommended for your vehicle.Use the correct specification of battery recommended
for your vehicle.
The original equipment vehicle battery may often be identified by a product code, typical examples are:
002 , 005 , 015 , 017, 027, 037 , 038, 048 , 049 , 054 , 063 , 065 , 067 , 069 , 072 , 075 , 077 , 085, 088 , 089 ,093
, 096 , 097 , 110 , 154, 334 ,335 , 421 ,622 , 627 , 629 , 643 , 644 , 647 , 648 , 655 , 656 , 663 , 664 , 678 , 895, 896
Safety
reminder :
Batteries contain acid which can cause burns.
Car batteries can emit hydrogen gas which is an easily ignited and explosive gas. Metallic objects in contact with battery
terminals, and terminal disconnection / connection can cause sparks which may ignite hydrogen gas causing explosion. Avoid
smoking and other sources of ignition.
High currents can be discharged through metal objects such as jewellery causing burns. Batteries contain Lead and can
be heavy. Dispose of correctly.
Ensure all battery terminal clamps are clean and in good condition. Corroded or damaged battery terminal clamps should
be cleaned or renewed depending on condition.
On Negative ground systems always disconnect the Negative terminal first .
When installing the new battery
first fit the battery securing device. Then fit
the Positive terminal first and ensure the
terminal clamp is fully tightened before
fitting the Negative terminal and tightening.
Anti corrosion spray may be applied to the
terminals according to manufacturers
recommendation.
Charge Warning light on after the battery has been changed?
Low battery voltage due to a failed battery or charging system may cause computer system fault codes to be logged which may
need to be cleared using diagnostic equipment. Some vehicle computer memories are reset to basic setting by battery disconnection
and may have an adaptive learning period after the vehicle is restarted .
Dual Batteries, Split Charge, Battery Backup etc.
Link: For more information about auxiliary battery charging systems visit our Onboard Power page
There are times when just one vehicle battery is not enough. Linking of two 12 volt heavy duty batteries is commonly used
to attain 24volt system requirements on goods vehicles and heavy equipment.
Advanced battery charge management equipment
is often fitted to specialist vehicles such as ambulances ,fire fighting , breakdown vehicles, leisure and marine equipment.
This
may involve fitment of advanced voltage regulation devices, to optimise battery charging, together with additional batteries
and switchgear.
Typical situations when an extra battery is useful:
Commercial vehicle
on multi drop distribution
fitted with a tail lift :
Extra batteries are fitted on a split charge system to power the tail lift equipment which is isolated
from the main vehicle starter batteries whilst in use. Should the Auxiliary batteries become discharged the vehicle can still
be started on its normal batteries and the auxiliary battery be recharged as the engine is running.
Caravan
fitted
with deep cycle leisure battery
for internal lighting etc: The towing vehicle is fitted with a split charge relay to enable the
leisure battery to be recharged as the vehicle is driven. An inverter may also be fitted to supply electricity at higher voltage
for mains appliances, and possibly mains or solar powered battery charging equipment.
Breakdown vehicle
fitted with auxiliary
batteries to enable dead vehicles to be boost started without leaving the breakdown vehicle immobilised due to a discharged
battery.
Marine craft
fitted with a dual battery system so that the vehicle can still be started should one battery become
discharged or fail whilst out at sea.
Waste Battery Disposal
Dispose of your disused battery correctly.
If you are located in Shropshire, Car batteries can be taken for disposal at local authority waste sites located at Ketley,in
Telford, or Battlefield in Shrewsbury, or disposed of through your battery supplier.
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