14. WHAT ARE THE MYTHS ABOUT BATTERIES?
Last Updated on July 16, 2004
INDEX:
14.1. Storing a battery on a concrete floor will
discharge them.
14.2. Driving a car will fully recharge a battery.
14.3. A battery will not explode.
14.4. A battery will not lose its charge sitting
in storage.
14.5. "Maintenance Free" (Ca/Ca) batteries never require
maintenance.
14.6. Test the alternator by disconnecting the battery
with the engine running.
14.7. Pulse chargers, desulfators, aspirins or additives
will revive sulfated batteries.
14.8. On really cold days
turn your headlights on to "warm up" the battery
up before starting your engine.
14.9. Car batteries last longer in hot climates
than in cold ones.
14.10. Charging cables or jump starters will start
your car.
14.11. A larger capacity battery will damage my
car.
14.12. Lead-acid batteries have memories.
14.13. Bad batteries will not harm the charging system
or starter.
14.14. Once formed, batteries will not change
polarity.
14.15. Use tap water to refill batteries.
All
lead-acid batteries will naturally self discharge. The
rate of self discharge is most influenced by the
temperature of the battery's electrolyte and the
chemistry of the plates. Some experts believe that
storing car or deep cycle batteries on a colder concrete
floor might actually slow down the self discharge
(leakage) rate because the floor acts as a heat sink
and cools the battery. (Please see Section 13.)
In the early 1900s, when battery
cases were made of porous materials such as tar-lined
wood boxes, storing batteries on concrete floor would
accelerate their natural self discharge. Modern battery
cases are made of polypropylene or hard rubber. These
cases are sealed better, so external leakage-causing
discharge is no longer a problem, provided the
top of the battery is clean and free from wet or dried
electrolyte and the same temperature as the floor.
Large differences in temperature
could cause electrolyte stratification within very
large batteries (>250 AH) which could accelerate
it's internal "leakage" or self discharge if the
battery is sitting on an extremely cold concrete,
stone or steel floor in a warm room, boat or submarine.
Stirrers or bubblers are often used on these types
of large batteries to keep the electrolyte from stratifying.
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14.2. Driving a car
will fully recharge a battery.
There are a number of factors
affecting a vehicle charging system's ability to recharge
a battery, such as how much power from the alternator
is diverted to the battery, how long the power is available,
and the temperature. Generally, idling the engine or
short stop-and-go trips during bad weather or at night
will not fully recharge a car battery. When
a dead battery needs to be recharged, it is best to
use an external battery charger because you could over
heat and damage your vehicle's charging system and
your will save a lot of gas and wear and tear on your
engine. Please see Section 5.
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14.3. A battery will
not explode.
Charging a wet lead-acid battery
naturally produces hydrogen and oxygen gasses as electrolysis
of the water occurs. While spark retarding vent caps
help prevent external battery explosions, sparks occur
when jumping, connecting or disconnecting charger or
battery cables and ignite the gas causing an explosion.
Less common internal explosions usually occur while
starting the engine or using the battery and normally
just blow the filler caps or cover off the battery
and splatter electrolyte all over the engine compartment
or battery box.
The most probable cause of internal
explosions are from a combination of low electrolyte
levels below the plates in the battery and a low resistance
bridge is formed between or across the top of the plates.
This is called "treeing" between the positive and negative
plates. When current flows in the battery, a spark
occurs and ignites the residual gas in one or more
of the cells. A second possible cause is a manufacturing
defect in the weld of one of the plate connecting straps.
The largest number of internal battery explosions occur
in hot climates due to
the loss of water while starting the engine. Most internal
battery explosions could have been prevented if the
plates were always covered with electrolyte. Please
see Section 3.
[Source: Popular Mechanics]
Periodic preventive maintenance
(Please see Section 3.), working on batteries in well-ventilated
areas, or using sealed AGM or Gel Cell type batteries
can significantly reduce the possibility of battery
explosions. To neutralize residual battery acid, be
sure to thoroughly wash the engine compartment and
the back of the hood with a solution of one-pound baking
soda (bicarbonate of soda) to one gallon of warm water
and rinse thoroughly with water. While not fatal, each
year battery explosions cause thousands of eye and
burn injuries from the electrolyte (battery acid). Should
a battery explosion occur and battery electrolyte (battery
acid) gets in someone's eyes, flush them out with any
drinkable liquid immediately because SECONDS count.
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14.4. A battery will
not lose its charge sitting in storage.
Depending on the type of battery
and temperature, batteries have a natural self discharge
or internal electro chemical "leakage" at a 1% to 60%
rate per month. Over time the battery will become sulfated
and fully discharged which make it more susceptible
to freezing. Higher temperatures will significantly
accelerate this process. A battery stored at 95° F
(35° C) will self-discharge twice as fast than
one stored at 75° F (23.9° C). (Please see Section 15. and Section 16.)
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14.5. "Maintenance Free" (Ca/Ca)
batteries never require maintenance.
The term "Maintenance Free" generally
refers to a wet, sealed lead-acid car and deep cycle
batteries with calcium positive and negative plates,
such as those made by Delphi (ACDelco). (Please see Section 7.1.3 for more information on these
types of batteries.) In hot climates, the water in the electrolyte is lost due
to the high under hood temperatures. Water can also
be lost due to excessive charging voltage or charging
currents. Non-sealed wet Low Maintenance (Sb/Ca) batteries
(with filler caps) are encouraged in hot climates
so distilled, deionized or demineralized water can
be added when this occurs. (Please see Section 3. for other preventive maintenance procedures
that should be performed on "Maintenance Free" (Ca/Ca)
batteries.)
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14.6. Test the alternator
by disconnecting the battery with the engine running.
A battery acts like a voltage
stabilizer or filter to the pulsating DC produced by
the alternator. Disconnecting a battery while the engine
is running can destroy the
sensitive electronic components connected to the electrical
system such as the emission computer, radio, audio
system, cell phone, alarm system, etc., or the charging
system because the peak voltage can rise to 40 volts
or more. In the 1970s, removing a battery terminal
was an accepted practice to test charging systems of
that era. That is not the case today.
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14.7. Pulse chargers,
desulfators, aspirins or additives will revive sulfated
batteries.
Using pulse chargers, desulfators
or additives are very controversial subjects. Despite
claims of the manufacturers, most battery experts agree
that there is no conclusive proof that pulse chargers
work any better than constant voltage chargers to remove
permanent sulfation. They also agree that there is
no evidence that additives or aspirins provide any
long-term benefits. Short term gains are achieved by
increasing the acidity (Specific Gravity) of the battery,
which could increase the Amp Hour capacity, but increase
the water consumption and grid corrosion and decrease
the overall service life of the battery.
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14.8. On really cold days turn your headlights on to "warm up" the battery
up before starting your engine.
While there is no doubt that turning
on your headlights will increase the current flow in
a car battery, it also consumes valuable capacity that
could be used to start the cold engine.
Therefore, this is not recommended. For cold temperatures, externally powered battery warmers
or blankets and engine block heaters are highly recommended
if the vehicle can not be parked in a heated garage.
AGM and Ni-Cad batteries will perform better than wet
lead-acid batteries in extremely cold temperatures.
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14.9. Car batteries last
longer in hot climates than in cold ones.
Car batteries last an average
of two thirds as long in hot climates
as cold ones. Heat kills
car batteries, especially sealed Maintenance Free (Ca/Ca)
batteries, and cold reduces the battery's starting capacity. (Please
see Section 11.1.)
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14.10. Charging cables
or jump starters will start your car.
The cigarette lighter charging
cable's advertising states "charges weak batteries
in minutes." There is little doubt that charging cable
products will certainly recharge your car battery if
you have enough time and your battery is in good condition.
Cigarette lighters are normally fused at 10 amps, so
to be safe they probably limit current flow to 7.5
amps. Given the diameter of the wire used in the cable,
the amount might be even less.
They work by applying higher voltage
from the vehicle with the good battery to "charge" the
bad one. In order to charge a battery the charging
voltage need to be approximately two volts greater
than the the battery voltage to overcome the internal
resistance. Now let's assume it is a hot day and that you need just of 3% of the battery's
capacity to start the engine from a 40 amp hour battery.
This means you will need at least 7.5 amps for 10 minutes
to flow from the good battery with the engine idling to
the bad one. Now let's also assume that it is below freezing and you have left your lights on. You will
need at least 50% capacity or 20 amp hours to start
the vehicle. This will take over two hours to partially
charge the dead battery. Using jumper cables with the
engine running at high idle will partially charge a
dead battery much faster. Please see Section 6., but be sure the battery is not frozen
or the case is cracked.
Some auto jump starter uses special
high current batteries to provide up to 900 peak amps
to start your engine. It can provide 200-300 amps for
up to 8-10 seconds. Standard AA alkaline batteries
are used to trickle charge the special batteries to
maintain their charge. This type of emergency starter
should start all but diesel engines up to six or eight
times on one charge, depending on the capacity of the
battery, condition of the engine and the temperature.
After this, the jump starter should be recharged for
24 to 48 hours.
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14.11. A larger capacity
battery will damage my car.
A starter motor will only use
a fixed amount of current from the battery, based on
the resistance of the motor. A larger CCA, RC or AH
capacity battery supplies only what is required.
It will not damage your vehicle; however, using batteries
with higher or lower voltage or physically too
tall could potentially cause harm.
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14.12. Lead-acid batteries
have memories.
Lead-acid batteries do not have
the "memory effect" mistakenly identified with first
generation Ni-Cad batteries; however, continuous undercharging
will lower the capacity of the battery over time. Deep
discharges below twenty percent State-of-Charge (approximately
12.0 volts) can damage batteries and will shorten their
service lives.
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14.13. Bad batteries
will not harm the charging system or starter.
A bad or weak starting battery
causes additional stress on a charging system, starter
motor or starter solenoid. It can cause premature failures
due to compensating for the voltage or current. If
you replace a battery, alternator, voltage regulator
or starter, you should test the other components for
damage and repair or replace them as required.
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14.14. Once formed,
batteries will not change polarity.
If a battery is fully discharged
and continues to have a load, for example leaving the
headlights on, it is possible for one or more cells
to reverse polarity. When the battery has been recharged
with reversed polarity the polarity can change. This
is referred to as "cell reversal". To change polarity,
fully discharge the battery and recharge it with the
correct polarity.
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14.15. Use tap water to
refill batteries.
Use only distilled, deionized
or demineralized water to replace the lost water in
batteries because using tap or reverse osmosis water
from residential systems can produce calcium or magnesium
sulfate crystals that can fill the pores and coat the
plates. In an emergency, use rain water because rain
water does not contain calcium or magnesium.
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