I drove it home and it was fine, i shut it off and within five mins i tried to start it and it would crank but wouldnt turn over, i tried a few more times and it nothing, but now my battery is going low...
Hello,
The first and most likely indication of a low battery
would be a hard starting problem caused by slow cranking. If
the battery seems weak or fails to crank your engine normally,
it may be low. To find out, you need to check the battery's "state
of charge."
A battery is nothing more than a chemical storage device for
holding electrons until they're needed to crank the engine or
run the lights or other electrical accessories on your vehicle.
Checking the battery's state of charge will tell you how much
juice the battery has available for such purposes.
If your battery is low, it needs to be recharged, not only
to restore full power, but also to prevent possible damage to the
battery. Ordinary automotive lead-acid storage batteries must
be kept at or near full charge to keep the cell plates from becoming
"sulfated" (a condition that occurs if the battery is
run down and left in a discharged condition for more than a few
days). As sulfate builds up, it reduces the battery's ability
to hold a charge and supply voltage. Eventually the battery becomes
useless and must be replaced.
The charge level depends on the concentration of acid inside
the battery. The stronger the concentration of acid in the water,
the higher the specific gravity of the solution, and the higher
the state of charge.
On batteries with removable caps, state of charge can be checked
with a "hydrometer." Some hydrometers have a calibrated
float to measure the specific gravity of the acid solution while
others simply have a number of colored balls. On the kind with
a calibrated float, a hydrometer reading of 1.265 (corrected for
temperature) indicates a fully charged battery, 1.230 indicates
a 75% charge, 1.200 indicates a 50% charge, 1.170 indicates a
25% charge, and 1.140 or less indicates a discharged battery.
On the kind that use floating balls, the number of balls that
float tells you the approximate level of charge. All balls floating
would indicate a fully charged battery, no balls floating would
indicate a dead or fully discharged battery.
Some sealed-top batteries have a built-in hydrometer to indicate
charge. The charge indicator only reads one cell, but usually
shows the average charge for all battery cells. A green dot means
the battery is 75% or more charged and is okay for use or further
testing. No dot (a dark indicator) means the battery is low and
should be recharged before it is returned to service or tested
further. A clear or yellow indicator means the level of electrolyte
inside has dropped too low, and the battery should be replaced.
On sealed-top batteries that do not have a built-in charge
indicator, the state of charge can be determined by checking the
battery's base or open circuit voltage with a digital voltmeter
or multimeter. This is done by touching the meter leads to the
positive and negative battery terminals while the ignition key
is off.
A reading of 12.66 volts indicates a fully charged battery;
12.45 volts is 75% charged, 12.24 volts is 50% charged, and 12.06
volts is 25% charged.
In recharging the battery do not attempt to recharge a battery with low (or
frozen) electrolyte! Doing so risks blowing up the battery if
the hydrogen gas inside is ignited by a spark.
Your charging system should be capable of recharging the battery
if it is not fully discharged. Thirty minutes or so of normal
driving should be enough.
If your battery is completely dead or extremely low, it should
be recharged with a fast or slow charger. This will reduce the
risk of overtaxing and damaging your vehicle's charging system.
One or both battery cables should be disconnected from the battery
prior to charging it with a charger. This will eliminate any
risk of damage to your vehicle's electrical system or its onboard
electronics.
Take care and good luck
NB: Your alternator might not also be charging the battery while the car is on, so try to check the alternator.
Alternators are pretty rugged, but can succumb to excessive
heat and overwork. They can also be damaged by sudden voltage
overloads (as when someone attempts to jump start a dead battery
and crosses up the jumper connections or if someone disconnects
a battery cable from the battery while the engine is running).
Sometimes alternators can partially fail. In the back of
every alternator is a "diode trio" that converts the
alternators AC (alternating current) output to DC (direct current).
If one or more of these diodes fail, the alternator's amperage
output will be reduced. It may continue to produce some current,
but not enough to keep the battery fully charged -- especially
at idle or low speed.
Most service facilities have test equipment that can identify
these kind of problems. So if you suspect a weak alternator,
you should have it tested to see if it needs replacing.
Most service facilities do not repair or rebuild alternators
because it's too time consuming and requires special parts. Most
will replace your old unit with a new or remanufactured unit.
Your old alternator is usually traded in or exchanged for a credit
(so it can be remanufactured and sold to someone else).
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