Q. I think I
may need a new battery soon. A friend rode with me and commented
that my engine didn’t crank over as fast as it should as we
departed early one morning. Does this sound right? Can you give me
some help on how to deal with this? I don’t recall when it was
replaced last; it was probably a long time back.
— Cathy M.
A. Your friend
sounds like a great person to have onboard! Symptoms of an aging
battery are slow cranking, particularly during a cool morning
start-up, after a long period with doors open or headlights left on
for a bit. A noticeable change in headlight brightness from engine
idle to faster is another symptom.
Just to be
sure it’s truly time to replace the battery, there is a quick and
easy test called a conductance test, which requires a diagnostic
tool. Many auto parts stores and repair facilities offer this as a
free service, hoping you’ll follow up with a battery purchase if
needed. Other possible causes of a noticeably weaker battery include
corroded/loose terminals, excessive draining of battery energy while
parked, insufficient charging of the battery or starter problems (if
poor/no cranking is the only symptom). These are easy to check, if
symptoms warrant it. Batteries usually show aging symptoms during
colder weather as their performance is reduced and starting system
requirements are higher.
advice if you do need to shop for a new battery. Your particular
automotive battery has a group number (usually two digits, all
vehicles have one) as specified by BCI (Battery Council
International). This number indicates physical size, terminal type
and orientation, hold-down method and other characteristics, making
replacement shopping easy. In addition to the group number,
carmakers specify a CCA (cold cranking amps) rating for a vehicle
depending on engine size and the quantity of electrical accessories.
CCA is the number of amps (quantity of electrical current) the
battery can deliver for 30 seconds at zero degrees F, while
maintaining at least 7.2 volts — kind of an odd yardstick but
useful for comparisons. Depending on a battery’s physical size,
plate composition and design characteristics, CCA can range from
about 400 to 1,000. Typically, a physically larger battery has a
higher rating, and it doesn’t hurt to go larger if it will fit. Be
sure to meet or exceed the recommended CCA rating.
capacity (RC) may also be specified. This is a measure of the
battery’s ability to deliver current without being recharged,
perhaps while the vehicle is parked or driven with a charging system
failure. RC is the number of minutes the battery can deliver 25 amps
of current without the voltage falling below 10.5 volts (12.6 volts
is the normal no-load voltage of a fully charged battery).
batteries can also be optimized for climate. Cold weather reduces
performance and hot weather shortens life. Another possible choice
is a pricier AGM (absorbed glass mat) battery instead of a
traditional flooded cell battery. This design is spill-proof, more
vibration resistant and longer lasting, and it doesn’t
self-discharge as quickly during storage, among other advantages.
shopping, take a look at the warranty offered. There’s a full
replacement time (typically two to three years) often followed by a
prorated period, perhaps another three to four years. I look for the
best full replacement period, as the prorated warranty limits