Battery test?

My garage has recommended that I replace the 5 year old battery in my
car and avoid failure in cold weather. The mechanic mentioned that it
failed a test twice. At the moment, the car starts admirably and after
topping up with my trickle charger, a cold start is just as good as a
warm start.

What battery test is conducted to determine potential failure in cold
weather?

 

What is the battery's rated life? Most are 60 to 72 months and they last
about that long. As for testing, read here, about half way down the page
http://www.batterystuff.com/tutorial_battery.html#6

I do know that having a battery fail when it is 4 degrees and windy sucks.
Why did you have to top up the battery with the charger? How cold is cold?
The cranking power drops rapidly along with the temperature. Should you buy
a new battery as we are heading into winter? That depends on your tolerance
for pain and inconvenience. If you are starting to have problems, yes,
definitely. If your garage is just trying to sell batteries, get another
test someplace else.

 

If you trust your mechanic, then you better take his advice. That's
because a 5 year old battery is quite old. Only a few last 5 years,
and fewer still last to 6. Believe me, it will let you down at the
worst possible moment.

The cheap batteries last ~4 years, the expensive ones last ~5 years,
but cost nearly twice as much. So it's your call on how much to spend.

A standard load test will usually reveal the problem.

If you don't have a load tester, a simple voltage test will give you a
rough idea: When you come home, do a simple voltage test with the
engine turned off. You should get ~13.5v give or take. Check the
voltage the next morning, preferably after a chilly night. If your
voltage didn't change much, it's a good sign. If the voltage drops ~1v
or more, it's a bad sign. Keep in mind this is a rough test, but it
can be a useful indicator.
-

Bob

 

13.5V is charging voltage. I've never once seen voltage this high on a car
that was off.

 

Mine usually stays between 12.85 and 13.50v. Charging voltage is
usually around 14-14.5v. I guess each vehicle will vary by .5v or so.

The real test is not the absolute battery voltage, but the difference
between warm and cold battery voltage.
-

Bob

 

13.8-14.7 is typical charging voltage. Optimal target voltage for
charging has to be calculated against the battery's temperature. I'm
not sure about the Hyundai but my Dodge has a sensor on the bottom of
the battery tray for this reason.

JS

 

If you are seeing above 12.8V from a lead-acid battery that has set for
any length of time at all after charging, then you need to have your
voltmeter calibrated.


Matt

 

True! The self-discharge curve is very steep for the first hour or 2
after a full charge. You can actually stand there and watch the
voltage drop pretty quickly in .01v increments.
-

Bob