My 2008 XK has 42k miles, and the battery has been serviced regularly, and is not demonstrating any problems. But I worry that 9 years is too long for an original battery (just bought it but I'm guessing original). How often do most of you buy new batteries for your XKs? This is a convertible, won't be a daily driver, and is kept double locked, top up at night, but will be driven with the top down. Can't seem to find a length of life for these batteries.

Thanks.

 

I replace all of my batteries every 4 years. That's a typical life spawn for them. I find it easier to just replace them as preventative maintenance rather than having one fail at an inconvenient time and leaving me stranded. Batteries aren't too expensive.

 

I replaced my original 2010 two years ago, so about five for me. Course, it was working fine before I did a four-hour door-open-and close detail.

 

I've been thinking about the battery question lately and not being an engineer or someone knowledgeable about them, would total "cycles" come into play? Just like a properly produced spring only loses its tension due to compression cycles and not being compressed for a long duration, I wonder if a battery that is used often in one of these cars has a different lifespan than one that is used sparingly? Often would be every day to every other day, sparingly would be once a week or less frequently.

 

It depends on a lot of things.

Has the battery been fully discharged (left the lights on)? That will kill it quickly.

High ambient temperatures? I live in Tucson and batteries only last 24 to 30 months. Parts stores don't even test them when you bring them in for replacement after two years.

Low temperatures? Supposedly hard on batteries. I can't speak from experience on that. (If palm trees don't grow there, I won't live there.)

Overcharged? That kills them fast.

i have never had a battery last nine years. I would guess that you are due for a replacement soon.

 

Carfax only show "battery serviced" which has happened several times. I assumed that was refilling the distilled water for electrolytes, but I live in yesteryear. Anyone know if CARFAX speak for "battery serviced" actually means replaced? Waiting for my CTEK 3300 to arrive in the "mail" at the end of the week. At that point, I am having a good independent mechanic look the vehicle over, and do a few things for my "new to me" 2008 XK. But not being made out of money, or having much confidence in taking out parts that require proper sitting to make sure the top goes down (luggage cover) and calibrations, I am looking to the indie repair folks. Like them, but not looking to put their kids through college :-)

 

Is it a Jaguar branded battery? Is there a date sticker on it? I see your concern but no use replacing it if it a year or so old.

If it is original, 9 years is great. 4-5 years is average for me.

 

Lead–acid batteries lose the ability to accept a charge when discharged for too long due to sulfation, the crystallization of lead sulfate.[27] They generate electricity through a double sulfate chemical reaction. Lead and lead dioxide, the active materials on the battery's plates, react with sulfuric acid in the electrolyte to form lead sulfate. The lead sulfate first forms in a finely divided, amorphous state, and easily reverts to lead, lead dioxide and sulfuric acid when the battery recharges. As batteries cycle through numerous discharges and charges, some lead sulfate is not recombined into electrolyte and slowly converts to a stable crystalline form that no longer dissolves on recharging. Thus, not all the lead is returned to the battery plates, and the amount of usable active material necessary for electricity generation declines over time.
Sulfation occurs in lead–acid batteries when they are subjected to insufficient charging during normal operation. It impedes recharging; sulfate deposits ultimately expand, cracking the plates and destroying the battery. Eventually so much of the battery plate area is unable to supply current that the battery capacity is greatly reduced. In addition, the sulfate portion (of the lead sulfate) is not returned to the electrolyte as sulfuric acid. It is believed that large crystals physically block the electrolyte from entering the pores of the plates. Sulfation can be avoided if the battery is fully recharged immediately after a discharge cycle.[28] A white coating on the plates may be visible (in batteries with clear cases, or after dismantling the battery). Batteries that are sulfated show a high internal resistance and can deliver only a small fraction of normal discharge current. Sulfation also affects the charging cycle, resulting in longer charging times, less efficient and incomplete charging, and higher battery temperatures.
SLI batteries (starting, lighting, ignition; i.e., car batteries) suffer most deterioration because vehicles normally stand unused for relatively long periods of time. Deep cycle and motive power batteries are subjected to regular controlled overcharging, eventually failing due to corrosion of the positive plate grids rather than sulfation.
There are no known, independently verified ways to reverse sulfation.[8][29] There are commercial products claiming to achieve desulfation through various techniques (such as pulse charging), but there are no peer-reviewed publications verifying their claims. Sulfation prevention remains the best course of action, by periodically fully charging the lead-acid batteries.

 

https://en.wikipedia.org/wiki/Peukert%27s_law

 

2 year old Interstate, now on a CTEK 3300. Thanks everybody!