This week, I went through a problem with my Bluetooth screen locking up. It turned out to be a defective battery that was replaced yesterday under warranty. Before posting about it, I read many Bluetooth posts and many other posts. The writers of many of those posts and others about electrical gremlins routinely recommend the usage of a battery tender, usually a CTEK.


I recognize that battery issues are the cause of many gremlins and that the Jag is supersensitive to the charge on the battery. I also understand that many members use their cars infrequently and really should be using a battery tender. I also very much appreciate all the help that was offered.


But, that said, it is my opinion that the slavish adherence to the opinion that everyone should have a battery tender is misplaced for those of us who are daily drivers and perhaps for others who drive somewhat less frequently. And, I think I have the history to support my opinion.


I've had my XK for over 8 years and I've put 135,000 miles on it. I'm a daily driver. There have been times when it has been idle for 1, 2 or 3 weeks when I would be out of state on vacation. In those 8 years, it has never been on a tender. While my recent Bluetooth issue was caused by a defective battery, a tender would not have solved the problem. This defective battery was a replacement a year ago for the original battery. I replaced that original one just on principle because it was so old. In all that time and even counting the idle periods, I've never had an issue that I've traced to the battery except for one time when one of the battery cables came loose.


Before getting my XK, I was a Nissan 300ZX driver (drove that one to 310,000 miles) and then a Corvette driver (3 separate ones over 11 years and 300,000 miles). These vehicles also had their computer gremlins not at all unlike the kind I read about on this forum.


Perhaps, members shouldn't be so quick to recommend a battery tender for ever electrical glitch that shows up.

 

I don't take issue with anything in your post. However, I keep a CTEK battery tender hooked up to my Jag every minute it sits in my garage, same for my NSX and my motorcycle. I've done this for longer than I care to remember and have never had a battery issue or electric gremlins. I'm not saying they are absolutely necessary, I just consider a CTEK as a type of insurance policy with a one-time premium of $60. To each his own. Cheers!

 

This is of interest to me since I just bought an XKR. Do you use your car as regularly in the winter as other times of the year?

 

+1. Another point is that you will extend the life of your battery by keeping it fully charged. It takes less than 30 seconds to open the trunk lid, attach the quick connect plug, close the lid and lock the doors. A small price to pay for peace of mind.

 

Rob this is easy. You absolutely need a battery tender. Here is why.

AGM battery's life can be halved, or even less depending on how much you discharge it. So for instance if you discharge it 10%, you will get 2000 cycles, (many years) if you discharge it 75% you will get 300 cycles. (year or two)

If you use it only once a week without plugin it in, you are depleting much more that 10%.

If you drive it daily than you are hardly ever depleting it more than 10% and you get the lifespan this thread owner experienced.

I manufacturer a product that requires expensive batteries and potential warranty headaches, so really familiar with battery life characteristics.

 

I drive my Jag 12 months a year ... EXCEPT ... when there's snow, ice or salt built up on the streets. If the streets have been plowed and are clear and dry, I drive. Since I have a heated garage, whenever I pull into my garage after driving in the winter, any snow and/or ice that's stuck in the wheels, on fender liners, rocker panels, etc. melts completely off after which I then either spray off those areas or wipe them dry and clean.

 

Here is a table for those who need visual aid.

 

Agreed. Voltage loss in a 2-3 week period of inactivity is minimal.

I attach a tender to mine only when the period of storage will exceed a month or so and obviously all winter. The battery in my S-type is eight years old and still works like new (touch wood).

 

You are correct, but for those that post looking for help there has to be a starting point. A solid battery charge is the go-to in all high end cars that are reporting electrical glitches and is a solid recommendation. For those who ask looking for help with internet diagnosis it is a crapshoot anyway. Really the smart thing to do is have the whole electrical system tested, could be battery or alternator/voltage regulator or something else entirely.

Even daily drivers can experience battery drain. For instance, my Wife has very short commutes to work through stop and go traffic. The car is on for 20 minutes and never reaches any real speed/RPM to max out the alternator output. Being a daily driver does not guarantee that our battery will maintain it's health. I usually put it on a maintainer once a week, not because of gremlins, but to prolong battery life. It is always a bit low, not so much that we have problems, but still not very well charged.

 

5.0L X150 models came from the factory with AGM batteries; 4.2L models did not. Either way, a battery maintainer is cheap insurance, as Snide72 mentioned.

 

Here's another way of looking at it -
you posted of your experiencing electrical issues which many here have also ran into. Instead of doing your own search which would have shown this same issue has been brought up MANY times you chose the easy way out and just posted... no harm no foul. You also stated that you recently had work done then had your problem right afterwards. I was kind in responding to your post and luckily happened to be right that your battery was not "defective" as you still try to say but rather that it was likely diminished in capacity from them not locking the car properly while working on it. You on the other hand wrote back saying that you didn't not believe me sand said that "you didn't think it was the battery as it was only a year old". I was right, you were wrong

Would a tender have solved/fixed your issue - with the little information you provided we cannot tell if your battery was low before it wen to the mechanic but certainly likely it was low afterwards. Would a tender have helped prior, that depends on whether it was at it's peak voltage or if you had driven it enough to bring it up (it won't be to the top as alternators don't do that), would it have have resolved your issue afterwards - YES. So to answer your question it WOULD have fixed your problem and you would not have encountered those issues unless you had brought that newer battery down to levels beyond the point of no return

Now the fact that you have others cars has zero to do with this car, XK's are pretty unique, how many miles or how long you've had the other cars makes little difference not even worth bringing up. Their color, engine size, miles driven mean nothing to this issue or conversation. They do not have the same current draw so their mention is irrelevant.

So instead of you writing back "thank you for your responding to my initial post kindly offering suggestions that not only probably showed the cause of the issue (low battery due to mechanics working on the car) but also how to perhaps not run into this issue in the future (maintainer)" you come back with correcting me and admonishing me in saying that I/we shouldn't be slavish and "not be so quick to recommend battery tenders?!?!??! In the future I'll be sure to not offer you any help as I'd hate to be right once again, kind to you, then get corrected... I'll save that for those who appreciate the help. Oh by the way... you're welcome. I see your parents thought you well. Lesson learned. Sorry to have wasted your time with being right trust me it won't happen again in your case.

 

I'm pretty much in agreement with the only difference being the change to the charging system after MY 2010. The 2007-2009 systems usually put out a constant 14+ volts so in normal usage the battery would be under charge regardless of the distance that it is used. The newer charging systems are ECU controlled and the charging rate is variable from 12.4V to 14.4V depending on how you drive. Until I bought this car I never used a battery tender even though my toy cars would sit from Oct. to March without starting or driving. So in my opinion as I drive the car maybe 3-4 times a week it is simple just to keep it on the charger. If I would drive it every day I would probably not put it on a charger. The other thing I had never done was lock the car after getting out which is now a new habit.

 

Yep most of these other guys on this thread dont have an AGM battery. The difference between the two is night and day.

AGM almost has to have a maintainer. Thats why you see Jaguar offer one, as does virtually every car manufacturer that has switched to AGM.

 

I am of the camp of "no battery tender". I have a few modern cars in my family from BMW to Mercedes to Lexus and not one of them requires a battery tender and neither does the Jaguar xk in my personal experience. If your car is draining the battery in such a short period of time, then I suggest that you get it fixed. My 2007 xk has over 100,000 miles and never had a battery tender on it. I have left my car in the garage for two, even three weeks at a time without driving and it starts right up with no issues. The day I need to put a battery tender on a gasoline car is the day I will get rid of it and just buy a Tesla.

 

I am amazed when you mention the use of a battery tender to resolve an electrical issue on a jag how it is generally received. After 16 Jags trust me ALWAYS start with the battery. And that was the advice given. Good solid sound advice. You can lead a horse to water... Leeper do not give up on those who realize how valuable this forums information is and appreciated.

 

See what I mean. Like talking about tires or politics or religion. Very touchy subject.

 

I use it year round but Winters in Southern Maryland tend to be pretty mild. If I know we're going to have trouble during rush hours when I worry more about being hit by someone, than I take my Honda Ridgeline.

 

1 of 19 - I don't let people like this get under my skin and thank you for your words. I'm not butt-hurt just realized some people appreciate help but some don't and not to waste my time. It looks like it is probably a "cultural" difference in the OP, perhaps he'll learn maybe he won't but I'm done with him (I'd act/respond the same if he acted that way towards anyone else). I'm not now nor will I ever be PC, I'll call people out, apologize when I'm wrong, but I don't coddle or spoon-feed anyone. Though I disagree with Q&C or CeeJay in certain threads I still really appreciate their inputs and opinions... we're big boys and discussions sometimes differ in opinion all good! The line of respect/appreciation was crossed with Meng, won't happen again

With regard to a tender - some use them pro-actively, some decide later it helps after they have experienced issues, while others adhere to the idea that it is ridiculous and unnecessary. The latter people are right in that it "shouldn't" need one but the bigger question is not right or wrong but how to deal with the issue. I let me car sit for 1-3 weeks without driving it just sits not on my tender but about every month or so I do top it off AND I've dumped my battery to the point of not starting more than once, while doing work on it so topping it off every few weeks has helped me a lot. We can argue all day about why these cars are so touchy voltage-wise but at the end of the day the problem exists and the solution is there and until you have a problem you don't care to deal with it.

 

No disrespect was intended. Perhaps you missed this line in my post: "I also very much appreciate all the help that was offered."

 

Leeper you are right- all batteries ONLY benefit from the use of a maintainer.

Cant believe you put me in the same looniebin as CeeJay, I know I suffer from all sorts of retardations, but he thinks the Michelin Man is more nefarious than Ghostbusters warned of.