Wow, lots of sales-folk for the Ctek charger here I see, but really?

I put a Interstate AGM in my cat back in February of 2013 and have NEVER had to do a thing since but get in and fire her up...

She's not my DD, and has sat for weeks (admittedly not much over 3 before withdrawals set in), but I know she will light every time.
From my perspective, problem solved!

"Look Ma! No wires!"
Vince

https://www.jaguarforums.com/forum/x...acement-54583/

 

Putting miles on a car helps offset the engine oil contamination issue created by using the car for short trips only.

 

What is your definition of a short trip? I live 4 miles from work which takes around 15 minutes and I rarely make trips of more than 20 minutes at a time in my XKR.

A year and a half on from changing my battery for an AGM I am electrical glitch free but used to see loads of issues with the old battery. Maybe the AGM batteries cope better with this type of use?

 

15 minutes-4miles, i.e. low speed- is a short trip. In couple of ways. Think of it this way, if you had an uncharged new battery, could you charge it in 15 minutes with the alternator. No. But in your case, you are actually also using the power from the alternator while operating- so its output is even less.

Second problem with conventional cars or 4.2l jags is that in 15 minutes of running you havent really cooked off the impurities in the oil left over from you previously doing the same trip. You havent heated the mufflers to get the water out. Dont forget cars produce a ton of water in the combustion cycle. If you have the 5.0l like mine, you should be borderline ok, it has an ingenious way of expediting the engine warmup process.

 

That is the conventional wisdom of old but if you believe the internet you can fully charge an AGM battery up to 5 times faster than a normal battery so maybe that is why I am not seeing any issues. They can also supposedly deliver significantly more power a lot more quickly.

I have mentioned it in a previous thread but with my old battery when I started the car, unless the battery was 100% charged, I used to see the Jaguar logo appear on the touch screen for at least 5 seconds so I used to put my seat belt on while I waited to see if the touch screen would hang. Since changing to the AGM battery I see the logo for a split second only so the car seems a lot happier with it.

 

Yes but you left out 2 VITAL points in your consideration. I'll put it as a puzzler to you- yes its more powerful, yes it charges faster- then why does a sports car have that monstrous size, which is twice the size of the one in my 6 liter 8 passenger SUV? in both physical size and amperage.

1. the Jag needs the added capacity; 2 AGM is notorious for changing its capacity over time. This is whats happening. So a 4 year old battery may as well be half its original capacity. Now a short trip is not enough to charge the battery, Keep in mind a great deal of the output from the alternator goes to running the car, which has priority over charging. Alternatively, thats why even with a bad battery once you get it started you can run exclusively from the alternator.

 

The battery for my 07 XKR is rated at 90Ahr and 800 Amps so if the one on your SUV is only 400 Amps that sounds rather under sized!

I am not an electrical engineer but the AGM battery seems to be doing the job in my car without any extra assistance even though it is subjected to very short trips and the car is not locked overnight so convenience mode runs for the full time.

My comments are simply based on what I am actually experiencing not on a theory of how fast a battery may or may not charge. Others are also reporting no issues so the first thing I would recommend to people is to try changing their battery, not get locked in to a life of plugging in their car every night because they really shouldn't need it unless they are often left standing for weeks on end or laid up over the winter.

People seem to be blinded by the thought that the XK is some exotic sports car that needs special attention and pampering. Under that gorgeous body it has many common components with the XF and I doubt you will find many of those owners plugging their cars in to a battery maintainer every night. They have the same spec battery as the XK as do some of the X351's and the F-Type without stop/start. The X351 can have a 950 CCA battery specified and the F-Type an 850 along with a smaller secondary so the one in the XK seems OK to me. I would rather have one that is over specified than under specified anyway.

 

Yes mate, 550 CCA and 55amp hr. And half the physical size
I dont know what all goes on with Jaguar either as to why they need twice as much as a big suv. Perhaps its in anticipation of the decline in capacity that I am warning about.

So a regular batteries dont loose their capacity sitting on the shelf. AGM apparently does. Thus its entirely possible that if someone got a battery that had been in inventory for 2 years and they had further owned it for 2, it could be at only 60% capacity. I.e. a 600CCA battery. Which will give them all the trouble they are describing.

 

Huh? All the information I found when trying to decide whether to go AGM or tradition automotive battery listed slower discharge rates as one of the benefits of AGM technology.

e.g. AGM has very low internal resistance, is capable to deliver high currents on demand and offers a relatively long service life, even when deep cycled. AGM is maintenance free, provides good electrical reliability and is lighter than the flooded lead acid type. While regular lead acid batteries need a topping charge every six months to prevent the buildup of sulfation, AGM batteries are less prone to sulfation and can sit in storage for longer before a charge becomes necessary. The battery stands up well to low temperatures and has a low self-discharge.

 

Yes AGM has low discharge. However it does not maintain its capacity. Very important point. I owe you one for the excellent brake explanation. This is its battery equivalent. Study at the table below, it will tell you more than anything else you will ever read on batteries. Those who dont know, gel is the older technology. Do you see its all predicated on how many cycles you have used and how much you have taken out of it on each cycle.!! Forget about sulfation is not pertinent here.

 

SECRET TO GETTING TWICE THE LIFE OUT OF YOUR AGM BATTERY:

Here is what I have learned from the table above.

If you use 50% of the battery every time you use it, you will get 370 days of use.
If you use 25% of the battery every time you use it, you will get 925 days of use.

How do I only use 25% or less- start with a battery that is totally full. I.e. charge it everyday.

 

On a V12 Jaguar (1992 V12 Vanden Plas of which only 100 were made; this was number 92/100) I got a full 12, yes twelve years out of the battery and I sold the car in year 12 with the battery still fully functional. How was that done? By keeping the battery fully charged always. For the entire 12 year period the battery was always connected to a battery maintainer ( not a CTEK...a Schumacher) when the car was not actually in use. For all I know the battery may still be fine because the permanently installed charger went with the car. So yes, indeed...the secret to a long battery life is to keep it consistently fully charged. The CTEK units promoted by so many of us will do just that...but the best thing is that if the battery in the XK is fully charged there will be no electronic gremlins.

 

I also heard a rumor that if you top your petrol tank up every time you pass a petrol station you will never run out of petrol!

Each to their own. I will stick with changing my battery every 3 or 4 years if I have to rather than plug my car in EVERY night. I only tend to keep my cars for that long anyway so it shouldn't need to be changed more than once during my ownership.

My XKR has been by far the most reliable Jag I have owned (7 in 28 years) so it is such a shame after years of being plagued with electrical issues (Lucas, Prince of Darkness) that people are now starting to tarnish the reputation of Jaguar again when simply changing the battery could fix a lot of issues.

 

Did you mean to confuse us. On one hand you say that people should not tarnish Jaguar reputation by ignoring to maintain the battery.
On the other you say you would rather just replace the battery every 4 years.

Mate you dint quite catch what was being said. There are oodles of folks prematurely having battery trouble. People who have different driving routines than yours. You do see where they would be running into trouble long before you.

here is a question, have you ever had a low battery on a relatively new battery? I have.

 

Gregory,
This thread was an eyeopener for me. I did not realize that unlike standard batteries, AGMs fade in capacity over time, so it becomes a runaway problem with age, what would be 50% consumption on a new battery becomes 100% on an older one, and then you have even less life left. It only takes a second to plug it in. Its worth not having the headaches that come when a battery does fail. Its a bloody mess on the 5.0 engines. You cant jump the thing from another car- do that and you permanently damage the car.

 

Note the person who asked for help on this thread had a battery less than 2 years old!

 

Just my 2 cents……. my Jag has never really been a true daily driver. Its a 2007 and only has 43000 kms on it. Having said that, it certainly sees more usage as the weather improves. I do not profess to know anything about batteries, but, I do know that since using a Ctek tender for the last 3 years, I have not encountered any gremlins which popped up on occasion prior to the Ctek. When I get home it gets plugged in, regardless if I will be driving it the next day or not. It works for me.

 

Nope just saying that my car seems to be maintaining the battery quite fine on its own so why would I bother plugging it in every night? Expecting to replace a battery every 4 years doesn't seem unreasonable to me. It is just one thing on a long list of items that you can expect to replace at some point during the typical ownership of a car.

It was really sad to see someone post on another forum recently that they understand they will need a battery maintainer now that they have bought an XK so wanted advice on which one to get. I wonder where they got that impression from?

A lot of people on this forum have a fleet of cars to choose from so don't drive their XK's every day. I therefore understand why they would want to use a battery maintainer and I have no problem with that and would consider doing it myself if I only drove mine every few weeks but a mainly daily driver like mine should be more than capable of being used like any other car and not need plugging in. The first owner of mine didn't need to do it and now I have changed my battery nor do I. I very much doubt the first owner of your car needed to either if it was a daily driver.

The OP of this thread left his car for 4 weeks so it is not too surprising he found a flat battery on his return especially if it was partially run down already. For peace of mind that is one of the few situations where I would consider using my battery maintainer which is what the first responders advice was. The rest of the time I expect to be able to just jump in and go.

The comment I took issue with was "even if it is your daily drive, lock it and plug it in every night." In my opinion and experience that is not necessary. I don't disagree about using one in other scenarios though.

I also feel that switching to an AGM battery has made a big difference to the way the car starts. As mentioned earlier I used to see the logo on the touch screen for quite a few seconds with the old battery and did from the very first day I bought the car. Now it is a case of blink and you will miss it so something has changed. After a year and a half of abuse I would have expected to start seeing the logo appearing for longer again but it isn't so the characteristics of the AGM seems better suited to the needs of the XK and all of its electrical components as it is being started.

 

The use of a battery maintainer seems to be supported by those of us who don't use our cars daily. Also the Ctek is the charger of choice by several of the exotic car mfg's. and sold as an acc . even with their car name on them.Seems like a good marketing ploy. My XK is not a DD as I use my truck for that. My bride has her DD and we have another car we use for out of town driving. Being retired there is no preference to which vehicle to use so the Jag usually sits longer then others. It is on a smart charger (doesn't matter which brand ) because it sits in the garage. Out of all of the cars both Jags and non Jags I have only used a smart charger on 2 of them. Any car that I would drive daily does not need a smart charger in my opinion. By the way I have a smart charger on my garden tractor and there is one in my house generator. So use them if you want as all you have to satisfy is your own comfort.