While I don't have exact specs on Jag's charging cycle, chances are nearly 100% it is as poorly designed as all manufactures. AGM requires very specific charging parameters that are quite complex and take time, namely, AGM must receive a finishing charge (high V at very low amps for approx 24 hours) before long term float charging. Since high demand applications like a Jag are always floating without finishing, or worse, draining without finishing between charges, they sulfate badly.
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So what we are left with is AGM performance that is on the shortest side of "normal" AGM battery life expectancy, which is 6 to 48 months. If you want to use the recommended AGM style battery in your Jag, expect to replace it every 6 months with a brand new one. This is normal.

That is why a smart, AGM battery tender is a cost effective option. Hook it up anytime the car will sit more than 24 hours. Then you can expect 48 months per battery. Plus, fewer tows to a dealer who will only screw things up.

Another cheap option is a traditional sealed lead acid battery which will not sulfate on the car's float cycle or when sitting longer than 24 hours between charge cycles.

 

My F-type sits in a cold garage for the winter months, and has done so since new (aprox 5 months a year). I connect a CTEK charger every 6 weeks and leave it connected only til it shows green light/fully charged. That usually takes 5-8 hours.

The car is now almost 5 years old, and I have so far not had any problems with the battery/low voltage.

 

Why the disconnect? If you left it permanently connected, you wouldn't have to recharge every 6 weeks and the battery will always be in tip-top condition.

 

Thank you for taking time out of your day to respond in detail to my question. Thank you again and Happy New Year to you!

 

Similarly, my F-type sits in a heated garage for the winter months, approximately 5 months a year, and I simply disconnect the battery when I park the car. So far, it started right up every spring.

 

Probabely due to old habits. I have used CTEK chargers/conditioners this way for many many years, and I have never had to replace a battery on any of my cars/bikes. If it works, why fix it...?

And to connect/ disconnect take 10 secs, and is a good reason to have a look at the car during winter hibernation every 6 weeks

 

Ah, I forgot about the secondary benefits!

 

I think that is a bit alarmist. I used an AGM battery in my '07 XKR for 3 years before I sold it. Although it was a daily driver, my typical usage was just driving around town with trips of less than 5 miles to work and back so a very battery unfriendly pattern of usage. I also only used a battery tender if I was doing work on the car or giving it a spring clean.

If and when the battery on my '10 XKR needs replacing I will definitely be buying an AGM to replace it because, amongst many things, they have quicker recovery time and are better in colder weather.

 

Of course it depends on the car, model, and your driving habits. Many of us are experiencing battery related issues every six months or so. This is within in the range of "normal" for a consistently undercharged (short trips, 12.6V nominal alternator) and overcharged (long trip's sustaining charge after no finishing charge) AGM battery.

Easy fixes to cars requiring frequent replacement: Battery Tender if sitting for longer than 24 hours, or a one-time SLA replacement.

 

 

Has your car been serviced recently where a diagnostic tool was plugged in to the OBD reader port? Are you getting a low battery reading before you cannot start the car?

 

I guess my AGM battery is on its' last legs?

Car was built in May 2015. I have always used a CTEK 5.0 (with AGM mode) from new, and as I work offshore, often the battery stays connected for 4-6 weeks at a time.

Over the last year, I have noticed that the cold crank speed has slowed, and occasionally when out, I have had the odd "Battery Low - Start Engine" warning.

Interestingly, whilst away for the last few trips, I have had the better half go into the garage and disconnect the CTEK and just connect it once every week for one night then disconnect again - Cold crank speeds have increased and no battery warnings....explain that one!

 

My car was built in Oct 2014 and I have connected a battery tender/charger to it every two or three weeks, and I have never had an electrical or battery problem, not even a warning.
Maybe there is something to what JIMLIGHTA says about over-charging an AGM battery?
Then again I live in a hot climate and the car never sees temps under 0 C (32 F).

 

Got i mine one night, and nothing....no lights, no crank, nothing. Had towed home and then to dealership next day. Mine had a dead key fob receiver module. Had to replace module and reprogram both keys.

Thank god for internet and smart phones. Was able to find how to put electronic transmission into neutral without power. Under console cove in middle, you will see on the left side a plastic cover. Once you get it off and its a bitch, you will see a handle with a orange material piece that looks like a control for an ejection seat. There is a large screw that you use a coin to rotate from being up and down to being sideways. That is the unlock so you can pull the handle up and puts it into neutral. To put it back into gear, lower the handle and turn the locking screw back to pointing up and down.... the car would not have been able to be towed without knowing this....

 

ok so I am. Custom car guy and have a 1986 Monte Carlo with a smart system I built and installed using aftermarket parts and had similar issues.

1. Antennae broke - mixed or faulty signal from key
2. wire cracked coming out of smart key reader/antennae
3. had something short the ignition module (stupid mistake not paying attention to wiring loom position) and had to replace the ignition module component where it gets the key token hash confirms it then trips the relay to start the car.

my money is on the antennae since it eventually starts - bad connection or broken wire. My humble opinion - might also be a low key battery.

 

I was gifted 2 pair of 6.5" component speakers. I mounted the rear units last week, there was little space for the crossover box.
Is there room for these guys within the door:door interior panel?
wj

 

Surely this posting is in the wrong place?

 

yep, lost it with some fat finger action!

should be in x150, https://www.jaguarforums.com/forum/x...upgrade-74410/

wj

 

You say "If they can't find a specific cause, they will start replacing parts to see what works."
If they are planning to resort to a suck it and see method of diagnosis, surely the very first item on the list of parts to try must be a new battery? Relatively cheap, simple to apply, most likely cause?

 

The post you replied to is over 8 years old. Not quite a record here, but close…