Hello, all. I know quite a few of your are technically minded, so I'm hoping to capture some of your collective knowledge.

Although not my primary driver, I drive my Jag more than any of my other 2 fun cars. The build date was April, 2015. On my last included Jaguar funded maintenance trip - w/o my prompting, the dealership determined that the battery was sub-par and replaced it as a warranty item . That's a 6 year run. They put in a Jaguar battery; the sticker on it says May 2020, made in Germany

Sometime last year I started getting the low battery warnings. This is after we leave home for 2 to 3 weeks at a time. I now hook up a trickle charger overnight anytime I get the message. It then goes a while before getting the message again (week or two).

My experience with traditional lead-acid batteries is that more often than not, they go from good to bad with limited warning. You are lucky if you get a couple of days slow cranking before they belly-up and die.

I can start dragging around my jump start lithium battery with me - but I'm curious, how do the AGMs fail? Is the end near? How will I know; are there particular tell-tale signs? This is more a question out of curiosity since almost all my driving is local and I have other cars I can use. Thanks in advance.

 

Hi!

I had to change mine a few months back. It went out with 0 warning. Like today starts normally and tomorrow won't start at all. I noticed right away as it struggled to open the side mirrors
I was lucky that it managed to open the boot, so I left it half open and went to buy a new battery. You can change it yourself but it's very heavy and awkward to take out from where it is.

 

A slow drop in voltage is often a tell tale sign of failing AGM battery. Your car should be able to go weeks and weeks without saying 'low battery'. Given its 5 years now and showing the signs, you should make a change

Easy to change - get a good AGM from your local auto parts store and it's a 10 minute job. (At least in the coupe, I assume pretty similar in vert but not sure about access)

 

Yep, I can attest to this, DIY replaced my original 10+ years old battery a few months ago and it was way easier than I had feared and yes only 10 minutes.
However you really should wait 20 minutes after removing the old battery before you connect the new one, this is to allow all modules, capacitors etc to completely discharge and reset, otherwise you risk stuffing up the BMS.
Also, as has been pointed out many times on here, most "new" batteries have been sitting on the shelf for a few months and are not fully charged so it pays to whack your battery maintainer on the new battery and bring it up to full charge before you chuck it in the car.

 

First…don’t use a trickle charger. Use a battery maintainer like a ctek.


Take the batter to an auto parts store, or battery store to have it load tested.

A 5 year old battery is on borrowed time.

 

When I bought my 2017 , built late 2016, in fall of 2020, I got the low battery warning "drive more "!! Dealer replaced it under warranty. I keep it connected to a Ctek from about November to February, in a heated garage ( Wisconsin). I've read that the general lifespan of an AGM is 5 years. From your collective experience, should I be looking to replace the battery this fall?

 

As I said my OEM battery lasted 10+ years and I put that down to connecting it up to my battery maintainer whenever the car was not being driven and parked in the garage. Not from new though, for roughly the last 6 years of it's life.
IF you do the same then your battery should also last 10+ years.

 

My orig battery almost made it to 11 years. Even then if I drove it everyday it never showed the warning.

 

Another data point for others. As stated by BritCars above, mine has exhibited the slow decline. It started with a more frequent notice of a low battery if sitting for days at a time. I started using my Schumacher maintainer periodically. Of late, I had a couple of instances of low battery, and the car would not open the rear hatch. Of course, starting the car (or charging again) and all fine. Never once did I have any issues cranking the car - each time it cranked like a new battery. I like their cascading levels of function as the battery level drops, giving you enough head's up that at least in my case I could always start it.

Of course, the last instances were when I trailered the car up to the Tail of the Dragon with my nephew and his buds. Couldn't have started the more significant decline at home! In any case, I ordered a replacement. We got home Friday; I just now got around to changing it. It took me about 20 minutes (I went and did some irrigation repairs before hooking up to have at least 30 minutes disconnected). It started right up with the new battery, no issues. I did not have to reprogram my windows. It even defaulted to my USB source of music which was last used.

I'll update later if I notice anything odd.

 

If you think that's awkward try changing the battery in an XKR!

 

In my 2015, my original battery dated from 2014 just went out last April. AGM's if maintained properly and do not get to hot or cold will last a long time and yes mine is a rarity lasting over 10 years.

 

My '13 dated battery made it to this spring! It never went dead just gave the warning after sitting.