Daily driver @ about 19,000 miles per year, 2015 V6SC on third 850CCA AGM Interstate battery last replaced 3 years ago (yes 3 batteries + ECO batteries replaced multiple times in first 2 years along with BMS all under warranty). Mostly short trips under 10 miles with an hour plus idling in park each day, but at least one long weekend trip each week.

Earlier this year put it on a CTEK and took almost 3 days to fully charge despite no apparent battery issues. About a week ago noticed sometimes starting seemed just a little bit slow by a fraction of a second and meant to check battery/put on CTEK again.

Well, this morning it started up, ran some errands and then at the last store went to start to go home and nothing, just a dead battery message. Started it with a battery jump box and made it home. Battery was just over 12 volts (too low) and put it on the CTEK and it fully charged in just a couple of hours which is a record for CTEK. On load (all electrics on but engine off) battery holds steady at around 11 volts, off load it holds steady at around 12.6 volts. With engine on idle and electrics off, voltage holds steady at 14.15 volts and with electrics, climate etc on it holds steady at around 14.01 volts, occasionally dropping to 13.8-13.9 volts.

Anyone with good knowledge of batteries and alternators have any input on what would cause this battery to fail then charge fully so quickly with just a maintainer? I've had a great number of JLR vehicles and never had an issue like this (other than the earlier issues on this specific vehicle, most batteries last at least 6 years for me over the last 30 years.

 

If it charges that quickly it seems your battery has lost most of it's capacity, so probably time for a new battery again - recond on the ctek may help, but probably should only be done with the battery off car. Perhaps you have a massive number of start cycles if the 19k miles is made up of mostly 10 mile trips.

Things to check,
Have you got a loose battery terminal?
Are you connecting the negative cable from your CTEK to the chassis? ( if you connect it to the negative clamp on the battery the BMS can't measure the charge you're adding via the CTEK. ) ( bolt on the top of the battery terminal where the negative cable attaches is ok, but the bolt that closes the clamp, or croc clips on the clamp don't go through the BMS )

 

Does your car have a battery system monitoring module on the negative battery lead? I have just brought my 2012 XF home today and have been reading the Service Manual for 2009-2010 XF and on page 2504 there is interesting reading about the battery and charging system. Charging appears to be controlled by the above mentioned module. It is suggested the applying external sources of power through the negative lead may damage the control module and recommends using the hold down for the spare tire as the ground. There is also a procedure for calibrating this control system. You would probably need SDD to check DTC for this unit.

 

Yes it has BMS and yes always earth to earth. My biggest concern was replacing the battery only for it to happen again if perhaps there's a fault with the alternator.

 

There are DTC for those cases. The battery on the car I just got is a 3year old Interstate, when I put my CTEK 3300 on it it took 10 mins for the green light to come on. With just the trunk light on battery sits at 12.9v.

 

I ran SDD and didn’t find anything amiss. Keep in mind as a daily drive it does not get connected tot he. To but perhaps once or twice per year. As noted in the original post earlier this year it took 3 days for the CTEK to go green and the battery was working then. Today it went flat straight away and only took a couple of hours to reach green status. I’ll monitor it for a couple of days and decide from there. How long do you think the if the battery has indeed lost capacity before ill
see a noticeable Voltage drop?

 

UPDATE -

Made multiple trips yesterday without issue. Monitored battery voltage, fluctuated between 12.6 and 12.9 even after sitting for some time. Engine even seemed to run smoother. Placed on charge overnight and this morning it did not start quickly. Checked voltage and all was fine but still seems like not enough amperage to start. So I suspect while the battery charges and maintains voltage it has lost its amperage?

 

Sounds like it, in which case a load test may be revealing (or just replace the battery).

 

I'd imagine if you leave if for 4-5 Days without starting it ( I know probably not possible ), you'll find it doesn't start again. Probably the battery is at more like 20Ah capacity fully charged ( unless it was a long drive back from when it wouldn't start for you, or you've got a high powered ctek ) If you think 2 hours charge on CTEK at 5A max can't be putting more that 10Ah in. I think mine took about 3 weeks ( not driven in lockdown ) to drop to ~12.3V ( with an OK battery at ~7 years old )

If you've got access to SDD, then I've heard there is a test for battery charging ( alternator ) in it and that it's the only way to test it properly, because the charge rate is controlled by the ECU, which bases the charge rate on the state of the battery measured by the BMS, along with an estimate of the current max capacity of your battery based on BMS stats (i.e. how worn your battery is. ) Also around every 6 months the ECU will disable the charging and partly discharge the battery to update it's estimate of it's wear state, so other measurements can be skewed by that. Did you reset BMS when fitting the battery when it was new? ( otherwise it can be up to 6 months before recalibration, and it'll be charged wrongly meanwhile )

It's often the case with battery failures that they measure ok, when not under load.

I've heard the negative cable from the engine to body can have problems and hence effect the starter on the XF, also there is a junction box used for the starter ( big red cap on it) hidden behind the wheel arch cover on the right hand wheel arch next to the bottom of the windscreen washer bottle ( not sure if they're on the other side for LHD cars. ) that can get badly corroded, but given the jump start was ok, that seems an unlikely cause.

 

So, you're saying that on a modern Jag, a battery should last more than 3 years.

 

Yep.
My F-Type is the first car I have ever owned with an AGM battery, and so far it has lasted 6 years with zero problems.
That said I stick it on the battery maintainer once every two or three weeks coz I do 95% very short trips and sometimes go two or three days without driving it at all.
All my past cars, including the XFS and XFR, had "ordinary" lead acid flooded cell batteries and in every case 4 years was the limit before they started to get a bit dodgy and needed replacement.
All modern Jags, well at least since around 2012, have AGM batteries from the factory.

 

As I said aside from the issues early on that appeared to be sorted with the replacement of the BMS, I'd never had a battery with such a short lifespan on any marque including multiple JLR vehicles. I've had many, many vehicles with flooded and AGM batteries and 5-6 years has always been expected. This particular one is AGM and the vehicle is driven nearly 20 grand per year. My primary concern really wasn't the annoyance of a short lifespan but any possible issue with the alternator. It is maintained quite regularly either by myself or the main dealer. About a year ago I noticed an increasingly frequent rough idle as more and more electrics and climate were engaged simultaneously. I had wondered if perhaps the alternator was getting a bit tired with age and not able to provide enough current but the dealer was unable to find any concerns and I've just dealt with it. I did notice after that first CTEK charge the other day the idle roughness appeared lessened. But along with the battery now struggling again the roughness has also returned.

Well, I'm off to have a new battery fitted and we'll see if that sorts anything.

BTW one of the marketed benefits of an AGM battery is increased resistance to wear due to high frequency of start cycle. Obviously not the case this time round...

 

Definitely the battery, after being on charge overnight again, battery voltage measure 12.1. Went to dealer and had them exchange it prorated. Everything running perfectly now, engine completely smooth with no roughness whatsoever. So apparently this one was one its way out since a year ago.

However I had not really paid much mind to what batteries they were using other than the brand is Interstate which is quite common as most franchise dealers her use them. Anyhow since I've been paying better attention I noted that both the failed battery and the new replacement today are rated at 80Ah and I believe the factory specification minimum is 95Ah. Anyone one here know what the headroom is and how much of a difference 15Ah is going to make?

 

When I replaced mine I went for a 100ah battery (same size).EA1000 4 Year Warranty Exide Battery 100AH 900CCA W017TE Type 017

 

I think the ECU/BMS has the expected capacity coded into it, when BMS is reset it will be expecting a new battery with that amount of capacity, so will probably under charge as calculations on how much capacity is left will be out.

 

Glad you've solved it. At least for now. I'm less convinced by this BMS thing. I've changed mine a couple of times over the years without resetting bms and never had any issues. I struggle to believe they put in technology that would mischarge it if not reset

One thought for OP - wonder if you have some parasitic draw from a module or system not shutting down properly? That deeper discharge of the battery could explain why it gets harder to start and why the battery ages quickly. May be worth doing the electrical tests to see if it is shutting down properly when parked and going into sleep mode

 

There is a routine to test for that. And I will check the CCF for set battery specs.

 

BMS info......

 

It is interesting to note that the XF Service Manual states that AGM batteries should not be charged with voltages in excess of 14.8 volts to avoid damaging the battery, and yet if you read the Calibration procedure it suggests that the optimum charging level involves voltages between 12.6 volts and 15 volts. This could be the cause of the relatively short lived AGM batteries.