I've got it on the Ctek now, so if all is well tomorrow il assume it was a low voltage fault. If I was to check the voltage, can that be done using the same posts that the charger uses?

Rang up the dealer who sold me the car, tried to fob be off with 'nothing wrong with a 10 year old battery'. Any car I would change the battery after 5 years, especially a jag, just common sense

It's gonna be on charge whenever it's sat anyway as I have to carshare for work, week on week off.

 

Just call me crazy.

 

We all know about you, jagtoes. Nothing to be ashamed about.

 

You can, and it would probably be correct, but if possible I would go directly to the battery posts.
Also, a CTEK isn't an actual Charger. I was talking about the 10-20 amp or higher chargers that are the size of a loaf of bread or larger.

 

I hope that you didn't attach the negative (-) CTEK pigtail directly to the negative (-) battery post. If you did, disconnect it immediately and pray that you didn't damage the Battery Monitoring System module that's attached to that battery post (terminal). The CTEK negative pigtail must be attached to a chassis ground for the 5.0L models.

For details, see:
https://www.jaguarforums.com/forum/x...estion-227331/

 

Don't worry I did the remote hook up, using a nearby ground behind that little cover as suggested by another member.

 

Why do you keep saying it will damage the BMS? It just confuses it, not harm it.

 

Actually, it disables the BMS. To me, anything that doesn't work is damaged. AFAIK, the BMS module can't fix itself.

So, what difference does that make? Will you notice any difference in the driveability of your car? No, because if the BMS module is disabled, the ECM will automatically take over control of the alternator. So why should I worry about it? Because the BMS was designed to maximize the life of your battery and to generate DTCs. Without a functional BMS module, your battery won't last as long and it probably will take longer to diagnose battery and alternator problems.

From the X150 5.0L Workshop Manual:

 

The remote positive battery terminal is behind that cover. The remote negative (ground) terminal is in front of the spare tire.


My XKR hookup:

 

Stuart, I have no reason to believe you are incorrect, but out of curiosity how did you come to this conclusion? Do you mean by "disable" that a direct hookup to the battery from a maintainer bypasses the BMS. Or does it actually take it out of service?

Thanks.

 

Bill, the 5.0L X150 Workshop Manual says that the ECM will override the BMS Module if a fault is detected. The Owner's Handbook for my 5.0L 2013 XJ emphatically states "Do not connect a booster cable to the negative (-) terminal of the battery." I interpret those statements to mean that connecting the negative pigtail directly to the negative battery terminal BMs Module can cause the BMS Module to be bypassed and replaced by the ECM.

It seems to me that we're arguing about semantics - the branch of linguistics and logic concerned with meaning. It doesn't matter to me what you call it because I hope we're all in agreement that if it walks like duck and talks like a duck then it's a duck.

Bottom line: Attach the negative pigtail to a chassis ground, not the negative battery terminal. Time to stop



Stuart

 

presumably a charger's behavior confuses the hell out of the BMS because it steadily reduces current as it detects the battery reaches a complete state of charge, whereas the car's alternator does no such thing.

it also says the DTCs generated by the BMS are stored, so something you can do is clear them, operate the car on a battery that's just gone bad and won't hold a charge anymore, and see if the BMS is still throwing codes.

manual says the ECM overrides BMS but it doesn't say if that is permanent or temporary, and under what conditions the BMS starts doing its job again if so. is there additional information about that elsewhere maybe?

 

No where has Jaguar ever stated the BMS will be damaged all they are saying is direct connection via a booster* is not the appropriate manner of connection. BMS is used by other manufacturers as well and it is known when using a maintainer the connections must not be direct to the battery so the BMS is able to properly account for the trickle charge.

*Speaking of semantics a booster is NOT a maintainer! A booster is used for jump
starting and I reckon jump starting via the BMS COULD damage it.

I’ll also take this opportunity to add that my experience with BMS has shown it to be an utter failure at improving battery life. I’m on AGM battery number 4 and BMS module #2 in a 5 year period whereas the 12 year old rarely driven XKR is on battery # 2 now.

 

Stuart, I did not mean to provoke you, or to make some superfluous point. I was asking what I thought was a legitimate question. And you gave a good answer, which I appreciate.

I think precision in language helps convey meaning, so yes, we are talking about semantics, but not in a bad way.

Thanks for your clarification.

 

Bill, you asked a fair question and didn't provoke me. Unfortunately, Jaguar's manuals are somewhat vague and ambiguous. I've previously posted my favorite example of imprecise language, so this is for those who haven't already seen it.

John mopped the floor with Fred. Here's poor Fred, literally:


That's very different from John and Fred mopped the floor.

Stuart

 

jahummer, thanks for the semantics lesson! You are absolutely right about a "booster". I learned that it's a portable battery device that works just like using jumper cables from another car to start a vehicle that has a weak or dead battery. A booster is not a battery charger or battery maintainer, and works by increasing (boosting) the battery's amperage to (hopefully) crank the starter motor, which will (hopefully) run the engine and thereby cause the alternator to eventually recharge the battery.
https://itstillruns.com/portable-jum...k-5006532.html

I am not an automotive tech, but have learned from doing basic repairs and maintenance for decades. As you rightly pointed out, my limited knowledge can be dangerous, particularly since I don't speak the Tekki language.

I am now not so sure that a low amperage device like a battery maintainer will damage the BMS Module if the negative pigtail is attached directly to the negative battery terminal. I don't have to be concerned about it for my XKR because it's a 2009 4.2L and doesn't have the BMS. But I'll continue to keep my CTEK (with a chassis ground) on my 5.0L XJ since I've been driving it so infrequently during the pandemic.

Stuart

 

The technical guide for the 5 litre does mention maintainers as well:

 

I am one of the crazy few also! Had the car into the dealer early on for some other work, they reported the battery was faulty so I authorized replacement. A $120 battery cost me $320.

When that battery failed recently I put it in my self, so I guess I am only half-crazy now. Not only did I overspend $200 at the dealer but while my car was in I met a client at the nearby gentlemans club, the dealer trip cost me another several hundred when I donated to the SMOAGTC fund (Single Mothers of America Going To College).

 

It looks like we're now back to Square One. It's been a fun and informative journey, but a convoluted way to simply tell 5.0L owners to attach the negative pigtail of their battery maintainer to a chassis ground and not directly to the negative battery terminal.



Oh well, at least we got some exercise doing mental gymnastics!

 

Did a 200 mile journey on Saturday, then popped out twice a few miles at a time later on that day, on the way back from the 2nd trip, got a low battery warning when starting the car...

Update, dealership insisting that I must have left something on for it to go flat in two days (bollocks), so they are asking for a battery test report.

I've wanted to go jaguar themselves as they will be able to use the proper IDS and also make sure the electronic modules are going to sleep correctly. However, jaguar want 168 quid for this privilege, and I'd assume the same again if the battery needs replacing..

Is the best idea to go for aa/rac quick battery test, then dealership if battery is fine, and therefore drain needs investigation?

Dealer also said they had car sat for 4 weeks with no problems. Is it possible that it's just the cold that has shown up my tired battery, and that in their warmer showroom it was behaving itself?