About 18 months after purchase, the low battery warning started showing every morning. My dealer wanted me to drop it off for testing however long that took, and my appointment is a month away.

Just talked with another dealer's service manager who said just locking the car at night will probably fix it. Apparently locking it turns off all the computers, sensors, etc., which were running off the battery all night long. So lock your Jaguars at night even in the garage.

 

That's strange. My 2018 XF is always unlock when parked inside the garage. Maybe your car's battery is slowly dying. Have it check at your local auto parts store for load test. it's free testing as long as they sell car batteries. Did you attach an OBD2 scan tool? When the scan tool is unplug incorrectly the central computer may never sleep. To check if you unplug the scan tool correctly is to observe the red Hazard Warning Button is still remained lit up after 20 minutes. To correct plug the scan tool and turn it off correctly, then unplug it or you can disconnect and reconnect the battery to reset. Also, if you didn't used your car for several weeks you'll most likely get a "Low Battery Warning" message. If you need to buy a new battery, Walmart sells for less than $200 and the size is H7 AGM

 

Yes, that doesn't sound right to me either. I leave my car unlocked in the garage all the time, plus over Thanksgiving my X260 sat in the garage for 2 weeks while I was out of town. Got back and it started right up. I would say you have a battery drain somewhere while it's unlocked or it just needs a new battery. My Range Rover went through one of my batteries in 18 months. The new one was still going strong for 4 years when I sold it. JLR products need great batteries, and even a slightly defective one can fail or underperform rather quickly. And they may test okay at O'Reilly's, but that doesn't mean it is okay. I would just replace it, reset the BMS, and try go from there.

 

You need to measure the resting voltage after the car has sat all night. Jaguar wants 12.6 VDC.
I think you due for a battery as sb53 posted above.
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I never lock my car in the garage. The low parasitic draw by the systems when the motor is off is necessary for the correct operation of the car. I've measured SOC (State of Charge) and it does not change overnight. How much do you drive? Maybe you need to hook up a battery maintainer.

 

how far do you drive each day , to keep that battery charged .if not far you have to lock the doors each time you use it

 

Locked or unlocked, it should go to sleep and not draw more than ~40mA, which won't affect the battery level enough. Is your key staying close enough to the car to wake it up? I've seen that cause issues when a car is in the garage or close to wherever the keys get left.

If your car was sitting, even at the dealership for months, it's possible the battery monitor has gotten far enough out of range to trigger the warning, even though the car may start just fine. It would be worth letting the dealer test the battery, update the GWM if software is not at the highest level, and reset the battery monitor if there is any issues. This also affects the way the car charges the battery (it will gradually charge the battery less as it ages, to protect it), meaning it can undercharge a healthy battery and lead to premature failures.

 

I believe to "wake it up" you have to touch the car. You can tell when this happens if you have LED headlights because you can hear the headlight heat sink fans turn on.

I haven't been able to find a definitive explanation of how the "smart charging" works on an X260. If you have, please share it. From what I've read it measures SOC at the moment and charges, or not, accordingly.

 

like i said, it should go to sleep but when you shut it down dead with the key fob its lights out, when you drive a short distances your alternator does not fully charge the battery, now when the the stop start is in action there's another drain on the battery cause now the alternator has to charge 2 battery's or if you have one that's another strain ,but you may have a parasitic draw i don't now in your case ,yes you can update the GWM software but a waste of time ,When you install a new battery you reset the GWM with SDD anyway, MY Battery is 10 years old removed stop start and lock my doors when not in use very simple , but you may have a different problem just my 2 cents

 

This may help, not the most detailed explanation but it's what they give us in the workshop manual.

 

Thanks. Not much help though. Don't want to hijack this thread but here's my questions about BMS in general, seems all cars have it now. What happens when you use a trickle charger? Does it cause the BMS to reset? Sometimes, rarely, the battery SOC goes to 100% (around 12.7 volts) on its' own. Does the BMS treat that like a new battery? It seems like the BMS likes to keep the battery at just above 50% SOC.I replaced my battery at 7 years just because but I could still trickle charge it to 12.7V and it always discharged down to the 50%+ range. I disconnected my Start/Stop so that's not an issue.

 

Target is around 80% SOC at 'max' to allow room for the active recovery during overrun or other conditions. BMS does look at voltage but the primary function is the amperage flow in and out of the battery. When running it is constantly monitoring energy into and out of the battery. We 'reset' it using the scan tool during a battery replacement, so it assumes that is a 'charged' battery and acts accordingly. If you are adding charge to the battery on your own, the car does not know about it via the BMS system.

 

The BMS measures Temperature and voltage so it relays that measurement to the BMS/GWM so they can control the limbus system when i lock my doors it shuts down the voltage draw then when i drive the car the alternator charges the little loss of voltage ,Now if the voltage drops below standard the signal from the BMS sends that info to the BMS/GWM and tells the limbus to shut down some non essential modules so the car can start ,its goal is to get the Jaaaag to start , so locking your doors removing the stop start will help the battery to last like mine for 10 years without a battery maintainer ,but idrive my car 1/2 hour to work and a 1/2 back so it gets a good charge ever day and i have no problems ,the XF now has 150,000miles ,and my X-Type has 270,000 miles of pure fun no breakdowns ,just simple common sense maintenance

 

I don't want to get pedantic about this but it doesn't make sense. If the BMS measures SOC then it doesn't care/know where the charge comes from unless it is below a pre determined value so it can engage the alternator or not. Correct? I've been trying to get the algorithm the BMS uses to start and stop the alternator output. None of the manufacturers list this that I know of. Now I do mostly short .... 1 to 5 miles .... trips so I measure SOC every so often and put it on a trickle charger over night if it drops below 40%. Is that a waste of time? Even after long (1000 mi.+) road trips the SOC never goes above 75% when I get back. I believe the BMS is a waste of time and cost and causes more problems than the minuscule/supposed gas savings claimed.

 

I guess it depends how you connect your charger. The BMS uses an amp clamp on one of the terminals/cables, so if you are connecting directly to the battery, it is seeing no flow across the sensor. It cannot measure the chemical state of charge of the battery, only the voltage, and keeps a running log of how much amperage has passed through the battery to infer a charge level/health of the battery. If you are connected at say the jump point, then yes the power passing through the sensor is seen by the system. When you say "the SOC is 40%", where are you getting that value? Just a flat voltage check assuming 'full' is 12.6 and flat is 12.0? This is not wrong, but not the only metric the GWM uses in it's calculations.

I agree fully that the whole system is not a great design, another thing added to 'reduce emissions' for testing, and in the real world causes more headaches than anything else.

Also you won't find much in the 'when it uses the alternator or not', the smart charging in the PDF I added talks about it, the battery is recharged using recovered energy when possible, and the alternator is turned down to reduce load under advantageous conditions to conserve fuel/reduce tailpipe emissions. Remember we are not just on/off on the charging, we can vary the voltage setpoint of the alternator and provide a progressive charge as needed, it's driven via PWM/LIN by a computer, not a simple switch control anymore.

 

Yes, I connect at the jump points.

At the jump points. I understand that SOC is not a definitive check of battery health. I trusted the BMS when the "low battery" light came on and changed out the battery even though it read 50% SOC. That's after 7 years on the original battery. with occasional trickle charge top ups.


Most cars use it now. I see it as just another check point to appease the EPA. I think it reduces battery life by maintaining it a lower than full charge level and encouraging sulfation even though AGM are less prone to it.


Added to a system was wasn't broken Thanks for the information. Mark

 

Right the 'low battery start engine' warning is a combination of the current voltage readings and the calculated "voltage available to start vehicle" which is based on those amperage history readings, age, outside temp, and other things. Not things we have a formula even available to measure. You can look at the factors in the live data but that's of little help when the car is already telling you it's not happy, whether that's a valid concern or not. The target is somewhere below 10v, when you see that error message the calculated available voltage number will be <9v usually.

Not to appease the EPA but to get the manufacturers within range, as they have to meet CAFE standards to avoid fines, and be within emissions targets to be legally able to sell cars in certain markets. Stop/start is a great thing for emissions testing as an engine that is off produces no emissions. How it plays into maintenance, lifecycle of the car/parts and the customer experience is not a concern to that engineering team, they don't have to deal with the issues. Sadly we do, and most people don't care for the system, I have it defeated in my Audi as it's quite harsh with the big V6, in some engines/cars you almost don't notice it and the new ones with the 48V MHEV system that use the generator to restart the engine are much smoother.

 

That is correct if you have an x250 with a remote key/ then you need to lock the vehicle or else the vehicle will never sleep. You may get away with it in a day or so but no longer than 2 days if unlock after that you need a battery booster or a maintainer
If it's an x260 with fob/smart key technology, the system sleeps in 15 - 20 minutes after shut off and leaving it unlock will not drain the battery.