Good afternoon, I have a 2014 V8S.

What should the voltage be at the battery at idle? I'm getting 14-14.5 at high idle then 12ish as the idle drops to normal.

The car was on a battery maintainer until 2 weeks ago. It has been sitting unused since I moved the maintainer to a different car 2 weeks ago. Saturday I had the car inspected, then drove it 40 miles to cars and coffee. The car sat at the event about 2 hours and then while leaving, the Service Charging System alert appeared along with the red battery icon. The car drove fine the 40 miles back to the house. Once home I shut the car off and immediately restarted it - the Service Charging System error and red battery were gone. I shut the car off and left it alone.

Today I dug out my multi-meter and measured 12.5 volts at the battery, and then started the car where voltage raised to between 14-14.5 while the engine was on high RPM idle, and dropped to 12-12.1 when the idle reduced to normal RPM.

No errors or alerts today on the dash. While I'm aware of issues after an OBDII port is connected, often as a result of a vehicle inspection, I've not experienced that myself even though it's been inspected several times prior to this Saturday.

I'm happy to disconnect the battery for a few minutes and reconnect, but before I do that, does the above condition sound like that type of problem?

Jeff

 

The check for the battery drain condition is the light in the hazard switch doesn't go out after about 15 minutes from locking the car. Your voltages seem about right to me - they're what I get in mine.

 

The obvious question: are you still running the original battery? Mine was fine after 7 years, but I preemptively replaced it anyway, as they tend to die quickly and inconveniently.

 

Good questions. The red triangle does not stay on, I confirmed that yesterday after the indirection, before the issue occurred. It behaves as it did prior to the inspection.

The battery was replaced in October 2018.

 

If your alternator has fully charged the battery on the previous trip, then the only thing the alternator has to 'recharge' just after starting is the current needed to run the starter. So, you experience would seem normal to me.

Can you hook your multimeter to the front jumper connections and read the power continuously? If so, try turning on the headlamps...that should cause the voltage to go up to 14.0 - 14.5.

Many new cars have gas-saving charging systems that let the car run 'off the battery' unless needed.

 

I’ll give that a try in the morning. Thank you.

 

With the multi-meter connected to the front jumper connections, I started the car (headlights on automatically, as they were yesterday) and saw the same behavior as yesterday when I was connected at the battery. The voltage stabilizes around 14.39 at high idle then drops to 12 volts as the idle drops to normal (within 1 minute of starting the car). Turning the headlights off makes no real change. Turning on the A/C and the seat heaters makes no effective difference either (12.04 volts with headlights on, A/C on, both seat heaters going).

 

I think you're worrying over nothing. When things stop working, that's the time to worry!

 

I'm happy to believe that is the case. When the Service Charging System alert popped up, I rushed home before I risked running out of battery power. My experience with older (classic) cars told me to check the battery voltage at the battery with the engine running, and if I've got > 12.5 volts the alternator/generator is working, or if very high the regulator failed. So I was surprised when the Jaguar measured 12 at idle. But it does make sense a more modern car would do a better job of regulating the charge going to the battery.

I'll drive it locally a bit before getting too far from home, see if this blip returns or if was just a blip.

Thank you all for your replies.

 

Update - The problem returned, and I have new and different voltage measures now. Today I drove the car after letting is sit since the problem first happened in December. The car has been on a battery maintainer and I believe the battery fully charged when I drove it today.

I put my power-port volt meter in place and drove the car normally, with seat and steering wheel heater, and radio the only accessories. The volt meter showed 14.1 to 14.3 volts as I drove. After driving about 8 miles the same charging system fault appeared that I experienced in early December. With the car running I measured 14.3-14.5 volts at the battery with a multi-meter. I shut the car off and restarted it, the error message cleared but the voltage remained over 14. I drove the car another 15 miles or so before the error returned. Again I measured the voltage with a multi-meter at the battery with the car running and it was in the 14.3-14.5 range.

While in December I was measuring a steady 12ish volts at the battery after the first minute from cold idle, today I'm consistently getting over 14.3-14.5 at the battery with the car after a drive or after the first minute from cold start.

So now I'm wondering, is this error actually due to a bad regulator leading to an overcharge condition? The battery felt cool to the touch after driving the 23 miles or so with 14+ volts showing at the power port. So I don't think I'm cooking the battery but I'm definitely not getting the same measures as before when I had 12-ish volts. My feeling is in December a problem temporarily happened triggering the error, and then today that problem returned persistently.

 

Greetings. have been researching the charging system operations, seems overly complex with an on-battery monitor sensing need and controlling voltage based on battery condition. Anyway, any thoughts on the error message? All diagnostic data I can read about talks to under-charge conditions, haven't found overcharge as a possibility yet. I have a Foxwell, I'll plug that in and see what I can learn next time I'm with the car.

 

Update for info only because I learned something today that I wanted to share. Nothing is solved, the car sat in storage most of the year and still needs to be repaired but if you wish to read the rest of the post, there's new behaviors learned and something curious at the end.

After leaving the car in storage for much of the year, on a battery maintainer, I started driving it a few weeks ago and it was fine, with no errors for a few hundred miles. I put a volt meter into the dash power port where things generally stayed in the 12.5-14.3 range, and the measures were pretty steady until about 2 weeks ago.

While driving it the voltages started stable as before during the first 30 miles or so of my trip, but then they began varying wildly. I recorded a 44 second video where the voltage went (in order): 11.8, 12.5, 14.0, 14.2, 14.3, 14.1, 12.6, 12.0, 12.7, 14.2, 14.3, 14.0, 12.5, 12.2, 12.0, 11.8, 11.9, 11.8, 11.9. I drove another 25 miles to my destination and parked for the day without the voltage stabilizing. Later in the afternoon when heading home for the day, the voltage continued to vary as noted but then it stabilized at 13.3 at the exact moment the charging system error alert appeared on the dash board. I drove the car home about 50-55 miles with the voltage generally stable, staying around 13.2 to 13.3.

A new learning
This morning I decided to drive it. Started it up and the charging system error message is gone (that's the same behavior as before), but now the dash power port voltage stayed around 11.8-11.9, with a very very brief spike to 12.5-13 for seconds only. Turned around and came home and did some more testing and learned something interesting.

With the car running, a volt meter in the dash power port and another connected to the battery:
1) With the driver's door shut, the power port at the dash shows < 12 volts. The multi-meter connected to the battery shows around 11.95-12.1 volts.
2) However, if I simply open the driver's door - I get 13.5 - 14.3 volts at the power port and about the same at the battery.

I suspect my Dec 2021 measurements of close to 12 volts were with the door closed, and the January 2022 measurements of 14+ volts were with the door open.

Note that leaving the driver's door closed but opening the passenger door does not have any effect, it's only the driver's door opening and closing that causes changes.

 

Good troubleshooting but I think you need a better tool?
Can you get the car hooked up to a SDD setup?
With your symptoms I am betting there are errors we need to see.
No guess yet but possible alternator or something is wrong with the battery monitor system.

Check this thread out. It seems somewhat close to your problems?
He has a code of B11DB and had a bad battery monitor module. He quoted part C2Z20517. Around $100.
Jaguar Battery Monitor Problems

Your battery was replaced in 2018 and it's now 2022. We have seen batteries go out in this time frame too. So that is another possibility.
But I really think if we can get the codes it will lead us to the solution.

So codes next!

Attached is a large Jaguar document on batteries and charging systems. Don't know how much it will help but maybe take a look?
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Another thing to check is the condition of the various earth straps.
Just yesterday I watched two YouTube vids about this, one where the root cause of multiple electrical faults was a badly corroded earth strap: and the latest one from Watch JR Go about putting a replacement engine in an F-Type V6S: In the one from Watch JR Go he doesn't mention the condition of the earth strap(s) at all but it struck me that the main one hanging off the bottom of the engine was very greenish, the colour of copper corrosion.

 

The easy way to check ground connections is to connect a volt meter right across the connection. If it's a good connection, it should stay very near zero, but if you see more than maybe 0.1V, it needs cleaning and retightening.

 

Thank you for the detailed replies. This morning I connected my Foxwell scanner, which I'm still learning how to use.

The car has about 23,800 miles on it now, the error happened in December at what I believe to be 23,317 miles.

With the engine off, accessory mode on:
ODBII scan shows 1 DTC:for the Engine: U0447, Invalid data from serial gateway module A (both current and pending). A module-specific scan returns a PCM U0447-00 error, invalid data received from gateway A, and freeze frame data for that error shows the error was captured at 17,869 miles, which according to my gas log book, is May of 2019.

Module-specific scans show a range of intermittent and historic errors which, based on mileage, largely happened years ago. I've got random things such as HVAC left, right, center, defroster motor errors at different mileages, invalid steering angle errors, intermittent ABS errors, etc. The freeze frame data for many errors show mileages thousands of miles in the past.

However the Gateway module, which appears to be tied into the battery system, shows 2 errors:

• B1 3C5-92, Secondary Battery, at 17,869 miles. This doesn't surprise me as the start/stop battery is dead and still in place
• B1 402-96, Dual Battery Fuse Box, Contactor 1, 23,317 miles.

The second error appears to be important, because although this error originally occurred in Dec 2021, I can pretty accurately estimate the charging error message happened at around that exact mileage. I had the car inspected the morning of and prior to the charging error, and I documented the mileage at the inspection. Then I dove to Cars and Coffee and adding the distance to the inspection mileage, the mileage should have been 23,313 when I parked at Cars and Coffee. The error happened a few miles after leaving cars and coffee, so 23,317 miles makes sense.

Curiously I have a series of errors whose freeze frame data show all occurred at 22,023 miles, so sometime in 2021:

• Chassis Control Module - U0415-68, Invalid Data from ABS module (historic)
• Headlamp Control Module - U0428-00, Invalid Data from Steering Angle sensor module (historic)
• HVAC - B1 085-00, Defroster motor (intermittent)

So with Foxwell in hand, anyone have suggestions on what to check or test next?

Jeff

 

Is the secondary battery still connected? If so unhook it completely. The start/stop system is very failure prone and the good thing is when it fails it does not usually affect anything else. It will leave an error that can be seen with SDD.

Can you clear that code? Does it come right back?
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it is connected, I can disconnect it when I get back to the car in a few days.

I can clear any code but have not done so. Is the Gateway module code the one you suggest I clear?

 

Yes. As you have seen the car literally records every error and at what mileage it occurred. The vast majority of these are just temporary issues and are not really problems we need to fix. So we want to be sure that what we are chasing is a current and a repeatable code. As you know U codes are network codes and it's very common to have these happen as network data collisions and the like will set the code. That can easily happen due to temporary battery fluctuations.

Now the downside is whenever the codes are cleared the readiness monitors are also reset. Again this is not a problem unless your doing a smog check in the near future. They will reset automatically as you drive but that can be quite a while depending on your driving conditions.
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Got it, thank you for the reply. I do have a smog test coming up Saturday so I'll wait. I've been hesitant to clear any codes or freeze frame data in case the indy to which I will likely have to take it if I can't solve it, needed those details.