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Discussion Starter · #1 ·
About a month ago I had a battery problem on my 2011 XF 3.0d. The battery was around two years old but it was obviously failing to keep a charge of more than 11.5v. It was covered by the seller so I changed it.
Today I thought that after a month the BMS must have done its job so I plugged a volt meter into the 12v socket on the centre console and it read a constant 14.8v even after a twenty mile run it didn't move from 14.8v.
My question is, is the alternator over-charging or do I have a faulty BMS module?
Maybe someone here could tell me how I do a testing process to find out what is going on with what, or maybe everything is working as it should?
 

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Hi, I would start by resetting the BMS, they don't always reset themselves. Phil
 

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Discussion Starter · #3 ·
Hi Philayl. I've read all sorts of things about the BMS. Some say it will do it itself and others say its best to actually do it. I do have an Icarsoft and its supposed to be suitable to re-set the BMS but to be honnest I cant for the life of me work out how to do it, and I did try! Maybe I should give it another try.
 

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That's normal for XF generators, 14.8 is the upper limit. Don't worry, but telling the car it's got a new battery won't do any harm
 
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Discussion Starter · #5 ·
Ok, I'll have another go as I'm thinking 14.8v all the time would maybe shorten the life of the battery.
I had an over-charging problem on my 97 XK a while ago which cooked a few modules, including the main IPK. Took a long time to fix that one.
 

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Mine is usually/very often at 14.8V so I wouldn't worry about it, I do big mileage and even after 150-200 miles in a day It will still likely be at that voltage, or maybe dropped to 14.5/6V

And don't think that your meter is necessarily that accurate.. it may well not be...
 
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Hi Philayl. I've read all sorts of things about the BMS. Some say it will do it itself and others say its best to actually do it. I do have an Icarsoft and its supposed to be suitable to re-set the BMS but to be honnest I cant for the life of me work out how to do it, and I did try! Maybe I should give it another try.
If you have the iCarsoft LR V2.0 it is very easy to do, it is intuiative. Phil
 

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P.S. 14.8V is acceptable but the upper limit according to the Jaguar workshop manual for an AGM battery..
 
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Discussion Starter · #11 ·
I have both the LR II and the LR V2.0.
I was using the LR II when I was having problems re-setting the BMS so I'll give it a try using the V2.0 and see how it goes with that.
Its ok just ignoring a constant 14.8 but it isn't right and I don't want to keep buying batteries every couple of years and doing a re-set isn't going to cost anything.
 

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Discussion Starter · #12 ·
Plugged the LR V2.0 in. Its a lot easier with this version of the Icarsoft. I've re-set the BMS so let's see how that goes over the next week or so.
The LR II has more DPF info though so I'll hang onto that as well. Not that I've had any problems with that in the four years in my ownership. Thanks for all the help.
 
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Plugged the LR V2.0 in. Its a lot easier with this version of the Icarsoft. I've re-set the BMS so let's see how that goes over the next week or so.
The LR II has more DPF info though so I'll hang onto that as well. Not that I've had any problems with that in the four years in my ownership. Thanks for all the help.
I found with the similar CR2.0 I could get more dpf info for my 2012 XF by going into the 2013+ section. Worth having a look.
 

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Monday (Nov 21st) it was 2°c and my car wouldn't start. Engine wouldn't turn over and I had loads of warnings on the dash.
Checked the voltage and it was about 12v. (The car does approx 250 A road/motorway miles a week and on Saturday was driven around Birmingham for an hour and a half).

Charged the battery for 30 minutes and the car started.

Took the 18 month old battery back to Halfords and they said it was fine and needed a charge!

Charged the battery for a few hours and put it in the car, charging was around 14.6v at the battery, but 14.4v at the cigarette lighter!
Checked the voltage at 9pm and it was 12.6v

At 6am this morning it was 12.53v. Cranking was sluggish.
Drove to work and it charged at 14.5v until the temp went above 4°c and the heated screen turned off, then the charge rate was about 14.95v at the cigarette lighter and on Icarsoft. Checked this when I got to work with the engine at idle and it was14.93 volts at the battery and the cigarette lighter/icarsoft.

Checked the battery at 10:30 this morning and it's sat at 12.56v.

Obviously the cold weather affects the voltage of the battery, but I was shocked on Monday.
I think my battery cranking capacity is bad, even though it passed on the Halfords tester. I'm tempted to invest in a booster pack as I think it will fail again.
 

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Could it be worth getting somewhere else to check the battery as well just for a second opinion?
I may wait until it does it again and call the RAC out.

Have you checked for battery drain when parked and switched off?
Yes, it was about 50mA which is a bit high, but I'm not sure whether the car was fully asleep or not.

Fully charged the battery and reset the BCM, battery was 12.6v this morning, charging was a similar voltage at approx 14.85v. Will check it through the day.
 
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