I have a 2015 Bentley Continental GT V8 with 40,000 miles. How long do the original batteries last? When should I consider replacing them. I go on long trips and don't want to have trouble on the road. Thanks for your help

 

Odd spurious dash lights start to come on when the voltage of the big LHS battery drops .Long runs can mask battery health.
Deep discharges shortens battery life .Battery conditioners extend there life .
Ferrari tend to change them every 3 years as service item and equally recommended a conditioner when park @ home .Saves owners ringing in with spurious dash lights .

 

Hello Gerald,
I would think by your mileage you must use her as your almost DD, if so you may be ok for a while, some say every five years, some say longer..
I can tell you that my 2005 Audi A8L W12 it had the original battery up until 08/15, I drove her almost every day, I replaced the original with the AZ unit as pictured Aug/Sep 2015, but as I did not drive it much, and did not put a tender on it, it failed this past 10/18, when I again replaced it with a unit from Advanced.

...

 

Off topic but how has reliability been and have the batteries normally been on a tender?

 

Interestingly I have found my “ tell tale “
The first thing that goes / alarms off if the house battery voltage drops to around 12.45 of lower Is the big pink “ seat back unlatched “ warning symbol on the centre display .
So after a start up ( winter obviously......parked outside in the cold ) without the battery tender ....all seems well we drive off .
Then the auto lights come on .....some extra batt drain , but if we turn the nav on the radio ....and heated seats ....ie max out on the LHS bat drain I get that “seat back “ warning illumination.
first it flashes sort of flickers ( no beeps ) ....we turn something off like one seat heater does not matter which side then it disappears.
If the LHS battery cannot quickly recharge ( alternator) above 12.4 v we get the chimes as well . After a good run the voltage recovers and say on a return trip we can run every accessory with no indication of low volts .

Parked at home on the tender it’s 13.2 v immediately after start and we get no spurious warnings what so ever .....can run / drain as many accessories as we wish .

I figured all this out using a voltmeter on the tender pig tail at the various times and circumstances .

First I thought naturally I had a problem seat back micro switch , but it only comes on in the winter .Never returns after a good run out say 1 hr on a motorway on the return journey home .Is not dependent on any seat movement/ adjustment .
So I started ( from a ECU supply perspective) measuring the voltage from the batt tender pigtail before setting off and after a run parking and after a cold night parked outside say a hotel carpark with no tender .

So my car seat(s) ECU ,s seem voltage sensitive and the “ seat back unlocked “ alarm chimes in at exactly 12,45 volts on the LHS batt .


Before anybody asks ......yup I did back in April ( spring rising temps ) change out the passenger seat micro switch on a warm sunny day .Problem went away all summer ,then returned when temps started to drop .........we actually could sync it turning stuff on / off after a cold morning start .So I started to measure the tender pig tail volts .Seat ECU must be voltage sensitive ........ anyhow that’s my tell tail .

We are currently monitoring the situation, but if the batt struggles to keep above 12.45 V or quickly drops down to around that t level from its tendered 13.2 V with consumers on while running the engine .....then it’s struggling to hold it charge = time to replace I think ?

 

With other marque say Range Rover after a cold night start in the open say minus 10 ( easily achieved in Switzerland btw ) you would get a message on the central display saying which consumers are temporarily out of service .
eg “ Navigation temporarily unavailable “ etc etc .So the system would lock them out until batt voltage came up ......importantly notify you as well .

With the Bentley it seems no such feature , what happens is the ECUs don’t function properly , have “ hissy fits “ and throw spurious alarms/ codes / CEL s , dash can look like a Christmas tree .

Tantrums cease once the house batt voltage is above a certain level .Porsche Cayenne ( another VAG car ) always had cold morning tantrums .

 

For these cars to be over $150,000 new I feel this is unacceptable. Like they are made only for the first owner With no issues, telling everyone else, “we have our money, screw everyone after that.”

 

For what it's worth, I bought my 2013 GTC in November, 2020, with 14,000 miles. I just replaced the original batteries (marked 2012), even though they passed
the tests at the dealership's service center. I didn't want to deal with some of the odd warnings well described on this blog related to failing batteries.