Just got back from a trip. Had my Bentayga parked in my garage, locked, and after 5 weeks come back and the battery is so dead that it won't even unlock. I had to use the emergency key to manually unlock the door. My question is why does this happen? The battery is almost brand new. It was replaced with a new battery about six months ago. It was fully charged before I left. How does such a huge battery, in new condition, completely 100% discharge to the point it can't even open the door? I even locked the car before I left as I assume locking it allows more of the electronics to shut down as opposed to if you left it unlocked in your garage. I know some people say you have to leave a battery tender connected to a Bentley, but why? There are plenty of just as technologically advanced cars out there that don't completely drain their battery in little over a month.

 

Modern batteries need frequent driving or they will run down. With everything turned off, connect an amp meter between the positive terminal of the battery and the positive lead to determine if there is any current draw (you may have a short drawing current). Then turn on alarm system and see how much current drain there is, if your alarm draws 60 milliamperes (3.6 amps per hour) and you are gone a week (168 hours) you are down more than 100% on a 600 amp cold cranking battery. Any competent mechanic can check system drain under various conditions. Also, it’s a good idea to have a battery maintainer on during periods of low use. They are inexpensive and can keep you running.

 

If you're going to leave the car for more than a few days you need to use a charger. That's just the way a Bentley works and why they typically provide one with every new car they sell. The CTEK charger Bentley provides does an excellent job but you don't have to buy it from them. The exterior magnetic connector on the Bentayga's liftgate (above and to the right of the license plate) makes hooking it up a 2 second process.
As far as "technologically advanced" cars go, Bentley is not at the forefront and the battery drain is one their quirks.

While not cheap, this one is about $100 less than the dealer. Check ebay too.

https://alpineperformance.com/products/bentley-continental-flying-spur-gt-gtc-battery-charger-maintainer-2850?variant=44487000948955&currency=USD&utm_mediu m=product_sync&utm_source=google&utm_content=sag_o rganic&utm_campaign=sag_organic&gad_source=1&gclid =Cj0KCQjwpNuyBhCuARIsANJqL9NoOmTF3WR70aBJsVjoQV6Uw xGrY5ioflCDM6MjwCgOkTPu11nT-0oaAvX8EALw_wcB

 

Thanks guy. But *why* does a Bentley work this way? It's a $250,000 car, and it drains its own battery when parked and locked whereas a $25,000 car does not? I have the CTEK charger and that's what I put on it to restore the charge after I got home and found it completely dead.

 

I know what you mean. In my own case I chalk it up to short trips that don't provide enough of a charge to recover. The more I use it the less it needs charging. I have the charger mounted on the wall and I just connect it without thinking about it when I get home.

 

I think that’s what I’m going to have to start to do, too!

 

It is not just the Bentley. All modern cars have a lot of integrated electronics that don't ever truly shut down. Couple that with the fact that new batteries are crap, and you will need to have a battery tender for any of your vehicles that you don't drive for anything over a week at a time. We have 6 vehicle and whatever ones are not being driven frequently are on the battery tenders.

As Bruce said, Bentley makes it the easiest, by placing an external magnetic connector near the license plate. With our other vehicles, I use the Battery Tender brand and install the quick connect provided with the product permanently to the battery terminals. With those, I still have to open the hood or trunk (depending on the vehicle), but hookup is literally seconds after that.

https://www.batterytender.com/plus

You do need to get used to disconnecting them before driving or bad things can happen!!!!

 

To that end, this is what I do...

 

Smart. It's magnetic though... wouldn't it just pop off if you drive away? Sort of like the MagSafe power plug on Apple MacBooks if you trip over it? I think I'm going to screw my CTEK charger into the garage wall. I would imagine the holding force of those screws will be much greater than the magnetic clasp and if I ever drove away with it attached, the magnetic end would just pop off. I guess if not, I'd get a big surprise and it would rip the CTEK out of the wall.

 

It is magnetic and would pop off. I got in this habit when I had a Gen 1 GT that involved opening the trunk each time and my wife does the same with her Bentayga.

 

I do not trust that it would pop off! So I use one of the "Remove Before Flight" tags on the driver's door as shown in BruceR's post. Safer option! Just needs the cable to get caught on something as it pops off to be the surprise you do not want! Always put the GT on charge if it is not used for a few days.

 

Here's a link to the 'Remove Before Flight' tags if anybody's looking:
https://www.amazon.com/gp/product/B00VIOLFXI/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I used the hook end of a wire coat hanger covered with a piece of aquarium tubing for the door tag and a zip tie for the one on the charger cable.

 

when you locked the car, you armed the alarm and you triggered the periodic checks for keyless go.

even if you have everything ok with your electrics, the fact of armed alarm and keyless go your car successively eats the energy from your battery.

make a test - charge your battery to full, dont lock the car, come back after 1month, see if the problem occur again. you should not have the problem.

 

Who replaced the battery? And what battery was used. Did they program the new battery? When the Bentayga launched they integrated smart charging technology. If the vehicle isn’t told a new battery is installed (programmed) the alternator may not be charging correctly. Also you may have a parasitic draw on the vehicle as I’ve seen many Bentayga’s sit for longer then 5 weeks without a battery maintainer and start up no problem.

 

Interesting! So you're saying the battery will last longer if the car is left unlocked?