I drove my XKR 2-3 days ago, no problem. Of course it was sitting in the garage for months with a 0.5 Amp auto trickle-charger connected.

After parking it, I did not plug in the charger. Today, the battery was ultra dead. How dead? 5.2 VDC across the terminals. I am an Electrical Engineer still, I have never seen a battery to discharge to those levels. The battery was manufactured 36/11 and the blue sticker seems to indicate that it was installed 5/12. It is a Jaguar labeled battery.

I pulled it out of the car and charging it right now outdoors, just in case it has some internal shorts and may blow up. After more than an hour of 12 Amps charge the battery is up to 12.5 VDC. Will keep charging overnight and see tomorrow if it holds the charges. Can't imagine what could cause 5.2 VDC. It would have to have 3 different cells ruined to see such low voltage. I have never seen anything, like this.

Any comment or experience?

 

Wow...Can't say I have ever seen a car battery discharge that bad either. Just for the fun of it, I walked out to the garage and stuck a meter across an old battery that I replaced in my FX about uhhh 4 years ago. The Fluke says 4.813VDC

 

By any chance did you take a load test to see if you've got a few bad cells.

 

No, I have not. I have to poke around for some 12 V items that I could use for load. Just before taking the battery out of the car I did put an Ammeter in series with the Neg post to see if something in the car was drawing a lot of current to cause such deep discharge. There was no measurable discharge, good news.

It still charges but, when I remove the charger the voltage does not seem to hold. The last time it dropped from 12.5 to 11.95 in minutes with nothing connected to it. That indicates a bad battery but, will keep charging until it reaches 13.2 V then see if it holds at all.

I suspect I have an AGM battery on the horizon. Late model Jags just draw a lot of current which seem to eat batteries. The battery is 10 months old in my XJL and I am getting a lot of Low Battery warnings again.

When I connected this battery back for a few minutes, the center display came on together with the dual trunk lights. I have the cabin lights off by default The current draw was 11+ amps. Not quite up to the XJL draw that is over 16 Amps with the 2 screens energized with the Leaper display.

Seem to me the AGM would be a better choice as it takes high charges and discharges better than regular batteries.

 

WOW. I used to have some older batteries sitting around and don't remember ever seeing them anywhere close to that low.

 

Funny you post this today. Last weekend I returned to my car after 2 week's absence. It's a 2001 XK8, and I've never put a charger or tender on it. Battery about a year old, common lead acid.

Had no response from the car, and with cables still attached I measured 2+ volts. Same with cables disconnected.

Like you, I have no idea of what drew it down. I left it disconnected and charged it by jumping it to another car for about 10 minutes, after which it had recovered to almost 11 volts. So connected it up again, and jumped from the other car, and started the XK8. Ran it for another 15 minutes, and took it for a short drive. Next day I was able to start it normally, and now 5 days later the voltage is back to 12.6 and all appears normal.

But I still don't trust the battery, or the car! I would like to know what happened. On another thread long ago I remember someone mentioned that the car's systems won't shut down completely if the little shutter on the ignition doesn't return to the closed position when the key is removed. Is there such a thing on your model car?

Steve

 

Steve

The newer gen car does not have a key, so that is not my problem. Sounds like with 2 Volts you just set a record

I simply can not imagine how batteries run down that low and, in your case, recover to near normal operation. I fully expect this battery to be gone but, after you posted I am not sure. Just like you, I would never trust it again. It was perfectly fine Tuesday when I shut it down.

 

We had 0.6V from one battery in a friends Toyota back in Switzerland, it had been parked outside all winter, temps down to -15°C and we thought no way it was coming back.

Hooked it up to my C-Tek on the "recondition" function and 2 days later it was holding 12.7V steady. Back in the car and it started up fine, his wife drove it for a couple of months afterwards and it never looked like giving up, they sold the car after that.

True story!

 

I have a 5 month old AGM duracell battery in 09 xk. Bought and installed at sam's club for $160. Just returned from over 2 wks being gone. I don't have a trickle charger. Car started up and runs just like it was driven every day. Rapid screen light up. AGM is just a better battery.

 

All very interesting answers. What I see from them is:

1) There are still unknown gremlins in our Jaguars that, out of pure boredom, decide to drain the batteries, only when they feel like. That drain can be ultra severe in a relatively short time period, just as shown in my case. For me, the first, and hopefully last time such drain occured with my 5 late Jaguars.

2) I must be living in an ideal world where batteries do not get sucked down to levels shown in this thread. While being a high voltage (60,000 V and above), specialist engineer, I have been around plenty of lead/acid batteries both at home and at work. Never seen a battery drawn down to those levels.

I could see the need to develop a simple protective electronic circuit in our cars that would simply signal if it detects an unusual draw from the battery AFTER a normal time delay following the shutting down of a vehicle. Saying this because I still believe that something must have remained activated in the cars that drew currents. Batteries don't just simply self-discharge to such levels for no other reason. I will think about such circuit.

My battery is fully charged this morning, actually spilling some electrolyte right now. I think that the fluid levels are a bit high, some needs to come out. After disconnecting, I will have to see if it holds the charges. Yesterday, after the partial charge it did not seem to hold it. If it holds, dilemma time; keep it or exchange it, not knowing the causes. I will also connect it later today (if charges hold) and check one more time for any current draw while the car is entirely shut down.

 

Albert, did you lock the car while it was in the garage?

 

Absolutely. I always do that. The car was locked all times.

Looks like it has been holding the charge since morning (for 10 hours now). The dilemma is should I keep it or exchange it for an AGM, like below:

SLI49AGM Duracell Platinum AGM Battery - 2010 to 2013 V8 5.0L 800CCA - XKR - Jaguar - Car and Truck - Batteries Plus

Also, I will order one of this BatteryBrain products from Amazon that basically cuts off the battery from all load if the voltage drops to about 11.8 - 12 VDC. Sounds like a good idea for cars that tend to sit long. You can just push either a button at the battery or a remotely installed button to reconnect to start the car. It could lower the anxiety level when going on long trips, far away from home, and wonder if your car would start the next morning. With this device, even if there is a spurious current draw (like I had) it would cut the Positive power off and leave enough battery voltage levels to start the car.


There is also a version listed on Amazon without the remote switch for less cost.

 

I think that batteries in modern cars live in a state of perpetual partial charge.

This is due in part to the standby currents that are drawn while parked, but is also affected by high current draw while active. Combining those with short drives and long layups results in apparently dead batteries.

In the newest vehicles, there are also aggressive fuel saving algorithms that come into play in the ecu charge regulation.

This is a lot like deficit financing.

If you have a hundred dollars, draw down five dollars and put back four dollars every day ... eventually you're flat broke.

The remedy seems to be a full 48 hour trickle charge every few months. A real pain for apartment dwellers. The battery is 60'ish pounds.

One way to monitor the state of charge is to install a digital voltmeter with four digits of precision. About $4 with free shipping off ebay. Once installed, note the voltage on a freshly charged battery upon entry to the vehicle with the key in position one. This is your benchmark reading.

If upon entry the voltage is above say 12.4 volts it is safe to presume that the battery will not strand you away from home. If below, better make sure your auto club membership is paid up.

If parking at the airport for an extended period, don't leave without fully charging the battery prior to the drive to the airport.

 

I placed the battery back into the car and took some current draw measurement, as follows:

Initial startup current (including leaper screen energized, two trunk light come on: 11 amps.

Removed the two light bulbs from the trunk, reading dropped to 10 amps and kept dropping for a number of minutes to 7 amps then in a few minutes to 2.4 amps than for a longer time to 1.4 amps. It remained stable at 1.4 amps for quite a while and started to worry me, as that value would be about what was required to draw the battery down in my case in just 3 days.

But, after a while the current dropped to 0.12 amp, which is still more than what I expect. It remained stable there for a long time. Finally, I decided to shut the hatch door, at which time the current jumped to over 2 amps again and eventually kept dropping to 0.04 amp or 40 milliamps. That is what I consider normal current draw on a car with all electricals turned off. All the while the voltage levels remained high, around 13 VDC, indicating a good battery.

So, everything seems to be working normally but, still no explanation for the battery going to 5.2 VDC. I have ordered the BatteryBrain the one listed for $80 but, the linked Amazon page showed me that there were 2 available for $55 plus $4.95 for shipping. So, I took it for $60 total, a really good buy. Someone should grab the second one quickly from the link shown in my previous post.

 

There have been a number of service actions for battery related issues published over the years on the XK's so it might be worth checking that you have all the latest firmware loaded.

 

Hi,
I have an '08 XKR in my future and have been keeping tabs on all of these discussions regarding the battery life, or lack thereof, in these XKRs. I can only guess there is not too much difference between the '08 and '09 regarding battery types. What is the model number of your AGM? One may be in my future. Thanks!

 

The problem I see with the BatteryBrain is that it cuts off power to the car. That means you will lose things like the ECM adaptions, park brake calibration, window settings every time the BatteryBrain kicks in. It is just like disconnecting the battery, after which you need to carry out the reset procedure:

https://www.jaguarforums.com/forum/x...nstall-113965/

It doesn't seem a good idea to have to go through all that whenever you've left the car for a few days.

 

You are correct but, which one is better; finding a dead car that will not start (at which point everything needs to be re-programmed) or, at least, saving the battery levels to allow a start when needed. If the battery voltage drops to below 12 volts, I think, I rather have the cutoff activate because in all probability there is a spurious current drain that will take it to all the way down, like mine did. It is very damaging to allow those deep discharges on flooded batteries.

If the system is anywhere normal, it should not drop the voltage to or below 12 volts even in a month in the garage. Normal discharge, as measured on my XKR, is 0.04 amps x 30 days = about 30 Ampere/hours from a 90 Ampere/hour battery. On my five late Jags this is the first time the battery died. A cutoff would have saved it, most likely.

 

Oh, I agree that it's better than a dead battery - but it would be better to find and cure whatever is draining the battery. If the battery is running down every few days, you'll have to reset everything each time you use the car, which would be a pain in the buttocks. As you commented on another thread, this is a bandaid, not a solution. I'm not saying a bandaid isn't a good thing, but it has consequences.

 

In regards to the query of locking your car while it was garaged; Did you DOUBLE LOCK IT! (Yes, it’s a ‘thing!’)

When your car is single locked it assumes you’ll be returning soon and if it picks up your RFID key fob it will, more or less get your vehicle ready for you to come start it.

Double locking it puts all that to sleep. It’s surprising how strong the key fob signal can reach. I work in a 6000 square-foot building with a parking lot in front where you pull in straight and sometimes I park across the street along the curb so & my office is in the back of the building and I’m usually seared near the very back wall.

At that distance, my car trunk was open and I assume someone messed with it but when I saw the mirrors, I realized the car was still locked. (So I butt-opened the trunk.) Yes, I had only single locked it.

Now I double lock my XJL. Except the other night, I assumed I was going to be traveling soon and plans changed and I did not. Then the next morning the car wouldn’t start probably because the key fob was too close to the vicinity of the car (Normally I keep my fob in an Altoids Tin to block the RFID signal. I know this works because I put the fob in the tin in my pocket, and stood right next to the door, and it would not recognize it.