www.jec.org.uk

Many owners of modern Jaguars experience electrical problems especially in cold weather. Those problems can also occur in the summer but the immediate effect is not so prominent.

If you look at postings on this board and XK8 and X308 sites, you will see a common thread has formed. That of frequent starting and ancilliary services malfunctions. Time after time, cars around five years old suddenly refuse to co operate with their owners.

Why? Tired batteries. Often as simple as that. My personal view is that any battery of that vintage, is approaching old age and it`s failure will occur at some time in the near or not so distant future. I regard a battery as a consumable item in the same way as brake pads, oil, filters or petrol.

The first sign of failure is the usually start up scenario. It won`t go!
This may be accompanied by bullish door locking, ballistic windscreen wipers, an irritable alarm/immobiliser system, flashing headlights and or indicators, non functioning windows and insufficient voltage to fire the electronic fuel injection and management systems. The DSC dysfunction warning lamp is also likely to illuminate when battery voltage is low.

In my opinion and experience, any battery off load after a twenty minute rest which shows 11.5 or less volts should be binned as it is unlikely to recharge successfully and be reliable in service. I like to see at least 12.8 volts at battery terminals giving some surity that the battery is healthy. Around 12.4 volts off load, the battery is partly discharged and some investigation is needed. Expect to see 14.4volts with the engine running and the altenator functioning.

Jaguar electronic control modules are voltage greedy and like a minimum of 12volts to fire off on start up. Any less and the car is unlikely to start.

Cold weather reduces battery voltage due to slower chemical reaction and that is where the problems often start.

Take a look on the X308BB under the electrical section. Open the topic "quick battery/starter question". My appraisal is towards the bottom of the postings and I hope that will give you a good insight into the best ways of battery management, Jaguar gremlins and how to get over them.

Once one accepts that elderly batteries can be a nightmare, then sorting out some of these very basic problems becomes more understandable and much less of a mystery or worry.



Mike Kennedy. S-type Coordinator.

Hi Mike
Just red the article in in next months mag about battery condition ect. Many years ago I had a ford cortina I bought the car when it was about 3 years old with its origional battery.
After another 3 to 4 years I was speaking to someone who told me that if you totally drain a battery ie headlights on full beam heated rear window ect and then charge it back up again slowly ie overnight " which I did " It would give the battery a new lease of life.I sold the car when it was 11 years old still with the same battery. I`m just wondering if you could do this procedure with our cars or would it damage all the electrical gizmos.
I know most batterys ie mobile phones like to be run right down and charged back up again.What do you think?

Regards Jeff.

Lead acid batteries do not like being discharged to such a low level. They are a totally different animal to a Ni-cad type battery in a mobile phone or electric hand held drill/driver. Forget any ideas of Ni-cads and lead acid units having any similar recharge or storage similarities.

Discharging a lead acid battery is likely to kill it stone dead. You can try it, but Ill bet you a new battery that you regret it!

Nominal voltage of a cell when new and uncharged, is as I recall 1.8volt multiplied by 6 for a twelve volt lead acid battery. That equates to 10.8 volts or thereabouts.

I will condemn ANY lead acid 12volt battery that I come across that reads less than 11.5 volts. Although recharging may perhaps initially be successful, the battery is likely to be extremely unreliable in service. A couple of cold starts and the battery will be finished. That`s why people end up replacing batteries as soon as the first snow falls.

In my experience, people struggle to keep an old battery going when it has done its lifetime cycle. To cut out condition guess work with volt meters etc, bite the bullet and have the battery "drop tested". It takes less than a minute and leaves an experienced drop test operator in no possible doubt about a batteries true condition. The result cannot be sensibly argued with.

I have a Draper test unit which cost around £70. Iit places a heavy load on a battery under test. An electrical element rather like that found in a kettle acts as a load for around 15 seconds. The unit gets mightily hot when in use. The unit shows the apparent voltage under test conditions and experience of the operator interprets the speed of voltage increase (if any) when the load is taken off. Non existent increase or immediate increase indicates a time expired battery. All the charging in the world of a bad battery will NEVER increase or improve its potential.

The advice given in the article that appears in the X350 magazine column should give answers to most questions although there may be some basics that for copy space reasons I have not been able to include. I advised the need for possible replacement of a battery after four years service. After that, most batteries given typical neglect will begin the slid towards scrap. How long that takes depends on maintenance and use patterns. There is no hard and fast rule on this and each battery must be regarded as an individual unit and not as an identical unit when compared to other batteries if placed "side by side" with other examples.

The advice I gave in the X350 column needs to be fully understood as first principles of common lead acid battery characteristics. Unless those principles are absorbed, accepted and understood by the reader and thus taken as a base knowledge starting point, then the core operation of a lead acid battery will always be a mystery. Laws of chemistry and physics cannot be changed in an attempt to get an ailing battery going again. As I stated, a lead acid battery must be regarded as a consumable item. Use to the limit of life and then dis-guard.

A 90amp hour battery generally retails at £100. Bought from a whole sale or trade outlet, the price will generally be around £75. At that price, why muck about trying to resurrect the dead when reliable operation is what is needed to keep the car starting and systems reliable.

Low battery conditions will not harm on board car services but one thing is for sure. Services will become erratic and glitches and gremlins will begin. On most modern Jaguars, low battery terminal PD will cause locking mechanisms to cycle madly, the horn to start blasting, wipers to go ballistic, flashers to flash and the car to become a huge embarrassment in public! In addition, starting may prove impossible even if you can get the car to crank. The reason for this is that the electronic switch packs within the many ecu modules will be unable to operate at under 12volts. Net result, the car won`t go!!


Mike

Mike
The battery I was talking about was in perfectly good order. I wasn`t trying to revive a duffer.
I just simply tried the said procedure and it seemed to work. Having said all this I allways keep my car in a garage so maybe this helped!

PS. All the cars I have owned have been kept in a garage over night and Iv`e had long battery life out of them all.

Cheers Jeff.

Temperate conditions do help a battery when it comes to cranking amps available in cold weather. No doubt about that.

What does shorten the life of a battery not in use, is where it is kept and how it is placed when in storage. A battery kept on a cold concrete floor will die very quickly. I`ve a couple in store with my Father. They live on a timber bench and have a piece of Cellatex foam under each. They are permanently connected to a small switch mode charger similar to the one our Barry details in his X350 Forum article.

I have batteries permanently connected here on the boat which acts as my normal base. Some 600amps of stored energy are available to me at any moment for domestic services and large diesel engine cranking. The charger is a 30amp Sterling International switch mode unit which again looks after the battery banks.

My last set of batteries lasted nine years which I regard as the exception rather than the rule. Battery electrolyte levels only need checking every six months. Topping up is very infrequent due to the electronic circuitry which never under or over charges the cells. My quick check reference comes from volt meters for each bank which I can see at a glance each time I pass by the helm position. Permanent charging keeps the chill away and like you, Jeff, think that is a contributory factor in long battery life.

J44 however lives in the open in the boat yard. However regular use of the car to keep battery condition on the right side of wrong ensures that cell condition doesn`t deteriorate beyond reasonable limits.

Mike

Further to writing the above post last year, an incident occurred just before Christmas 2011.

I managed to lock myself out of the car and had to smash the drivers door glass to gain entry. Details in the January 2012 magazine.

I had to leave the drivers door stripped down for a few days and left the door lock module disconnected. Unbeknown to me, this left the interior lights on which drained the battery. This type of abuse does a battery no good at all, and in this case I knew this battery would have a shorter than usual life span. How true those words turned out to be. Having not used the car very much over the last few weeks, regular recharging was minimal and in the end the battery expired. Only two and a half years use on this unit. A short life indeed but that is how it sometimes pans out. No one to blame except myself.

When I had repaired the car, the battery refused to start the car. Terminal voltage was down to 7.5volts and I knew I might have a future problem even if the battery were to accept and hold a recharge. To my amazement, the battery responded and all has been ok apart from a few misfires and a car that felt a little tetchy to drive. I put that down to lack of use although I had considered that the car might be unhappy on the new set of AC Delco spark plugs I had recently installed.

A couple of weeks ago with temperatures down to -4 degrees C, I turned the key. Whilst the starter solenoid chattered, that was all. A jump start got the car going again. A few days later, I tried to unlock the car on the key fob. Nothing at all. There was so little power available that even the key lock failed to operate. Totally dead battery.

Fortunately, the boot key lock does not need power and the well oiled lock responded to the key and access to the battery gained. Note the key hole for the boot lock is below the letter U in Jaguar on the boot lid plinth. Not a lot of people know that. Keep that lock oiled. Thin machine oil works well. WD40 tends to loose its qualities after a while so I avoid using it in locks. Having removed the battery from the car, I clipped on my drop tester which showed a terminal voltage of only 6 volts. Definitely a dead battery. I applied the load unit to the battery and voltage fell to an unacceptable 1volt. Out of curiosity, I tried a quick recharge via mains charger which showed a whopping 16volt input on the drop tester. That dropped rapidly to 11volts - which was far to low to have the correct effect. Again I load tested and only 0.5volts was evident. At that point I gave up the fight. I stole a well maintained battery out of my boat which fitted the battery carrier in the car. Being a typical marine unit of 110ah capacity, it was 30mm taller than the standard 90ah battery it replaced. I had to re bend the lock down tie rod to suite the height and make a longer new negative lead as battery terminal positions were differently placed on the ex boat battery. Nice to have 20ah extra capacity. I always thought the standard battery size was right on its limit in cold weather. The car cranks and starts more quickly than before and having driven it around, the engine seems sweeter and more oily than before the replacement battery was fitted. Certainly the engine runs without misfires better at idle speed and is more even especially when the exhaust sound is listened to.

I believe there is a voltage related issue here. Whilst the alternator does supply recharge current to the battery, I am convinced that as low voltage can cause so many problems as described in earlier postings on this thread, I am similarly sure that a stable and sound battery "platform" is needed to ensure that spark plug feed and ignition module performance is dependent upon the need for a battery in prime condition. Anything less than good condition also leads to issues with the Power Control Module and its inability to perform when under 12 volts are available at the battery terminals.

All these little issues add up and make sense once a prime component is replaced. A decent battery is the heart and soul of an electronically managed car and it is worth remembering if your car suddenly acquires a string of irritating electrical glitches. At the end of the day a battery is a consumable item with a finite life span. Some batteries last well, others not so.

Mike

An update here on batteries, voltages, cold weather problems and glitches.

The new battery works a treat. No problems there.

The misfires are still present on slight hills in light throttle conditions.

So that's it then. All the triple electrode AC Delco spark plugs will have to come out again and I`ll go back to the conventional type. Seemingly the new plugs appear unsuitable for the engine.

Mike