Hi all.


I would like to share some thoughts on batteries and charging.


Our XK8's have a fairly advanced charging system, but it is an old system constructed back in the nineties. The generator has a nominal output of 120 A (Amperes) at 5000 rpm which equals approx. 1600 engine rpm.


The battery has a nominal capacity of 95 Ah (Ampere hours).


All the electrical gizmos in the car may consume up to 2000 W (Watts). If you on a cold winter day put on heated screens, heated seats, heating fans, lights and so on you may exceed the capacity of the generator leaving no current for the battery which is already down from the cold start.
If you now drive only 15 minutes and park, repeatedly, your battery will eventually die. The battery capacity earlier stated is also theoretical. After some years the capacity may be down to 50%.


Now if you leave your car in the garage for the winter, what then. If you lock up your car, it will drain less than 30mA (milliAmpers) or even less after 28 days standstill. Theoretically it will then take more than 4 months to drain the battery completely. But in real life don't count on more than a couple of months as your battery never is up to nominal values.


In the old days the first sign of a weak battery was failure to start a cold winter morning. Not so any more. The first symptoms nowadays are malfunctions of electronic black boxes giving all kind of false warnings. Most typical in the XK8 is window drop troubles.


I would not put in a different technology battery (gel) as the charging circuit is optimised for the old type lead battery. Other batteries may require higher charging voltage.


Get yourself a battery conditioner and give your cat a boost now and then, just as you would give your girl some flowers occasionally. Marvellous results.


What I have said is in no way a negative critique of Jaguar. The electrical system as the hole car is very advanced, but bear in mind it was constructed more than twenty years ago.

 

Hi Oyster,

thanks for the rundown on the science and history of the charging system. I'm astounded at the 2000W - no wonder the battery occasionally gives in!

+1 on the conditioner. For all I know, my battery is the original one, which would make it 12 years old. The CTEK was the best flowers I ever got for my second girl. Leave her double-locked and massage the battery for a few hours once a week or so and I'm good to go on those all-too-rare winter "Penny days". The ones with dry roads and no recent salting. Then I give her a stretch of the legs and make it a long one.

Yes, I call her Penny, after Penelope, Odysseus' faithful wife. A bit on the cute side, but hey - just hoping she will live up to it :-)

 

What would you recommend as a replacement battery for a 1999 XK8 4L Convertible?

I'll get a charger, but I figure I should start with a new battery, too.

 

The Advance Auto Parts AGM top-of-the line battery (900 cca) is what I bought. At $157 after a TRT30 discount code the price cannot be beat and it has the vent system required for a trunk mounted battery.

 

+1 on Testpoint's recommendation. Advance also installed mine at no extra charge, keeping an outside power source on the cables so I didn't lose any of the settings, radio, window up and down, etc.

 

Do you have a recommendation for a solar battery charger or maintainer? I live in a rowhouse and need to park my car in the street, often a block away from my home, so I have no electrical outlet into which I can plug a charger?

 

Do you have a recommendation for a solar battery charger or maintainer? I live in a rowhouse and need to park my car in the street, often a block away from my home, so I have no electrical outlet into which I can plug a charger?

 

Any good brand like BatteryTender would be OK. Select something that's at least 10 watts. But given that you're constrained to deploy the thing inside the car, it's going to be tough to grab more than a few amp-hours per day.

This will buy you some time, but over the long term you'll need some extended driving and/or an occasional plug-in charge to keep the battery happy.


Good luck.

 

I've seen Forum members criticizing Battery Tender in a number of posts. There seem to be a lot of CTEK fans, but I haven't found any solar chargers manufactured by CTEK. Are there any?


If not, I'm looking at a Battery Tender 021-1164 10W Solar Charger on the internet. Would you consider that a good option?


On a related front, in posts relating to newer Jaguar models, I've seen people say that the chargers cannot be hooked up through the cigarette lighter because the cigarette lighter is disconnected from the electrical system when the key is removed from the ignition. Would this also be the case for my Jag, which is a 1999 XK8. (It would obviously be nice if I could hook up a charger through the lighter.)


If I can't hook up a charger through the lighter, does the Battery Tender 021-1164 Solar Charger come with pig tails that I can leave connected to the battery when not using the battery, or do pig tails need to be bought separately -- and if they need to be bought separately, is there any brand or are there specs I should concern myself with?


Sorry for all the great many questions, but I don't want to buy something and then find out that I can't use it because I first need to buy something else to make it work.

 

Dennis,

I've seen Forum members criticizing Battery Tender in a number of posts. There seem to be a lot of CTEK fans, but I haven't found any solar chargers manufactured by CTEK. Are there any?


If not, I'm looking at a Battery Tender 021-1164 10W Solar Charger on the internet. Would you consider that a good option?


On a related front, in posts relating to newer Jaguar models, I've seen people say that the chargers cannot be hooked up through the cigarette lighter because the cigarette lighter is disconnected from the electrical system when the key is removed from the ignition. Would this also be the case for my Jag, which is a 1999 XK8. (It would obviously be nice if I could hook up a charger through the lighter.)


If I can't hook up a charger through the lighter, does the Battery Tender 021-1164 Solar Charger come with pig tails that I can leave connected to the battery when not using the battery, or do pig tails need to be bought separately -- and if they need to be bought separately, is there any brand or are there specs I should concern myself with?


Sorry for all the great many questions, but I don't want to buy something and then find out that I can't use it because I first need to buy something else to make it work.

 

I've seen that too. Apparently it goes for all X100/X150's.

If in doubt, you could try charging your mobile phone via the cigarette lighter socket with an appropriate adapter. Mine charges fine with the ignition on, no charge with ignition off.

 

Hi all, Just wondering when you say conditioner you are talking about charging? Something to be added to each cell of the battery?
I have never had any battery last anywhere near 10 years regardless of what kind of maintenance done to it.
Are you saying if you lock the doors and arm the alarm system there is less chance of drain?
I have been disconnecting the battery since the previous owner told me he had a quick disconnect added to the negative wire. Since I learned about the window programming I'm leaving it connected but charging the battery weekly with a 1 amp charger. Thanks

 

JCJ,

I've had good luck with the Battery Tender brand, but it would be good to gather as many opinions as possible.

I've never tried the cig lighter socket, but if it can't be used, I'm sure we can find unswitched power by pulling some panel around the dash. Or ...

If you were to place the solar panel in the rear window, it would be relatively easy to run some wire to pick up power in the trunk.


Lufferman,

Conditioning as used here means following a certain charging protocol, not adding anything to the cells.



Good luck, gents.

 

Hi.


There is nothing to be added to your battery.


A battery conditioner is a kind of an intelligent charger measuring the state of your battery and adjusting the charging accordingly. In this way you can leave it connected for a long time without any danger of destroying the battery. A popular brand is CTEK.


An old time charger will charge with more or less the same current constantly. It will eventually overcharge your battery causing evaporation and destruction if you don't watch the charging time.


The gas evaporating is hydrogen which is highly EXPLOSIVE, and will give you a Hindenburg disaster by the tiniest spark. The vent line is important.


You have to lock your car to minimize current drain. All modern cars are constructed this way. Locking is also an instruction to power down most of the "black boxes" after a specific time limit.

 

I have also used the Battery Tender for the past few years with no problems.

 

No. A battery conditioner, or a battery charger with a conditioner operating mode agressively discharges
and charges the battery to get rid of sulphation.

The CTEK is like Apple, lots of hype, lots of fans, big price tag, no better than anything else
and for some uses, less capable.

A midrange Schumacher sold at Walmart costs less and will actually have decent output
if the battery is really low and needs a fast charge.

 

"No. A battery conditioner, or a battery charger with a conditioner operating mode agressively discharges
and charges the battery to get rid of sulphation."


As english is not my native language, I thought that was called a reconditioner.

A reconditioner promise to wake up a dead and destroyed battery. I don't believe too much in that.


What I am talking about is a device charging your battery now and then without overcharging causing gas evaporation.


I couldn't care less about the brand. If you find a high quality Walmart product, that is fine.


By the way, I don't like apples either.

 

I have gone through several types of chargers, batteries, etc. I now charge once per week(out of car or bike) and use a charger specific to the type of battery(gel.-lead/acid,etc.). I make sure the battery isn't frozen and charge at 10 amps for 20 minutes to drop dust and then 6 amps until fully charged. I use a memory minder on the cars brain to avoid drop-outs while the battery is indoors. I know it keeps them alive; however, whether it is extending life is unknown.

 

I'm still doing it the old fashion way. My. Boat came with a Smart charger installed. I though that it was for marine deep cycle batteries.
I've never over charged a battery with my 25 year old 2/6 amp Craftsman charger or my 1 amp dumb trickle charger for $46 on Amazon I'm wondering if I should spring for CTEX US 800 now and rejuvenate my batteries.

 

I have a Vector Smart Charger that I bought after I bought my boat almost 15 years ago. You are correct, the term that they are looking for here is "Smart Charger", which is one that uses different amp levels to charge the battery and then, when fully charged, it maintains it, like a trickle charger does. Yes, you must have a charger when you have a trolling motor and a deep cycle battery because typically the trolling motor is not connected to the other battery and does not get any charge at all from the running of the engine. When my boat battery is low, it will typically start out charging at 12.4 amps for a minute or so and then gradually reduce the amps over time to give the battery a deep charge. I attach it to my Jag battery when I haven't driven it in a while just to keep that battery fairly full as well. Due to the size of that battery, it takes quite a while to come up to full charge and it lingers at about a 1.5 amp charge for nearly an hour or so before it reads FULL.

I am not any sort of expert on charging batteries, but I don't think that such a charger wears out over time so that it does not give a full charge any longer. I think that as long as they are working properly, there is no need to replace them for not charging well enough. I am kind of happy about how long mine has lasted since in modern society it seems that just about everything else that you buy has "planned obsolescence"
built into it so that you have to buy a new one every few years.

I was talking with a refrigeration guy a while back and he told me that refrigerators and window unit air conditioners typically last only about 3-5 years, whereas they used to last over 10 years. He said that they are much more cheaply made than they used to be, which is something that I think is true pretty much across the board for most products we buy today.