Through the winter months my Jag will spend a lot of time in storage. To this end I wish to maintain the battery. Based on success with a domestic auto I purchased a Deltran 1.25A /12VDC Battery Tender. I used one of the rubber plugs in the spare and battery compartment to bring the cable through and connect directly to the battery. I have every reason to believe the battery is in excellent condition and near, or at, full charge. Even after an extended charging period of more than an hour the battery tender is still in "CHARGE" mode and has not switched to the "MAINTAIN" mode. Has anyone had XK-8 experience with a Deltran Battery Tender who might offer some wisdom and suggestions.

Thanks for your time and consideration. Regards, Ken

 

I have the same unit and it does often take overnight to get a green light. I have used it for long periods on a motorcycle and it does not cook the battery dry like some trickle chargers will do. Please verify that your battery has a vent tube as you don't want hydrogen building up in a closed trunk.

. . . and welcome to the forum.

 

Mine can also take a day or two to bring the battery up to float charge. You are adding voltage at very low current, so it takes awhile. This can be educational as far as battery charging, because we don't always fully charge a battery by driving. Using a three-stage algorithim, the smart chargers and battery tender get almost every last electron in there, and then keep them there without overcharging the battery.

 

Like Mike66 says, mine takes 2 days to get the green light.

 

You are all very kind and informative. I was concerned after several attempts failed to get the "green" light. I had never left it charging anywhere near as long as you all have indicated. I store my Jag away from home and was afraid I might be imposing an unnecessary risk on my "baby" not to mention the building where she sleeps. I now have the confidence and information to attempt a much longer experiment. Very much appreciated! Warm regards, Ken

 

Different generation of technology, but my 1966 E-Type lives on the battery tender permanently - then nearly always starts on the very first push of the start button after weeks of inactivity. No worries!

 

I have the CTEK 3300, and when I first hooked it up, I didn't get a green light until the next day. Then it switched back and forth, and it wasn't until the following day that I had a solid green light, so it took a good day and a half for that to happen.

After a run this afternoon, I had a green light in an hour or less, so from this I infer that my battery was down quite a bit when I first plugged in the CTEK.

 

I have CTEK 3100 and it does exactly the same.

Seems like this is normal behaviour for battery tenders.

Graham

 

Once used a tender (optimate, it uses charging decharging cycles) on a motorcycle battery. After a few months the battery was ruined, 2 plates were bent onto each other. Never used it again on the motorbike. Bike is stored in a warmed garage so not really needed, after 6 months still more than good enough to startup.

On the XK8 it is a different story. In 5 years it is already the 3th battery.
Would like to know, if you put a battery tender, you leave the battery in the car fully connected? How do you get the battery connected to the tender while closing the trunk.
Does the car lock properly with the trunk open? Do you leave the tender on all the time?

Thanks for replying

 

There are terminals under the hood that can be used to attach the tender. See 2nd post, by Paul Pavlik, this thread ...
https://www.jaguarforums.com/forum/x...rminals-56664/

Seems likely something is off the mark in your car if it's eating batteries like that. Just as a point of reference, I'm on my 6th year with an Autozone battery.

 

The Deltran has ring terminals that fit on the bolts that hold tight the battery terminals onto the battery posts. Those wires terminate in a weatherproof connector and can stay attached to the battery. The Battery Tender has a long flexible duplex wire that plugs into the others, and is flat enough to close the trunk lid on. Just unplug and go. Not a bad way to go for max battery life. Boaters use these "smart chargers" as basic equipment to maximize battery life of $$$$$ battery banks. Most of those are deep cycle batteries, which are a little different, but the same principles hold for starting batteries as well.
BTW, another option where power is not available at the storage site is to switch to an AGM (Optima) battery and disconnect it from the car when not in use. The AGM has a very low self-discharge rate.

 

The car is stored, fully locked in winter under a fully dry carport. After 4 to 6 weeks of freesing and snow the battery is flattened and she will never fully charge again. Sadly enough the last winters where harsher than normal. So although the battery is good enough for other cars it will not work in the jag. The windows need reprogramming after a week, the abs/track alarm comes on intermittend. So best is to change.

 

Again, thank you all for sharing such useful information. I initially tried connecting my battery tender between the frame at a strut mount and the positive feed (large cable) at the fuse box on the driver's side (port side) in the engine compartment. Perhaps I should try again armed with this new knowledge - but - in this configuration after a couple of hours the battery tender was very warm to the touch and no green light. I thought that perhaps there was excessive line loss down that long cable back to the battery. I had confirmed with a meter that the cable provided battery power with the key switched off and removed. My wife is petite and was willing to get in the trunk to judge when the trunk lights extinguished. She advised that they remained illuminated until the boot lid latched closed. I do not want my support cable to squeeze between the boot lid and body forcing extra compressing on a small area of the gasket. I searched the battery/spare compartment and found two rubber grommet plugs near the battery. My intent is to mount an AMP (TI Connectivity) CPC connector into one of those holes and permanently wire the ring lug cable that came with my charger form that connector to the battery. Next I will modify the alligator clip cable that also came with my charger to fit the CPC mate. This way I don't have to empty the trunk and remove the floor to access the battery. The chassis mounted connector is available more or less behind the rear wheel. I will fit the chassis mounted connector with a dust cover to protect its contacts. Ken

 

Colquan,

The terminals in the engine compartment are just fine as a point to attach the tender.

There will be essentially zero voltage drop across those long cables back to the battery since they are quite thick (capable of handling hundreds of amps). You could verify this by hooking up the tender there and then comparing a voltage measurement taken there to one taken at the battery.

Good luck.

[edit] Just so I don't mislead anyone ... those cables are thick, but not so thick as to make them suitable for jump-starting the car.

 

If you disconnect the negative terminal, put a blanket on the battery until your ready to come out of storage, you'll be fine.Been doing it this way for years.
Just reset your clock, radio settings and window re learn.

 

Mine can get pretty warm too. Have you measured your current draw on the battery with everything off? You may have a drain that needs attention. As an experiment, you can hook up your tender to the disconnected battery and see how long it takes to go green. Mine took three days when I first hooked it up after 5 months of downtime here in FL. There are no outlets in our parking garage, so I bring the battery up to my condo. Good luck.