I've got an '07 XJ8 VDP and after returning from a 2 week trip the battery was dead. I was told by a Jag owner that that's pretty common since so many low-voltage systems are running even with the car turned off. Is that so?

But what's really concerning me now is that I attached a charger and have it set at 2amp trickle charge. I've got it properly connected with the positive lead to the battery and the negative lead the the earth ground bolt on the left of the trunk. There is a clicking noise in the trunk (fuse box? computer?) and also a clicking in the car itself which sounds like it's coming from near the glove compartment. Occasionally a beeping noise occurs in the dash somewhere?

At the moment the battery is at 8 volts and the clicking continues and the car won't start yet.

Are these clicking and beeping noises typical and what are they?

 

The noises are probably because the battery is low.

Since there was no obvious reason why the battery was dead I would have it
load tested.
The Jag battery is very big and a 2 amp charger will be very slow.
My charger is 8 amp but physically quite small.

 

Did you disconnect the battery during the trickle charge? 2A is not a lot, and if the car senses voltage and the control units come back to live this will easily consume a lot more than 2A. That may cause the voltage to break down again, and the units shut back down, repeat ...
The symptoms (clicking and maybe a beep) sound exactly what happens when reconnecting a disconnected battery, just that it happens only once then. But if you "simulate" continuous disconnection and reconnection by too low power supply this may be the reason.

I would suggest to follow meirion1's lead and feed the battery a decent current. The alternator also easily feeds more than 20A, a lead acid battery is made for this.
Or alternatively, if your charger is limited to the 2A, disconnect the battery during charge.

 

Never charge a dead battery without disconnecting the cables.

 

Thanks for all the input which now makes perfect sense why the car was discombobulated with only a 2amp charge. My charger has three settings: 2, 10 and 20 amp. I set it to 10 amps and the clicking and beeping stopped and the battery was fully charged after some hours. I was surprised I had to do so much afterwards - reset the electric parking brake, reset the windows anti-trap, even reprogram the key fob. Next time I leave town for a couple weeks I'll disconnect the battery to prevent all this nonsense!

 

If you have power around the car I would rather suggest to get a little charger that can keep the battery permanently fresh when it is standing for longer times.
If you leave it with disconnected battery it is effectively a hard reset every time and the car will wake up stupid every time.
That means not only parking brake and windows, but also learned engine fuel trims, gear shift adaptations, radio stations, seat memory and probably more. Some of the adaptation values need quite some miles to settle again.

 

So are you suggesting a trickle charge or sorts? Any particular model or type that you or others recommend? I have a small solar panel which plugs in through the car lighter, but I don't know if it offers enough power to keep up with the drag n the battery for a long time of no use.

 

Exactly, trickle charger was the name, pardon my English I always used one for the motorbikes over winter.
Some X350 seem to have the habit to wake up occasionally, some control units power up and it takes more than half an hour again at up to 0.8A consumption until they fall back asleep. Same as after shutdown and locking the car. This drains the battery quickly. Mine was dead after two and a half days at the airport, after a 270km drive, so I parked it full for sure.
A month ago it was dead in the garage after a week. And I parked backwards to fix the front brakes, so no chance to jump start, and no chance to push it out, because the gear lock pin in P is operated electrically. Quite some fun. Solar is worth a try if you like me have no electricity around the car. But connect directly to the battery, the cigarette lighters are switched with ignition.

 

Regarding the charger brand, I have a ctek. They have a wide selection.

 

Yes, I forgot the cigarette lighter was only active with the ignition on. I think maybe the one in the back seat or glove compartment are live at other times, but that said, a solar charger doesn't have the sophistication of a trickle charger/battery mender and adjust load as per battery demand. I do have an outlet nearby so I'll start looking into those including the ctek that Aix recommended.

Question: if one were away for a few weeks, would you trust a charger that's just 3 or 4 amps to do the trick or better to have one that's 10 amps? Battery requirements for this type thing confuse me.

 

For trickling it will be enough to have a few Amps. It's not about charging an empty battery. I have 100Ah in the car, for real charging I'd choose at least a 10A capable charger. For keeping it fresh 24h a day something like 1 or 2A should be ok.
Best check with ctek. They (and others too) have chargers that can do both, charge at high rates and switch to a keep-fresh trickling mode when the battery is detected full.
Especially with the occasional insomnia of the X350 electronics it's probably a good idea to have one that can do both.

 

Thanks for the info Aix. I'll start researching menders/charger now.

What do you think about these battery conditioners that attach to the battery permanenently and send pulse charges to break dowbn sulfa compounds?

 

I'm not really a battery specialist, but these permanent attachments sound like snake-oil to me.
Some chargers claim that they can crack sulfate by high voltage pulses, I think that may work. But once you use a trickle charger to keep the battery fresh that should not happen, as long as you drive the car sometimes to stir up the acid again. Everything beyond that falls into the realm of black magic for me

 

Yeah, it feels snake-oily to me, too, but that said ctek speaks about that feature in their literature: on the the 8 steps their battery mender/charger does is a maintenance step that pulses so maybe there is something to it. But that feature is probably there for "long-term" hook ups to the mender/charger and wouldn't be necessary if one was driving often as I do. It's just the occasional short trips that pose a problem. I've only had the car a few months and this was my first trip )~16 days) so coming back to a dead battery and a car that had, as you said, gone stupid was a real surprise to me so I'm going to be prepared next time. Thanks again for all the info.

 

I would add a caution about solar chargers, I had some battery issues due to lack of use, so I got one of these and attached it to the rear screen and directly to the battery, all was great for a couple of months, but now the battery goes flat even with the solar charger on and I can't get it to take a full charge from a trickle charger, even when removed from the car, I think the solar charger does not cut off at full charge, but just keeps going and has possibly overcharged and damaged the battery internally.

 

Sounds like this solar charger was leaking current when there was no sun. Any charger is effectively a connection between the poles of the battery. So especially in a solar charger there need to be diodes preventing backflow of charge when no light falls on the panel, i.e. no voltage is present to "pump" the electrons the right way around into the battery against the battery own voltage. If this electric one-way valve is not good the battery is discharging over the charger at night, or when there is not enough light around. Was your battery flat after being connected to the solar charger for a longer time? This may have damaged it permanently. Deep-discharged lead-acid battery tend to lose capacity or even get shortcuts between cells due to lead sulfate building up that is not solving in the acid again when recharging, thus reducing the active amount of acid working in the battery (well, at least that's put into my battery-layman's words)

BTW, if a battery is flat, as mentioned above, trickle charge is not the right strategy. You should apply a charger then that can do around 1/10 of the battery capacity in Amperes (e.g. 100Ah => 10A), but lead acid batteries can also stand some more.
Trickle is the strategy to keep a full battery fresh and charger over a longer time of standing around. But also then the charger must be able to detect when the battery is full and stop charging, then wait for the charge (i.e. voltage) to drop below a certain threshold and restart charging, and so on. The charger should specifically state that it is capable of this function.