Recharging a flat battery using the Ctek mxs 5.0

[MikeF]

The battery on my MY16 Coupe is completely flat and I have to open the driver’s door using the emergency key. This means I can open the bonnet and get to the charging points but cannot open the boot to get at the battery.
Does anyone know if it is possible (or advisable) to recharge a flat battery from the charging points using a Ctek mxs 5.0. The Ctek manual shows the charger being connected directly to the battery.
My thinking is it would be better to recharge the battery properly rather than try and jump start the car and then leave it running or go for a long drive ( not recommended at the moment).
Any advice would be greatly appreciated.
Regards

[Deleted User 1715]

Jaguar don’t recommend connecting direct to the battery as it can upset the battery management system. If you connect it to the jump start points under the bonnet it might be able to recover the battery, but leave it to charge as long as you can. Running the engine to charge a flat battery can lead to excessive current going to the battery which can reduce its life. If your battery is completely dead it may not work but no harm in trying.

[Tel]

Although the ctek is just a crude maintenance device, it can recover completely flat batteries.
I have done it many times myself.... It merely takes longer as the current that it can supply is limited.

Leave it on overnight, doesn't matter where you connect it in this scenario, that shoukd give enough charge to be able to start the engine.

Once started you need a drive of say 30/40 minutes, then putting it back on the ctek overnight should bring everything back to initial state.

For maintenance mode, neg to body, pos to busbar in fuse box.

[scm]

The Ctek manual shows the charger being connected directly to the battery.

The CTEK manual shows a battery being charged out of the car. I've invested in a TACKLife jump starter in case I get stuck in your situation (it's already happened once!) which I'd connect under the bonnet to get the car alive (but have your fob handy to turn off the alarm!

[MikeF]

Thanks for the advice guys. I will give it a try tomorrow and let you know how I get on.
Regards

[johnsoncp]

Jaguar don’t recommend connecting direct to the battery as it can upset the battery management system. If you connect it to the jump start points under the bonnet it might be able to recover the battery, but leave it to charge as long as you can. Running the engine to charge a flat battery can lead to excessive current going to the battery which can reduce its life. If your battery is completely dead it may not work but no harm in trying.

I find this battery management thing very interesting. It may depend on the age of the car? On my F-Type there is a heavy duty red cable from the battery positive to the recommended connection strip and there is a heavry duty black cable connected to the chassis directy from the negative terminal. So the battery terminals and recommended connection spots are electrically idential. The battery monitoring system runs in parallel with the black cable so it cannot possibly make any difference where you connect it. I am aware of the risk of spark and explosion which would be a good reason not to connect to the battery but given that I don't plug in the CTEK until after the charge cables are attached there is no risk of a spark.

[Deleted User 1715]

Jaguar don’t recommend connecting direct to the battery as it can upset the battery management system. If you connect it to the jump start points under the bonnet it might be able to recover the battery, but leave it to charge as long as you can. Running the engine to charge a flat battery can lead to excessive current going to the battery which can reduce its life. If your battery is completely dead it may not work but no harm in trying.

I find this battery management thing very interesting. It may depend on the age of the car? On my F-Type there is a heavy duty red cable from the battery positive to the recommended connection strip and there is a heavry duty black cable connected to the chassis directy from the negative terminal. So the battery terminals and recommended connection spots are electrically idential. The battery monitoring system runs in parallel with the black cable so it cannot possibly make any difference where you connect it. I am aware of the risk of spark and explosion which would be a good reason not to connect to the battery but given that I don't plug in the CTEK until after the charge cables are attached there is no risk of a spark.

As an electronics engineer I find it quite interesting too! The problems I’ve heard and read of seem to be due to the management system ‘learning’ the voltage level of the battery and adjusting alternator output so that in some cases the battery wasn’t charging very efficiently. How it does this with the connections as you say is beyond me. My gut feeling is that this was an issue with the earlier cars that had a 2 battery system and more complicated wiring because of it. I don’t see how it can be the case for newer cars with a single battery. The battery in mine is ‘sealed’ so sparking should not cause an explosion, although many years ago I did see the result of a 100AH lead acid battery explosion after one of the guys decided to do some welding close to the (vented) battery which he was too lazy to remove first, so I am always careful around batteries!

[johnsoncp]

Jaguar don’t recommend connecting direct to the battery as it can upset the battery management system. If you connect it to the jump start points under the bonnet it might be able to recover the battery, but leave it to charge as long as you can. Running the engine to charge a flat battery can lead to excessive current going to the battery which can reduce its life. If your battery is completely dead it may not work but no harm in trying.

I find this battery management thing very interesting. It may depend on the age of the car? On my F-Type there is a heavy duty red cable from the battery positive to the recommended connection strip and there is a heavry duty black cable connected to the chassis directy from the negative terminal. So the battery terminals and recommended connection spots are electrically idential. The battery monitoring system runs in parallel with the black cable so it cannot possibly make any difference where you connect it. I am aware of the risk of spark and explosion which would be a good reason not to connect to the battery but given that I don't plug in the CTEK until after the charge cables are attached there is no risk of a spark.

As an electronics engineer I find it quite interesting too! The problems I’ve heard and read of seem to be due to the management system ‘learning’ the voltage level of the battery and adjusting alternator output so that in some cases the battery wasn’t charging very efficiently. How it does this with the connections as you say is beyond me. My gut feeling is that this was an issue with the earlier cars that had a 2 battery system and more complicated wiring because of it. I don’t see how it can be the case for newer cars with a single battery. The battery in mine is ‘sealed’ so sparking should not cause an explosion, although many years ago I did see the result of a 100AH lead acid battery explosion after one of the guys decided to do some welding close to the (vented) battery which he was too lazy to remove first, so I am always careful around batteries!

As you say, it may be related to the age of the vehicle. My much older XJ has the battery monitoring system in series with the black cable so I cannot say for sure if the negative terminal and the chassis end are electrically the same. On this car I can see the logic of attaching the negative to the chassis but having said that given that the cable can handle a start current of several hundred amps I still expect they are actually the same.

[KenC]

So, to be clear as I have a 2020MY P300, can I can ignore all the threads I've been reading over the last week or so and attach a battery conditioner directly to the +/- poles of the battery in the boot?

[scm]

So, to be clear as I have a 2020MY P300, can I can ignore all the threads I've been reading over the last week or so and attach a battery conditioner directly to the +/- poles of the battery in the boot?

If you're using clips that's probably okay, but if you're wiring in a Comfort Connector, it's probably better not to add wires at the battery terminals to make changing it easier.