XK battery going flat.

[Sploosh]

Well just bought this great car however the battery has gone flat in a week. I disconnected the battery (which looks like a new Bosch one) charged it over a 6-7 hour period. Reinstalled and then measured the voltage after about 1 hour and it was showing about 12.6 volts which I felt was a little low. I then disconnected the battery and straight  away the voltage went up to 12.8 so I felt that there was some load.

I charged the battery again and connected the +ve terminal. I had my multimeter set on Amps and connected the negative terminal via the meter. To my surprise it was showing 9 Amps. So I have a serious issue, any suggestions would be greatly appreciated.

pete

[Jimbov8]

3 hours ago, Sploosh said:

I charged the battery again and connected the +ve terminal. I had my multimeter set on Amps and connected the negative terminal via the meter. To my surprise it was showing 9 Amps. So I have a serious issue, any suggestions would be greatly appreciated.

Not quite Pete. As soon as you reconnect the battery, the infotainment centre will flash up and that is where your 9A is coming from.

You would need to wait 30 minutes for the various modules to shutdown to get a more accurate reading of any parasitic drain.

The most common fault is the alarm chirp sounder internal batteries shorting out causing the drain. The sounder sits under the driver’s side bonnet hinge and is quite fiddly to get to.

[Sploosh]

Hi Jim,

Thanks for the information, will re connect battery in the morning and give it time to settle. Will for sure have a look at the alarm sounder as when locking the car it really does not make much of a sound, it made more noise when I connected the battery🥴

appreciate the prompt response, thanks.

Pete

[X100XKC]

On the XK8 a second press of the remote sets the deadlocks and puts the car into a low power mode - that seems to conserve the battery better. Perhaps it also works on the XK.

[Sploosh]

Hi Jim,

Thanks for the information, will re connect battery in the morning and give it time to settle. Will for sure have a look at the alarm sounder as when locking the car it really does not make much of a sound, it made more noise when I connected the battery🥴

appreciate the prompt response, thanks.

Pete

[Sploosh]

Well I have now managed to measure the current drain with only the boot open and the rest of the car locked. 0.52 Amps is what it’s pulling all the time. I think I did read a thread where somebody suggested that it should only be about 0.32 Amps. So is my current drain excessive? Is that a typical value indicating that the alarm sounder batteries are faulty. Any information would be appreciated.

Pete

[Big John]

Hi Pete

That sounds very high. My understanding is that quiescent drain should be less tham 30mA. That is 0.03A.

That sort of drain would easily flatten a fully charged battery in a week. Car needs at least 30mins after being shutdown for all of the moddules to go to sleep

John

[Sploosh]

Thanks for the information John, I felt it was a bit high. The other sign is that I have a new battery so the previous owner knew of the problem and now passed it on to me!!
Will look at the alarm sounder early next week as I get the impression that this is the first port of call to resolve the issue.

will update as and when progress is made😂

Pete

[Jimbov8]

2 hours ago, Big John said:

That sounds very high. My understanding is that quiescent drain should be less tham 30mA. That is 0.03A.

Quite right John.

 

2 minutes ago, Sploosh said:

Will look at the alarm sounder early next week as I get the impression that this is the first port of call to resolve the issue.

You should be able to disconnect it to prove the theory, Pete.

Just another thought, you don’t have a tracker fitted or something plugged into the OBD port, do you?

[Sploosh]

Well I have now managed to change the alarm sounder, not a job I enjoyed as I am not happy up close to air bags!! But too it steady and once the air bag and its frame was out of the way the alarm sounder was easy to see hidden low down on the bulkhead.

the replacement fitted and air bag put back it only took a couple of hours in total. Reconnected the battery, reset parking brake, windows etc. and went for a spin. Some two hours later measured the current drain which was now some 100mA far better. Not quite down to the 30mA mentioned by John but a big improvement.

so thanks to all for your input, will enjoy the driving now with more confidence that my electrics are all working well.

Pete

[Jimbov8]

Excellent news Pete and thanks for the update.🤙