Flat battery

[dattrike]

I drove back from visiting Mum on Saturday (25 miles aprox), when I started the car there was a feint ticking sound from behind the dash/under bonnet, thought nothing of it as car started straight away. Got home and parked on drive as normal. Sunday I was going to take the car to the local car wash,the remote did not unlock the doors, tried the spare remote, same thing no sound from the door actuators. Flat battery instantly popped to mind as the car still has the original 2007 battery fitted. Checked the battery voltage, 0.45 volts. Took the battery out of the Jaguar to discover that the Negative terminal clamp had broken. A quick trip to Halfords for a Negative terminal and earth lead, took the battery off the Rover 75 fitted it into the space and connected it up, a small spark when I connected the negative (expected), started the car everything seemed ok, reset the park brake, windows etc. Went out to the car today to go to battery megastore for a new battery, totally flay battery again. I borrowed SWMBO's car and got my new battery. Took the Rover battery off, fitted the new Jaguar sized one, connected the positive, put my multimeter to check the quiescent current drain and discovered a drain of over 10 amps.

Sorry for the long preamble, but my question is, has the broken negative terminal clamp caused a spike and blown something, my best guess is alternator diode pack, but I don't want to totally flatten the new battery whilst I check the charging voltage with the engine running, so any suggestions would be very welcome.

PS waiting for the old battery to charge up before reconnecting it to do charge voltage test.

[Russ68]

Mine was flat this morning but is fine now after a jumpstart and 20 mile run. I think the issue was related to either locking or the cooling fan, I'll investigate further. But your 10a drain is really significant David. Too high to relate to a small component, such as a light staying on. I think you're on the right track and hope you sort it soon 

[Borg Warner]

You need to identify what is causing the drain, 10a is quite a lot.  Suggest you pull the fuses one at a time until the drain drops off, making a note of which ones you remove as you go along.  Sure Paul will be along shortly to give you some more pointers.

As for charging the battery, hopefully you are using a quality trickle charger - Ceetek are recommended, but if the terminal volts were that low it may be beyond recovery.  Leave it on charge for at least a day anyway.

Hi Dave by the way.

 

Gary M.

[dattrike]

Hi Gary, thanks to all for the replies, old battery has now reached full charge after two days so will refit tomorrow after work. I use the Lidl copy of the C tech, I will borrow the amp clamp meter from work to see what the actual drain is as the fuses are removed.

[Nick2]

I had a very similar problem with a boat.  Battery going flat with everything switched off and no obvious drain.

It was the alternator, although the figure was only about 2 amps.  10 amps > 120 watts > something will be getting very hot!

[dattrike]

Update,

Refitted the fully charged original battery, put the clamp meter on and connected the negative terminal and got a reading of a 50 amp drfain, quickly removed the negative terminal, there was a beeping from under the bonnet, the alarm went off as well. Reconnected the battery and locked the doors to stop the alarm, then disconnected the battery again, that stopped the beeping after locking the car.

Does anyone have a wiring diagram I can use ( 57 plate diesel ) to look at the battery and associated fuse boxes and the charging circuit.It is almost looking like the positive lead from the battery is partially shorting somewhere. I unfortunately cannot kneel down any more, so I will contact my local garage to see if they can pick the car up and sort it for me, but I'd like to point them in the right direction.

Any help would be greatly appreciated.

[ay_jay]

50 amp battery drain does sound like a short somewhere (a big one). Can I ask how you are measuring that? If possible try and pull off the connection to the alternator to rule that out perhaps?

[david moore]

david open this file and see if there is anything that helps in the   s type,  jaguar Electrical 02-20-02.pdf 

[dattrike]

50 amp battery drain does sound like a short somewhere (a big one). Can I ask how you are measuring that? If possible try and pull off the connection to the alternator to rule that out perhaps?

I'm using an amp probe from work, it encircles a cable and measures the current in the cable. Unfortunately due to replacement knees I can't get under a car like I used to. I have only had the car 6 months, I don't even know where the alternator is on the engine ( hangs head in shame 😩 ) it's been so reliable. The problem is with the thicker positive cable which runs to the front of the car which is the starter cable I think. I will have another look at the weekend.

[dattrike]

Further update:

Took the car to the local garage, they diagnosed glow plug relay stuck on (hence the battery drain), probably caused by the broken battery terminal, they ordered and fitted said unit, everything fine now I'm £200 lighter though. Happy with that though as apparently it's difficult to get at. I had to contact H A Fox in Cheltenham for the radio code, which they supplied free of charge, as the radio reset method in Paul's document only works on cars up to 2006. As everything has been reset, the car seems more responsive especially when accelerating quickly from stationary. Hopefully with a bit of "spirited" driving it will stay more responsive. All in all happy result for me.

[Borg Warner]

A good result Dave.

Gary M.

[Russ68]

Glad you got it sorted David, with that amount of current draw, it had to be something pretty major!