Query about battery on a car....non-boaty!

NealB

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I've got an oldish Jaguar X-type, 3.0 sport, that is used just for fun.

If it's left for a couple of weeks, the battery is flat.

A local garage has tested the battery and alternator, and assure me everything's fine.

They also measured a discharge of 0.2A with everything switched off, and the car locked.

They tell me that is normal, but it seems high to me. That's 4.8AH a day, so nearly 70AH over a fortnight....no surprise the battery is struggling.

Any views on whether that is a 'normal' discharge rate?

If so, what do I do....are those small solar panel things worthwhile, or should I fit a master switch for when it's left?

Any ideas welcomed.
 

Spyro

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Try and find out where the current draw is coming from. Fit an ammeter in series with the main feed then start pulling fuses until the current draw drops. that's your faulty circuit. It may be something you can do without.
 

Trundlebug

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It must be one, or a combination of:-
-Alarm Circuit (sensors waiting for a plip)
-Clock
-Alternator diodes faulty? they can leak back and discharge quite a bit when they've had it
-courtesy light left on or stuck on somewhere e.g. boot, glove box, or somewhere not very obvious.

I would try isolating all the above circuits first to see which it is.

Good luck!
 

elton

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Just fit one of these to the dashboard to isolate the battery

images
 

Avocet

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You have to be a bit careful with modern cars (and I include that one in the term)!

As has been said, pulling fuses out to see if it stops is a good idea, but lots of cars these days have a "sleep" mode, so the 0.2A might not be a 24/7 thing. You might find that it only allows that for about half an hour or so and then goes into "sleep mode" where the current draw will be much less.

Disconnecting the battery is a pain because it will stop the clock and also cause your various "computers" to loose their memories. At best, it will be all the "adaptive" bits and fault codes stored in the engine management system. At worst on a fancy car like that, it could be electric seat memories and all sorts!
 

Fantasie 19

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I know nothing about cars (and precious little about boats) but a long time ago my missus had a similar problem with her Mini which turned out to be a duff earthing strap... worth checking?
 

NealB

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You have to be a bit careful with modern cars (and I include that one in the term)!

As has been said, pulling fuses out to see if it stops is a good idea, but lots of cars these days have a "sleep" mode, so the 0.2A might not be a 24/7 thing. You might find that it only allows that for about half an hour or so and then goes into "sleep mode" where the current draw will be much less.

Disconnecting the battery is a pain because it will stop the clock and also cause your various "computers" to loose their memories. At best, it will be all the "adaptive" bits and fault codes stored in the engine management system. At worst on a fancy car like that, it could be electric seat memories and all sorts!

Good points, well made....thanks!
 

rafiki_

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It sounds about right for the residual current draw. I expect a car to loose its charge in 2-3 weeks. You could phone Jag technical help and ask if this residual is right.
 

2Tizwoz

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Is it simply that the battery is getting old?

I have the same car, 2004 original battery, but after occasionally standing for a fortnight it starts with no apparent problem.

Apparently the current is supposed to be less than 30mA. Your 200mA is high it seems.

The Jaguar service information is below:-

BATTERY CARE MANUAL

Published June 2002 by Service Communications Jaguar Cars Limited Publication Part No. JTP875 17
BATTERY CURRENT DRAIN TYPICAL VALUES
The battery drain should be measured (see page 16 using WDS where available) with the vehicle in the double
locked armed state (i.e. vehicle alarm fully armed), with all doors and other body apertures either closed, or
latched so as to appear closed from an electrical point of view.
The test should take place after the vehicle has entered shut-down mode. The time taken for this to occur after
key-off varies according to model. (Refer to the table below)
Note: That when the vehicle is armed, the effect of the LED flashing is to cause a pulsation in the measured
current drain. In this case, either the time average current should be taken, (using a meter with an averaging
function), or the current reading should be taken, ignoring the brief high current peaks.
The current drain after the initial shutdown period, should not exceed the value shown in table.
Note: * Further drop after 72 Hours, to 30mA, but this would not be part of the standard test.
Note: The total current drain will be higher if certain Jaguar approved accessories (e.g. Tracker; Cool bag;
Trailer Tow Module) are fitted.
Model Shutdown Period (Mins) Typical values Battery Drain (mA))

X-TYPE 30 <30.0

VEHICLE QUIESCENT CURRENT TESTING

If an open circuit voltage test gives a result in the region of 12.45 to 12.49 Volts it is recommended that you
ensure the battery isn’t slowly being discharged by an electrical consumer that is remaining on after the
vehicles shut down period (see page 17 for typical shut down periods) Like wise if a customer complains of a
vehicle battery that discharges continuously or when left for a prolonged period of time it is recommended
that you perform a quiescent drain test as described below.
Method of Measurement
In order to correctly measure quiescent drain, it is preferable to use WDS with the current probe attachment.
If this is not possible, then an ammeter may be used. Whichever method is used, technicians MUST adhere to
the following procedure:-
Using WDS with current probe:-
– Switch off all electrical loads & remove the ignition key.
– Connect current probe to WDS.
– Calibrate the probe.
– Clamp around the battery lead / fuse box lead.
Go to test results.
Using a multimeter rather than WDS:-
– Disconnect the battery negative lead.
– Connect the ammeter between the battery negative post and negative lead using clips.
– Select high meter range (i.e. equal or more than 10 amps) then switch the multi meter on.
Goto test results.
Test results (both methods):-
– Switch ignition ‘on’ then ‘off’ (DO NOT CRANK) and remove the key.
– Close or latch all doors and remove any other potential electrical consumers.
– Observe / compare the readings obtained over the time scales identified on (see page 17).
– Enter the reading obtained on to the battery report form (see page 13).
Note: The preferred method of testing following an excessive current consumption figure is to use the clamp of the ammeter around individual fuse box leads to the various suspected circuits to identify a potential cause.
Rather than the old method of pulling fuses out, in a one after the other fashion.
The main reasons for using the current probe to determine which fuse box/circuit the drain is going through is that:
a) Many modules take a considerable time to power down, every time the fuse is removed and refitted, the quiescent drain figures will need 45 minutes to reset.
b) Sometimes the drain is caused by a module “holding on” to something that has been switched off. Sometimes it is only a relay winding that is activated. Pulling the fuse can allow this to “reset” and the drain will be lost and undiagnosed. Similarly, if for example, the headlights of an S-Type are switched on, removing the switch input will not turn them off. Therefore the reading obtained would be incorrect and could mislead.
 
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vyv_cox

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0.2A doesn't sound too unlikely to me. The only one I know for definite from boat use is the radio. The permanent connection on my Sony takes 0.06A. On top of that there's a clock and several computers, the more expensive the car, and the more memories, the more computers.
 

rotrax

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Hi,a freind at work had the same problem. I suggested an inexpensive switch to isolate the battery when not in use and all is well. Apart from the already mentioned likely culprits for current draw when not in use I found the dash had a couple of Liquid Crystal Displays that were drawing current as well. Technology is OK but........
 

SnippyDog

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If you don't want to lose stereo/computer memory etc..

the c-tek (and probably many others) chargers come with a handy 2-pin connector - you connect a small lead (with a weatherproof connector on the end of it) permananently to your battery terminals.

When you're leaving the car idle, you lift the bonnet and plug the charger lead into the connector on the car. The charger is designed to automatically go into maintenance mode when the battery is fully charged, so it won't boil or overcharge the battery.

I use one for leisure batteries, you can leave it for a few days without worrying - it's designed to switch off if the battery develops a fault.

http://www.ctek.com/EN-GB/consumer/Car.aspx

Hope this helps
 
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