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How to check for draw on battery ???

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battery draw
4K views 7 replies 4 participants last post by  lizzard-t 
#1 ·
Ok you techno wizards . I've got a 1.9 tid 2005 vector sport 120 manual
And I think I'm suffering battery draw from somewhere , I just want to know how to Che k for a draw .
This has only happened since my turbo went ( coukd be a fluke but just thaugt I woukd add that )
I first noticed it 2 days after the event ( battery was slowly going flatter )
Until, it was kaput .
So just left it
Got it all back together , charged the old battery and found it was cranking over slowly .
So got new battery and all was well .( also new alternator ) Used it over the weekend no truble
Went to start it the other night ( wendensday) and just a click !
Charged it over night , and Started fine . ( Thursday )
Been at work all day , came home and it was just a click !
I've taken the battery off to recharge it , but whilest doing that I found that the bonnet alarm trigger switch was unplugged . Now I don't know if that coukd cause battery drain ?
Anyway I've checked the simple stuff ( lights and amp and such like ) all ok .
So at the mo the battery is on charge , I just want to know if it's a duff new Battery or do I start pulling fuses .
So if anyone has any pointers as to how to Che k for battery draw I would be very greatful
I'm a bit wobbly with electrics so take you time
Many thank
Paul
 
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#2 ·
pull the battery cables, take a reading, compare to reading with battery connected. there should be a slight variation due to the alarm and certain other draws but not much difference. i am sure someone will tell you and also you can pull the alarm fuse to see what diference it makes.

it could be a dodgy earthing strap/earth or even a faulty new battery - it happens.

good luck.
 
#3 · (Edited)
First of all eliminate the battery by fulling charging it and taking it to Halfords for a load test.

After that it can only be something that is wrong with the car ie alternator or drain.

When running do you measure 14v at the battery? If not then suspect the alternator or cable.

Testing for a drain it isnt easy, but the only way is to identify the circuit that is contributing the drain so first up you need a basic multimeter.

You need to work systematically and this can take a lot of time.

A quick rough and ready test is to measure for voltage across each of the fuses...if there is any current flowing then you will get a low mv reading.

https://www.youtube.com/watch?v=T6rDTtxaeJ4

This helps pinpoint the offending circuits and you work down stream from there pulling fuses.This should give an idea of where the problem lies.

Unfortunately the car has lots of electronics (alarms/ecu/transponder etc) which go to sleep and wake up etc depending on the status of the car.
This then draws current and hence this also varies with time. eg Opening a door wakes stuff up and draws current from the lights etc.
If you are working on the fuses in the cabin then blank the door switches for obvious reasons.

Next stage would be to fit an ammeter (20A fused multimeter say) in series with the battery on the ground side and you also need
a battery isolation switch also to avoid continually blowing the 20A meter fuse.

You can buy all the bits you need to do the testing for around £30.


http://www.ebay.co.uk/itm/MASTECH-M...613790?hash=item46321f299e:g:tnMAAOSwWKtUt3Do

http://www.ebay.co.uk/itm/Car-Van-B...823743?hash=item2a3875157f:g:tX8AAOSwajVUM6PX

With this setup you can mount the meter externally to the car (say on the bumper) and then monitor what happens to the current draw
when you lock the car...the current will drop in stages as various parts go to sleep.Typically on sleeping car you shouldnt have more than
5-10mA.



I battled with this for about 2 years with a 9-5 before I decided to spend a weekend investigating things and didnt want to fork out a fortune for an auto electrician.

My problem turned out to be an incorrectly mapped ECU which meant the evap purge valve was continuously on giving about 100mA leading
to a dead battery over say 2-3days.
 
#5 ·
hi mate have you checked yet if you are getting close to 14v at the battery with engine running as suggested above

it is possible at idle you only get just over 13v that's fine but buy holding revs at 2k you should get nominal 14v

if all ok with that start turning high current draw items on such as main beam heaters etc which should see an output around 14v

do this test both at the battery post and the lug which should so minimal if nothing difference

then go from there

what alternator did you buy ?
 
#6 · (Edited)
Hello Kez so far I've run it at idle with no load and I'm getting 13.95 v .
Have not tried it with heavy load items yet .
This maybe me being a bit lateral in my thinking , but this draw started after the turbo went , and due to oil getting into the intercooler hoses the car was crying oil . So I'm thinking that some oil may have got into a connector . But that's just me thinking .
And I remember the battery went flat after a few days of sitting there looking sad for itself .
Which I thaught was odd but at the time I just left it .
the alternator I got was off a alternator seller on that well known auction site .
 
#7 ·
worth checking around area work was carried out, they could have undone some connectors thus as you say oil got in, its also worth checking for any pinched cables depending on how carried out the job

any reason the alarm bonnet switch was unplugged was it down to the repairing garage or was it like that before. I take it you have reconnected it, also was there any messages on the sid relating to this ?
 
#8 ·
Hello Kez , I was a brave ( and stupid ) enough to carry out the whole repair myself . All went well !.
Though I do remember when I was under the car on the back of the A/C compressor THERES a plug and there was some evidence of oil on the back off it , and I remember thinking " I should clean up that aera and take. The plug apart " , but you know what ................ I forgot ! :crazy: so at the week end I'm going back under .
Also the bonnet switch unplugged ......... Well when I moved the positive battery lead out the way of the battery , the only way to stop it reconnecting. Itself is by tucking it behind that switch .
No warning messages .
 
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