Current draw problem

[g8rvn]

I'm having issues with power at the minute, most times when i turn on the ignition, the climate control thing flashes for a bit and also with the headlights on, all the instrument lights are dimming with the stereo only at half volume on a small set up (400w amp)

I have checked the current draw and there is a contant 600mA being drawn on the 2nd big wire off the battery, (handbook says passenger cabin) when key is out and absolutely everything is turned off. The battery voltage reads about 11.8v...

What I want to know is, is 600mA the normal current draw for an ibiza?
I can stop the supply altogether by disconnecting the large black plug on the ecu under the dash (drivers side), I think this may be the BCM body/battery control module, or whatever seat call it.

Could somebody with access the ELSA possibly look up what that connector powers please?

Ive had the battery load yested and its fine, the alternator is ok too (14.4v)

 

[beezanick]

I would guess that that current draw is far too high (as I think youve gatherd). With a draw of 0.6A, the battery would be flat in a few days and if you dont drive the car for long journeys (>1hour) each day the battery will loose a lot of power needing the altornator to charge it up. This will mean the altornator cant keep the voltage stable at ~14.4V meaning the lights dimming ect.

I think that wire goes to the cabin fuese box (drivers side end of the dash) and supplys everything inside - from heaters, fans,instruments radio ect. Perhaps the best place to start fault finding is to measure the current draw across each of these fuses when the ignition is off?

 

[Nath.]

600ma is 0.6 of an amp, this is about what it takes to run a clock. your battery is probably rated at 55 amp hours so 55 devided by 0.6 is about 90 days.

11.8 volts tells me that your battery is probably OK but not in tip top condition. As said you should be looking for 14 and a bit volts across the battery with the engine ticking over (this is the battery being charged by the alternator)

All Ibiza's suffer with lights dimming with the power steering as the P/S draws a few amps. Also maybe your amp and sub draw quite a bit with heavy bass notes. You can get a large capasitor to help with this. Normally called a "power cap" by employees at Halfords because they don't know what a capasitor actually is.

 

[g8rvn]

Well i forgot to put that in my first post, I took each fuse out in turn while watching the current draw on a meter, not one made any diffrerence apart from the rado one, but that was only about 70mA drop...

When I disconnected that black plug, the current remained for a couple a seconds then a relay type click sounded and the current draw dropped to about 90mA, taking out the stereo fuse dropped it by another 70mA or so, which indicates to me that that plug doesnt 100% power the fusebox.

I should be able to fix this considering what I do, but without any drawings and stuff i'm stumped

 

[g8rvn]

600ma is 0.6 of an amp, this is about what it takes to run a clock. your battery is probably rated at 55 amp hours so 55 devided by 0.6 is about 90 days.

11.8 volts tells me that your battery is probably OK but not in tip top condition. As said you should be looking for 14 and a bit volts across the battery with the engine ticking over (this is the battery being charged by the alternator)

All Ibiza's suffer with lights dimming with the power steering as the P/S draws a few amps. Also maybe your amp and sub draw quite a bit with heavy bass notes. You can get a large capasitor to help with this. Normally called a "power cap" by employees at Halfords because they don't know what a capasitor actually is.

Yeah I understand where you are coming from, what makes me think twice though is that my amplifier is a relatively low powered one and even on a medium volume, there is still significant dimming. By fitting a capacitor would probably solve the problem but I feel it is just covering the problem up rather than fixing it?

 

[Nath.]

Why are you worried about 0.6 of an amp? as said that will take 3 months to flatten a 55 amp hour battery. Check any car and I would guess that half an amp is about right.

Personally I don't think you have a problem, my stock ibiza does this a little with a stock head unit up loud.

 

[g8rvn]

your battery is probably rated at 55 amp hours so 55 devided by 0.6 is about 90 days.

Your 90 days is actually 90 hours
And im sure I should be able to leave my car for more than 4 days without it being completely dead...

I appreciate that power is still needed to run the security ecu etc
but nowhere near 600mA, our Bentleys at work with all thier extra electrical gadgets only draw 250mA.

 

[beezanick]

Sorry Nath, but as said - 55/0.6 ~ 90, which means 90 hours. I would be surprised if it takes over half a amp to run a clock - when you think about the ones on a wall which run for months on a AA battery, this starts to make sense... Plus a lead acid should not be discharged below 50% of its capacity, so that gives a discharge time of 45 hours or 2 days.

Wiring diagrams are hard to come by for this car - I know as ive looked for them for a long time! it is possible to pick up a slightly dodgey copy of ELSA from ebay which should have the info on, but in my experience a lot of these dont work properly. I suggest in the meantime you just try and follow the wiring, although I know it is easier said than done.

 

[Paul C]

Try checking the current draw with the key out and the doors shut (leave bonnet up) and leave the car for 10 mins without touching anything, this gives the ecu`s chance to shut down to an idle state, then go check the current draw.


Also check your alternator output, make sure its charging at over 13V, anything less and I would be considering a new alternator.

Also after a decent run to charge the battery leave it half an hour to settle down and check the voltage, anything less than 12.2V and I would be considering a new battery!


Hope that helps!!

 

[g8rvn]

I'll try and get hold of some wiring diagrams before I go any further I think, otherwise I could be chasing non existent faults for ages...

Unless anybody has any more info of course