battery drain

[shane55]

whilst in the process of trying to sort out power steering failure on my sisters 2001 mpi fabia anoither problem has arose which I dont think is related.

The car battery is going flat every 3 to 4 days. I am measuring a current drain on the battery of 120mA with everything off. If I break the circuit by disconnecting the meter and reconnecting it again the current draw will decrease to about 4mA which I presume is what it should be.

However operating anything electrical momentarily eg interior light or cycling the central locking will cause the draw to increase once again to 120ma at which it stays. I found that by removing a fuse, identified from the fuse layout on the fabia-vrs.com website as "no. 43 central control unit" the current draw will decrease again to 3 or 4mA.

When this fuse is removed however, windscreen wipers,indicators, some instrument panel indications do not work. Also when this fuse is removed the central locking cannot be locked with the key fob although it will lock by using the door key. Strangely, with the fuse removed, the central locking can be opened with the key fob as well as the door key. The key fob also operates an alarm which I think was fitted shortly after the car was bought which operates normally with or without the fuse removed.

Anyone know what might be causing this?

Thanks

[Rob.]

What happens if you leave it an hour and then test the drain? Or is this what you've been doing?

I would imagine the central convenience unit stays live, or in a sleep mode for 10-30minutes or something because the windows still work once the car is locked and the radio will turn back on with in this time to.

How old is the battery, could it just have gone duff at the same time?

[ap0gee1978]

My money's on the battery - both our Fabias have had new one in the last year!

And right enough, the central convenience module stays live for a while after you switch off the engine like relex88 says. Best bet with that is to leave the bonnet popped and the alarm off for an hour or so (if it's safe to do so), then test it once the CC unit's timed out...

[shane55]

thanks ap0gee and reflex 88, I'll leave the meter on an hour or so tonight and see does the current draw decrease, the battery isnt old though, about 2 1/2 yrs

[shane55]

I tried that and the current did drop back down after an hour, was wondering would it be anything to do the with the dead power steering pump somehow preventing the battery being charged properly???

[ap0gee1978]

Could be. Could also be a problem with the exciter cable - try a search!

[shane55]

whats the minimum recommended capacity battery for the fabia ???, Ive just read on another thread that the power steering pump draws 60 Amps!

[TriggerFish]

I think its 66 (or there abouts). I think some people have ended up with 44 fitted instead which has casued issues.

[Soot1e]

There are so many electric gadgets in a VRS to test but 1st. I would check the battery, is the electrolyte topped up? or if it is over 5 years old it's worth changing.

[MoggyTech]

Battery should be 75AMP type.

[shane55]

Battery should be 75AMP type.

is that for Vrs or any fabia? sounds very big for a small car

[MoggyTech]

is that for Vrs or any fabia? sounds very big for a small car

VRs diesel. I believe the 1.4 petrol engines use 66Ah.

[AndyPandy]

Shane55 mentions 'Power Steering taking 60 amps!.'

Dont forget when the car is being driven,the Alternator is able to put out anything from 50 to 120 amps max ,at the same time. The Power Steering current ,and any other currents, including recharging the battery, are being supplied by the Alternator. The only time the battery supplies power is to start the car (huge current 250 to 400 amps for parts of a minute) ,and radio ,lights, etc(very small current) when engine is not running. Problems arise when the Battery ampere hour capacity reduces due to quality,age ,and temperature.

[shane55]

Shane55 mentions 'Power Steering taking 60 amps!.'

Dont forget when the car is being driven,the Alternator is able to put out anything from 50 to 120 amps max ,at the same time. The Power Steering current ,and any other currents, including recharging the battery, are being supplied by the Alternator. The only time the battery supplies power is to start the car (huge current 250 to 400 amps for parts of a minute) ,and radio ,lights, etc(very small current) when engine is not running. Problems arise when the Battery ampere hour capacity reduces due to quality,age ,and temperature.

not quite true, if for example you are parking the car on a winters night with your heater fan on, Lights, heated rear window and mirrors. the pump is going to draw 60 amps, one headlight bulb will draw about 4 amps, total current draw could be in the region of 100 amps. the alternator isnt going to supply that at engine idle so the battery has to make up the shortfall

Edited 27 May, 2009 by shane55

[shane55]

I tried that and the current did drop back down after an hour, was wondering would it be anything to do the with the dead power steering pump somehow preventing the battery being charged properly???

I disconnected the failed power steering pump and the battery has been ok for 2 weeks

[AndyPandy]

Shane55,OK , you are suggesting the worst case ,winter, heater etc, which does not occur very often in one year of driving . I believe the term 'Diversity' springs to mind -in house electrics for example ,we could not,and would not plug a 13 amp load ,into every socket we have ,and expect the 80 or 100 amp Company Fuse fitted to survive.I agree that the battery will supply the shortfall,but as soon as the engine goes above say 1500 revs, 100 amps or so will be available, to supply the load,and any extra to recharge the battery. After all the Manufacturers ,could fit a larger capacity battery ,but the cost would be greater, and as proved over many years would not be needed. Another thought- If you were parked ,the Steering Pump would not be running?

[shane55]

while parking, not parked, the steering is used alot