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Hi
My alfa 147 JTD seems to have a battery discharge problem. Bought a new battery about 2 weeks back, and the starter seems to be taking longer and longer to start the engine.

This has happened before (the batter that I had to replace was itself not very old). Most suggestions are that the body computer is failing somehow - and that the lights are receiving some power, I checked this in a dark garage and saw no light at all. Any of you have any suggestions?

Regards

T
 

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1) get your battery checked out by someone other than the person who you bought it from
2) get your alternator checked by the same place as above
3) check all your ground wires for corrosion, you're at the sea, so expect some
4) check all terminals for "white rust" build up on terminals - clean off with warm water and bi-carb then rinse with boiling water
5) get the car to an auto-electrician to check for voltage drain

All that said, you haven't given us much else to go on, do you have anything aftermarket in your car? radio, sound system, alarm, anti-hijack, tracker, etc. More info the better we can assist.

Good luck :thumbs:
 

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Put an ammeter on the battery (in series) with everything turned off. If there is current flowing, pull fuses one by one until you identify which circuit is drawing current.

Alarm and trackers etc are the usual suspects.
 

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Alarm and trackers draw current as well as clocks, radios, ecu's, amplifiers and what-not, but shouldn't pull enough current to cause your battery to steadily drain without recharging in under 2 weeks. Your car should be able to stand for 2 weeks before requiring a jump start.

Know this: New batteries can be supplied with up to 14.4V between terminals.
Alternators supply max 13.8V
Your battery is considered good and charged if it still contains between 12.3V and 12.8V, which is where it will spend most of it's life, and showing 13.8V when the engine is running. The starting voltage during this period is a good 1.5V to 2V down on a new battery's voltage.

Consider this:
A diesel requires a lit more current to start than a petrol, due to much higher internal friction levels due to heavier components (pistons, cranks, etc), and pumping losses due to higher compression.
A diesel's battery is usually rated much larger in capacity than a similar petrol powered vehicle due to the staement above, as well as having to usually supply glow plugs with enough current before then having to crank the engine as well.
For the same reason a diesel car's alternator is rated at a higher capacity, to be able to keep the bigger battery happier, as well as delivering higher output at lower revs.

Your starter loses efficiency as the vehicle ages due to wear and electrical aging. That can be a reason for slower cranking as well.

Once you are happy that your amplifiers are not drawing too much current, your battery is exactly the same as required, your alternator is providing the juice to keep the battery happy and your starter motor is fine, then start searching for electrical faults.
 

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Hang on, you're driving and using the vehicle? Or it stood unused for 2 weeks and didnt start?

If you have been using it during that period and its loosing charge, it isint charging properly.
Could be a dodgy alternator or regulator.
 
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