Battery flat regularly

[David_Dublin]

Hi. Don't know loads about cars. We don't use our car much, but the last couple of times the battery hasn't been able to start the car. The dash lights come on, the battery has just enough power to turn the car over, but not enough for the engine to catch. Trying again, the battery is just dead.
Because there's some power left in the battery, I don't think there's a rogue light left on - it should be completely dead, given the car might be out of use for 10+ days at a time.
As I understand it, the alternator is responsible for charging the battery when the engine is in use. So it feels like its either the alternator or I need to update the battery. I have a feeling its the battery, in winter it can often take quite a bit for the engine to catch. It's a 2010 2 litre Diesel.

 

[Bronte]

Not much clue about cars, but they run down if left unused, as happened to a lot of people during Covid. How old is the battery and how much would a new one cost?

 

[Fortune]

A 2 litre diesel uses a lot of power to start. If your driving is all short journeys, the alternator won't be running long enough to replace the energy used, and the battery will run down.

 

[Sarah Ryan]

You are just not using your car enough plain and simple, as the above poster said the alternator needs to be running for longer periods of time to work effectively.

 

[David_Dublin]

We use about once a week. I reckon the issue is a mixture of short trips and age of battery. I'll replace and see.

 

[huskerdu]

We use about once a week. I reckon the issue is a mixture of short trips and age of battery. I'll replace and see.

No one here can remotely diagnose it . Take it to a garage and they can check the health of the battery and replace if required

 

[Sarah Ryan]

We use about once a week. I reckon the issue is a mixture of short trips and age of battery. I'll replace and see.

You could have faulty glow plugs either just before you replace a battery.

 

[AndroidMan]

Check if there are any lights remaining on, eg in the boot, glovebox and even interior reading lights

 

[Fortune]

We use about once a week. I reckon the issue is a mixture of short trips and age of battery. I'll replace and see.

The issue is you have the wrong car. Although it can be/was hard to get the right car that isn't a diesel second hand.

 

[David_Dublin]

That's its current use, not what it was bought for, or indeed will be used for in the future.

 

[Dr Strangelove]

My personal experience is that a battery needs replacing every 100,000km or so.

 

[newirishman]

If the battery is 5+ years or older and gives you trouble, just replace it.

 

[mathepac]

My own suspicion is that what you need is an external battery charger, run from the mains. Connect the charger to the battery the night before you need to use it to top up the power.

Another alternative is a battery booster which you charge until needed. Connect to the car battery and when the car starts, disconnect.

Be very careful about crossed wires blowing expensive electronic components. By all means, take it to an auto-electrician for diagnosis.

I agree with posters who commented that your expectations of a 2ltr diesel engine subject to the use you describe are completely unrealistic.

 

[Savvy]

I have a 05 Audi A4 1.8 petrol and I left it for 3 weeks over our cold snap and turned over straight away and my battery is in it since I got it back in 2019.

Sorry to go off on a tangent but I had a 2001 A4 1.9tdi that was sitting in my back garden unused from 2018 to 2020 as I had a new company car.
I faffed about and was going to sell it or sell parts of it, eventually with covid I got a car dismantler crowd to just take the car and the car turned over on the first click of the key, I didn't even think it would have started due to age of diesel fuel or battery degradation but it just goes to show. I shed a tear that day seeing it getting loaded for the car crusher!

 

[Brendan Burgess]

As the OP did not like some of the answers he got, I am closing the thread.