battery power reading 10% in the morning .

[Ross montgomery]

Hi all 

My car is an audi A6 2.ltr tdi 54 plate . Having had a problem for the last 3 months when I get into my car in the morning and finding it at sometimes 10% or totally flat I decided to put it into my local garage for a week of full testing to try and find the fault . I have used these guys for years and they do my whole families cars so fully trust them . The lads having ran full diagnostics etc decided to change the battery under warranty . Having had the car for a week, as i said, they ran every test they could to try and find the fault. They couldn't find a fault with anything after trying and testing everything imaginable. Now having had the car back I find even leaving the car unlocked through the night the battery reads 10% in the morning . Any help or advice would be greatly appreciated.

many thanks 

[Magnet]

Hello Ross,

Irrespective of the old battery reading being low, did the car actually start OK? 

Also does the car start Ok with its new battery? 

Kind regards,

Gareth. 

[Ross montgomery]

Hi Gareth 

yes the car starts at 10% , but I have been advised that a battery that size shouldn’t start at that level . 

[Magnet]

Thanks Ross. Now you will have to pardon my ignorance, but what actually reads 10% on your model? A battery condition/efficiency gauge? 

Irrespective of what this reading indicates, if a battery reliably turns the engine over at a speed adequate to start the car, then we must suspect the ‘gauge reading’ rather than the battery itself.

Kind regards,

Gareth. 

[Ross montgomery]

Hi Gareth 

when you press car on the console you have a list of settings , you go down to battery level and it reads 0% to 100% . In the morning when I go into these settings mine reads 10% . 

[Magnet]

Hello Ross,

Logic would suggest that the reading is incorrect. Possible to recalibrate it via. plugging it into some sophisticated kit? 

Kind regards,

Gareth. 

[Ross montgomery]

Maybe, but when it hits 0% after the car has been locked , it won’t start . All the locking system has also been checked , immobiliser etc etc . 
Thanks for your help 👍🏻

[Ross montgomery]

Ok last night I checked the car before I went to bed , battery power read 100% . Car unlocked , nothing on . Get into the car 9am this morning the battery power reads 10% 😡. Could this have anything to do with the electronic handbrake as that was the only thing on . 

[Magnet]

OK Ross - the story has now changed from the car starts, to the car doesn’t alway start.

Different diagnosis then! Detail is king when trying to diagnose anything at a distance. 

So indeed it sounds as if something is wrong, and the indicated efficiency is probably not at fault. 

If this were mine, I would be getting the car checked for a parasitic drain i.e. checking what current the car battery is drawing when the car is fully locked up and immobilised. This should be measured after at least a minute after the car has been locked up, to ensure the system has ‘set’. Ideally, the current draw should be not much over 50mA. I would not be entrusting this to a local garage, but to a trusted local auto electrician. If the current draw is more than that, then it’s a question of isolating each circuit in turn until the offending circuit is found. More detail later if necessary.

Kind regards,

Gareth. 

p.s. ‘......changed battery under warranty..’. What make battery was the ‘old’ one, and what make has now been fitted? 

[Ross montgomery]

Hi Gareth 

thanks again great advice . My headache is when it’s locked up it goes flat and won’t start without a jump . When unlocked with handbrake on it drains to 10% but will start . Tonight I’m gonna disconnect the battery before I go to bed as the car will be sitting at 100% . Re connect in the morning and see the result . The battery in the car at the moment is a YBX 3000 12v 95Ah 850A , same came out . 
thanks again 👍🏻

[Magnet]

Hello Ross, 

Battery make? 

If the battery retains its voltage when disconnected, then you have a parasitic drain, and I would strongly advise using the services of an auto electrician to find the offending circuit - unless you are equipped with the knowledge (and suitable meter) to do it yourself. 

Kind regards,

Gareth. 

[Steve Q]

29 minutes ago, Soniabailey said:

Strange I have such a problem only in winterStrange I have such a problem only in winter

Cold weather puts more strain on a battery and saps it's energy quicker as well as a cold engine is harder to start.