I haven't used my car for several months and now the battery is absolutely dead.  If I am able to recharge this battery, will I already have lost the radio code?  If yes, is there a free or cheap way to retrieve it?

Edited 14 July, 20196 yr by harry vederci
Clarification

Radio will be fine, battery may not.

19 hours ago, Wino said:

Radio will be fine, battery may not.

 

And if the battery needs replaced?

Replace it. The radio will talk to the other modules when power is restored, its identity will be checked and Ok'ed, and normal service will resume.

Great, thanks.

 

I was sure I'd seen other threads where people had to get the code (at a price) from the dealer after a DIY battery change.

No need for the code unless you swap the stereo...

If you remove, clean and give the battery a very slow, long charge, you MIGHT revive it but most sites like Eurocarparts and/or Carparts4less, will have heavily discounted batteries which they deliver free and usually within a few days.

If you choose one with a long warranty and use the relevant discount code (They always have one somewhere), Charging a half dead battery is most likely a false economy anyway! Keep the old one if it keeps a slight charge, to use temporarily, every time you want to remove the new one to top up its charge. I find charging them up fully once every six months or so, helps keep them healthier then just relying on the alternator to keep them charged. 

They tend to go downhill slowly over time and often, you will have only around 50-75% charge in the unit. Under 50% you will get faults or problems with the electronics.

The battery is wrecked.  After five conditioning cycles it gave an error code showing it is sulphated and not recoverable.  Like for like replacement is coming tomorrow.

Excellent service from tanya.co.uk, the battery (Varta E39) arrived less than 24 hours after ordering and my car is now back in action.

Correction to my previous post, the battery company is tayna.co.uk

For future information, standard vehicle starting batteries never like being totally flattened as they have very thin plates in the cells and the build up of sulphate cannot be removed even with clever chargers, once fully flattened damage is already done.......

 

this is why deep cycle / leisure batteries are ok going fully flat and are recoverable with charging and used for running loads when the vehicle charging system is "off".

Edited 18 July, 20196 yr by UrbanPanzer