New battery - did I really need one?

[V6Leaper]

2011 XF 3.0D Premium Luxury - December last, I attempted to start the car but there was no response to pressing the start button.  A light on the instrument panel (I think red) advised me that the battery was flat.  As I had owned the car for a couple of years and wasn't sure how old the battery was, I bought a new one and plonked the old on my garage bench.  A couple of weeks ago, I had the exact same fault light show and engine not turning over.  I was suspicious that my battery wasn't dead (we are in May so temperature is well up)!  I took off the battery and replaced it with the original one from my garage bench which had been charged once in those 5 months.  Started straight away and has continued every day since!  The only thing that I did was to rub the terminal leads with fine grade wire wool as there was a very slight build up of lead sulphate or corrosion (not at all excessive I must add).  However, cleaning the terminals may have helped the flow of current to the sensitive electrical system on my XF.  Hopefully I will be fine now but I am a bit disappointed that back in December last year, I never thought to check for any build up of lead sulphate before fitting new battery.  If I had wiped any build up from the battery leads at the time, I might not have had to buy a new battery!  Or could this be something else?  Any known faults?

Has anyone else done what I did and bought a new battery just because you thought yours was dead?  This phenomenon has made me think, how do we know when a battery is actually beyond use? The guy in the battery store tested the battery and (no surprise as it was flat) told me it was dead probably a bad cell!  Well I know the present temperature will make a huge difference to starting so bad cell or not that battery is holding charge and again back on the car.  I intend keeping it on until at least the autumn when I will ask for another test for "dead cells"!

 

[JOE-DOT-COM]

Hi

A bad terminal connection would cause it

only way to no for sure is put a multimeter on it and see what current drain is on there, then you can work out how long the battery will last

also if you car is going to sit for more than two weeks, I'd get a trickle charger for it, the electronics on these now days will drain a battery over a period of 2 to 3 weeks

I bought a Jaguar one, but CTEK make the exact same unit for half the price

cheers

Joe

[V6Leaper]

As I don't do a lot of miles I probably would benefit from a trickle charger Joe.  In fact, I will look into it how/where the inlet could go right away.  Cheers

[Leo]

I have been using a CTEK for the last three years, since my XK is not my daily drive. It works a treat, and the knowledge that the battery is always fully charged is very comforting indeed!

[Daveboy916]

Hi i had a new battery fitted because my old battery was on its way out it was 7 years old so done its job and you have too tell your ECU that you have a new battery had too do the same when i had my BMW .