Battery problem

I have an intermittent problem with S80 T5 diesel(NOV 99 66K). When problem arises, battery shows completely flat, clicks sound and clock display shows --:--.Car jump-starts easily and shows no further symtoms. The shortest period between car usage that this has occured is 3Hours. A similar problem occured after only 20 minutes sitting in the car with radio on and sidelights on. Is this a common problem? I have had the battry checked and tests "GOOD 90%". I sometimes get an error message which says"position bulb failure ",what is a "position light"? Thanks for any response to this annoying problem.Otherwise the car is beyond critism.

[Paul Wildsmith]

If its the original battery, then it's past its best. With the S80, turning the ignition on the 'accessory' position powers up all its electronic systems, and 20 minutes is not untypical of then having a low battery.

Position lights are front/rear side lights.

Paul
VOC S80 Register Keeper

I will purchase a new battery today, and see if that solves the problem. Thanks for your reply, will post further if still unresolved.

Be aware that the extreme cold that we've experienced recently gives the battery a real pounding, so if the battery is weak at all then this will give the symptoms described. When purchasing a battery, always aim for the largest amperage that you can afford or the car can take, say, if the battery is a 55amp then try and go for a 75amp if possible, staying within the dimensions of the original battery. What has happened here is that the manufacturers have found a way of installing an extra cell or two in the same casing. Where it benefits you, is that you're safe in the knowledge that in extreme cold, you've left your lights on say, and then you go to start the car, you'll have perfect cranking power to turn the engine over without worry. The extra amperage allows for the running of heaters, wipers, rear demister, lights etc and still has the power to turn the block over.

Hope this makes sense and helps.....

Regards
Dave M