Flat battery

[Dippydog]

Went to the 960 today and found the battery had gone too flat to start it,this is after the car had sat for 5 days.battery is a Bosch S5 610A 63AH and is[I think]from 2013.Anyway it's on charge now and will be refitted tomorrow then I'll do some tests to see if it's the battery itself,the alternator[although the light goes out-not that that takes much to do]or some kind of drain that's making it go flat so quickly.

[J liddy]

Hi if the battery is about 7 years old is it coming to the end of its life?

[Dippydog]

Can't really give a yes or no answer to that.Apparently the battery had a 5yr guarantee[I've only had the car a year and a half]but I've had cars where batteries have lasted a lot longer whilst others have had them replaced under the guarantee.

[TonyS9]

If you are not driving it for a week, how often do you drive it?

If it not getting a regular charge it will damage it, especially if its a short drive like 10-15mins.

Other problems that can exaserbate it are slow charging cause by corroded copper in crimp connectors. You need to test the charging system volt drop under load, like with the lights on.

There should little voltage drop between the alternator and the battery (on both terminals). >0.3V on a cable+connectors is not ideal. 1V will lead to very slow charging.

[deeman940]

Battery probably dead mate, The cold weather will always show up a weak battery! i have had my car 5 yrs or so and it still had the battery i bought it with, Recently , i had the hazards on for 10 minutes outside a mates house and i couldn't start it. Jumped it and all was good for a week or so til i got a wheel alignment done which required the brake pedal being depressed for 10 minutes or so and same thing. needed a jump. i got a new battery the next day as i knew it was dead...mo problems since. Winter is nearly here, don't wait til a cold morning.....

[Laird Scooby]

Worth checking for things like the boot/load-space light being on (it's easy to knock the switch while leaning in), map reading lamps (especially if you've had rear seat "younger" passengers) and obviously the sidelights.

After that, i'd say your battery is getting near the end of its life. This one will do the job :

https://www.ebay.co.uk/itm/HB096-Lea...v/192434766703

You'll notice it's NOT a calcium battery, they need a higher charging voltage to get them to start charging (14.7V+) which your alternator won't put out unless you modify it. Some calcium batteries will work for a time (like your Bosch Silver has) but it's becoming more common that calcium batteries need the higher voltage.

[Dippydog]

Ran tests after it had passed the M.o.T. and it's the battery that's on its last legs.I drive the car at least once a week going nowhere in particular but for at least an hour at a time.I've taken the bulb out of the boot light[it's a saloon]as I did sometimes catch the switch putting great granddaughters wheelchair in there or taking it out again and did once flatten the battery because the light had stayed on.