A battery related Q - is this normal?

[Martin J]

As mentioned before, heated screen draws several amps.

 

Your first journey home sounds like mine when I picked up the car post SVA,

In the dark, raining cats & doges & stuck on the M25 with lorries around me.

It does get better Tom.

[Guest]

Quoting oldbutnotslow: 

Just for reference a fully charged battery after standing for 1 hour without charge or load should give a reading of 12.65 volts

Idle charge should give 14.25 volts

If it discharges as you have described either there is a fault with the alternator:- belt lose or the alternator charging side internally is faulty or the battery is US

 

Hmm, I don't think I'm getting as much as 14.25v at idle although I did the test previously on a warm engine which made it difficult as the fan kept kicking in. I'll do the test again and see what readings I get.

[Guest]

Quoting Martin Jeffrey: 

As mentioned before, heated screen draws several amps.

 

Your first journey home sounds like mine when I picked up the car post SVA,

In the dark, raining cats & doges & stuck on the M25 with lorries around me.

It does get better Tom.

 

What would be the easiest way to tell if mine is indeed on and effecting things. Is there a switch on the dash that turns it on or is it permanently on when the car is running?

 

I haven't got the car with me to look at.

[Stationary M25 Traveller]

Heated screen is switched by a switch on the dash. Looks like a tintop heated rear sceeen icon on the switch.

[Smiffy69]

I had a similar problem with mine. Slow when cold cranking but would start then a short drive to the shops and it would not start afterwards 😔

 

It also would cut out on a long drive then not restart with no lights or heater etc running as it was a sunny day.

 

In the end it was 2 problems. The engine cutting out was due to a poor earth to the immobiliser which was causing it to cut out and requiring a reset. The non-starting was due to a knackered banner battery (only 2 years old !) I tested it by disconnecting from the car, fully charging and then taking voltage samples every couple of hours. Sure enough with no load on it the voltage would decay away over a couple of days down to about 11.5V.

 

Bunged in a new battery and it’s been spot on ever since. Noticeably better when cold cranking and spins over like a dream now.

 

[Guest]

Thanks for that, sounds like a good easy test to do. Might try that this weekend to see how well it holds a charge.

 

Although a new battery it may have been sat around for ages for all I know.

 

Tom

[Stationary M25 Traveller]

Aren't we all missing one vital point. If I understand this correctly, you just got the car from CC days ago. Don't prat about trying to sort it out ..... take it back !!!!! Especially as you live so close to their Crawley facility.

 

Warranty warranty warranty 🙅🏻‍♂️

[Martin J]

I agree, get them to sort it, you have spent a shed load of money with them.

I think a an alternator should be more than man enough to cope with current drain on tick over but for it to work efficiently it has to have a minimum voltage (not sure how much) powering it's field otherwise it won't work.

Dymamos are different & will function even with a dead battery. On my old mini fitted with a lucas dynamo you could disconnect the battery with the engine running & it still kept running!

My money is on a duff banner battery, ask for a new one.