Flashing red light

[Trebor]

Hi there fellow jazzarites,my car battery went flat on me yesterday afternoon it was ok the day before,i noticed when I locked the car the security system indicator was flashing and continued to flash,I’ve never noticed this before,could this have drained the battery?

[Steve_M]

Its normal to have the flashing security light.

[Lord Voltermore]

Yes. It could be the cause.   Not so much the light itself, but what it represents  - ie an alarm system constantly monitoring the car,

It can be the 'straw that  breaks the camels back'  if the battery is not getting much charge  due to short infrequent journeys.  Certainly over a period of a few days.   
If the drain is major  -eg from well charged to completely flat overnight  then maybe there is another cause, such as a faulty battery, or lights left on.  By lights I also mean interior lights, or the boot light not going off as it should .

I  once had a main  dealer fitted alarm system on a car.  It frequently flattened the battery due to parasitic loss.  I discovered this was the cause when I unplugged an optional extra 'shock sensor' module  ,which although hidden away, had a flashing led. Problem solved. 

I dont suggest you disable the alarm.   The occasional trickle charge, or long journey  ,may sort things.

[culzean]

Its normal to have the flashing security light.

+1,  the immobiliser red light flashes whenever car is locked...

[Trebor]

Thanks guys for the reply’s.

[nowster]

The drain on the battery is probably about 1mA at most. However, over a long period of time, that's going to drain any battery.

However, it would take about 4 years to discharge a fully charged 80Ah battery to 50% at that rate.

[Jocko]

The light might draw 1mA but a normal amount of parasitic draw for newer cars is between 50-milliamp to 85-milliamp current draw. A normal amount of parasitic draw for older cars is a reading of less than 50-milliamp.
if the battery is suspect that will flatten it over a short period of time. In fact, the internal drain on an old battery will soon flatten it. That is why I have my car permanently connected to my Smart charger.

[Trebor]

Jocko,please excuse my ignorance but is a smart charger.??

[Lord Voltermore]

Smart chargers can detect  the state of battery charge and vary their rate of charge, or stop completely when the battery is fully charged.  The better ones can be left connected for as long as you wish, maintaining the battery in good condition.

Cheaper conventional  chargers can over charge and damage the battery if left connected for too long. They may be ok for an overnight trickle charge as long as you remember to disconnect it.

But for newer cars with more sophisticated batteries and computer systems a smart charger is a better choice.

More details here    https://www.whatcar.com/news/best-smart-battery-chargers-2021/n22796

Sorry to highjack your question Jocko   

[Jocko]

Sorry to highjack your question Jocko   

Not at all. Very well answered. When I was doing 100 miles a week (sometimes a day) and the car was garaged, I didn't worry about the battery. Now that I do 5 or 6 miles every fortnight, usually just the one trip, and the car is standing out in all weather I have it permanently connected to the Smart charger. I just disconnect it when I need to use it and the battery is always fully charged.

[Trebor]

Thanks for the info guys much appreciated 👍

[Neil Ives]

I'm reminded of Allo Allo and the old lady's 'FLASHING KNOBS!'

[fatlad]

I'm reminded of Allo Allo and the old lady's 'FLASHING KNOBS!'

OOO MATRON !!