How long for a fully charged car battery to drain....
31 January 2008, 01:32 PM
#1
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How long for a fully charged car battery to drain....
....when interior light has been left on?
Had a funny thing happen yesterday. I went out early afternoon to a meeting and had my car parked next to my wife's Suzuki Jimny (back to back). When I got back at around 6.30pm and parked up again in same spot it was starting to get dark and I noticed the car interior light was on in my wifes car.
I went and had a look and the drivers door was not totally shut properly but door was locked and couldn't be opened.
I went indoors and told the Mrs but she said she hadn't driven it all day...and it was parked against the kerb at same angle as when I left. I checked inside and nothing had been touched...drivers seats forward to suit her height, nothing nicked etc.
Just wondering if an interior light would stay on for 24 hours without flattening the battery (car started fine) because this one is very odd...either light had been on 24 hours and not flattened battery else someone had been in car without damaging lock, taking anything or moving seat and then locked car afterwards?
R
Had a funny thing happen yesterday. I went out early afternoon to a meeting and had my car parked next to my wife's Suzuki Jimny (back to back). When I got back at around 6.30pm and parked up again in same spot it was starting to get dark and I noticed the car interior light was on in my wifes car.
I went and had a look and the drivers door was not totally shut properly but door was locked and couldn't be opened.
I went indoors and told the Mrs but she said she hadn't driven it all day...and it was parked against the kerb at same angle as when I left. I checked inside and nothing had been touched...drivers seats forward to suit her height, nothing nicked etc.
Just wondering if an interior light would stay on for 24 hours without flattening the battery (car started fine) because this one is very odd...either light had been on 24 hours and not flattened battery else someone had been in car without damaging lock, taking anything or moving seat and then locked car afterwards?
R
31 January 2008, 01:41 PM
#2
Depends on the ampere hour the battery can supply. So for example, if your car battery can supply 100 ampere hour and a current drain of 25 amps was being drawn then your battery would be flat in 4 hours. There's the theory, but in practice many factors determine the battery life.
31 January 2008, 01:56 PM
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I am sure the car battery would power a dinky little interior light for a day or so. Now leaving headlights on is a different matter. I guess the light was on 'cos the door wasn't closed properly? dl
31 January 2008, 02:07 PM
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As above: its down to battery size and bulb wattage; Say the battery is 60amp hours (fairly large).
Caravanner/campers will know this off the back of their hand (or they should if they run a mini-fridge
)
Its useful capacity so that it can still start the car would be around 30Ah (50%)
A single interior lamp is about 10watts which is about 1.2amps
1.2amps divided into 30Ah is 25, so thats 25hours. And still being able to start the car.
That's a bit half-arsed maths because temperature, battery condition and battery type (low current deep discharge vs high current stater batteries), will have a factor in this as well.
In reality, I have an old 65Ah sealed battery which I use to run my 4 amp cooler box whilst camping. Which gives about 12hours of cold beer.
Caravanner/campers will know this off the back of their hand (or they should if they run a mini-fridge
)Its useful capacity so that it can still start the car would be around 30Ah (50%)
A single interior lamp is about 10watts which is about 1.2amps
1.2amps divided into 30Ah is 25, so thats 25hours. And still being able to start the car.
That's a bit half-arsed maths because temperature, battery condition and battery type (low current deep discharge vs high current stater batteries), will have a factor in this as well.
In reality, I have an old 65Ah sealed battery which I use to run my 4 amp cooler box whilst camping. Which gives about 12hours of cold beer.
31 January 2008, 02:22 PM
#6
Scooby Regular
Thread Starter
As above: its down to battery size and bulb wattage; Say the battery is 60amp hours (fairly large).
Caravanner/campers will know this off the back of their hand (or they should if they run a mini-fridge )
Its useful capacity so that it can still start the car would be around 30Ah (50%)
A single interior lamp is about 10watts which is about 1.2amps
1.2amps divided into 30Ah is 25, so thats 25hours. And still being able to start the car.
That's a bit half-arsed maths because temperature, battery condition and battery type (low current deep discharge vs high current stater batteries), will have a factor in this as well.
In reality, I have an old 65Ah sealed battery which I use to run my 4 amp cooler box whilst camping. Which gives about 12hours of cold beer.
Caravanner/campers will know this off the back of their hand (or they should if they run a mini-fridge
)Its useful capacity so that it can still start the car would be around 30Ah (50%)
A single interior lamp is about 10watts which is about 1.2amps
1.2amps divided into 30Ah is 25, so thats 25hours. And still being able to start the car.
That's a bit half-arsed maths because temperature, battery condition and battery type (low current deep discharge vs high current stater batteries), will have a factor in this as well.
In reality, I have an old 65Ah sealed battery which I use to run my 4 amp cooler box whilst camping. Which gives about 12hours of cold beer.
R
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