battery going dead

[james butler]

my battery is only lasting about two days from fully charged. anyone had any typical faults i should look at before i rip into the electrical system just as a starting point, as im at wits end having to jump the car every time i want to use it.
alternatir is def charging as ive tested it on the battery with engine on and off. get 12.3 engine off and 13.8 with engine on.
the car has alarm and imobiliser and stereo with sub. but i ran all the equipment in a golf i had before with no problems.
its a problem ive allways had with the car but is getting worse as time goes on.
james

[Mr Funk]

I'd put money on it being a constant feed from the stereo. Try taking it all out and seeing if that works.

[dozzum]

Put an ammeter in series with your battery to see what your current draw is when the engine is switched off.

With an alarm and stereo I would guess the most it should be drawing is 50 milliamps but I'm no leccy wizz.

If your getting anything excessive then leave the ammeter in series an start pulling fuses one at a time to see what is causing it.

On an old peugeot I had it was drawing 130 milli amps and turned out to be a CD changer drawing 100 of that. So it sat nicely at 30 when I unplugged it, most of that 30 was the stereo and the rest was the clock and alarm.

Good luck

[james butler]

so far i have put an ammeter in series with the battery and positive wires and found 165mA is being drawn. so went to work removing the interior bulbs and then the fuses one at a time. i found that fuse 3 was the cause of the power drain. this runs the interior lights, cigarette lighter, the clock and the STEREO!!! so next step is to remove the stereo and see if the power drain disapears. didnt get to do it today as ive been welding up a bmw alpina. but i think i know why. when i fitted the stereo i connected the memory live and the switched main live together so i can run the stereo with the engine and ignition off.
hmm thats why the switched live is called a switched live

[DT1]

when i fitted the stereo i connected the memory live and the switched main live together so i can run the stereo with the engine and ignition off.
hmm thats why the switched live is called a switched live

There's nothing wrong with that, that's what I did as well because there isn't a switched live in the stereo loom, you would need to take one from somewhere else.

0.165A seems excessive just to keep the memory in your stereo, but even that shouldn't kill a good battery in a couple of days.

[dozzum]

If your battery has 50 Ah then it will last 50 Ah/0.165A = About 303 hours = 12 days

Thats 12 days till it is fully discharged, which obviously it does not need to be in order to stop the car from starting.

That calculation is also assuming the battery provides a constant 12 V the entire time which it will not so the time will be even less.

And that's if its a decent battery in fully working order.

So your couple of days is about right.

[Nate]

i've come accross this before, when even switching the stereo off (not putting it in standby) it was still drawing power. best fix is to find a switched live to supply it with. as a bodge, you could add a switch to the permenant live that goes to the switched live input, so you can switch it off.

[ghost123uk]

We have this problem with Gills GTII with fancy Stereo head. It draws 80Ma down the permanent live (memory) feed. This is a £120 unit. On my GTS I have an "old skool" Blaupunkt unit that does not even need a permanent live feed. Even if you take out of the car it remembers it's stations with no power at all !!

How come an 80's unit can do that yet a 2011 unit needs 80Ma to store the stations and the time !

Progress huh

[james butler]

sorry for any confusion i meant the main feed which was designed to be switched off with the cars ignition, as it happens this is the wire taking the power. ive just had the stereo out and disconnected the main switched feed and left the memory feed in place and the current draw dropped to nothing. (well done nate )
so i need to connect it to a switched live somewhere.
dozzum you are right, the battery should last nearly two weeks and it did last for about a week when i first bought the battery end of last year, but as ive been using the car mostly for short journeys lately the battery has had very little time to recover. as a result the battery must be running down bit by bit each time i use it, thus reducing the amount of days i could leave it before i have to jump start it. at the moment it lasts two days.
i really need to have the battery off to give it a good charge.
according to the FAQ relay 3 pin 5 is a switched unfused live so i was thinking of getting a fused relay from halfords and connect it to switch on my main feed to the radio.
that way i wont overload that part of the fuse board and i keep the amount of wiring i have to do to a minimum........ hopefully!
cheers guys