I have had this issue for about 6-12 months now, where now and again when i start the car the split second my 04 WRX STi starts up the alarm tone will sound for a brief second.

I dont use the car every day and it may sit for up to a week sometimes without being moved, in this instance the battery will appear to be completely flat, i say 'appears' because if i hook up my CTEK charger for approx 2 minutes disconnect it and try and start the car and it will start, so the battery cant be flat otherwise a 2 minute charge wouldn't produce enough charge to start the engine surely???

When i took it for its service in the summer i ask them to check the battery and they said the battery was fine and didnt need replacing i mention to them if i leave the car sitting for a week or so it seems to go flat and they said thats normal if scooby's are left for a prolonged period of time with out being started up.

Over the xmas period i used the car a good few times and it did the alarm tone on start up about 50% of the time and this was with it being used regularly so im not sure why the alarm tone is sounding. How fast should the alarm indicator light on the dash flash?, as at the moment its flash every second, which i sure it doesnt usually flash that fast.

Any ideas why the alarm tone is sound on start up and whey my battery seems to get drained within 10 days or so?

 

Normally happens to mine after two weeks of sitting idle, then after a long journey I'll CTEK it and all is usually well. I know the alarm will chirp on start up as the clock display is slightly dimmer than usual just before I turn the key. Not really sure why you are experiencing that often. Maybe change the battery? Sounds like it cannot hold the charge.

 

Your vehicle voltage is dropping excessively on cranking. Enough to temporaily cut power to the alarm so it chirps. An excessive drop can cause the imobilser to re-activate, so the engine doesn't crank.

Typicall a drop below 9volts whilst cranking the engine is regarded as enough to interfere with various electronics.

The cause from this can be poor connections, be it on the battery, earth straps, corroded cables at teh crimps, or a dying battery (becuase its charged, doesn't mean its not fecked; Some CTEKs (depends on model as some more expensive models have a self-discharge test/diagnostic function) do have a habit of finishing off a dying battery with a dodgy cell as it causes the other cells to gas excessively at a lower voltage. What this does is give you a fully charged battery but with a reduced cranking amp capeability so it drops too many volts when cranking and cause various electronics to go a bit spazzy.

A Midtronics tester will identify and rule out the battery and is one of the better testers (although it cannot measure parasitic loss or Amp-hours - testers that can do this cost thousands and usually only owned by battery manufacturers for dealing with warranty returns). Ask the garge what make/model tester they used...it its Draper or Sealey junk, disregard their findings.

 

Says battery's had it to me .had the same issue on Subaru's a couple of times,been fine once replaced the battery

 

I had this issue on my RB5. As others have said, I replaced the battery and the problem disappeared.

 

Thanks for the info guys. Replaced the battery about a month ago now and not had any issues since