The battery has been showing occasional signs of fatigue lately. It's over six years old so I guess that's pretty average?
Just to be sure it's not being drained I disconnected the neg. terminal and tested with an amp meter and got 0.11 amps (110mA) drain with nothing switched on. Is this a normal, at rest, figure?

(03 STi)

JohnD

 

I've had issues for years with something draining my battery on my blob sti.
disconnected numerous things and never found the issue.
tracker, gauges,radio...etc

 

 

Where'd my post go?!

I was saying that I think my alarm is the cause of battery drain on my classic!

 

What volt is it showing when started? I had same problem changed alternator and no issues now, Showing a nice 14v

 

Its more than likely due to subarus so called "smart alternators" which are more like stupid alternators if you ask me!
Unless you have it under load i.e. if lights or heaters are on the alternator will only charge sometimes,eventually killing battery. Some people drive with side lights on all the time so battery is always getting charged.

 

If this problem strikes you can turn on all the lights and other equipment you like and it will make no difference; leave the car for 4 - 5 days and the battery will be flat. I got fed up trying to solve it. If I know the car is going nowhere for a few days I now attach a Ctek battery conditioner or simply disconnect from the neg battery terminal. Not ideal but better than the dead car routine.

 

I had a faulty head unit on mine which kept killing my battery, try disconnecting it and see if your battery stands the test of time

 

The alternator is fine, I get over 14v after start and around 13v after some running.
The drain figure I quoted was without the alarm armed. I think 110mA is a pretty normal figure considering the stereo and ECU memory retention?

JohnD

 

Think battery should charge between 13.7-14.4v.
If you don't put alternator under load it will only charge battery sometimes,like when you first start it and at traffic lights etc. Keep side lights on and it'll charge the battery constantly like most other cars do.

 

It's not just about the volts anyway its about the cc's crank ampage. Go to an auto elections and they'll do a load test on it for free,it takes less than 5seconds.
Aswell, if you run a sub etc. And do a few shortish journeys without running your sidelights or headlight your alternator's not charging battery