ok changed my battery because it went flat for some unknown reason i desided to do a charge test with the multi meter and found only 12.56 volts at idle if i turn the lights on the voltage jumps up to a good 14volts.

this is an 03 sti guys if some 1 knows what the idle voltage should be b4 i lay out for a new alternator it would be good to here, or if u can check your motor if you have an 03, when i hold the revs with no aux turn'd on the voltage stays at 12.56 and does not increase at all. any help would be great thanx.

 

where did u take your reading from? the battery or alternator? take it from the alternator to eliminate the wiring.

 

checked from the alternator to body earth and across the battery terminals same results what i need to know is the voltage readings i should be getting at idle i know other cars read a constant once startedof around 13-14 volts but im not sure if this has a load activated regulator and a minimum charge at adle i cant find any info on it

 

Some Scoobs are fitted with a 'smart' alternator. These only charge when they sense a drain, hence why you are getting full charge when you put the lights on. Usual advice is always to run with at least you side lights on

 

OK JUST A LITTLE UPDATE ALTHOUGH I CANT GET A STRAIGHT ANSWER FROM ANY1 TECH FROM SUBARU I HAVE DONE SOME TESTS OF MY OWN I DRAIN'D THE BATTERY FOR 2 HOURS AND TOOK A READING B4 START UP 12.05 VOLTS WHEN FIRST STARTED FOR 10 OR SO SECONDS THE ALTERNATOR CHARGED AT 14VOLTS THEN DROPED TO 12.77 AUTO DATA STATS THAT IDLE CHARGE IS 12VOLTS ALTHOUGH THIS IS SECOND PARTY INFO. THEN I SWITCHED THE HEATERS ON THE LOWEST SETTING AND THE OUTPUT OVER THE ALTERNATOR INCREASED TO 14VOLTS ONCE AGAIN.

I CAN ONLY ASSUME THAT IT USES AN INTELIGENT CHARGE SYSTEM REDUCING EMISIONS AND LOAD ON THE ENGINE UNLESS IT HAS TO. THIS IS WHAT I ASSUME IF SOME 1 CAN TELL ME DIFFERENT PLEASE WITH FACTS OR TEST THERE 03 WITH A MULTI METER AT IDLE. IF I BREAK DOWN ILL POST LOL TY GUYZ

 

Yep its a smart system and only charges when it needs to or a load is put on it.

 

Those voltages are okay, aren't they?

Mine idles at about 12.5+, and when under load, then 13.5+ .

My battery is quite old I'm sure, but it still has no problem cranking - motor spins over strongly and fires first time, evreytime (I also run with sidelights on, to keep the alternator working... ).

 

same on mine, smart charge.

 

thanx for the replys as you can c im new to the forum but great to get so many replys. anyway been out all day in the motor no breakdowns lol, i had heard about inteligent charge but to be fair ive not come across it b4 mainly because you dont get asked to test something if its not broken.

its a comfort to know others have the same voltage and are like this i order'd a alternator that turnt up this morning and i didnt fit it because of the test i done and my suspitions lucky i have a parts account it can be return'd on monday. thanx again.

 

We're here to help mate, it is a steep learning curve

 

hmm bumping this one up again still got some issues, my motor now seems to not want to stand without use for more than a day or two. starting to get on my nerves and the neighbours as the alarm sets off when the voltage drops. ive now put a second battery on it incase i had a dodgy cell in it and i was just unlucky when i checked the amp drain it seemed to be in order 0.4amps with the alarm armed. its happen'd a few times now and if i dont use the car every day it gives me this aggro is it related to the alternator voltages i dont know yet. any way i said ide keep ya posted so this is the latest ill let you know how i get on. (Started running with an aux running since my last posts btw )

 

Subaru batteries are notoriuos for failing as soon as the warranty runs out. My last one passed a drop test and was charging fine, but when stood would drain in 3 days. Also there was an issue with the trackers fitted to the newage(If you have one). A faulty circuit board meant it would drain the battery in a few days.

As for charging, with my sidelights always on and the heater always on level 1 I get a constant 14v. When I switch them off the charging voltage drops to about 12.8v. With a new HD battery the car can stand for weeks and still start first time

 

you mention trackers fitted to the new age was this from factory cause i have a bloody great box in the car thats not the ecu or alarm. im just wondering if maybe 0.4 amps is to much drain maybe i should be looking for less could some 1 check there amp drain so i have a comparison it would be a huge help if possible on a new age.

 

think its quite a think with newages and trakkers. dont seem to go together well

 

0.4 amps seems about right from what I remember on my car that doesn't have a tracker. Given a standard battery runs at about 50AH and a HD one at avout 65AH, that level of drain is negligible.

 

right got some spare time at lunch today so got stuck in. linked up the multi meter and started to pull fuses and relays, now when i pulled the clock fuse under the bonnet i got a 0.15amp drop now from my knowledge that seems to be ok a bit high compared to the average motor but i know that other systems run off of this such as memory backups, other than that the rest of the fuses seem'd to have little if any effect at all. then i found the tracker unit stashed in a silly place and when i pulled the plug i got a 0.34amp drop i know i might be being a bit picky when i have a 60ah battery on the car but i want this thing right and ive had issues and from the sound of it many others have with these new age motors. this leaves me with a 0.12 amp drain keyoff alarm arm'd and im alot happier ill let ya all know if its sorted my problem once ive left the car for a few days. (btw thanx for the heads up on the tracker probs im looking at a new system at the mo that claims to only drain at 10 milli amps)

 

Glad you are making some headway

My bugeye doesn't have a tracker so I don't have that issue. I think the record at the moment is about 5-weeks before the car won't start. iirc it has to drop below 11v before the car won't crank