club.liberty.asn.au

It seems to me that the engineers at Subaru decided that controlling the output of the alternator was a good idea. Based on load I'm guessing.

I've logged and noticed that the battery voltage can fluctuate between 12.4V to 14V. I've also confirmed this on another exact same car. Also, others around the world have reported this too:-

http://www.subaruforester.org/vbulletin ... tor-38052/

I just talked to the Subaru importers, and they know all about this problem, including having looked for ways of fixing it without modifying the ECU software. They can offer no solution other than driving with the fan or lights on all the time. Apparently it affects all models since 2004, and is due to trying to get the best results from carbon emission tests by keeping the generator off-load.

Workaround is to have some ancillary load (like the lights or internal fan running) to get the ECU to command max charge from the alternator.

The reason I raise this is that in light of the fuel-pump rewire mod mentioned in this thread http://forum.liberty.asn.au/viewtopic.php?f=18&t=26838&hilit=dw65, something I was contemplating, it could be in vain if your alternator is not at max output

Has anyone experienced this? Other than leaving my lights on is there a way to force the charging?

Why are you concerned?

You do realise nearly every alternator on every car in the world since the 90's has a load sensing alternator that references battery voltage.

the only difference is that some of the newer ones also have a third and fourth input for completely shutting off (in low load cruise, idle if voltage is above a certain level etc etc). I dont get why you'd want it going all the time using 1-1.5hp of fuel when it's not needed.

Yep I get this aswell.

I normally drive without the VBG on during the day so I never saw the fluctuations only until I started driving with the VBG on and in the daytime it used to move around, at night its fine, that's when I usually have the VBG on with ancillary power so it used to sit on 14.4.

But my battery never died or had trouble starting so it looks like its doing its job

And as for your fuel pump... Is it dropping rail pressure at 7-7500rpm under full load?

If not, it's no issue and it's flowing enough to supply fuel at whatever voltage it likes, and any excess is just heating fuel in the tank for no reason.

Yes, fuel pressure dropping That is why I asked the question in the first place. I did some logs and with no ancillaries on, the voltage was 12.5 and when I booted it, the AFRs went lean. Voltage did not bump up at all. Turned on internal fan, voltage now 14, boot it, AFRs are normal. Seriously this is fugged. I'd expect my right foot to have some say in voltage. So until I can find a suitable workaround I may just have to drive with the internal fan on all the time

I have an AVO fuel pump which is getting on and am going to swap it for a DW65. Just to be safe.

Oh and yes, this adds to my theory about the FPCM wire upgrade mod. If you ain't getting good voltage/current from the alternator, then the mod is effectively useless.

Just leave the fan on then? doesnt matter if AC is on, as it switches off on full throttle anyway.

My fix would be to fit a bigger pump /shrug.

Just need the fan on, not the A/C. Something that triggers the charge. Will have to set an alarm on my infometer for when voltage drops below 13 so as to remind me to put my fan on LOL.

Interesting post Norbz

I have noticed this event also for a while now....didnt really go into details as to why....Only picked up on it and noticed when I installed the boostgauage VBG1 also....