Hi guys,
i'm trying to ascertain whats making my idle slightly lumpy, heres one thing i've found:

my MID is unlocked so when I run the voltage test while driving I usually see 13.88 V. When stopping at a traffic light the idle seems OK while the reading is 13.88V, but this slowly drops to about 12.2/12.6v and the idle gets lumpy.

could the two be related?

voltage (while the car is running) has more to do with alternator than battery condition-
You should be able to completely disconnect your batteries from the car while it's operating and not skip a beat. (Not necessarily recommending it as a test however)

I woulden't recommend to disconnect the batteries on the fly since this is an optimal was to get electric problems in the future. Some cars might deal with it, but as a general rule. Don't do it.

It will change the impedance(ohm) in the cirquit and can cause voltage travel to other components.
This will cause damage.
// Freddy

Hi guys,
i'm trying to ascertain whats making my idle slightly lumpy, heres one thing i've found:

my MID is unlocked so when I run the voltage test while driving I usually see 13.88 V. When stopping at a traffic light the idle seems OK while the reading is 13.88V, but this slowly drops to about 12.2/12.6v and the idle gets lumpy.

could the two be related?

I'm having the exact same problem here buddy! I also noticed that the dashboard lights go dimmer as well (headlights when dark too). The worst is that the engine stalled couple of time s yesterday!!
What turned out to be the cause and how did you fix it?? Thanks!!

Charge/tend your new batteries overnight with the CTEK 3000 then install. If still the same, check alternator.

Sounds like the altenators going south, Have them checked before it's too late, Do the cars crank as usual? or is it getting weaker by the day/week??

Update: using the onboard voltmeter, before starting it showed around 12 volts (don't remember exact figure). Started up and went to 13.9-14V straight away, no dimming of headlights/dash lights. Revved slightly (up to 3,000 rpm) and then let it idle, voltage stayed the same at about 13.9V.

As the engine was reaching normal operating temperature though, rpms dropped to about 500 and voltage did as well down to 12.5, then the dimming of the lights was noticeble. Revving up above 1000 rpm would fix it. My question is: is it low rpm that causes the voltage to drop (alternator needs to rotate faster, maybe not as efficient any more, slows down engine, needs refurb), or the low voltage causes the rpms to drop (more unlikely)??

Is it risky to drive the car like that for a few more days until I have time to take down the alternator next weekend? I hope it won't leave me in the middle of a journey...

Is your belt tension OK? Is it different cold and hot? A belt slipping a bit when warm and stretchy could do what you describe.

exactly, I forgot to mention that the belt seems a bit loose; it moves 1-2cm when I apply some force (between 2 pulleys, 20cm apart).
Where's the adjustment on this engine (sorry, I've had the car for only a few months, everything is so crammed, I can't see anything...)

My belt is self adjusting... does this mean that I have to change the spring arm (or whatver it's called)?