My red battery symbol warning light came on and a message said something like urgent- power system (needs service). What conditions trigger this? Also - are there other similar messages which, if I do not see them, would help troubleshoot. I can easily just drop in a new battery but I am thinking that it could be the charging system. I hope there is an cheap fix if so!

Lastly, I am thinking this might just a small problem created by my not driving the car much for 3 weeks - just a few short trips at low speeds - city driving.
Can that alone cause this red light due to battery discharge.

Also, on my other cars I used to just put an ammeter between the positive post of the battery and the positive (red) battery cable to observe the current draw when the car is off and sitting with nothing intentionally 'on'. I am wondering if, on a v70 this procedure could cause some sort of a problem with all the fancy electronic contrivances that afflict modern vehicles.

Also - do folks install better instruments to monitor current draw - is that still done? Or do they just read codes now? Would just a voltmeter on my cigarette lighter tell me anything. I happen to be going on a 1000 mile trip tomorrow so I will try to diagnose today.

Lastly, yesterday I drove at higher speed and with the lights off and now the red battery symbol is off. I think my next move is to just check the voltage at the battery at different RPMs - can I do that at the cigarette lighter or only at the battery itself? Thanks.

If your car had a newer type EPDM belt, those belts do not crack, they just wear out like a tire does - the grooves wear away.

The worn belts will slip, particularly on wet days.

Gates belt company makes a gauge that you can use to evaluate belt wear. They will send you one for free.

A asked my dealer if they used gauges - they told me that they just assume that you have changed your belts according to Volvo's schedule!

My son-in law, a Subaru tech had not heard about a gauge, but my local repair shop uses them and even has a Gates display explaining how the belts wear.

$1300 for a alt and belt???

If you already left on your trip, good luck. It sounds like a battery got low. That can happen when the alternator no longer puts out enough voltage. At idle, it should deliver 14.4V to the battery. Short trips, with the AC blower at high speed, the radio on, the lights on, etc. will drain the battery.

An autoparts store can check the battery and alternator, usually free of charge.
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Keeping it running is better than buying new

Well I just thought I'd post a follow up to the story. I drove the car to the Volvo dealership intending to just pay whatever to get my car quickly repaired. The alternator and belt was replaced ($1300) and I readied to leave the next morning. Just one problem... as I was pulling out for the trip the red light again came on. I drove back to the dealer and they were attentive. The story gets a little more interesting. A few hours was spent working again on the car and then a 'helper' drove my car back to me. He said that the mechanic recognized this as a problem with wiring in the driver's side door! He said something about some wiring that was to be used for some accessory that is not on my vehicle. He had seen this on other vehicles. Some repair was made to the wire (?). Maybe where the wire runs from the door toward the hood? I decided to begin my trip even though all of that seemed unlikely to me. I figured that if I could make it 100 miles I could make 1000. Anyway, the problem was in fact resolved.

Did they refund your $1300? Ouch.

It's great that they got it fixed ultimately that same day.

Thanks to all for the info. We also are having rain storms here so all I did was put a V.O.M. on the positive post and note that it was at about 12.2 volts and remained unchanged when I increased RPM. So I drove straight to the Volvo dealer - hoping they could put on an alternator today. They reported my battery was at 75% of charge and alternator need replacing. (Yep - I bet it was just the brushes or diodes or something but this could not be a project for me). By the way, I would say I drove about 10 miles mostly with headlights on (!) to drop the battery by 25% so I might guess a car could run for 50 miles or more with a battery only (?) and lights off. At least I will not need to actually run that experiment.

With a 1,000 mile trip tomorrow I bet you're out on your diagnostic mission.

Please remember to include things like year + mileage of vehicle + age of battery in posts such as these.

My alternator went bad at 150K. My interior lights started dimming/brightening rapidly. This is a symptom of a bad regulator. I could've replaced the regulator in situ but I decided to remove the alternator and have it rebuilt by a nearby, family owned shop which I know and trust. New bearings, regulator, freewheel pulley and collector ring all during one operation made sense to me.

They said my 8 year old battery was to be replaced even though it was doing its job well. Replacing it was verified by a pal who went to automotive school. "No 8 year old battery is still good" was what everybody said so I went along with it. How old is yours?

Without knowing your particulars I'd have the battery fully charged were I you. Then I'd go through measuring standing voltages and that while charging. You can do all this with a VOM.

The plug-in charging system testers for the cigarette lighter socket aren't worthless but the capabilities of these cheaper gauges are limited.

Alas, you mightn't the time to do all this. I hope your course of action gets the job done.

The first couple of things to check would be:

Clean and tight connections at the battery, and alternator. (for safety, disconnect the battery while checking).

Worn brushes in the voltage regulator, which is the black plastic module that is mounted on the rear of the alternator body. The entire voltage regulator pack can be replaced, or new brushes soldered in.

Had similar electrical problems; turned out to be worn brushes. I replaced the voltage regulator pack - charging resumed to normal.