cubic25
Hey all,
I seem to be posting here a lot lately........
I posted the following a few weeks ago on another forum, thinking it was a more general fault, rather than Volvo specific.
I replaced the battery, which was needed, but the 'fault' still persists.
Initial post:
In the last few weeks, my car has been getting harder to turn start. It takes a few more cranks than usual, which I thought was normal because the mornings are getting colder.
Then I noticed that the Voltage is fluctuating a fair bit. I have a OBD reader constantly hooked up to the car giving me readings.
In the morning, the car is usually sitting on 11.8-12v. The has dropped from the usual 12.4V it used to sit on. This is without the engine on.
When driving, depending on ambient temp, it has been sitting on 13-13.2V on hot days (no aircon on, so no extra load. 30deg C), and on cold days, such as yesterday morning, it was sitting on 14-14.6V.
Usually, the car will sit on a constant 14.4V when driving, regardless of ambient temp. Now, it seems to be all over the place. In the space of a few K's, I noticed it constantly jumping between 13.8-14.2v. I've never seen it reach highs of 14.6v before, never seen it lower than 14V when running and never seen it fluctuate so much.
Would it be battery, alternator or voltage regulator?
I always thought that once a car was started, the alternator will keep it at a constant voltage regardless of battery condition. As long as the battery is there to start the car and complete the circuit, the rest is up to the alternator.
Update:
Hey all,
I replaced the battery on Monday, as the last one was indeed dead. It was down to 80CCA, from 620CCA.
The car now starts instantly, as expected, but I'm still seeing voltage spikes and fluctuations.
This morning, our coldest morning yet, it was on 14.7V. Higher than I've ever seen it.
As the day has gone on, it gets lower and lower. It was on 13.8V when I got back home.
It seems that the hotter it is, the lower the voltage.
Again, up until recently, the voltage was a constant 14.4V.
What should I be looking at next?
Thanks.
AlexS
What model is it? Sounds like the normal voltages for a variable charging system. the low voltage when hot stops the battery from being overheated and high charge voltage when cold helps charge it quicker and wont damage the battery as it's cold. On newer models as low as 13v and as high as 15v can be completely normal.
