Hi Guys!
I have 2005 SX2.0 and my battery voltage is always 13.6 or sometimes drops to 13 (for short times). New alternator did not help, this Canadian version does not have temperature sensor on battery. What can be the problem?

 

When is the voltage dropping and why is it "low?" A fully charged car battery will rest at 12.6V. When charging, the voltage will be 13-something to the low 14s. With the information you provided, it sounds like everything is fine, and was fine with your old alternator too.

Here's a chart of resting battery voltages (again, this isn't when the battery is charging).

 

Thank you Darthroush,

Thank you very much,

Maybe you are right and it is just normal to have voltage in this range on this vehicle and there is no reason for panic...

I still feel uncomfortable when I see 12.3 V before I start the engine (which is still not too bad, I thought it is 50% charge but from your chart I see it is near 70% which is actually not too bad) and 13.6 the most and more frequently it is 13.4 often dropping to 13.0 (for short times) when motor runs (not only on low RPM). I had a dead battery one time last winter and after that I put a voltmeter in cigarette lighter. The shop owner who replaced the alternator also confirmed that the old one was good but he said I will have a better voltage with the new one. I suspect that he actually does not know these things well because this did not happen as well as some other things he said before. Same with myself - I could fix this things in old fashion cars but now when almost everything is controlled by ECMs I unfortunately do not know how things functioning. Before I would say anything less than 13.9 Volt at medium rpms is not good but maybe I am wrong for today's cars...

Could you please explain how alternators work this days - I understand they do not have attached or built-in voltage regulator any more? Or it is still there but not replaceable?
My alternator is three wires - main + and two wires of smaller AWG (I guess 16 or 18) - what they are for? I believe as before one is activated together with ignition, is the other one for voltage regulation and in what range of voltage it regularly has?

If motor's computer has a fried output for voltage regulation (if the computer controls the alternator), could a possible a solution be use of an old fashion external electronic regulator?

Sorry for these stupid questions, I feel like an old timer trying to learn modern things

Thanks again for your reply and the charts

 

I don't know that much about alternators, but specifically, I know the Neon's PCM has the voltage regulator in it.

My uneducated guess is the voltage might be lower than optimal during charging because your battery is getting older and subsequently, not holding as much voltage as it did when new. Remember, alternator output is different than battery capacity/charge. If your alternator is putting out around 14V, that's not a problem in the system. Again, IMO, there's no real specific voltage minimum (like the 13.9 you mention, though generally 13.5ish is about the minimum). Either the system is working and everything is good or not. I do know that on a Neon, especially the 03-05 ones with the electronic transmission, if your voltage starts to drop to "unacceptable" levels, you'll know it because the transmission will start freaking out.

As for the wires coming off of the alternator: the BK/GY main wire goes to the fusible link to the starter. The connector has a DG wire (generator field control) that goes to the PCM the BLK wire is the ground wire.

 

Thank you Darthroush

At least I now have some better understanding that there is no reason for panic Will watch. I noticed that voltage looks better when it is colder - was 13.6 to 14 today at temperature near 48F. This would not scare me if I see this before although on my older car I always had 14.4 all year round.

Interesting, from what you told about the alternator wiring it looks like it is similar to 40 years old fashion alternators before attached electronic regulators, so the excitation winding circuit is controlled from outside with the only difference that before it was relay unit and now engine computer...

Thanks again, best regards

 

Yeah, no little boxes randomly bolted down somewhere in the engine bay, lol. You're welcome. Hope some of that info helped out a bit!