I've a Mazda 323 2005 model. Today while at going to work in the morning the car had starting difficulty. Back getting home in the evening the car struggled to start, upon opening the hood I noticed the car battery charge indicator was "black" aka meaning charge.

My battery is an AC Delco maintenance free battery that was purchased 1 year 2 months ago. It has a charge indicator on it that indicates the charge: GREEN Color-Full, BLACK color-charge & White color-Dead. There is a lot of white powdery stuff around the positive terminal and battery acid seeping to the surface.

Got back home and cleaned the surface with baking soda.Measured the voltage with the engine OFF @ 12.6V and with engine ON @ 13.58V to 13.65V and while reviving very high it stays at 13.8V and stays pretty much there unless I rev very high it doesn't go to 14V as it should.

So, is my charging system faulty? Also is my battery going bad so soon because of it?

  • revving the heck out of it is pointless. You alternator normally has plenty of capacity to charge the battery at quite modest rpm.
    – agentp
    Nov 19, 2017 at 23:36

2 Answers 2


The voltages you state are right in line with where I'd think they should be. Charging while running, the voltage should be up to about 14.1vdc and not much beyond that. You don't want it any lower than about 13vdc. Anything in between and the system should be charging just fine. It really depends on how the manufacturer set the vehicle up in the first place.

I'd suggest the corrosion on the battery terminal was causing the issues. You may want to put a battery charger set on a low amperage on the battery and let it charge for several hours until up to snuff. If the battery charger doesn't bring the battery up to full voltage (about 13vdc when fully charged), then you'll want to look at getting the battery load tested and replacement if necessary. Considering it is only 1y2m old, it should still be under warranty (in most cases, anyway).

While you are at it, you'll want to inspect other portions of your charging system to ensure there are proper connections (tight, without corrosion). If you see any issues fix these, as they will be compromising the charging ability of the system.

  • I know this is an old post and I sold the car 2 months ago. But thought I did give an update for any future members looking. Th problem was as you had mentioned like 70% was corrosion at t battery terminal. Apparently the battery acid (or its vapors) seemed to be coming out and corroding the terminal posts heavily. After giving it a thorough cleaning was working fine. Also I took it to the mechanic before selling ti change the battery and he tole me that the alternator was slightly weak too. Jan 15, 2019 at 6:57

While your voltages may be correct or sufficient depending on the SoC of the battery, you could measure the current output of the alternator to be sure of what is happening.

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