Morning. I took the car to the mechanic for a bearing change and to change the airbag clockspring. The mechanic told me he would see if the car has any electrical problems before changing the clockspring, so it won't break down again. Just yesterday he told me that he had a new fault: when he uses the power windows or the AC, the voltage goes down to 0, and after 5 seconds of not using them it recovers completely, all this with the car started. I had noticed that, logically, when I use these things, the voltage drops from 14.5 to 14.3 or similar, but not to 0.

I don't know if he's exaggerating, or if he's just not looking right, because it's never happened to me before, and it's just happened with the car in the mechanic's shop. I don't think it was the bearings being changed because nothing electrical is touched.

He told me that he had checked the fuses, and that there was nothing wrong, so I don't know if he is exaggerating or if there is really a new problem (which is very strange and doesn't fit with any information I looked up on the internet and that the mechanic has been trying to fix for 2 days)

P.D.: the battery is only a month and a half old.

What is happening there? Can it be a bad alternator? A bad battery (again)? A short?

The car is a chevy aveo from 2012

  • How is he checking the voltage?
    – HandyHowie
    Jul 1, 2020 at 13:35

1 Answer 1


First, have the battery LOAD TESTED. What you have described is one of the symptoms of a failed battery.

If that's not it, the next thing to check is a poor connection from the battery to one of its cables or a poor connection from one of those cables to their attached to your vehicle. Check those to ensure they are tight and corrosion free.

It sounds to me, from what you've said, that your "mechanic" is really NOT very familiar with this stuff which makes be question his abilities.

  • In other aspects I have not had problems with him, but it seems that in the electrical problems he does not perform very well... I am worried about all the hours he is spending on this problem, when it can be solved with something so easy. I'll tell him so he doesn't have to spend a lot of time checking things out, because it seems to be going on for a long time... Jul 1, 2020 at 10:00
  • @FranciscoAguilera finding electrical problems is like finding a needle in a haystack...
    – Solar Mike
    Jul 1, 2020 at 10:17
  • Yeah I know but, if everyone says that's the main problem to check then I don't know... I think I'm getting desperate because new problems keep coming up Jul 1, 2020 at 10:41
  • Batteries' internal welds can fail; when this happens, they charge and can supply great looking voltage all day. However, with any load, the battery simply gives up. This is exactly the symptom. When there are electrical gremlins, the first thing to do is swap in a known good battery before checking anything.
    – Krista K
    Jul 31, 2020 at 15:37

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