Low battery voltage

[Dave-S]

Originally Posted by Fox Mulder

The alternator is internally regulated. However there is also external control of charging behavior by the PCM through an external sensor at the battery, so if you suspect any issues with the battery or charging system it would probably be best to have it checked at a dealer. Any problems should be covered under warranty, including a bad battery if it's within the full warranty or prorate period.

Fox

I will be taking it to the dealer next week but it is good to know that the charging system is controlled by more than one factor (thanks for passing along that information). I try to do all my own maintenance and repairs but when it comes to problems like this I realize I have to get a dealer involved especially if the warranty will cover it.

I considered the "AutoZone" approach but aside from them detecting a bad battery I wonder if their equipment is sophisticated enough to diagnose the charging system properly especially since the PCM is also involved in controlling charging voltage?

Dave

[fear24]

never had my battery checked...but, my car sat last summer for 13 days while we visited columbus, OH. came home....next day, fired right up. so...a few days shouldn't drain the battery.

[Fox Mulder]

All that Autozone will be able to do is check the basics, battery and alternator function. They do not have the equipment to test or diagnose the other systems on the car.
If you want to learn more about how the system functions you can get an account on the Hyundai service website, www.hmaservice.com
There are schematics and operational descriptions.

[destro]

My Sonata will sit for weeks at a time, summer and wonter, and never has a problem. Volts? yeah, 11.5 volts isn't bad, but not great. A cheap multimeter will get that wrong, though. It's the amps that you also need to worry about. If you are having problems starting, that's one thing. If not, I wouldn't worry about it. Especially putting a charger on it. Have seen many a battery cooked by overcharging.

[titaniumskull]

A normal indicator that a battery is at the end of its life. You will notice that it takes a little longer to fire up, longer cranking run time like 5-10 more seconds. Batteries can last as long as 4-5 years depending on temperatures. Average life is 3 years, At that point it is good to consider a change or definitely have it tested. Batteries can show signs it is fading, But there are still times when they simply quit.

My explorer cranked up fine one morning, at the end of the day it cranked lickity quick, but when I stopped by the grocery store and came back out it was flat dead. Turned out the lead post was burning out at the base of the negative post. And me as a tech didn't catch it ahead of time and routinely checked for corrosion and kept the clamps tight and coated, But it still happens on rare occasions.

Always keep 3 years in mind when you have no issues, they can pop up on you at any time after three years. Buying batteries like the 72 month battery is the same battery as the 24 month battery, all you do is pay for an extended warranty.

[robhancock]

I would be a bit skeptical of the readings from that meter. From what I see from Googling, a 12V maintenance-free battery voltage should range from 12.77V at 100% charge to 11.75V at 0% charge, so at 11.5 volts I would expect the car would not even start.