Battery question

[scarpi]

Hi all, I have an 02 Yukon 4x4 and recently I noticed the following when checking my battery. I checked it with a voltmeter with the vehicle off and got a reading of 12.1v. I think this means about a 50% or so charge. Then I started the vehicle and tested the battery with the vehicle running and got a reading of 14.55v. I believe this means that my charging system is working ok. Then I shut off the vehicle and immediately tested the battery and got a reading of 12.7v. The battery is a three year old GM battery, and it starts the vehicle but I was wondering what my readings say about the condition of the battery. Should I buy a new battery so I don't get stuck somewhere? I live in Phoenix and batteries have to put up with the hot summer temperatures here. Any thoughts?? Thanks, Don.....

 

[NathanJax]

That sounds about right. The battery is a 12v battery so it should read 12v when not being charged by the alternator. Unless you're having problems, I think it's fine

 

[OHSIXX]

I agree as well. Sounds like its charging just fine too. You have a few more years left in that battery IMO

 

[scarpi]

Thanks all. I'll keep an eye on it.

 

[Physh1]

Your numbers are fine but only indicate that a) the cells are all working and b) your alt is charging.

What you need to indicate estimated battery lift is the cold cranking value of the battery. Most auto part store can test your battery for you. If your battery is above ~70% of the advertised cold cranking value your ok. If you're test shows 40%-60% left you're likely to see issues in extreme hot/cold days.

The reason your battery went from 12.1 to 12.7 after a quick start is because it got a short surface charge. Over a few minutes to an hour you'd see that value start dropping.

If your concerned, just have it tested for cca value.

Cameron

 

[2001_yukon]

my battery rests at 12.8v and charges at 14.2-14.5

 

[ccapehartusarmyINF.(ret)]

this post kinda raises a few more questions with me
i was checkin to see what voltage i was getting at my stereo amp and it wa 13.90 at the amp at idol and about the same at the battery and this is with the zero guage wiring upgrade whatever they call it big 3 or some dumb like that
and its a brand new optima red top
and at a load of about 2000rpm its reads about 14 volts
does that sound about right