Dead Battery ?????

I went to start my Blazer this AM & the battery was completely dead. I noticed a couple of things.
ONE. Is when the battery is DEAD you can't turn the ignition key to lock.

TWO. It was drove 600 miles this weekend so it sat only 2 days. I have never had any problem with a dead battery on this truck before.

THREE. I had the battery tested after (I jumped it to get it started) It TESTED GOOD on a drain test. Alt. is charging 14.2 VOLTS.
Anyone have any ideas what to look for???? NO Codes.
I noticed that the VOLT METER on the gauge cluster reads crazy sometimes. It will read low, but not into the RED. But when I check the voltage it reads (13.9-14.2V) at the battery. All other gauges work OK. I have no lights coming on. :shakehead:shakehead:shakehead:shakehead
Thanks

Proper testing.
What was the amp draw reading after it set for 20 minutes?
How old is the battery?
What is the battery voltage engine off?
Are you battery cables and grounds good?
Any electrical stuff added or worked on recently?

Proper testing.
What was the amp draw reading after it set for 20 minutes?
How old is the battery?
What is the battery voltage engine off?
Are you battery cables and grounds good?
Any electrical stuff added or worked on recently?

I can't tell you the amp draw. WHAT SHOULD THE AMP DRAW BE???? The age I'm not positive, in the truck when I bought it, (it is an AC DELCO) Voltage with engine off is 12.9V, CABLES are clean & tight. I removed them to make sure. NOTHING has been added or changed.
Now this morning it started right up. I drove it on some errands & it is OK. I figured I would leave it set over the weekend & see what Monday brings. I'm wondering if something was left on, or a door not completely shut. This just came out of the blue. We had traveled all weekend in it without any trouble except this VOLT GAUGE went lower than it ever has (but not into the RED). I took it to a NAPA that I know the guys at in the eastern part of our State. They did a battery check & Voltage check & told me it was charging 14.2V & the battery checked out VERY GOOD.
I'll see what the weekend brings & post back.
Thank you for you response.

Amp draw should not be over .025 amps or 25 milliamps after the computers go to sleep and power off.Usually after 20-30 minutes.
If it is OEM ac delco or over 5-7 years old you are pushing you luck on it.
fully charged it should read 13.4-13.6 volts.
A good test isto let it sit about 3 days and the check for good over 13 volts voltage and see if it cranks good.
Let us know how it goes.
Good Luck
MT

Thanks for the info on amp draw. It sat a week before our trip & started OK. I'm pretty sure the Battery isn't the original battery. I may replace it just to know I have a new one. I'll leave it set over the weekend see what the volts are. See what happens. If there is a problem I'm thinking replace the battery. I can't imagine a draw increase just because. I haven't done anything but drive it. I'm not sure anything was left on but who knows. But I have seen batteries short themselves, but usually they don't come back. But a battery can do some strange things.
Again Thanks

You are welcome and let us know how it goes.
Good luck
MT

I left it sit from Friday morn until this evening (Sun). I checked the battery voltage yesterday AM 12.39V & today AM & it was 12.54V. It started this evening without issue. So I'm assuming I left something on or who knows. So for now I'm feeling I don't have an issue. Thanks for the help again. If anything changes I'll repost here.

You are welcome and thanks for posting back how it went.
Good Luck
MT