What causes the a good battery to die if vehicle is not started every day ,

START THE CAR PUT THE EMERGENCY BRAKE ON. YOUR VEHICLE HAS EITHER THE PULL TYPE BY THE SHIFTER OR FOOT PEDAL TYPE UNDER THE DASH BY YOUR LEFT FOOT. IF THE LIGHTS GO OFF THOSE ARE DAY TIME RUNNING LIGHTS A SAFETY FEATURE ADDED BY GM. IF THEY DONT THEN IT MAY HAVE TO DO WITH A ELECTRICAL ISSUE. HOPE THIS HELPS

Maybe you should look at the battery being the victim of the problem and not the cause. Unless you jump started the car and fried a component, something could have pulled the battery down due to a short.

The fluctuation you are experiencing is the part which may have drained the battery. In a few days the new battery may go bad too.

Go to Autozone, Advance, or Oreilys for a free charging system check. They can also scan the vehicle if the "check light" is on.

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Hi,

The possibilities are too numerous to get into here.

Either take your vehicle to AutoZone for a FREE diagnostic scan or they'll loan you a scanner. This will enable you to pinpoint the problem(s) almost immediately.

All the best,

Ben

check all your fuses and replace any blown ones, especially the high value ones

the alternator will not die in one day unless there is a direct short causing diode or coil winding failure which would give signs of smell, melted wires. Disconnect battery and give full charge. what year is this? while vehicle is running you should be able to briefly disconnect positive battery post connection and vehicle will still run if alternator is good. For a new battery to die in one day, one of two things i think has happened. Either the batt is faulty from supplier,( not likely but i have seen it ) or there is a direct draw or grounding taking place whether its direct in the starter selonoid or a direct draw through accessories. Are you sure all switches are off ? Push switches (on interior lights) nothing like dome lights,delayed lights are staying on! Does vehicle start hard like it almost needs a jump. If it has to be (and it takes time). to find out what is drawing the power ( i am old school) disconnect positive power source on batt. 2) disconnect ignition power source on starter. 3) connect pos batt wire to starter, 4) touch positive cable to positive batt post and look for spark or contact. if this reacts then selonoid or starter motor is shorted drawing the current. Or if you have volt meter and know how to use it, this is good to. If checks good then hook ignition connection back on starter.(disconnect pos terminal on batt prior to re-connect) I think the battery is having the life sucked out of it by a short in the system ( A DRAW ) this could be a quick find or fix or this could take days to track down. alot of variables here to try to explain. but i would seek into the starter first as usually this drains the battery quickly .

You are describing two different problems but I think I understand that the vehicle cranks over, tries to start but stalls right away (your last sentence "vehicle not cranking" suggests that there is an issue with the starter or the battery is dead).

Without question the first thing I would do is check fuel pressure. If you don't have a fuel pressure gauge lift up the drivers rear seat, pull back the carpet, remove the access panel. You are now looking at the top of the fuel pump. When you try to start the vehicle can you hear/feel it running? If not than its probably no good.

Fuel pumps are pretty common on theses.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

There is some things to check....

(1) Is your alternator charging? take your vehicle to Advanced Autos, Napa or someone like that and have them test your alternator.
(2) Is there something in the vehicle causing excessive drain on the battery when the motor is not running... like is the interior light may be on or something to that affect.
(3) Are you doing enough driving to recharge your battery? short stops and starts is not good for a battery as you may rob more energy from the battery then you are putting back in.
Sounds like something is draining your battery, something must be left on in the vehicle, Advanced Autos or Napa should be able to tell if something is draining your battery when the vehicle is off.

It may be a computer board problem. The board sometimes cracks causing intermitent random faults.

Alternator.