Battery not holding charge

check if any interior lights are left on when leaving vehicle, if none found will need to eliminate other causes, is the battery holding charge, which is different to being drained, is the alternator charging rate ok , start there and see how things are

try a different battery sounds like the battery is no good not holding charge long

hi Larue.
You're late for work and rush out to your car, only to find that it won't start. The headlights are dim and the engine simply refuses to turn over. You realize that your battery is dead. But how did this happen? There are five main causes of car battery drain or failure.

Human error

You've probably done this at least once in your life - you come home from work, tired and not really thinking, and left the headlights on or didn't completely close the trunk. Overnight the battery drains, and in the morning your car won't start. Many new cars alert you if you've left your lights on, but may not have alerts for other components.

Parasitic drain

Parasitic drain is due to components in your vehicle continuing to run after the key is turned off. Some parasitic drain is normal - your battery delivers enough energy to keep things, like your clock, radio presets, and security alarm operational at all times. However, if there's an electrical problem, parasitic drain can exceed what's normal and deplete the battery.

Bad charging

If your charging system isn't working properly, your car battery can drain even while you're driving. Many cars power their lights, radio, and other systems from the alternator, which can make the battery drain worse if there's a charging problem. Then you'll be stranded at roadside with a stalled car that needs a boost. And even then, bad charging will drain your car's battery. A professional mechanic will be able to diagnose what's causing a charging problem.

Defective alternator diode

A car alternator recharges the battery and powers certain electrical systems. If your alternator has a bad diode, your battery can drain. The bad diode can cause the circuit to charge even when the engine is shut off, and you end up in the morning with a car that won't start.

Old battery

If your battery is old, it might not hold a full charge. If your car consistently won't start, it's possible that the battery is worn out. You should generally replace your car battery every 4-5 years. If your car isn't starting consistently, and your battery is old, battery replacement should be the first thing you consider.
Having a battery that won't hold a charge is frustrating, and figuring out what's causing the problem can be tricky. Assuming that the cause of the battery drain is not human error, you will need the assistance of a qualified mechanic who can diagnose your car's electrical problemsand determine if it is the battery or something else in the electrical system.
you can read up some more at this link.

What is the most battery draining part when car sits over night Google...

If your battery is discharging while the van is parked up, there's 3 general causes:

• The battery itself is failing and cannot hold a charge. replacement is the only option.
• There is a fault within the alternator - either the alternator is not charging or it is allowing the battery to drain because the diodes (the rectifier in the alternator) have failed.
• There's a parasitic drain of power somewhere. Something is remaining 'live' when the van is parked up - and draining the battery.

Many places will do a free battery check.

Is the battery not holding a charge or is it being drained by something staying on? If not holding a charge then replace.....if something draining the battery look at interior lights or trunk/boot light!

It is possible your battery is bad,it does not hold charges again,or a parasitic drain problem,your electrician should be able to do that for u.

the alternator might be gone in it, either that or the battery is too old and the core inside it isnt doing its job, before spending money, if you can, try use another battery from another car or a friends car and try run it and see if it holds the charge, if its draining still and not charging then its your alternator, it will need to be replaced or rebuilt. only two things that will cause the battery to not hold charge.

The battery may not be holding charge. If you drained your battery a few times because of a bad alternator, it is possible to destroy the cells in the battery causing one or more of them to no longer hold a charge. Most batteries are manufactured to be cycled or completely drained 8 times. Other factors such as excessive load and age can decrease that number. You may also have a faulty voltage regulator that can result in overcharging and destroying the battery. Charge the battery on portable charger and have it tested. Also, It is possible that since most alternators are rebuilt they can be bad out of the box.

Parasitic drain on the battery . Could be caused by a number of thing's , not just the trunk light staying lit . A computer (module) not powering down when it's suppose to. Insturment cluster's have problem with silver migration , the solder they use . Google that . Testing for a draw on the electrical system is the way to see if this is your problem .
How To Perform Parasitic Draw Test EricTheCarGuy
The BEST Way TO Perform Parasitic Draw Test
The Trainer 27 3 Ways Of Finding The Cause Of Key Off Battery Drain...

I’m having this same problem on my 99 LHS, I’ve been told that it’s caused the body control module. Maybe a bad ground?