What causes the battery on a 2005 Honda Pilot to discharge and not start the car?

What causes the battery on a 2005 Honda Pilot to discharge and not start the car? - 1

Bad battery or you have a drain some where. My guess you have a drain so look for a light that is on someplace like in the trunk, under the hood, could even be a electric seat if you have them, etc.

Bad alternator. Diode rectifier is shot.

The alternator not charging the battery is the first thing to check. Charge your battery with a portable battery charger set to 12 volts, 10 amps, for 6 hours and then drive straight to an auto parts store, They test batteries and charging system for free.

A short.

One: Old battery. They don't last 12 years.

Two: loose alternator belt,
Three: Neglected battery, electrolyte low
Four: Loose, corroded connections, one to block often overlooked.
Slow discharge, like dome light
Could be defective alternator or blown fuse/fusib;e link

1st) remove the battery and clean the terminals from any corrosion…
use baking soda and water like a watery paste and brush it on…
rinse off with clean water and allow to dry - charge the battery a
couple hours on slow trickle charge…
install battery back into the battery box and only connect the positive
red cable to the battery (+ post). Get a volt meter and connect the
negative (black) cable to the negative (-) post of the battery.
Now take the red (+) cable and connect to the black (-) battery cable.
if the gauge moves, you ave a constant draw on the battery and this
is what is draining the battery. At this point, disconnect the red cable
from the alternator… If the gauge goes to zero - this is your issue and
the diode in the alternator are shorting out causing an unwanted ground.
if the gauge still show a reading other than zero - remove the red cable
off the starter and recheck the gauge… Keep doing this to one item at a
time until you see the gauge go to zero at which time you find your issue…

That's a lifespan for a Yuasa battery. Load test it and see. It's trying to go to battery heaven. Replace it so it doesn't take you to people heaven when it quits on the freeway.

BUY AMERICAN

Yup

May be a bad battery. Unhook the battery from car and test voltage. See if it drops, then you will know if its the battery or something draining your battery