Is it sufficient for two occurrences of "Oops I Left The Headlights On" to completely kill an automobile battery's ability to maintain a charge?
Today we had to replace the battery in Mrs. Armoir's car, a 2004 Hyundai Accent (120k miles now) which was purchased used but with which she's driven 90k miles with no major problems. The just-died battery was purchased new 16 months ago, to replace what I assume was the original battery, which had died after lights having been left on & could no longer hold a charge. It was a respectable mid-range battery, which seemed at least sufficient (if not more so) for our small car; I paid about $70-$80USD for it.
This new battery performed perfectly for several months, until 1 week ago, when the headlights were left on while parked for 2-3 hours. We called roadside assistance, who sent Roadside Assistance Dude #1 with a portable battery / "jumper" kit, which was unable to get the car started. RAD #1 asserted this was because the previous recipient of his services had a "very dead" battery, that drained his jumper-pack dry. So then he switched to jumping it via cables attached to his truck, which eventually got our car to start up. The car was then driven for about 30 minutes after that, then left overnight home in the garage. About 28 hours later, the car started up no problemo, but then was parked for about 4 hours once again with with lights left on (sigh). Again, the car was jump-started, then driven for about 15-20 minutes and parked at home in the garage.
Four days/nights pass, car sits in garage, no activity, no attempt to start.
On the afternoon of the fifth day, I attempt to start the car, it won't turn over. Check the battery with a voltmeter, it's at ~10.5V. I go to auto-gear store and purchase a Schumacher SC-600A
charger (with automatic shutoff feature, and also an Ability-To-Detect-IF-You-Hooked-Up-The-Clips-The-Wrong-Way feature, which was not triggered). It had no problem connecting to the battery and charging it up over the course of about 4-5 hours (on the lowest "2A" setting - not 4A, not 6A) after which I re-checked the voltage with my voltmeter - says 12.7V. Yay. I started up the car, let it run for no more than 8 seconds, then turned it off. Verified light were NOT left on :-)
Car sits overnight. Later in the day, Mrs. Armoir tries to start car -- it doesn't start.
Mrs. Armoir hooks the battery charger back up to the battery. The ground (black) clamp is not attached to the chassis of the car (as it says in the book to do, and as had been done previously) -- but instead it's attached to the negative/ground terminal of the battery. However the charger gizmo does not complain, it does light the "connected" LED and does proceed to charge the battery (though it unclear if the charger was left at 2A, or was set to 4A or 6A). Within less 60-90 minutes, the charger reports that the battery is charged. Mrs. Armoir disconnects the charger and attempts to start the car, it doesn't start. Roadside assistance is again called, comes to our house.
Roadside Assistance Dude #2 gets the car started with his portable battery-jumper pack, and while the car is running, he "performs some tests" on the battery, the result of which is his assertion that the battery "is unable to hold a charge" and his suggestion that my wife pay him $156 to install a new battery, which she accepts. Also, he points out something he hears in the sound of the car starting that indicates a problem with "the Lifter" (?) that needs to be remedied "soon" as it could "get expensive".
So, my questions:
1. Is it indeed possible that this battery could have been rendered "unable to hold a charge" merely by the two incidents of Lights Left On? If not, what Next Steps would you suggest for determining the true cause of the battery's apparent failure? Are we dealing with e.g. a fault in the electrical system of the car, or a faulty alternator, or ...?
2. Was RAD #2 actually able to ascertain the status of the battery's ability to hold a charge, in such a short period of time, while the car was running / charging said battery? Or was he simply trying to make a quick $150 off of my lovely wife (whose 2-year old was frittering about, much to her distraction / frustration)
3. What the hell is a "Lifter" ?
Thanks for your assistance.