Help me determine if this car battery is indeed the guilty party
July 6, 2012 11:13 PM   Subscribe

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.
posted by armoir from antproof case to Technology (17 answers total) 2 users marked this as a favorite
I'd suspect the alternator.
posted by Segundus at 11:22 PM on July 6, 2012 [1 favorite]

I'd check the alternator, but with the couple of full discharges it is very possible it was just dead.
posted by SuzySmith at 11:24 PM on July 6, 2012

Response by poster: SuzySmith: "just dead" as in:

(a) "it was temporarily in a state where it did not have enough charge stored up" ; or,

(b) "it had been rendered useless forevermore, unable to store enough charge to do its job" ?
posted by armoir from antproof case at 11:33 PM on July 6, 2012

Best answer: In good circumstances I would expect a less-than-two-year-old battery to survive what happened to yours. I have however had a more expensive battery fail sooner under less duress and the general verdict was that it was just a lemon. If it has been insanely hot where you are, excessive heat will contribute to battery failure. Failure in all cases meaning the battery has been rendered unable to hold a charge. 4 or less hours with the lights on shouldn't really drain a fully functional, charged car battery either so I think the battery was already in trouble before your problems.

Here is some information about how batteries work and different things that affect battery life. If you do a lot of short driving with heavy accessory use (air conditioner running, etc.) this can be very hard on the battery. It also gets into the limitations of battery testing.

I have maybe had inordinately bad luck with batteries but from my experience I consider it worthwhile to spend a bit more, and a 2 or better 3 year warranty is pretty standard in a better battery.

I think you are due for a trip to your mechanic to investigate if there is any other issue aside from the battery itself causing the failure (if it's something like your alternator you could be working on killing that $156 new-battery-plus-install) and to follow up the mechanic's comment about the starting noise. I think he is referring to this... This could get expensive so hopefully you have a mechanic you trust.
posted by nanojath at 12:03 AM on July 7, 2012 [1 favorite]

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.

Incidentally this will work but it is dangerous (contact sparks attaching or detaching the cable can ignite hydrogen emitted by the battery causing dangerous combustion. Show Mrs. Armoir how to do it properly.
posted by nanojath at 12:11 AM on July 7, 2012

Last thing, I don't think RAD 2 was being dishonest. While (as article 1 I linked above notes) battery testers have significant limitations, the fact is your batteries behavior - reading as fully charged off a charger but delivering no power - is pretty indicative of battery failure, especially since a new battery has at least temporarily solved the problem.
posted by nanojath at 12:17 AM on July 7, 2012

Just as some general rules-of-thumb:
  • Car batteries 20 years ago mostly failed chemically & slowly. Modern batteries mostly fail mechanically & quickly.
  • Sequential deep discharges, without a good long period of float charging between them, can accelerate both chemical & mechanical failure quite substantially.
  • One of the less-obvious upshots of that is that a battery can test good with no load (i.e. by voltmeter alone), not be able to provide enough current to turn the car over - then simply through the act of trying to draw the starting current, repair itself enough to be able to start the car & charge properly.
  • 15-20 minutes driving (not idling) with headlights off is barely enough to replace the power used to start most cars - it's not really enough to start putting more charge back in.
  • Yes, it's fairly easy to do a basic test of battery capacity / "quality" quickly - you look at the voltage under load (which is why a voltmeter isn't really sufficient), or the impedance. Most mechanics will have a suitable battery tester of one type or another.
In short, yes it's not overly uncommon for car batteries to fail at that age (though it's not particularly common either). Deep, deep discharges (like leaving the lights on) without good solid recharges & a period of float charging is not good for them. nanojath's comment links to some of the issues with battery testers - but, largely, they're issues of determining "how shagged is this battery?", not "is this battery shagged or not?". If a battery is ostensibly charged but tests broken, it's broken.
posted by Pinback at 12:34 AM on July 7, 2012 [2 favorites]

Best answer: Before you decide to toss your long-suffering, sadly abused battery, try giving it a full charge with your shiny new charger. To work out how long that will take, divide the battery's rated amp-hour capacity by the charger's output current, then multiply by 1.4. For example, if it's an 80 amp-hour battery being charged at six amps, a full charge would take 80Ah ÷ 6A × 1.4 = 19 hours.

It should be perfectly clear from that calculation that 90 minutes at 2 amps is barely enough to add enough charge for one crank.

And do clip the black lead to the chassis, because the battery may well be gassing a fair bit at the end of a full charge and you do not want to experience a hydrogen-explosion-powered acid bath; keep that disconnection spark well away from the battery. In fact the safest way is to turn off the charger's mains supply before unclipping it from the car.
posted by flabdablet at 12:54 AM on July 7, 2012 [1 favorite]

Also, while you're car's in the the shop having the lifters seen to, ask about having an accessory headlight minder fitted. This will make a really irritating noise if you turn the ignition off and leave the headlights on.
posted by flabdablet at 12:56 AM on July 7, 2012 [3 favorites]

Just FYI, whenever I've had a battery jumped, I've always been told to drive around for AT LEAST 40-45 minutes afterwards --- NEVER just 15-20 minutes.

Does your car have any kind of alarm/bell/other indicator that tells you when you've left the lights on? If not --- and in your case, maybe even if it DOES have such an alarm! --- you apparently need to do something else to remind people to turn off the lights. Perhaps find a way to hook something to the driver's inside door handle whenever the lights are turned on: then when the driver grabs the handle to exit the car, they'll encounter the reminder object and hopefully then turn off the lights.

I'd recommend checking out your alternator, but here's an oddball theory: I drive a 2003 PT Cruiser; it is a known problem that sometimes Cruisers develop a short in the wiring of the 'multi-function stalk' (i.e., the handle that operates the lights) that makes it literally *impossible* to turn off the lights, which as you can imagine is lots of fun all 'round. I haven't heard of this in other cars, but that doesn't say it coudn't happen, either.
posted by easily confused at 3:33 AM on July 7, 2012 [1 favorite]

What RAD was talking about: hydraulic lifters.
posted by jon1270 at 3:35 AM on July 7, 2012

This is random, but the battery in our 07 Accent drained a few times in a row, which was odd because we swore that the headlights turned off automatically when you took out the key and locked the car. It turned out that the brake light switch was faulty, and the brake lights were on permanently, even when the key was out of the ignition. This is apparently a common enough Accent problem, and some of the switches were even recalled (but not our model). This might explain why your car kept not starting after sitting a while, even after you jumped it.
posted by that's how you get ants at 7:34 AM on July 7, 2012

Yes, that's enough to kill a battery. $156 isn't a bad price for a new battery + install.
posted by gjc at 7:39 AM on July 7, 2012

In the two cars I've driven, both experienced an issue where a battery, probably at the end of its, life, managed to talk the alternator into a death pact. I got them both replaced the same day, because at some point I couldn't tell the "bad battery/bad alternator" symptoms apart, and it was about time on both.
posted by Sunburnt at 3:02 PM on July 7, 2012

Despite all the other possibilities mentioned above, I agree with flabdabbet: Your battery just hasn't been recharged yet. Connect the charger, set it to 6 amps, and let it run for a couple days. Since it has automatic shutoff, don't worry, just let it run and do its thing.

(The voltage on a battery is a misleading indicator of charge level. The important thing for your battery is that amps were pulled out of it for several hours. Hence, your battery charger has to pump amps back into it for several hours.)

If, after charging for a couple of days, it still won't start the car, then replace the battery.
posted by exphysicist345 at 3:42 PM on July 7, 2012

Take the car to a reputable mechanic. Explain the story thus far. Have him/her check the battery and the alternator, as well as a general diagnostic scan of the electrical/computer system.
posted by desuetude at 12:34 AM on July 8, 2012

I re-checked the voltage with my voltmeter - says 12.7V. Yay.

Just popping back in to say that 12.7V is not enough. A fully charged car battery, open circuit or lightly loaded, should be around 13 - 13.5V.

A typical healthy car electrical system voltage while the alternator is actively charging the battery is 14.4V.
posted by flabdablet at 12:57 AM on July 8, 2012

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