Huh? How did I drain a DISCONNECTED battery?

[BerniniCaCO3]

Hi!

Did more work on the audio system with the car in the garage the past couple days.
Really just building the sub box to fit in the storage compartment, where the third row of seats would have been in my wagon.

I went to pull it out of the garage this morning so I could sweep up. I lifted the hood, tightened the positive lead back onto the battery (I undid the positive, because I expected to hook up the amplifier and didn't want to shock myself), closed the hood, went inside, turned the key. Dash lights came on, but the starter did not crank, and no noise from the fuel pump (I know what to listen for now).

I went back and checked that my power line for the amp wasn't shorting anywhere. It wasn't; I've been careful about that. (it's not connected, so theoretically it could touch something-- but it's a stiff cable and I've had it bent up out of the way. Been driving for a week with it installed, so plenty of time for it to show a major short if there was a nick somewhere).

Got back into the front seat.
Turned the key just one more time. There was a brief buzzing sound, a warning buzzer? Like the sound your drier makes when it's done with your clothes. This time, no dash lights. Turned the key backwards. Clock comes on. If I try to turn on the headlights, or force the interior lights on by turning the headlight knob to the left, they don't come on but the clock cuts out.


I'm terribly embarrassed to confess that I don't have a voltmeter, but, this sounds very much like a dead battery? Just enough power for the clock, or maybe a single interior light bulb but not all of them at the same time?

I'm thinking I might run out and get a voltmeter. Handy to have in any case!
I haven't tried jump starting the car, just yet. I'm worried: WHY is the battery dead?

For the past two days, the positive lead has been completely disconnected. I've really just been building my sub box. The only wiring I did, was to solder some wires to the OEM amplifier by the spare tire, to pull out the old amplifier and bypass it. But I haven't, yet, actually hooked up my new amplifier or the stereo. All these wires are just hanging loose.

The battery tested at 12.53 volts and 576 amps mid last week (when I thought I had a battery problem, and it was just the fuel ignition switch )
Do batteries die all of a sudden?

Or, about the same time, I also replaced the starter motor and starter solenoid (new starter sounds much better than the original), possible that the new solenoid suddenly died? I drove it for a couple days just fine.

Before I hook up the jump start, do I have some major short somewhere?? What was the buzzer warning about-- just a low battery, or something else?

Finally, I'll mention that before I pulled into the garage, I disconnected the factory amp, AND I wanted to get a sense for how good my connections would have to be by deliberately shorting the power lead for my new amp against the chassis. At only 12 volts, it wouldn't even conduct through a thin layer of paint; a direct connection to a bit of bare metal on the chassis produced a spark. Satisfied, I bent it out of the way again. Then I started the car and drove it into the garage.
I guess the point I'm making there, is that with only 12 volts, any short would have to be copper against copper, not two bare wires even 1/8" apart. The likelihood that my amp power cable directly touched my amp ground cable, or any other cable (speaker, ai net, etc.) is very slim indeed.

But I can't think of anything, that I've changed in the past couple days. Just building the carpeted box for the subwoofer and amplifier, and installed the speaker cables that connected to the old amplifier output harness, but aren't connected to the new amplifier on the other end yet.

Do batteries, just die without warning at only 3 years of age, and it's purely coincidence?

[BerniniCaCO3]

btw, I don't think I saw a low battery light on the dash board: i.e., all the lights lit up (to make sure there's no burnt-out bulb), then it failed to start when I turned the ignition all the way.

And now the dash lights just don't come on at all
But I still have a hood and trunk light when I open them.

[gadget73]

the batt light on the dashboard is related to the charging system. If its on, it doesn't neccesarily mean low voltage, it means the alternator isn't working.

If a fully charged battery went flat from sitting, I'd almost guarantee its bad. When the cells short internally, it will create a drain inside the battery that makes it go dead without any external connection. On the other hand, if the connections are poor, it will act like a dead battery.

[BerniniCaCO3]

Oh, ok. No, it wasn't on: and I was wondering if it should have been (if the battery were dying).

I went ahead and got a new (and larger) battery. I jumped the car and drove 10miles to the shop with a deka battery for the best price, when they tested it there it still read "good battery 100% charged). After just a 20 minute drive, from being dead....
Is it possible that a battery with bad cells, could still read 12.5 volts, but just have a severely reduced capacity (which could explain how it would "fully charge" in 20 minutes, when a remote battery charger would take 2 hrs?).

I assume that if it was cables, that the jump would not work, and the new battery would not work.

Oddly enough, wanting to avoid driving a car with a bad battery to the shop, I was going to pick up the new battery with the family's suv-- and its battery was also dead! Can heat shorten battery lifespans?
Granted, the suv has a 7 year old battery with 83,000 miles on it... it was amusing timing for both cars to have bad batteries at once, but we were waiting for that battery to give up the ghost.

[gadget73]

yes, batteries fail from heat. Moreso than cold actually, but engines need more current to spin over in the cold so you'll find batteries being replaced mostly in the winter and during a hot spell.

[BerniniCaCO3]

Now when it's cold, the battery just can't crank out as many amps (AND if you're right about engines needing more current, I have no reason to disagree, it's a double whammy).

But when batteries fail in heat, do they just run down? And need to be recharged?
Or are they gone for good?
I.e., should I reclaim my old battery back from the dealer then

[BerniniCaCO3]

I know also for example, that a cell phone left out in the sun will discharge itself. Not good for it, but the battery won't be ruined-- just deep drained one more time than it should have been.

[BerniniCaCO3]

While the old one is 3 years old, and smaller, and I like a new large battery; I'm still curious if it might still have been good, and salvageable; and simply drained itself in the heat?

In any case, this is interesting:
(from http://www.windsun.com/Batteries/Battery_FAQ.htm)
Even though battery capacity at high temperatures is higher, battery life is shortened. Battery capacity is reduced by 50% at -22 degrees F - but battery LIFE increases by about 60%. Battery life is reduced at higher temperatures - for every 15 degrees F over 77, battery life is cut in half. This holds true for ANY type of Lead-Acid battery, whether sealed, gelled, AGM, industrial or whatever. This is actually not as bad as it seems, as the battery will tend to average out the good and bad times.