Battery cable came off!

The battery does as Jim said. But another condition called load dump
could have created a destructive transient. Load dump is defined by
the ISO to be as large as 270 volts on the 12 volt system. SGS
Thompson defines it as 80 to 100 volts. But then better automobiles
are designed with electronics that make load dump not destructive.

Of course when you connect a computer to the car using a discount
inverter, does it have load dump protection - or did you just save some
pennies?

The damage, if it occurred, would be complete in milliseconds.
Apparently you did not suffer load dump damage. But you, like many
others who replied here, should know of load dump and what automotive
electronics (properly constructed) cost more money.

sharx333 wrote:
> Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard
> the idle sound change: it seemed higher. I stepped on the gas a bit,
> and I heard a soft electrical "pop" near the stereo panel. I hurriedly
> shut down the engine, I found that the negative battery cable had come
> off! (It had a quick-release connection). I connected it, restarted and
> found everything working fine, even checked all the stereo functions,
> LEDs, and the ECU.
>
> I've read that the battery acts as a big capacitor to smooth out
> voltage spikes. The entire episode didn't take more that 10 seconds,
> but I'm worried... could there be any permanent damage?

Tegger wrote:
> Matt Ion > wrote in
> newsvefh.470560$R63.142904@pd7urf1no:
>
>
>>sharx333 wrote:
>>
>>>Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard
>>>the idle sound change: it seemed higher. I stepped on the gas a bit,
>>>and I heard a soft electrical "pop" near the stereo panel. I
>>>hurriedly shut down the engine, I found that the negative battery
>>>cable had come off! (It had a quick-release connection). I connected
>>>it, restarted and found everything working fine, even checked all the
>>>stereo functions, LEDs, and the ECU.
>>>
>>>I've read that the battery acts as a big capacitor to smooth out
>>>voltage spikes. The entire episode didn't take more that 10 seconds,
>>>but I'm worried... could there be any permanent damage?
>>
>>You read wrong. The battery reacts too slowly to absorb spikes, it
>>lives at 12V versus your alternator's typical 13.5-14.5V, your
>>alternator wouldn't produce a spike unless it failed spectacularly,
>>and having the terminal come off wouldn't cause a spike either.
>
>
>
>
> It absolutely would. Damage may not always occur, but there will be spikes.

Fair enough - a SIGNIFICANT spike.

> The battery's secondary function IS to provide a buffer for the
> alternator's pulses.

And pray, how does it do that? It's not a voltage regulator, it's not a
capacitor. Internal resistance limits how quickly it can react to voltage
changes.

> Connecting the cables together without the battery in
> between is dangerous to the car and should NOT be done.

You mean the battery cables? Yeah, that'll fry your alternator in a hurry,
since you're basically shorting its output.

> You could to that n 1976, but not now.

I wouldn't even try it in a '76.

> http://www.uuhome.de/william.darden/carfaq2.htm
>
>
>
>>Ultimately, cars have batteries for one purpose: starting the engine.
>>Once the engine is running, the alternator provides for all the car's
>>power requirements.
>> Yes, batteries are also used to power accessories when the car is
>> off, but the
>>only reason they're there in the first place is to crank the starter.
>>
>
>
>
> See the above link.

See the phrase "IN THE FIRST PLACE" in my above paragraph.

Of the four uses Darden lists for the battery, I've already noted the first and
fourth above... for the second ("filter and stabilize") it can only do so much -
there's still ripple in the voltage measured even with the battery, as the
charging voltage is usually well above the battery's voltage... as for the
third, if the battery is really needing to "provide extra power" while running,
then the charging system is under-rated to begin with, and the battery is acting
as a band-aid.

Matt Ion wrote:
>
> Tegger wrote:
> > Matt Ion > wrote in
> > newsvefh.470560$R63.142904@pd7urf1no:
> >
> >
> >>sharx333 wrote:
> >>
> >>>Hi, was checking my '95 Civic 1.6L today. It was idling, and I heard
> >>>the idle sound change: it seemed higher. I stepped on the gas a bit,
> >>>and I heard a soft electrical "pop" near the stereo panel. I
> >>>hurriedly shut down the engine, I found that the negative battery
> >>>cable had come off! (It had a quick-release connection). I connected
> >>>it, restarted and found everything working fine, even checked all the
> >>>stereo functions, LEDs, and the ECU.
> >>>
> >>>I've read that the battery acts as a big capacitor to smooth out
> >>>voltage spikes. The entire episode didn't take more that 10 seconds,
> >>>but I'm worried... could there be any permanent damage?
> >>
> >>You read wrong. The battery reacts too slowly to absorb spikes, it
> >>lives at 12V versus your alternator's typical 13.5-14.5V, your
> >>alternator wouldn't produce a spike unless it failed spectacularly,
> >>and having the terminal come off wouldn't cause a spike either.
> >
> >
> >
> >
> > It absolutely would. Damage may not always occur, but there will be spikes.
>
> Fair enough - a SIGNIFICANT spike.
>
> > The battery's secondary function IS to provide a buffer for the
> > alternator's pulses.
>
> And pray, how does it do that? It's not a voltage regulator, it's not a
> capacitor. Internal resistance limits how quickly it can react to voltage
> changes.
>

Uh, the battery is nothing more thann a large capacitor. Capacitors are
the main components of voltage "smoothing." You know, like radio noise
suppression etc.

JT

Grumpy AuContraire wrote:

> Uh, the battery is nothing more thann a large capacitor.

Actually, they're not. Capacitors /store/ electrical energy. Batteries
/create/ it via a chemical reaction. Charging a battery is not storing energy;
it's (to oversimplify) merely reversing the checmical reaction.

Matt Ion wrote:
>
> Grumpy AuContraire wrote:
>
> > Uh, the battery is nothing more thann a large capacitor.
>
> Actually, they're not. Capacitors /store/ electrical energy. Batteries
> /create/ it via a chemical reaction. Charging a battery is not storing energy;
> it's (to oversimplify) merely reversing the checmical reaction.


Technically yes, but both smooth voltage..

JT

Grumpy AuContraire wrote:
>
> Matt Ion wrote:
>
>>Grumpy AuContraire wrote:
>>
>>
>>>Uh, the battery is nothing more thann a large capacitor.
>>
>>Actually, they're not. Capacitors /store/ electrical energy. Batteries
>>/create/ it via a chemical reaction. Charging a battery is not storing energy;
>>it's (to oversimplify) merely reversing the checmical reaction.
>
>
>
> Technically yes, but both smooth voltage..

Batteries do, to a degree. That's not what they're designed for though.

Matt Ion > wrote in
news:P8fgh.485006$R63.220768@pd7urf1no:

> Grumpy AuContraire wrote:
>>
>> Matt Ion wrote:
>>
>>>Grumpy AuContraire wrote:
>>>
>>>
>>>>Uh, the battery is nothing more thann a large capacitor.
>>>
>>>Actually, they're not. Capacitors /store/ electrical energy.
>>>Batteries /create/ it via a chemical reaction. Charging a battery is
>>>not storing energy; it's (to oversimplify) merely reversing the
>>>checmical reaction.
>>
>>
>>
>> Technically yes, but both smooth voltage..
>
> Batteries do, to a degree. That's not what they're designed for
> though.
>


But it's one of the things they're *used* for.

Do you want to email Bill Darden and tell him he's wrong?


--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

"Matt Ion" > wrote in message
news:Clegh.480395$5R2.401317@pd7urf3no...
> Grumpy AuContraire wrote:
>
>> Uh, the battery is nothing more thann a large capacitor.
>
> Actually, they're not. Capacitors /store/ electrical energy. Batteries
> /create/ it via a chemical reaction. Charging a battery is not storing
> energy; it's (to oversimplify) merely reversing the checmical reaction.

Batteries most definitely do have capacitance, do you have a meter?

Batteries most definitely do store energy when charged. Or are you
suggesting that when it is used up that more is created out of nothing?

Matt Ion > wrote in
news:Clegh.480395$5R2.401317@pd7urf3no:

> Grumpy AuContraire wrote:
>
>> Uh, the battery is nothing more thann a large capacitor.
>
> Actually, they're not. Capacitors /store/ electrical energy.
> Batteries /create/ it via a chemical reaction. Charging a battery is
> not storing energy; it's (to oversimplify) merely reversing the
> checmical reaction.
>

The plates of a battery have capacitance.
They are charged by the chemical reaction.

--
Jim Yanik
jyanik
at
kua.net

On Thu, 14 Dec 2006 11:40:44 -0700, jrk > wrote:



>"Matt Ion" > wrote in message
>news:Clegh.480395$5R2.401317@pd7urf3no...
>> Grumpy AuContraire wrote:
>>
>>> Uh, the battery is nothing more thann a large capacitor.
>>
>> Actually, they're not. Capacitors /store/ electrical energy. Batteries
>> /create/ it via a chemical reaction. Charging a battery is not storing
>> energy; it's (to oversimplify) merely reversing the checmical reaction.

>Batteries most definitely do have capacitance, do you have a meter?

>Batteries most definitely do store energy when charged. Or are you
>suggesting that when it is used up that more is created out of nothing?

Capacitors are electrostatic while batteries are electrochemical.
A capacitor capable of storing the energy within a car battery and power
capability needed to start a car would be the size of a double long semi.