At what point is a vehicle battery charging or discharging? 12.6v ?

On Sun, 2 Jan 2005 17:27:35 -0500, "Dave VanHorn"
> wrote:

>> 2.15 times 6 equals 12.9 volts..
>> So.. 13.75 would be charging?..
>
>In a theoretical sense, yes.
>How long can you wait? Oh yeah, sorry, you'll need a CURRENT meter to answer
>that!

You get what you pay for when you buy a battery charger, but yes, even
at 13.75 volts, which is what MY personal alternator/regulator
delivers to the battery, if the battery impendence is almost ZERO to
begin with, you can have a HELL of a current flow going on with that
little voltage differential, as 1 ampere is defined, IIRC as 1
coulomb/second through a 1 ohm resistor.

Since you can't measure the impendence of the battery directly, you
DERIVE IT as the variable with the known current flow and voltage,
using ohm's law, I=e/r.

Lg


Lg

On Sun, 2 Jan 2005 17:27:35 -0500, "Dave VanHorn"
> wrote:

>> 2.15 times 6 equals 12.9 volts..
>> So.. 13.75 would be charging?..
>
>In a theoretical sense, yes.
>How long can you wait? Oh yeah, sorry, you'll need a CURRENT meter to answer
>that!

You get what you pay for when you buy a battery charger, but yes, even
at 13.75 volts, which is what MY personal alternator/regulator
delivers to the battery, if the battery impendence is almost ZERO to
begin with, you can have a HELL of a current flow going on with that
little voltage differential, as 1 ampere is defined, IIRC as 1
coulomb/second through a 1 ohm resistor.

Since you can't measure the impendence of the battery directly, you
DERIVE IT as the variable with the known current flow and voltage,
using ohm's law, I=e/r.

Lg
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

Let me rephrase that.

1 Ampere is the current that flows when 1 volt is applied to a 1 ohm
resistive load.

Lg

"Lawrence Glickman" > wrote in message =
...
> ...., as 1 ampere is defined, IIRC as 1
> coulomb/second through a 1 ohm resistor.
>=20
> Since you can't measure the impendence of the battery directly, you
> DERIVE IT as the variable with the known current flow and voltage,
> using ohm's law, I=3De/r.
>=20
> Lg
> =
/////////////////////////////////////////////////////////////////////////=
////////////////////////////////////////////////
>=20
> Let me rephrase that.
>=20
> 1 Ampere is the current that flows when 1 volt is applied to a 1 ohm
> resistive load.
>=20
> Lg

Glad you rephrased that, Larry.
One ampere is one coulomb per second through ANY resistor.

On Mon, 03 Jan 2005 00:06:01 GMT, "John R. Copeland"
> wrote:

>"Lawrence Glickman" > wrote in message ...
>> ...., as 1 ampere is defined, IIRC as 1
>> coulomb/second through a 1 ohm resistor.
>>
>> Since you can't measure the impendence of the battery directly, you
>> DERIVE IT as the variable with the known current flow and voltage,
>> using ohm's law, I=e/r.
>>
>> Lg
>> /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
>>
>> Let me rephrase that.
>>
>> 1 Ampere is the current that flows when 1 volt is applied to a 1 ohm
>> resistive load.
>>
>> Lg
>
>Glad you rephrased that, Larry.
>One ampere is one coulomb per second through ANY resistor.

You guys are smarter than the average bear.

I'm duly impressed.

Lg

Lead/acid batteries using a sulfuric acid sg of 1.260 will have
a full static voltage of 13.2 volts. At 12.9 system volts it ain't
going to be charging too well. Automotive regulators are usually set at
around 13.8 or 14 volts, some higher. Systems using smaller batteries
will have the reg set a bit lower to limit charging current.
I prefer the ammeter over the voltmeter. It gives me a
better idea of the overall performance of the system. Its fluctuations
probably bother the average non-techie driver, so that's why they went
to voltmeters, I think. Perhaps it's the fact that the airplanes I fly
all use ammeters, no voltmeters in sight at all. Pilots are trained to
know what an ammeter's for. As an aircraft mechanic as well, I
appreciate that ammeter every time I have to troubleshoot the system.
Dan