voltage cutoff

C

Chris C. Grier

Guest
I am looking for someone to built or somewhere to purchase a little device
that will cut the current off if the voltage of a car battery drops below 11
volts.

can you help.

Chris
 
On Mon, 28 Jun 2004 22:54:52 GMT, "Chris C. Grier"
<ccg@midsouth.rr.com> wrote:

I am looking for someone to built or somewhere to purchase a little device
that will cut the current off if the voltage of a car battery drops below 11
volts.
Click to expand...
---
Do you want to completely disconnect the battery from everything or do
you just want to disconnect one or several circuits from it if its
voltage falls below 11 volts?

--
John Fields
 
Just the item on the curcurit.

"John Fields" <jfields@austininstruments.com> wrote in message
news:cpa1e0tm11uup0gj4ofjruh1b449qb529g@4ax.com...
On Mon, 28 Jun 2004 22:54:52 GMT, "Chris C. Grier"
ccg@midsouth.rr.com> wrote:

I am looking for someone to built or somewhere to purchase a little
device
that will cut the current off if the voltage of a car battery drops below
11
volts.

---
Do you want to completely disconnect the battery from everything or do
you just want to disconnect one or several circuits from it if its
voltage falls below 11 volts?

--
John Fields
Click to expand...
 
On Wed, 30 Jun 2004 04:04:31 GMT, "Chris C. Grier"
<ccg@midsouth.rr.com> wrote:


"John Fields" <jfields@austininstruments.com> wrote in message
news:cpa1e0tm11uup0gj4ofjruh1b449qb529g@4ax.com...
On Mon, 28 Jun 2004 22:54:52 GMT, "Chris C. Grier"
ccg@midsouth.rr.com> wrote:

I am looking for someone to built or somewhere to purchase a little
device
that will cut the current off if the voltage of a car battery drops below
11
volts.

---
Do you want to completely disconnect the battery from everything or do
you just want to disconnect one or several circuits from it if its
voltage falls below 11 volts?
Click to expand...

Just the item on the curcurit.
Click to expand...
---
When the voltage falls below 11V and the item gets disconnected, do
you want it to:

1. Get disconnected permanently so that you later have to reconnect it
manually, (with a momentary pushbutton switch) or:

2. Get connected again automatically if the voltage
subsequently rises to say, 11.5V?

If you choose 1, then when the controller disconnects the item it will
also disconnect itself and will draw no current from the battery
unless it's reconnected again manually when the battery voltage is
higher than, say 11.5V.

If you choose 2, then the controller will disconnect the circuit from
the battery, but it (the controller) will still stay connected to the
battery so it can detect when the battery voltage gets back up to,
say, 11.5V, and reconnect the item automatically. Since the
controller will always be connected to the battery it will always draw
a small current when the item is disconnected, probably less than
10mA, so a car battery wouldn't even know it was there.

When replying, please bottom post or I will not respond.

--
John Fields
 
"Chris C. Grier" <ccg@midsouth.rr.com> wrote in message
news:jZqEc.174781$DG4.22806@fe2.columbus.rr.com...
: Just the item on the curcurit.
:
: "John Fields" <jfields@austininstruments.com> wrote in message
: news:cpa1e0tm11uup0gj4ofjruh1b449qb529g@4ax.com...
: > On Mon, 28 Jun 2004 22:54:52 GMT, "Chris C. Grier"
: > <ccg@midsouth.rr.com> wrote:
: >
: > >I am looking for someone to built or somewhere to
: > >purchase a little device
: > >that will cut the current off if the voltage of a
: > >car battery drops below 11 volts.
: > ---
: > Do you want to completely disconnect the battery from
everything or do
: > you just want to disconnect one or several circuits from it if
its
: > voltage falls below 11 volts?

This is a little more complex than is obvious from the statement.
Depending upon the total load, and the percentage of that load
represented by the circuit you wish to disconnect there will be a
difference in battery voltage. So as you remove the load the
voltage rises and (reconnects?) the load, which drops the voltage,
....

More detail of a more positive indication of whether the circuit
turns on automatically or only manually is needed, as is a
percentage of the total load (if Known).

Do you only want one?
 
On Mon, 28 Jun 2004 22:54:52 GMT, "Chris C. Grier"
<ccg@midsouth.rr.com> wrote:

I am looking for someone to built or somewhere to purchase a little device
that will cut the current off if the voltage of a car battery drops below 11
volts.

can you help.

Chris
Click to expand...
See.....

Newsgroups: alt.binaries.schematics.electronic
Subject: RE: voltage cutoff question from s.e.misc - PowerSwitch.pdf
Message-ID: <pf1ce0dok4nlou9u58in21lcfca8em98a6@4ax.com>

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
Chris C. Grier wrote:

I am looking for someone to built or somewhere to purchase a little
device that will cut the current off if the voltage of a car battery
drops below 11 volts.

can you help.

Chris
Click to expand...
A TL431 with two resistors as a voltage divider on the adjust pins (and
a small capacitor from adjust to ground to prevent oscillating), will
give you the turnoff point. Put a pot in the middle of the two
resistors to give some adjustment.

Add a PNP power transistor for the higher current (you didn't say how
much current you needed).
 
On Tue, 06 Jul 2004 07:23:33 -0700, "Watson A.Name \"Watt Sun - the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

Chris C. Grier wrote:

I am looking for someone to built or somewhere to purchase a little
device that will cut the current off if the voltage of a car battery
drops below 11 volts.

can you help.

Chris

A TL431 with two resistors as a voltage divider on the adjust pins (and
a small capacitor from adjust to ground to prevent oscillating), will
give you the turnoff point. Put a pot in the middle of the two
resistors to give some adjustment.

Add a PNP power transistor for the higher current (you didn't say how
much current you needed).
Click to expand...
On July 3 I posted that sort of structure to a.b.s.e:

Newsgroups: alt.binaries.schematics.electronic
Subject: RE: voltage cutoff question from s.e.misc - PowerSwitch.pdf
Message-ID: <pf1ce0dok4nlou9u58in21lcfca8em98a6@4ax.com>

except I used a power FET, and I put some hysteresis in it to avoid
"chattering".

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
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