Hi,

Hope someone can help me. When I start my car (Alfa Romeo 156) the
voltage drops to below 10v. This causes the radio to reset itself -
and an associated interruption. Is there anyway I can stop this
happening?

Thanks,

Walter.

doesn't sound right... Double check the alternator, I have always found
that voltage increases once the engine is started.

Garrett

Walter McCann wrote:

Hi,

Hope someone can help me. When I start my car (Alfa Romeo 156) the
voltage drops to below 10v. This causes the radio to reset itself -
and an associated interruption. Is there anyway I can stop this
happening?

Thanks,

Walter.


Walter McCann wrote:

Hi,

Hope someone can help me. When I start my car (Alfa Romeo 156) the
voltage drops to below 10v. This causes the radio to reset itself -
and an associated interruption. Is there anyway I can stop this
happening?

Thanks,

Walter.


Walter McCann wrote:

Hi,

Hope someone can help me. When I start my car (Alfa Romeo 156) the
voltage drops to below 10v. This causes the radio to reset itself -
and an associated interruption. Is there anyway I can stop this
happening?

Thanks,

Walter.

Walter McCann wrote:
Hi,

Hope someone can help me. When I start my car (Alfa Romeo 156) the
voltage drops to below 10v. This causes the radio to reset itself -
and an associated interruption. Is there anyway I can stop this
happening?

Have your battery tested. Your system shouldn't drop below 12 volts when
you start. This indicates that there is a problem in your charging
system. Either the battery is bad, or your alternator is no longer
charging.

Otherwise, you can use a very large capactior (100,000 uf) on the main
power wire, with a diode to isolate it from the cars electrical system.
Of couse, you'll get a slight voltage drop across the diode, but luckly
you're going to have to use about 4 diodes in parallel to be able to
handle the current of most decks (standard power diodes are about 3
amps), and this is going to reduce your voltage drop.

But fix the car before you start rigging ****.

--
Lizard

teamROCS #007 / Technical Director / Founding Member *res derelicta*
http://www.teamrocs.com/
X-Header-PO: This Line Exists to Violate Usenet Protocol, Disregard

Hi guys,

Thanks for the help. The voltage only drops while the starter is
engaged and it is only for a second or so. Once the engine start, the
voltage is always above 12v.

Thanks,

Walter.


The Lizard wrote in message ...
Walter McCann wrote:
Hi,

Hope someone can help me. When I start my car (Alfa Romeo 156) the
voltage drops to below 10v. This causes the radio to reset itself -
and an associated interruption. Is there anyway I can stop this
happening?

Have your battery tested. Your system shouldn't drop below 12 volts when
you start. This indicates that there is a problem in your charging
system. Either the battery is bad, or your alternator is no longer
charging.

Otherwise, you can use a very large capactior (100,000 uf) on the main
power wire, with a diode to isolate it from the cars electrical system.
Of couse, you'll get a slight voltage drop across the diode, but luckly
you're going to have to use about 4 diodes in parallel to be able to
handle the current of most decks (standard power diodes are about 3
amps), and this is going to reduce your voltage drop.

But fix the car before you start rigging ****.

I suspect that you've got a bad or weak battery (or the wrong battery).

Best,

Phil Sharkey

In article ,
The Lizard wrote:

Walter McCann wrote:
Hi,

Hope someone can help me. When I start my car (Alfa Romeo 156) the
voltage drops to below 10v. This causes the radio to reset itself -
and an associated interruption. Is there anyway I can stop this
happening?

Have your battery tested. Your system shouldn't drop below 12 volts when
you start. This indicates that there is a problem in your charging
system. Either the battery is bad, or your alternator is no longer
charging.

Otherwise, you can use a very large capactior (100,000 uf) on the main
power wire, with a diode to isolate it from the cars electrical system.
Of couse, you'll get a slight voltage drop across the diode, but luckly
you're going to have to use about 4 diodes in parallel to be able to
handle the current of most decks (standard power diodes are about 3
amps), and this is going to reduce your voltage drop.

But fix the car before you start rigging ****.

You should go measure your battery voltage while cranking before giving
such advice.

With the car off you should read 12VDC with a multimeter When cranking
there will be a small drop in voltage but, after it starts you should read
between 13.5VDC and 14.5VDC. It may level out to closer to 12VDC after a
long period of time when the battery gets to a fully charged state and you
hae no electrical item on that is draining power. If this is not happening
then you could have a weak battery or your alternator/voltage regulator is
not putting out properly. It could also be that the alternator needs to be
replaced with a high amperage one if you have a very high drain from many
audio amps.

Easy way to find out is go a local Walmart with auto services and they will
put a battery checker on it for free. The machine will tell within a couple
of minutes if the battery or alternator is at fault.

Also, if the battery is bad you could buy the battery they have with the
highest CCA cold cranking amps with the longest warranty(72 months I
believe). If it's the alternator go to a local shop to have replaced or a
parts store and do it yourself. It is quite easy. Nice thing about the
battery from Walmart is they will replace it for free any time within the
warranty period.

The other thing that could possibly be wrong is bad cables or faulty
connections. They should be corrosion free at the battery posts. Sometimes
corrosion gets down inside the cable itself and causes problems that you
cannot see.

12VDC from the alternator across the battery posts is too low and needs to
be checked to find out the problem before the battery causes the alternator
to fail or vice versus. Then you will have to replace both.

lter McCann" wrote in message
om...
Hi guys,

Thanks for the help. The voltage only drops while the starter is
engaged and it is only for a second or so. Once the engine start, the
voltage is always above 12v.

Thanks,

Walter.


The Lizard wrote in message
...
Walter McCann wrote:
Hi,

Hope someone can help me. When I start my car (Alfa Romeo 156) the
voltage drops to below 10v. This causes the radio to reset itself -
and an associated interruption. Is there anyway I can stop this
happening?

Have your battery tested. Your system shouldn't drop below 12 volts when
you start. This indicates that there is a problem in your charging
system. Either the battery is bad, or your alternator is no longer
charging.

Otherwise, you can use a very large capactior (100,000 uf) on the main
power wire, with a diode to isolate it from the cars electrical system.
Of couse, you'll get a slight voltage drop across the diode, but luckly
you're going to have to use about 4 diodes in parallel to be able to
handle the current of most decks (standard power diodes are about 3
amps), and this is going to reduce your voltage drop.

But fix the car before you start rigging ****.

Kevin I agree, in fact I am sure all would be shocked
if they knew the actual varriations that can be produced
in a vehicle electrical system over short durations, both positive and
negative including EMC transients.
Take a look at ISO-7647-1, DIN 40839 and SAE-J1113 to name a few.
Jeff

"Kevin McMurtrie" wrote in message
...
In article ,
The Lizard wrote:

Kevin McMurtrie wrote:

You should go measure your battery voltage while cranking before giving
such advice.

You should know what you're talking about before correcting my advice.
Under no circuimstance should a healthy electrical system drop
significantly below 12 volts while cranking, certainly not below 10
volts on a brand new 4 cylinder car. There is a small voltage drop
because of the internal resistance of a battery under heavy load, but
you're talking about losing an entire cell.

Having installed ass-loads of remote starts, I think I'm a bit more
qualified to asses the health voltage state of a car during ignition.

I think your voltmeter sucks.

My 96/97 Civic repair manual states:
Battery voltage should be no less than 8.5V while cranking.
Battery voltage should be above 9.6V at 300A.

My 88 Tercel had a starter without a gearbox. It's repair manual said
the battery voltage will be about 9V while cranking. A test showed it
was about 9.5V to 9.7V. I installed an oversized battery and it
maintained 10.5V while cranking.

A check with an oscilloscope shows that the actual voltage varies quite
a bit. 9V to 10V is only the average once the engine is spinning. I
know this because I have designed personal electronics for automotive
use. I built my first 100Wx2 audio amp from scratch, using descrete
components and my own schematic, when I was still in high school.