Doug McCrary wrote:
>
> Randolph <trash@junkmail.com> wrote in message
> news:41DE2CFF.5A3FFF3@junkmail.com...
> >
> > <snip-snip-snip>
> >
> > There are several gadgets available that will plug into the lighter
> > socket and measure the voltage. Whit the car running, such a measurement
> > will not be very accurate, as there may be significant voltage drops in
> > the cabling between the battery and the lighter socket.

> Voltage drop from what? Usually the lighter is on its own fuse straight from
> the battery, no?
> The RS unit I have only draws about 20mills...

The lighter plug in '96 - '00 Civics is connected to the ACC output from
the ignition switch, as is the stereo. There is a single wire between
the under-hood fuse box and the ignition switch. So the cigarette
lighter shares this wire with pretty much everything that is powered
through the ignition switch (emphasis on "powered through", a number of
the high current systems that are *switched* through the ignition switch
have relays so that power does not come through the ignition switch,
only current for the relay coil). The ground lead for the lighter plug
is also shared with a number of other devices.

 

"Doug McCrary" <dougmccrary@spamcop.net> wrote in message
news:QoJDd.969$F97.129@trnddc06...
>
> Randolph <trash@junkmail.com> wrote in message
> news:41DE2CFF.5A3FFF3@junkmail.com...
>>
>> <snip-snip-snip>
>>
>> There are several gadgets available that will plug into the lighter
>> socket and measure the voltage. Whit the car running, such a measurement
>> will not be very accurate, as there may be significant voltage drops in
>> the cabling between the battery and the lighter socket.
> Voltage drop from what? Usually the lighter is on its own fuse straight
> from
> the battery, no?
> The RS unit I have only draws about 20mills...
>
>
The lighter feed isn't straight from the battery; it shares the fuse box to
battery wiring with a lot of potentially high draw equipment. The
uncalibrated voltmeter in my Volvo drops a lot when I turn on the lights and
fan, even though the battery voltage doesn't waver. Even things you never
think about, like stereo amplifiers or O2 sensor heaters, can draw enough to
skew the reading several tenths of a volt.

Mike

 

"Doug McCrary" <dougmccrary@spamcop.net> wrote in message
news:QoJDd.969$F97.129@trnddc06...
>
> Randolph <trash@junkmail.com> wrote in message
> news:41DE2CFF.5A3FFF3@junkmail.com...
>>
>> <snip-snip-snip>
>>
>> There are several gadgets available that will plug into the lighter
>> socket and measure the voltage. Whit the car running, such a measurement
>> will not be very accurate, as there may be significant voltage drops in
>> the cabling between the battery and the lighter socket.
> Voltage drop from what? Usually the lighter is on its own fuse straight
> from
> the battery, no?
> The RS unit I have only draws about 20mills...
>
>
The lighter feed isn't straight from the battery; it shares the fuse box to
battery wiring with a lot of potentially high draw equipment. The
uncalibrated voltmeter in my Volvo drops a lot when I turn on the lights and
fan, even though the battery voltage doesn't waver. Even things you never
think about, like stereo amplifiers or O2 sensor heaters, can draw enough to
skew the reading several tenths of a volt.

Mike

 

Randolph <trash@junkmail.com> wrote in message
news:41DF7148.58D6164D@junkmail.com...
>
> Doug McCrary wrote:
> >
> > Randolph <trash@junkmail.com> wrote in message
> > news:41DE2CFF.5A3FFF3@junkmail.com...
> > >
> > > <snip-snip-snip>
> > >
> The lighter plug in '96 - '00 Civics is connected to the ACC output from
> the ignition switch, as is the stereo. There is a single wire between
> the under-hood fuse box and the ignition switch. So the cigarette
> lighter shares this wire with pretty much everything that is powered
> through the ignition switch (emphasis on "powered through", a number of
> the high current systems that are *switched* through the ignition switch
> have relays so that power does not come through the ignition switch,
> only current for the relay coil). The ground lead for the lighter plug
> is also shared with a number of other devices.

Hmm. OK, thanks.

 

Randolph <trash@junkmail.com> wrote in message
news:41DF7148.58D6164D@junkmail.com...
>
> Doug McCrary wrote:
> >
> > Randolph <trash@junkmail.com> wrote in message
> > news:41DE2CFF.5A3FFF3@junkmail.com...
> > >
> > > <snip-snip-snip>
> > >
> The lighter plug in '96 - '00 Civics is connected to the ACC output from
> the ignition switch, as is the stereo. There is a single wire between
> the under-hood fuse box and the ignition switch. So the cigarette
> lighter shares this wire with pretty much everything that is powered
> through the ignition switch (emphasis on "powered through", a number of
> the high current systems that are *switched* through the ignition switch
> have relays so that power does not come through the ignition switch,
> only current for the relay coil). The ground lead for the lighter plug
> is also shared with a number of other devices.

Hmm. OK, thanks.