Voltage Readings

[John Suter]

> John,
>
> Thanks for the wealth of information. I tested with
> a multi-meter
> today, and it looks like everything is fine...I
> guess maybe the
> voltage gauge is just tired.
>
> Scott

Great! Happy to hear of problems that turn out
relatively minor.

Generally speaking, if a direct current (DC) voltage
gauge displays, but occasionally or consistently
appears "lazy," one likely culpit is a "poorly"
grounded meter. As a DC dash meter often shares its
"ground connection" with other nearby 12v devices, and
all are located a good "electrical" distance from the
negative battery ground post(s), be on the lookout for
similar "lazy" behavior from other 12v devices,
lights, fans, etc., especially when they are
collectively "on" and draw significant
amperage/current. Satellite dishes, and other circuit
boards fed with 12v, are particularly sensitive to
aging and poor ground connections and can be damaged.
When you "get your fill" of the poor/lazy behavior,
consider adding an additional ground wire.

John Suter


> --- In WanderlodgeForum@yahoogroups.com, John Suter
>
> wrote:
> >
> > Hi Scott,
> >
> > --- Scott Forman <sforman@r...> wrote:
> >
> > > I don't know a lot about electricity, so I need
> some
> > > help here:
> >
> > Let's first chat a moment about 12V batteries.
> To
> > charge at all, they must be presented with 14.1
> volts
> > or more, and a fully charged, good, 12v battery,
> "at
> > rest" (i.e. without a load, and roughly an hour or
> > more after charging has ceased) should indicate
> 12.65v
> > while a "discharged" battery under the same
> > circumstances will show 12v or less. Note that if
> the
> > battery is not "at rest," measuring its voltage
> will
> > not present an accurate picture, and it really
> needs
> > to be checked with a "Load testing" device for
> true
> > accuracy.
> >
> > It is common to hear an inverter/charger "float
> > charges" at 13.4 or 13.1 or so; however, "float
> > charging" is generally understood not to mean
> "adding
> > any charge," but to be an "in-between state" where
> the
> > charger system has determined charging (14v+) is
> no
> > longer needed, but monitoring is necessary in the
> > event charging becomes necessary.
> >
> > > What should the voltage reading on the engine
> volt
> > > gauge be while
> > > driving?
> >
> > Engine alternator charging is controlled by a
> > regulator system which adjusts both voltage (still
> > must be above 14v to charge) and amperage, which
> is
> > "current flow." The two readings are positively
> > correlated, though not necessarily, directly, in a
> one
> > to one relationship.
> >
> > Voltage and Amperage can be read from the dash
> > gauges; however, the gauges are generally reading
> > totals and not simply the portion which is
> "battery
> > charging." Therefore, depending upon the
> regulator
> > settings and total system demands for
> current/power,
> > the regulator may provide voltages from 12 through
> 18,
> > and amperages from virtually nil to the maximum
> output
> > of the alternator. For most Birds, we'd not find
> it
> > unusual to see around 14 1\2 volts and 20-30 amps.
>
> > Significantly higher or lower of either, would be
> > cause to ask "why," but not necessarily become
> > alarmed.
> >
> > > I have always thought that when driving
> > > normally, the volt
> > > gauge should read somewhere around 14.5 when the
> > > alternator is
> > > putting out properly. Last night, when driving
> home
> > > from a repair
> > > shop where several items were replaced
> (including 4
> > > new batteries),
> > > the gauge was only reading a bit above 12 when
> > > driving. Should I be
> > > concerned about my alternator?
> >
> > With the engine running, turn on all
> headlights
> > and 12V circuits and see what you find, especially
> the
> > amperage.
> > No change, and assuming the gauges are
> reasonably
> > correct, I might be questioning the regulator. If
> it
> > is found normal, then the alternator.
> >
> >
> > > Also...what is the purpose of the 'Amps' gauges?
>
> > > What do they
> > > demonstrate? My 82 FC has one on the dash and
> also
> > > one at the power
> > > switch in the step well.
> >
> > Generally, the one(s) at the step well are
> measuring
> > the amperage of the 110V circuit(s). When
> connected
> > to shore power, turn on an air conditioner
> compressor
> > and watch the amperage gauge.
> >
> >
> > > Neither gauge ever seems
> > > to move much if at
> > > all. What should these two gauges be showing
> me?
> >
> > Hopefully, some of the above may have answered
> this
> > for you, Scott.
> >
> > >
> > > Thanks
> > > Scott Forman
> > > 82 FC35RB
> > > Memphis
> >
> > John Suter
> >
> >
> >
> >
> >
> > __________________________________________
> > Yahoo! DSL – Something to write home about.
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> >
>
>
>
>
>





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