Today's Message Index:
----------------------
1. 08:33 AM - Re: Battery Contactor Voltage Drop (Paul Eckenroth)
2. 09:03 AM - Re: Battery Contactor Voltage Drop (user9253)
3. 10:30 AM - Re: Battery Contactor Voltage Drop (Charlie England)
4. 03:48 PM - Re: Battery Contactor Voltage Drop (Robert L. Nuckolls, III)
5. 05:30 PM - Re: Battery Contactor Voltage Drop (Paul Eckenroth)
Message 1
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| Subject: | Re: Battery Contactor Voltage Drop |
Thanks for the information Charlie. The reason for the question is that I
have 1 EFIS each on the regular buss and the E buss which show .9V
difference. Does the diode degrade in a way that would increase voltage
drop.
Paul
On Sun, Apr 7, 2019 at 5:34 PM Charlie England <ceengland7@gmail.com> wrote:
> ceengland7@gmail.com>
>
> On 4/7/2019 2:16 PM, Paul Eckenroth wrote:
> > What is the typical voltage drop across the poles of a healthy battery
> > contactor. Is there a failure or aging mode where the voltage drop
> > increases. How about typical voltage drop across the diode bridge
> > rectifier for the essential buss. After eleven trouble free years I
> > need to sort out some problems with my RV9A. Thanks for any information.
> >
> > Paul
> Drop across a good contactor should be hard to measure reliably with a
> regular voltmeter.
>
> Drop across a typical silicon diode will be zero with no load, but will
> be around 0.7V at any significant load.
> If you have a Schottky diode (not likely, but possible), it will be
> around 0.5V or less under load.
>
> ---
> This email has been checked for viruses by Avast antivirus software.
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Message 2
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| Subject: | Re: Battery Contactor Voltage Drop |
Paul,
The diode is fine. A voltage drop of 0.9 volts across a diode is normal. The
voltage drop depends
on the diode characteristics and the current. Some power diodes will drop 1.5
volts or more.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488620#488620
Message 3
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| Subject: | Re: Battery Contactor Voltage Drop |
As long as the operating voltage with the alternator running is 'normal'
(around 14V), I wouldn't be concerned about a 0.9V drop from primary bus
across a standard diode block. If the diode is a typical 'full wave
rectifier' (square metal or plastic block with 4 leads), and the source
is feeding the '-' terminal and the load is on the '+' terminal, the
voltage drop will be higher since the path is actually through two
diodes in series. Not a big deal as long as you understand what's
happening. Only time it might matter is after alternator loss, at the
very end of battery life, *if* the E bus is still fed through the diode.
Charlie
On 4/8/2019 10:31 AM, Paul Eckenroth wrote:
> Thanks for the information Charlie. The reason for the question is
> that I have 1 EFIS each on the regular buss and the E buss which show
> .9V difference. Does the diode degrade in a way that would increase
> voltage drop.
>
> Paul
>
>
> On Sun, Apr 7, 2019 at 5:34 PM Charlie England <ceengland7@gmail.com
> <mailto:ceengland7@gmail.com>> wrote:
>
> <ceengland7@gmail.com <mailto:ceengland7@gmail.com>>
>
> On 4/7/2019 2:16 PM, Paul Eckenroth wrote:
> > What is the typical voltage drop across the poles of a healthy
> battery
> > contactor. Is there a failure or aging mode where the voltage drop
> > increases. How about typical voltage drop across the diode bridge
> > rectifier for the essential buss. After eleven trouble free
> years I
> > need to sort out some problems with my RV9A. Thanks for any
> information.
> >
> > Paul
> Drop across a good contactor should be hard to measure reliably
> with a
> regular voltmeter.
>
> Drop across a typical silicon diode will be zero with no load, but
> will
> be around 0.7V at any significant load.
> If you have a Schottky diode (not likely, but possible), it will be
> around 0.5V or less under load.
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
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Message 4
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| Subject: | Re: Battery Contactor Voltage Drop |
>If the diode is a typical 'full wave rectifier' (square metal or
>plastic block with 4 leads), and the source is feeding the '-'
>terminal and the load is on the '+' terminal, the voltage drop will
>be higher since the path is actually through two diodes in series.
All of my drawings show power input
on an AC terminal (~) and output
on the (+). This uses only one of
the four diodes to minimize voltage
drop.
> Not a big deal as long as you understand what's happening. Only
> time it might matter is after alternator loss, at the very end of
> battery life, *if* the E bus is still fed through the diode.
Correct. Your radios are 'speced' to function
to 10V or less. By the time a battery gets
down to 10v (lead acid) or 11.2v (LiFePO4)
the battery is 'used up'. This is why the
e-bus alternate feed switch is closed any
time the alternator is off line . . . which
lets the electro-whizzies suck the battery
dry.
Any time the alternator is working, voltage
drop in the normal feed diode is insignificant.
Bob . . .
Message 5
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| Subject: | Re: Battery Contactor Voltage Drop |
I appreciate everyone's comments. I thought I had a problem which has now
evaporated.
Paul
On Mon, Apr 8, 2019 at 6:52 PM Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> If the diode is a typical 'full wave rectifier' (square metal or plastic
> block with 4 leads), and the source is feeding the '-' terminal and the
> load is on the '+' terminal, the voltage drop will be higher since the path
> is actually through two diodes in series.
>
>
> All of my drawings show power input
> on an AC terminal (~) and output
> on the (+). This uses only one of
> the four diodes to minimize voltage
> drop.
>
> Not a big deal as long as you understand what's happening. Only time it
> might matter is after alternator loss, at the very end of battery life,
> *if* the E bus is still fed through the diode.
>
>
> Correct. Your radios are 'speced' to function
> to 10V or less. By the time a battery gets
> down to 10v (lead acid) or 11.2v (LiFePO4)
> the battery is 'used up'. This is why the
> e-bus alternate feed switch is closed any
> time the alternator is off line . . . which
> lets the electro-whizzies suck the battery
> dry.
>
> Any time the alternator is working, voltage
> drop in the normal feed diode is insignificant.
>
> Bob . . .
>
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