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revenson(at)comcast.net
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 Posted: Thu Feb 12, 2015 3:15 pm Post subject: 12v vs 14v System? |
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Is there any practical difference between a 12v and a 14v system?
At the airport, the question came up whether my Standard VR166 voltage regulator (12volt?) was appropriately rated for my system and it was suggested this regulator might not be right for a '14 volt system'.
"Did I have a 12v. or a 14v. battery?" Looked at the Odyssey docs and of course, it's a 12 volt battery (and there are no 14 volt batteries in the Aircraft Spruce catalog!).
My battery is an Odyssey PC-680, listed as a 12 volt battery. All batteries listed in the catalog are listed as either 12 (if not 24v).
Starter is a Skytec, listed as 12 volt. All starters are listed as 12v.
Alternator is an L40 from B and C. It's listed as 14 volt. Some manufacturers list theirs as 12v; some as 14v.
Regulator is a Standard VR166. 12 volt? Some voltage regulators are listed as 12v; some manufacturers list as 14v; even saw one listed as 14.2v.
My assumption has always been that some manufacturers list their equipment as 14v. and some at 12v., but that's just an artifact, and there's no practical difference. Am I correct?
Thanks, Roger.
"For I know the plans I have for you," declares the Lord, "plans to prosper you and not to harm you, plans to give you hope and a future." Jeremiah 29:11
[quote][b]
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user9253
Joined: 28 Mar 2008
Posts: 1925
Location: Riley TWP Michigan
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| Posted: Thu Feb 12, 2015 8:41 pm Post subject: Re: 12v vs 14v System? |
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| Quote: | | Is there any practical difference between a 12v and a 14v system? |
No, they are nominally the same. A fully charged 12 volt lead acid battery measures about 13 volts. A voltage regulator for a 12 volt battery is set at about 14.2 volts. A voltage regulator set at 13 volts would keep a battery from discharging but would not charge a battery that needs to be charged.
| Quote: | | there's no practical difference. Am I correct? |
Yes
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mmayfield
Joined: 09 Oct 2009
Posts: 40
Location: NSW Central Coast, Australia
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Eric M. Jones
Joined: 10 Jan 2006
Posts: 565
Location: Massachusetts
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| Posted: Sun Feb 15, 2015 8:59 am Post subject: Re: 12v vs 14v System? |
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The problem with standardizing battery voltages is how the batteries are made. This is not the same as "harmonizing" AC voltages (which elsewhere in the ISO world are now all called 230 VAC, 50 Hz., with large tolerances. The US is 120VAC 60 Hz. by ANSI standards.)
Their are innumerable DC cells between 0.03V and 4.10 that are can be combined to make batteries. These electrochemical combinations can be aimed at "something close to 12V-14V", but there is not much you can do if they actually wind up to be 11.76, 13.44, or whatever. One cannot set a general standard.
And yes, there are primary (non-rechargeable) and secondary cells (rechargeable), various environmental problems and conditions, weight and operation conditions...and Thomas Edison's 1.4 volts iron cells still work fine for many applications today.
So yes, I am all in favor of standardization, but in batteries--don't expect standardization just yet. This leads writers to use nominal terms.
en.wikipedia.org/wiki/Standard_electrode_potential_%28data_page%29
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Eric M. Jones
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nuckolls.bob(at)aeroelect
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| Posted: Sun Feb 15, 2015 6:57 pm Post subject: 12v vs 14v System? |
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| Quote: |
It's probably too much to ask for standard terms to be applied to electrical systems after all these decades. [Wink] |
Ain't gonna happen . . . batteries are chemical beasts with no
single cell offering anything closed to 12v. So combinations of
cells have to be joined until the target 'system' requirements
are met. In the case of lead-acid batteries, multiple cells in series
were '6-volt', '12-volt' and '24-volt' long before anyone stuck
them in a vehicle paired with a generator.
Boats and railroad cars featured '36-volt batteries' charged
at 42 volts. To this day, you can still buy a 32 volt lamp
for 'marine' application.
[img]cid:.0[/img]
C Kettering's 1916 Delco-Light plant for rural applications were offered to
charge 16 lead-acid cells in series . . .
[img]cid:.1[/img]
This would have nominally been a 32-volt battery charged by a generator
and (later a wind-mill) for a system voltage of 38 volts.
Just put a new battery in Dr. Dee's little red Saturn. Just for grins,
I sucked out most of the electrons in its off-the-shelf condition and
got this plot . . .
[img]cid:.0[/img]
With a 5A load, you can see that it started out a closer to 13 volts and tossed
in the towel before it about 11 volts . . . i.e. an average output of 12 volts.
Now, to stuff all those electrons back in at room temperature, I would need
to charge it at 13.8 volts for a few days . . . to get it stoked back up in
hours or less, a charge voltage of 14.2 to 14.8 is called for. Since
day-one, vehicles of all stripe have been said to operate at the battery's
maintenance voltage (i.e. 14v) while in fact, batteries delivered energy at
their label value of 12v (which is a more of an average over the discharge
curve of the battery).
Don't know if you could call it a 'standard' of any kind . . . but the
legacy vernacular for describing the alternator-battery combination speaks
of a "12 volt battery" in a "14 volt system."
Now comes the lithium family of cells. If you charge a stack of 4 cells
to the maximum rated charge voltage of 4.2 volts per cell, then you'd
have to do it in a 16.8 volt system.
[img]cid:.1[/img]
Referring to the family of curves above, the 16.8 volt operation
gives you a "15 volt battery". But put the same array of cells
into your "14v system" tuned to lead-acid chemistry and you get a
"13.5 volt battery" while giving up about 1/2 its max rated
chemical capacity.
Hence, it's entirely proper and logical to speak of batteries
in terms of the manner in which they deliver energy and to speak
of systems in terms a nominal operating voltage within which
all accessories (including the battery) are obliged to perform
to design goals.
Bob . . .
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nuckolls.bob(at)aeroelect
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| Posted: Mon Feb 16, 2015 6:19 am Post subject: 12v vs 14v System? |
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To: aeroelectric-list(at)matronics.com
From: "Robert L. Nuckolls, III" <nuckolls.bob(at)aeroelectric.com>
Subject: Re: Re: 12v vs 14v System?
It's probably too much to ask for standard terms to be applied to electrical systems after all these decades. [Wink]
Ain't gonna happen . . . batteries are chemical beasts with no
single cell offering anything closed to 12v. So combinations of
cells have to be joined until the target 'system' requirements
are met. In the case of lead-acid batteries, multiple cells in series
were '6-volt', '12-volt' and '24-volt' long before anyone stuck
them in a vehicle paired with a generator.
Early electrification of boats and railroad cars featured '32-volt
batteries' charged at 38 volts. To this day, you can still buy a 32
volt lamp for 'marine' applications.
[img]cid:7.1.0.9.0.20150216081041.010c09c8(at)aeroelectric.com.2[/img]
Chas Kettering's 1916 Delco-Light plant for rural applications were offered to
charge 16 lead-acid cells in series . . .
[img]cid:7.1.0.9.0.20150216081041.010c09c8(at)aeroelectric.com.3[/img]
This would have nominally been a 32-volt battery charged by a generator
and (later a wind-mill) for a system voltage of 38 volts.
Just put a new battery in Dr. Dee's little red Saturn. Just for grins,
I sucked out most of the electrons in its off-the-shelf condition and
got this plot . . .
[img]cid:7.1.0.9.0.20150216081041.010c09c8(at)aeroelectric.com.4[/img]
With a 5A load, you can see that it started out a closer to 13 volts and tossed
in the towel before it about 11 volts . . . with an AVERAGE output of 12 volts.
Now, to stuff all those electrons back in at room temperature, I need
to charge it at 13.8 volts for a few days . . . but to stoke it back up in
hours or less, a charge voltage of 14.2 to 14.8 is called for. Since
day-one, vehicles of all stripe have been said to operate at the battery's
maintenance voltage (i.e. 14v) while in fact, batteries delivered energy at
their label value of 12v (which is a more of an average over the discharge
curve of the battery).
Now comes the lithium family of cells. If you charge a stack of 4 cells
to the maximum rated charge voltage of 4.2 volts per cell, then you'd
have to do it at about 16.8 volts. We might call this a '17 volt system.'
[img]cid:7.1.0.9.0.20150216081041.010c09c8(at)aeroelectric.com.5[/img]
Referring to the family of curves above, the 16.8 volt operation
gives you a "15 volt battery". But put the same array of cells
into your "14v system" tuned to lead-acid chemistry and you get a
"13.5 volt battery" while giving up about 1/2 its max rated
chemical capacity.
Hence, it's entirely proper and logical to speak of batteries
in terms of the manner in which they deliver energy and to speak
of systems in terms a nominal operating voltage within which
all accessories (including the battery) are obliged to perform
to design goals.
Bob . . .
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mmayfield
Joined: 09 Oct 2009
Posts: 40
Location: NSW Central Coast, Australia
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| Posted: Tue Feb 17, 2015 4:19 am Post subject: Re: 12v vs 14v System? |
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I didn't ask for "standard voltages". I wrote "standard terms". That is, standard "terminology" to describe a type of system.
You have some manufacturers calling it a "12v system" and others a "14v system". What's so hard about keeping the terminology consistent when they're talking about the exact same thing?
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glastar(at)gmx.net
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| Posted: Tue Feb 17, 2015 4:49 am Post subject: 12v vs 14v System? |
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Mike agree with your confusion about standards. We might put it a bit
like following:
-with engine stopped you will have a 12V system
-with engine running you will have a 14V system
this not taking into account the digits behind the decimal as well as
assuming a standard PB battery
Cheers Werner
On 17.02.2015 13:19, mmayfield wrote:
| Quote: |
I didn't ask for "standard voltages". I wrote "standard terms". That is, standard "terminology" to describe a type of system.
|
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Bob McC
Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON
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| Posted: Tue Feb 17, 2015 6:20 am Post subject: 12v vs 14v System? |
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Throwing charging voltages into the mix is where the confusion arises.
Going back 100 or so years, cars were 6 volt, then in the early 50's along came the improvement to 12 volt. No one mentioned that those 6 volt batteries were charged at some higher voltage (which they were) and no one mentioned that the "new" 12 volt cars charged at a higher voltage still. Almost everyone referes to car electrical systems as "12 volt" and doesn't worry about the subtle detail of actual measured voltages unless trouble shooting for some perceived problem. When was the last time you heard anyone refer to their 14 volt car???? Aircraft are fundamentally the same. With aircraft (smaller ones at least) the "standard" systems have traditionally been 12 or 24 volt systems. While bringing the fact of higher charging voltages into the mix is technically correct, there is no need to play semantics of whether the system is 12V or 14V. (or 14.2V or 13.9V) It's the same system. The details of actual measured voltages at any point in time do not change the fact the system is either 12 volt or 24 volt even if you can measure 28.4 volts with your voltmeter. Keep it simple as you're unlikely to be technically accurate at any point in time.
Bob McC
| Quote: | Date: Tue, 17 Feb 2015 13:48:09 +0100
From: glastar(at)gmx.net
To: aeroelectric-list(at)matronics.com
Subject: Re: AeroElectric-List: Re: 12v vs 14v System?
--> AeroElectric-List message posted by: Werner Schneider <glastar(at)gmx.net>
Mike agree with your confusion about standards. We might put it a bit
like following:
-with engine stopped you will have a 12V system
-with engine running you will have a 14V system
this not taking into account the digits behind the decimal as well as
assuming a standard PB battery
Cheers Werner
On 17.02.2015 13:19, mmayfield wrote:
> --> AeroElectric-List message posted by: "mmayfield" <mmayfield(at)ozemail.com.au>
>
> I didn't ask for "standard voltages". I wrote "standard terms". That is, standard "terminology" to describe a type of system.
>================
|
[quote][b]
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Bob McC
Falco #908
(just starting) |
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