Today's Message Index:
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1. 05:59 AM - Re: Lithium batteries redux (Jan de Jong)
2. 11:16 AM - Re: Load Analysis Feedback Please... (idleup)
3. 11:30 AM - Re: Load Analysis Feedback Please... (idleup)
4. 01:58 PM - Re: Re: Load Analysis Feedback Please... (Peter Pengilly)
Message 1
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| Subject: | Re: Lithium batteries redux |
Quote from PPRuNe forum:
"The APU and main batteries are quoted as a Lithium Manganese in my 787
gen fam course notes. "
May not be LiFePO4 at all...
Jan de Jong
Message 2
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| Subject: | Re: Load Analysis Feedback Please... |
Peter (and others),
Peter,
It has taken me a while to address the items in your post. Thanks for reviewing
my load analysis so thoroughly I appreciate it I ended up moving the compass
light completely since it should be connected through the lighting controller
and I moved the controller to the endurance bus.
I understand what you are saying about the peak vs. transient loads. The loads
that I used were based on other load analysis worksheets that others have posted
and the documentation that I can find. When you said that a PC-680 would not
meet the requirement of 30 minutes you said that 22Ah would be be required,
where on my loan analysis did you get the 22Ah number from?
As for the fuse loads, I agree that it seems inconsistent. The 3A on a 2.5A load
seems too low to me as well, I was using the manufacturer recommended fuse size
in the worksheet. The EFIS's are AF-4500's and in the manual (v7.4) on page
69 it states to use a 3A fuse. Should I disregard this and go with say a 5A
fuse instead? maybe someone with these same EFIS's can tell me what they did?
The reason the strobe fuse is 10A is because the manual states that each strobe
uses 2.25A at peak for 0.33 seconds. Now, I remember reading about how quick
peaks do not require larger fuses but I guess this case I was being cautious because
I did not know. Based on this specification, what do you believe is a sufficiently
sized fuse for the strobe circuit if not 10A?
As for the wire sizes for the SL-40, Audio Panel, and CO Monitor, what size would
you recommend? I realize they are not consistent. Should I always use the same
size wire for a given fuse size on the circuit? if so, is there a chart somewhere
that says which size wire to always use for 5A or 1A fuses?
The 4AWG wire on the battery is in fact the main feed. I am using Bob's Figure
Z-13/8 as a reference which states that "All wires marked 2AWG may be downsized
to 4AWG depending on the size of engine and location of batteries". Should I
instead keep this at 2AWG based on my loads in your opinion?
Also, on my wiring schematic I have a 22AWG wire going from panel ground to the
Master Switch and then to the battery contractor, do you think this should be
18AWG instead based on your comment?
If I understand your question correctly then yes, the starter contractor takes
a different load than the battery contactor. The two contractors are wired together
with a 4AWG wire for the main load, but the starter contactor has a 3A load
coming off the main power bus to the switch. So I guess the starter contractor
has two power sources and the one off the bus is protected with a 7A fuse.
Is this what you were asking?
The audio panel is a PMA-8000B and the only current it shows in the specifications
is the maximum current of 2.5A on page 1-2. I have no idea what the transient
load is.
I am not sure what you mean by the flap motor load is not consistent. Are you saying
I should use the 3A for all phases of flight instead of using 1.5A? I figured
that it was not going to use peak load all the time but maybe I am wrong?
The landing light is a PAR-36 style Duckworks light. In the manual on page 7 it
says if you use a 100W bulb then use at least 10A fuse with 16AWG wire. However,
I bumped it up to 14AWG since I already will be using 14 elsewhere and do
not want to buy 16 just for this run. I changed the load to 7.5A per your recommendation.
In all reality, I may change this before I am done to a lower drawing
landing light (like 55W) but I want to plan it for what I purchased and what
I know is the worst case.
I do not currently have a back-up battery for either of my EFIS's. I know this
is an option that I can purchase from AFS but I believe it hooks directly into
the back of the EFIS and would not affect my load analysis worksheet at all.
Again, thank you for taking the time to review this. I would appreciate if you
also took the time to respond to my questions above. Thanks.
- Matt
peter(at)sportingaero.com wrote:
> Hi Matt,
>
> The only issue that might cause you a problem is the equipment on the
> battery buss - if you cannot switch most of those items off with the
> master switch you will drain the battery quickly. Are you sure the EI
> should not be switched? Are you sure you will always turn off the
> instrument & compass lights? The remaining comments are details.
>
> When I construct a loading table I use the steady state load as the
> value I'm interested in for load assessment, and the max draw to size
> the fuse and wire. A wiring diagram showing the feeds to the busbars
> (not to the individual loads) would also be useful. You appear to have
> listed the peak load only, for example you have listed an SL-40 taking
> 2A and a 430 taking 6A, these are probably transmit currents and would
> be pulled for only short periods. I would use the steady state figure
> for all the devices for load calculation, but use the peak load to size
> fuse and wire size. It is usually assumed that the battery will handle
> any transient loads, such as radio transmit, flap motor, trim or gear
> motor (if you had one), otherwise the alternator becomes huge. When
> calculating the size of the battery for alternator out purposes the
> increase in draw of large loads at the reduced battery voltage can be
> significant (landing/taxi light, pitot heat) so may be worth listing
> separately - your battery at 72% charge should be able to support the
> endurance & battery loads for 30 minutes. As written a PC-680 would not
> meet this requirement (12Ah available, 22Ah required).
> Some of your fuse sizes seem low (3A fuse on a 2.5A load, for example
> EFIS). Fuses protect the wire, double the load at least. Some also seem
> high (10A fuse on a 2.4A load on the strobes). Wire sizes seem
> inconsistent, the SL-40, a 2A load, has an 18g wire, but the audio
> panel, a 2.5A load, has a 22g wire, CO monitor, a 0.1A load, has a 20g
> wire.
>
> Some specific points,
> - Why 4ga wire of the battery connector, it only pulls 1 amp? If that is
> the main battery feed is 4ga large enough (2 or 0 is common)? There
> should be a switch to pull in the battery contactor, often wired with 18ga.
> - Starter, does that starter contactor take a different load from the
> battery contactor?
> - Does the audio panel really pull 2.5A continuously?
> - Flap motor load is not consistent
> - Landing light load is high, are you sure it is 100W? If so it will
> draw 7A on the alternator or 8A on the battery.
> - Do you not have a back-up battery on at least one of your EFISs?
>
> Hope this helps,
>
> Peter
>
>
> On 29/12/2012 06:08, idleup wrote:
>
> >
> >
> > Would you guys be so kind as to review my Load Analysis worksheet and tell
me if you see anything that looks incorrect or have recommendations to make it
better? I have spent quite a bit of time on this but at the end of the day still
question whether I know what I am doing and would appreciate some peer review...
Thanks.
> >
> >
> >
> > Of if you would prefer to download the PDF: http://www.mattandmel.com/rv/Master_Load_Analysis_v1.pdf
> >
> > Thank you much.
> >
> > Matt
> >
> >
> >
> >
> > Read this topic online here:
> >
> > http://forums.matronics.com/viewtopic.php?p=391129#391129
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=391926#391926
Message 3
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| Subject: | Re: Load Analysis Feedback Please... |
Jeff,
I did end up moving the lighting off the battery bus and onto the endurance bus.
I also moved the landing light and flaps to the main bus as per your suggestions.
I was thinking in an electrical emergency at night I would need the landing
light and flaps, but you are correct that those really are not needed during
the "endurance" phase of flight, just the landing. Hopefully there would not
be a problem that turning back on the master switch would aggrevate when I do
need them.
The main reason I used the maximum currents is because I was trying to plan for
worst case scenarios. As per Peter's recommendation I really should have two
sheets (or multiple columns) so one set of loads can be used to determine battery
endurance and the other for fuse and wire sizing. I have not seen this however
in any of the templates I used for the load analysis so I did not do it that
way.
Also, my architecture is using Bobs Z-13/8.
Thanks,
Matt
Tundra10 wrote:
> Matt,
>
> You definitely put a lot of work into this :-)
>
> You have used maximum currents, although in many cases, actual runtime
> currents will be much lower. The radios are a good example. The
> SL-40 is about 0.4A during receive. The Garmin 430 is about 2A for
> receive + nav. The audio panel probably uses less than 2A too.
>
> You decide what really needs to be on the endurance buss, but I would
> suggest moving the flap motor and landing light to the main buss.
> Once you have successfully arrived at the airport, you can turn the
> main buss back on and use the battery reserve to lower the flaps and
> maybe use the landing light (or just land without it).
>
> I would put the lighting controller and compass light on the endurance
> buss. You are less likely to leave them on accidentally draining the
> battery. More importantly, if you have an electrical fire, you want
> to be able to disconnect everything (except the ignition) by turning
> off the master switch.
>
> Using more typical currents, your endurance buss will be below 18A,
> allowing extended flight with a 20A backup alternator. You didn't
> mention what your architecture is.
>
> Jeff Page
> Dream Aircraft Tundra #10
>
>
>
>
> > From: "idleup"
> >
> >
> > Would you guys be so kind as to review my Load Analysis worksheet
> > and tell me if
> > you see anything that looks incorrect or have recommendations to
> > make it better?
> > I have spent quite a bit of time on this but at the end of the day still
> > question whether I know what I am doing and would appreciate some
> > peer review...
> > Thanks.
> >
> >
> > Of if you would prefer to download the PDF:
> > http://www.mattandmel.com/rv/Master_Load_Analysis_v1.pdf
> >
> > Thank you much.
> >
> > Matt
> >
> >
>
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=391928#391928
Message 4
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| Subject: | Re: Load Analysis Feedback Please... |
Hi Matt,
> where on my loan analysis did you get the 22Ah number from?
I simply added the total loads on the Endurance and Battery busses
(40.83 + 3.42), which in retrospect is probably pessimistic. I should
have used any of the night descent numbers - but they are all
significantly above that is available. If you look at the steady state
currents for night IFR cruise and then 10 minutes of descent I wonder
what the number is? There are many people using a PC680 as their only
battery, so I would guess it is possible.
>The EFIS's are AF-4500's and in the manual (v7.4) on page 69 it states
to use a 3A fuse. Should I disregard this and go with say a 5A fuse
instead? maybe someone with these same EFIS's can tell me what they did?
I have an AF-4500 in my aeroplane and used a 5A fuse. Bear in mind the
fuses protect the wiring more than anything.
>As for the wire sizes for the SL-40, Audio Panel, and CO Monitor, what
size would you recommend? I realize they are not consistent. Should I
always use the same size wire for a given fuse size on the circuit? if
so, is there a chart somewhere that says which size wire to always use
for 5A or 1A fuses?
Wire sizes are the subject of much debate (I'm sure others will chime
in), but there are really only 4 or 5 choices 22, 20, 18, 16 or 14g for
most runs. The only penalty in using 14g everywhere is weight (you would
be surprised just how much) and cost. You're right, there is no point in
buying 20' of one size for just one run. I use 22g everywhere I can -
particularly for radio and avionics feeds where the current draw is low
and the wire length (from fuse panel) is short. There is a chart which
equates current draw and wire length to gauge size - I think its in AC43.13
> The 4AWG wire on the battery is in fact the main feed. ... Should I
instead keep this at 2AWG based on my loads in your opinion?
Either will work, I tend to go for the larger diameter to ensure the are
no starting problems, particularly are a couple of years in service. If
you planning a permanent magnet starter the larger wire may be more
desirable as they take 2x current of slightly heavier starters.
>Also, on my wiring schematic I have a 22AWG wire going from panel
ground to the Master Switch and then to the battery contractor, do you
think this should be 18AWG instead based on your comment?
I was only pointing out you plan was inconsistent, it does not really
matter for short runs. For the last panel I wired up I bought 100' of
black 20g and used that for all the panel grounds.
>If I understand your question correctly then yes, the starter
contractor takes a different load than the battery contactor.
OK
>The two contractors are wired together with a 4AWG wire for the main
load, but the starter contactor has a 3A load coming off the main power
bus to the switch.
Could I suggest you look into the main contactor wiring in more detail -
what kind of OV protection are you using?
> The audio panel is a PMA-8000B and the only current it shows in the
specifications is the maximum current of 2.5A on page 1-2. I have no
idea what the transient load is.
2.5A is the transient load, as a guess the steady state load is probably
around 0.5A (no external speaker).
>I am not sure what you mean by the flap motor load is not consistent.
Are you saying I should use the 3A for all phases of flight instead of
using 1.5A?
Yes, if the flap motor takes 3A then use that - you could possibly use
1.5A for retract (wind is helping) and 3 for extension. However, I would
use 3A for fuse and wire sizing, but ignore from the rest of the load
sheet as the duration is very short.
In my AF-4500 the battery is internal and was fitted when I bought it.
As a further level of redundancy when something you haven't thought of
has stolen all of your electrons I think its worthwhile.
Hope this helps,
Peter
On 09/01/2013 19:15, idleup wrote:
>
> Peter (and others),
>
> Peter,
>
> It has taken me a while to address the items in your post. Thanks for reviewing
my load analysis so thoroughly I appreciate it I ended up moving the compass
light completely since it should be connected through the lighting controller
and I moved the controller to the endurance bus.
>
> I understand what you are saying about the peak vs. transient loads. The loads
that I used were based on other load analysis worksheets that others have posted
and the documentation that I can find. When you said that a PC-680 would
not meet the requirement of 30 minutes you said that 22Ah would be be required,
where on my loan analysis did you get the 22Ah number from?
>
> As for the fuse loads, I agree that it seems inconsistent. The 3A on a 2.5A load
seems too low to me as well, I was using the manufacturer recommended fuse
size in the worksheet. The EFIS's are AF-4500's and in the manual (v7.4) on page
69 it states to use a 3A fuse. Should I disregard this and go with say a 5A
fuse instead? maybe someone with these same EFIS's can tell me what they did?
>
> The reason the strobe fuse is 10A is because the manual states that each strobe
uses 2.25A at peak for 0.33 seconds. Now, I remember reading about how quick
peaks do not require larger fuses but I guess this case I was being cautious
because I did not know. Based on this specification, what do you believe is a
sufficiently sized fuse for the strobe circuit if not 10A?
>
> As for the wire sizes for the SL-40, Audio Panel, and CO Monitor, what size would
you recommend? I realize they are not consistent. Should I always use the
same size wire for a given fuse size on the circuit? if so, is there a chart
somewhere that says which size wire to always use for 5A or 1A fuses?
>
> The 4AWG wire on the battery is in fact the main feed. I am using Bob's Figure
Z-13/8 as a reference which states that "All wires marked 2AWG may be downsized
to 4AWG depending on the size of engine and location of batteries". Should
I instead keep this at 2AWG based on my loads in your opinion?
>
> Also, on my wiring schematic I have a 22AWG wire going from panel ground to the
Master Switch and then to the battery contractor, do you think this should
be 18AWG instead based on your comment?
>
> If I understand your question correctly then yes, the starter contractor takes
a different load than the battery contactor. The two contractors are wired together
with a 4AWG wire for the main load, but the starter contactor has a 3A
load coming off the main power bus to the switch. So I guess the starter contractor
has two power sources and the one off the bus is protected with a 7A fuse.
Is this what you were asking?
>
> The audio panel is a PMA-8000B and the only current it shows in the specifications
is the maximum current of 2.5A on page 1-2. I have no idea what the transient
load is.
>
> I am not sure what you mean by the flap motor load is not consistent. Are you
saying I should use the 3A for all phases of flight instead of using 1.5A? I
figured that it was not going to use peak load all the time but maybe I am wrong?
>
> The landing light is a PAR-36 style Duckworks light. In the manual on page 7
it says if you use a 100W bulb then use at least 10A fuse with 16AWG wire. However,
I bumped it up to 14AWG since I already will be using 14 elsewhere and do
not want to buy 16 just for this run. I changed the load to 7.5A per your recommendation.
In all reality, I may change this before I am done to a lower drawing
landing light (like 55W) but I want to plan it for what I purchased and
what I know is the worst case.
>
> I do not currently have a back-up battery for either of my EFIS's. I know this
is an option that I can purchase from AFS but I believe it hooks directly into
the back of the EFIS and would not affect my load analysis worksheet at all.
>
> Again, thank you for taking the time to review this. I would appreciate if you
also took the time to respond to my questions above. Thanks.
>
> - Matt
>
>
> peter(at)sportingaero.com wrote:
>> Hi Matt,
>>
>> The only issue that might cause you a problem is the equipment on the
>> battery buss - if you cannot switch most of those items off with the
>> master switch you will drain the battery quickly. Are you sure the EI
>> should not be switched? Are you sure you will always turn off the
>> instrument & compass lights? The remaining comments are details.
>>
>> When I construct a loading table I use the steady state load as the
>> value I'm interested in for load assessment, and the max draw to size
>> the fuse and wire. A wiring diagram showing the feeds to the busbars
>> (not to the individual loads) would also be useful. You appear to have
>> listed the peak load only, for example you have listed an SL-40 taking
>> 2A and a 430 taking 6A, these are probably transmit currents and would
>> be pulled for only short periods. I would use the steady state figure
>> for all the devices for load calculation, but use the peak load to size
>> fuse and wire size. It is usually assumed that the battery will handle
>> any transient loads, such as radio transmit, flap motor, trim or gear
>> motor (if you had one), otherwise the alternator becomes huge. When
>> calculating the size of the battery for alternator out purposes the
>> increase in draw of large loads at the reduced battery voltage can be
>> significant (landing/taxi light, pitot heat) so may be worth listing
>> separately - your battery at 72% charge should be able to support the
>> endurance & battery loads for 30 minutes. As written a PC-680 would not
>> meet this requirement (12Ah available, 22Ah required).
>> Some of your fuse sizes seem low (3A fuse on a 2.5A load, for example
>> EFIS). Fuses protect the wire, double the load at least. Some also seem
>> high (10A fuse on a 2.4A load on the strobes). Wire sizes seem
>> inconsistent, the SL-40, a 2A load, has an 18g wire, but the audio
>> panel, a 2.5A load, has a 22g wire, CO monitor, a 0.1A load, has a 20g
>> wire.
>>
>> Some specific points,
>> - Why 4ga wire of the battery connector, it only pulls 1 amp? If that is
>> the main battery feed is 4ga large enough (2 or 0 is common)? There
>> should be a switch to pull in the battery contactor, often wired with 18ga.
>> - Starter, does that starter contactor take a different load from the
>> battery contactor?
>> - Does the audio panel really pull 2.5A continuously?
>> - Flap motor load is not consistent
>> - Landing light load is high, are you sure it is 100W? If so it will
>> draw 7A on the alternator or 8A on the battery.
>> - Do you not have a back-up battery on at least one of your EFISs?
>>
>> Hope this helps,
>>
>> Peter
>>
>>
>> On 29/12/2012 06:08, idleup wrote:
>>
>>>
>>>
>>> Would you guys be so kind as to review my Load Analysis worksheet and tell
me if you see anything that looks incorrect or have recommendations to make
it better? I have spent quite a bit of time on this but at the end of the day
still question whether I know what I am doing and would appreciate some peer review...
Thanks.
>>>
>>>
>>>
>>> Of if you would prefer to download the PDF: http://www.mattandmel.com/rv/Master_Load_Analysis_v1.pdf
>>>
>>> Thank you much.
>>>
>>> Matt
>>>
>>>
>>>
>>>
>>> Read this topic online here:
>>>
>>> http://forums.matronics.com/viewtopic.php?p=391129#391129
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=391926#391926
>
>
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