Re: [AFMUG] PacketFlux shunts

[George Skorup]

Yeahbut.. it's more fun when you and Forrest make something we want 
and/or didn't even know we needed and we can say.. shut up and take my 
money.


On 6/16/2017 1:33 PM, ch...@wbmfg.com wrote:
Never mind.  This one need to be installed in the circuit.  Not sure 
of the advantage other than isolation.

*From:* ch...@wbmfg.com
*Sent:* Friday, June 16, 2017 12:32 PM
*To:* af@afmug.com
*Subject:* Re: [AFMUG] PacketFlux shunts
https://www.sparkfun.com/products/8882
*From:* Bill Prince
*Sent:* Friday, June 16, 2017 12:08 PM
*To:* af@afmug.com
*Subject:* Re: [AFMUG] PacketFlux shunts

A Hall effect sensor would be the gold standard for a non-intrusive 
way to sense current. I looked at cobbling together something on my 
own, but it was more complicated than I anticipated.


bp
<part15sbs{at}gmail{dot}com>

On 6/16/2017 11:01 AM, George Skorup wrote:
All we've ever bought are the 10A version. They read accurate enough 
to see when a 1/2 or 1A DC-UPS is charging as well as 3-7A the other 
direction when the load is running on battery. Typical 24 and 48VDC 
systems with <200W load. And then me not paying attention with the 
Traco BCMU's 12VDC. Using the 2-relay/3-switch module, remotely I 
could see that the "Batt OK" contact was open after power came back 
up at the site at like 4am and still open around 8am. Since the site 
went down sooner than expected, I figured either the battery fuse on 
the BCM blew or it was sensing some other issue. So I get there and 
put my clamp-on ammeter on it and zero current. Two fused 20AH 
batteries in parallel both sitting at 13.1 volts. OK, WTF. Then it 
all made sense with the shunt.


Another thought I had is... what about Hall effect sensors? Could you 
do a module for that? That would be pretty cool.


On 6/16/2017 11:00 AM, Forrest Christian (List Account) wrote:
There will likely be a 20A shunt in our future.I'm in the 
process of redesigning these so that they're less expensive to build 
since the existing design is being sold at or possibly below cost.  
I'm trying to end up with a 20A shunt as a result but I don't know 
for sure if this will happen.
On Jun 15, 2017 5:47 PM, "George Skorup" <george.sko...@cbcast.com> 
wrote:


Forrest,

Would you be willing to make a 20A shunt? Would the traces on
your current design handle it?

Reason I'm asking is... I'm stupid. I had a 10A shunt on the
batt negative side of a Traco BCMU360. Didn't occur to me that
230 watts @ ~12VDC can get up to 20A. So the shunt went kaput
after about 25 minutes and the site went down. Not a problem at
most other sites with less load. This one happens to be the most
heavily loaded with two Trango ApexPlus, various APs and PTPs
plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[Bill Prince]

And it is limited to a 5A circuit.

bp
<part15sbs{at}gmail{dot}com>

On 6/16/2017 11:33 AM, ch...@wbmfg.com wrote:
Never mind.  This one need to be installed in the circuit.  Not sure 
of the advantage other than isolation.

*From:* ch...@wbmfg.com
*Sent:* Friday, June 16, 2017 12:32 PM
*To:* af@afmug.com
*Subject:* Re: [AFMUG] PacketFlux shunts
https://www.sparkfun.com/products/8882
*From:* Bill Prince
*Sent:* Friday, June 16, 2017 12:08 PM
*To:* af@afmug.com
*Subject:* Re: [AFMUG] PacketFlux shunts

A Hall effect sensor would be the gold standard for a non-intrusive 
way to sense current. I looked at cobbling together something on my 
own, but it was more complicated than I anticipated.


bp
<part15sbs{at}gmail{dot}com>

On 6/16/2017 11:01 AM, George Skorup wrote:
All we've ever bought are the 10A version. They read accurate enough 
to see when a 1/2 or 1A DC-UPS is charging as well as 3-7A the other 
direction when the load is running on battery. Typical 24 and 48VDC 
systems with <200W load. And then me not paying attention with the 
Traco BCMU's 12VDC. Using the 2-relay/3-switch module, remotely I 
could see that the "Batt OK" contact was open after power came back 
up at the site at like 4am and still open around 8am. Since the site 
went down sooner than expected, I figured either the battery fuse on 
the BCM blew or it was sensing some other issue. So I get there and 
put my clamp-on ammeter on it and zero current. Two fused 20AH 
batteries in parallel both sitting at 13.1 volts. OK, WTF. Then it 
all made sense with the shunt.


Another thought I had is... what about Hall effect sensors? Could you 
do a module for that? That would be pretty cool.


On 6/16/2017 11:00 AM, Forrest Christian (List Account) wrote:
There will likely be a 20A shunt in our future.I'm in the 
process of redesigning these so that they're less expensive to build 
since the existing design is being sold at or possibly below cost.  
I'm trying to end up with a 20A shunt as a result but I don't know 
for sure if this will happen.
On Jun 15, 2017 5:47 PM, "George Skorup" <george.sko...@cbcast.com> 
wrote:


Forrest,

Would you be willing to make a 20A shunt? Would the traces on
your current design handle it?

Reason I'm asking is... I'm stupid. I had a 10A shunt on the
batt negative side of a Traco BCMU360. Didn't occur to me that
230 watts @ ~12VDC can get up to 20A. So the shunt went kaput
after about 25 minutes and the site went down. Not a problem at
most other sites with less load. This one happens to be the most
heavily loaded with two Trango ApexPlus, various APs and PTPs
plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[chuck]

Never mind.  This one need to be installed in the circuit.  Not sure of the 
advantage other than isolation.  

From: ch...@wbmfg.com 
Sent: Friday, June 16, 2017 12:32 PM
To: af@afmug.com 
Subject: Re: [AFMUG] PacketFlux shunts

https://www.sparkfun.com/products/8882


From: Bill Prince 
Sent: Friday, June 16, 2017 12:08 PM
To: af@afmug.com 
Subject: Re: [AFMUG] PacketFlux shunts

A Hall effect sensor would be the gold standard for a non-intrusive way to 
sense current. I looked at cobbling together something on my own, but it was 
more complicated than I anticipated.


bp
<part15sbs{at}gmail{dot}com>

On 6/16/2017 11:01 AM, George Skorup wrote:

  All we've ever bought are the 10A version. They read accurate enough to see 
when a 1/2 or 1A DC-UPS is charging as well as 3-7A the other direction when 
the load is running on battery. Typical 24 and 48VDC systems with <200W load. 
And then me not paying attention with the Traco BCMU's 12VDC. Using the 
2-relay/3-switch module, remotely I could see that the "Batt OK" contact was 
open after power came back up at the site at like 4am and still open around 
8am. Since the site went down sooner than expected, I figured either the 
battery fuse on the BCM blew or it was sensing some other issue. So I get there 
and put my clamp-on ammeter on it and zero current. Two fused 20AH batteries in 
parallel both sitting at 13.1 volts. OK, WTF. Then it all made sense with the 
shunt.

  Another thought I had is... what about Hall effect sensors? Could you do a 
module for that? That would be pretty cool.


  On 6/16/2017 11:00 AM, Forrest Christian (List Account) wrote:

There will likely be a 20A shunt in our future.I'm in the process of 
redesigning these so that they're less expensive to build since the existing 
design is being sold at or possibly below cost.  I'm trying to end up with a 
20A shunt as a result but I don't know for sure if this will happen.


On Jun 15, 2017 5:47 PM, "George Skorup" <george.sko...@cbcast.com> wrote:

  Forrest,

  Would you be willing to make a 20A shunt? Would the traces on your 
current design handle it?

  Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt 
negative side of a Traco BCMU360. Didn't occur to me that 230 watts @ ~12VDC 
can get up to 20A. So the shunt went kaput after about 25 minutes and the site 
went down. Not a problem at most other sites with less load. This one happens 
to be the most heavily loaded with two Trango ApexPlus, various APs and PTPs 
plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[chuck]

https://www.sparkfun.com/products/8882


From: Bill Prince 
Sent: Friday, June 16, 2017 12:08 PM
To: af@afmug.com 
Subject: Re: [AFMUG] PacketFlux shunts

A Hall effect sensor would be the gold standard for a non-intrusive way to 
sense current. I looked at cobbling together something on my own, but it was 
more complicated than I anticipated.


bp
<part15sbs{at}gmail{dot}com>

On 6/16/2017 11:01 AM, George Skorup wrote:

  All we've ever bought are the 10A version. They read accurate enough to see 
when a 1/2 or 1A DC-UPS is charging as well as 3-7A the other direction when 
the load is running on battery. Typical 24 and 48VDC systems with <200W load. 
And then me not paying attention with the Traco BCMU's 12VDC. Using the 
2-relay/3-switch module, remotely I could see that the "Batt OK" contact was 
open after power came back up at the site at like 4am and still open around 
8am. Since the site went down sooner than expected, I figured either the 
battery fuse on the BCM blew or it was sensing some other issue. So I get there 
and put my clamp-on ammeter on it and zero current. Two fused 20AH batteries in 
parallel both sitting at 13.1 volts. OK, WTF. Then it all made sense with the 
shunt.

  Another thought I had is... what about Hall effect sensors? Could you do a 
module for that? That would be pretty cool.


  On 6/16/2017 11:00 AM, Forrest Christian (List Account) wrote:

There will likely be a 20A shunt in our future.I'm in the process of 
redesigning these so that they're less expensive to build since the existing 
design is being sold at or possibly below cost.  I'm trying to end up with a 
20A shunt as a result but I don't know for sure if this will happen.


On Jun 15, 2017 5:47 PM, "George Skorup" <george.sko...@cbcast.com> wrote:

  Forrest,

  Would you be willing to make a 20A shunt? Would the traces on your 
current design handle it?

  Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt 
negative side of a Traco BCMU360. Didn't occur to me that 230 watts @ ~12VDC 
can get up to 20A. So the shunt went kaput after about 25 minutes and the site 
went down. Not a problem at most other sites with less load. This one happens 
to be the most heavily loaded with two Trango ApexPlus, various APs and PTPs 
plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[Bill Prince]

A Hall effect sensor would be the gold standard for a non-intrusive way 
to sense current. I looked at cobbling together something on my own, but 
it was more complicated than I anticipated.


bp


On 6/16/2017 11:01 AM, George Skorup wrote:
All we've ever bought are the 10A version. They read accurate enough 
to see when a 1/2 or 1A DC-UPS is charging as well as 3-7A the other 
direction when the load is running on battery. Typical 24 and 48VDC 
systems with <200W load. And then me not paying attention with the 
Traco BCMU's 12VDC. Using the 2-relay/3-switch module, remotely I 
could see that the "Batt OK" contact was open after power came back up 
at the site at like 4am and still open around 8am. Since the site went 
down sooner than expected, I figured either the battery fuse on the 
BCM blew or it was sensing some other issue. So I get there and put my 
clamp-on ammeter on it and zero current. Two fused 20AH batteries in 
parallel both sitting at 13.1 volts. OK, WTF. Then it all made sense 
with the shunt.


Another thought I had is... what about Hall effect sensors? Could you 
do a module for that? That would be pretty cool.


On 6/16/2017 11:00 AM, Forrest Christian (List Account) wrote:
There will likely be a 20A shunt in our future.I'm in the process 
of redesigning these so that they're less expensive to build since 
the existing design is being sold at or possibly below cost.  I'm 
trying to end up with a 20A shunt as a result but I don't know for 
sure if this will happen.


On Jun 15, 2017 5:47 PM, "George Skorup" > wrote:


Forrest,

Would you be willing to make a 20A shunt? Would the traces on
your current design handle it?

Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt
negative side of a Traco BCMU360. Didn't occur to me that 230
watts @ ~12VDC can get up to 20A. So the shunt went kaput after
about 25 minutes and the site went down. Not a problem at most
other sites with less load. This one happens to be the most
heavily loaded with two Trango ApexPlus, various APs and PTPs
plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[George Skorup]

All we've ever bought are the 10A version. They read accurate enough to 
see when a 1/2 or 1A DC-UPS is charging as well as 3-7A the other 
direction when the load is running on battery. Typical 24 and 48VDC 
systems with <200W load. And then me not paying attention with the Traco 
BCMU's 12VDC. Using the 2-relay/3-switch module, remotely I could see 
that the "Batt OK" contact was open after power came back up at the site 
at like 4am and still open around 8am. Since the site went down sooner 
than expected, I figured either the battery fuse on the BCM blew or it 
was sensing some other issue. So I get there and put my clamp-on ammeter 
on it and zero current. Two fused 20AH batteries in parallel both 
sitting at 13.1 volts. OK, WTF. Then it all made sense with the shunt.


Another thought I had is... what about Hall effect sensors? Could you do 
a module for that? That would be pretty cool.


On 6/16/2017 11:00 AM, Forrest Christian (List Account) wrote:
There will likely be a 20A shunt in our future.I'm in the process 
of redesigning these so that they're less expensive to build since the 
existing design is being sold at or possibly below cost.  I'm trying 
to end up with a 20A shunt as a result but I don't know for sure if 
this will happen.


On Jun 15, 2017 5:47 PM, "George Skorup" > wrote:


Forrest,

Would you be willing to make a 20A shunt? Would the traces on your
current design handle it?

Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt
negative side of a Traco BCMU360. Didn't occur to me that 230
watts @ ~12VDC can get up to 20A. So the shunt went kaput after
about 25 minutes and the site went down. Not a problem at most
other sites with less load. This one happens to be the most
heavily loaded with two Trango ApexPlus, various APs and PTPs plus
the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[Bill Prince]

... but I still like the 2 10A shunts in parallel. Even if they are not 
exact, it would be close enough.



bp
<part15sbs{at}gmail{dot}com>

On 6/16/2017 10:34 AM, ch...@wbmfg.com wrote:

The 100 mV is not a problem.  .1 volt/20 amps is .005 ohms.

So, 2 feet of 14 gauge will produce 100 mV at 20 amps.
Just feed it into the SiteMonitor.
Assuming aesthetics are not an issue.
-Original Message- From: George Skorup Sent: Friday, June 16, 
2017 11:30 AM To: af@afmug.com Subject: Re: [AFMUG] PacketFlux shunts
Because Forrest makes them in a nice little DIN rail package and 
designed to work on his SiteMonitor base and modules with a nominal 
100mv.


On 6/15/2017 8:07 PM, Chuck McCown wrote:
Assuming they were EXACTLY the same resistance.  Otherwise there will 
be an uneven division of currents.


I prefer to use #10 wire.  1 foot is .001 ohms.  Make your own shunt. 
Assuming 20 mV full scale is enough.
20 gauge (which is hard to find) is close to .01 ohms per foot. 
However that exceeds the ampacity.


I would be OK with one foot of 14 gauge for a 20 amp shunt. .0025 
ohms per foot.  that would give you 50 mV full scale.
Of course this assumes you have the room for and don't mind the look 
of a coiled up foot of wire.


-Original Message- From: Bill Prince
Sent: Thursday, June 15, 2017 4:55 PM
To: af@afmug.com
Subject: Re: [AFMUG] PacketFlux shunts

This may be a bozo approach, but if you took two 10 amp shunts and
connected them in parallel, you would get a 20 amp shunt out of the 
deal.



bp
<part15sbs{at}gmail{dot}com>

On 6/15/2017 3:47 PM, George Skorup wrote:

Forrest,

Would you be willing to make a 20A shunt? Would the traces on your 
current design handle it?


Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt 
negative side of a Traco BCMU360. Didn't occur to me that 230 watts 
@ ~12VDC can get up to 20A. So the shunt went kaput after about 25 
minutes and the site went down. Not a problem at most other sites 
with less load. This one happens to be the most heavily loaded with 
two Trango ApexPlus, various APs and PTPs plus the DC-DC 
inefficiencies.

Re: [AFMUG] PacketFlux shunts

[Bill Prince]

That wouldn't be too bad to coil up. 2/pi would be the diameter of a 2' 
loop (about 7-1/2 inches). Two loops would be about 3-3/4 inch, and so 
on. Three or four loops would make a nice tidy package.



bp
<part15sbs{at}gmail{dot}com>

On 6/16/2017 10:34 AM, ch...@wbmfg.com wrote:

The 100 mV is not a problem.  .1 volt/20 amps is .005 ohms.

So, 2 feet of 14 gauge will produce 100 mV at 20 amps.
Just feed it into the SiteMonitor.
Assuming aesthetics are not an issue.
-Original Message- From: George Skorup Sent: Friday, June 16, 
2017 11:30 AM To: af@afmug.com Subject: Re: [AFMUG] PacketFlux shunts
Because Forrest makes them in a nice little DIN rail package and 
designed to work on his SiteMonitor base and modules with a nominal 
100mv.


On 6/15/2017 8:07 PM, Chuck McCown wrote:
Assuming they were EXACTLY the same resistance.  Otherwise there will 
be an uneven division of currents.


I prefer to use #10 wire.  1 foot is .001 ohms.  Make your own shunt. 
Assuming 20 mV full scale is enough.
20 gauge (which is hard to find) is close to .01 ohms per foot. 
However that exceeds the ampacity.


I would be OK with one foot of 14 gauge for a 20 amp shunt. .0025 
ohms per foot.  that would give you 50 mV full scale.
Of course this assumes you have the room for and don't mind the look 
of a coiled up foot of wire.


-Original Message- From: Bill Prince
Sent: Thursday, June 15, 2017 4:55 PM
To: af@afmug.com
Subject: Re: [AFMUG] PacketFlux shunts

This may be a bozo approach, but if you took two 10 amp shunts and
connected them in parallel, you would get a 20 amp shunt out of the 
deal.



bp
<part15sbs{at}gmail{dot}com>

On 6/15/2017 3:47 PM, George Skorup wrote:

Forrest,

Would you be willing to make a 20A shunt? Would the traces on your 
current design handle it?


Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt 
negative side of a Traco BCMU360. Didn't occur to me that 230 watts 
@ ~12VDC can get up to 20A. So the shunt went kaput after about 25 
minutes and the site went down. Not a problem at most other sites 
with less load. This one happens to be the most heavily loaded with 
two Trango ApexPlus, various APs and PTPs plus the DC-DC 
inefficiencies.

Re: [AFMUG] PacketFlux shunts

[chuck]

The 100 mV is not a problem.  .1 volt/20 amps is .005 ohms.

So, 2 feet of 14 gauge will produce 100 mV at 20 amps.
Just feed it into the SiteMonitor.  

Assuming aesthetics are not an issue.  

-Original Message- 
From: George Skorup 
Sent: Friday, June 16, 2017 11:30 AM 
To: af@afmug.com 
Subject: Re: [AFMUG] PacketFlux shunts 

Because Forrest makes them in a nice little DIN rail package and 
designed to work on his SiteMonitor base and modules with a nominal 100mv.


On 6/15/2017 8:07 PM, Chuck McCown wrote:
Assuming they were EXACTLY the same resistance.  Otherwise there will 
be an uneven division of currents.


I prefer to use #10 wire.  1 foot is .001 ohms.  Make your own shunt. 
Assuming 20 mV full scale is enough.
20 gauge (which is hard to find) is close to .01 ohms per foot. 
However that exceeds the ampacity.


I would be OK with one foot of 14 gauge for a 20 amp shunt. .0025 ohms 
per foot.  that would give you 50 mV full scale.
Of course this assumes you have the room for and don't mind the look 
of a coiled up foot of wire.


-Original Message- From: Bill Prince
Sent: Thursday, June 15, 2017 4:55 PM
To: af@afmug.com
Subject: Re: [AFMUG] PacketFlux shunts

This may be a bozo approach, but if you took two 10 amp shunts and
connected them in parallel, you would get a 20 amp shunt out of the deal.


bp
<part15sbs{at}gmail{dot}com>

On 6/15/2017 3:47 PM, George Skorup wrote:

Forrest,

Would you be willing to make a 20A shunt? Would the traces on your 
current design handle it?


Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt 
negative side of a Traco BCMU360. Didn't occur to me that 230 watts @ 
~12VDC can get up to 20A. So the shunt went kaput after about 25 
minutes and the site went down. Not a problem at most other sites 
with less load. This one happens to be the most heavily loaded with 
two Trango ApexPlus, various APs and PTPs plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[George Skorup]

Because Forrest makes them in a nice little DIN rail package and 
designed to work on his SiteMonitor base and modules with a nominal 100mv.


On 6/15/2017 8:07 PM, Chuck McCown wrote:
Assuming they were EXACTLY the same resistance.  Otherwise there will 
be an uneven division of currents.


I prefer to use #10 wire.  1 foot is .001 ohms.  Make your own shunt. 
Assuming 20 mV full scale is enough.
20 gauge (which is hard to find) is close to .01 ohms per foot. 
However that exceeds the ampacity.


I would be OK with one foot of 14 gauge for a 20 amp shunt. .0025 ohms 
per foot.  that would give you 50 mV full scale.
Of course this assumes you have the room for and don't mind the look 
of a coiled up foot of wire.


-Original Message- From: Bill Prince
Sent: Thursday, June 15, 2017 4:55 PM
To: af@afmug.com
Subject: Re: [AFMUG] PacketFlux shunts

This may be a bozo approach, but if you took two 10 amp shunts and
connected them in parallel, you would get a 20 amp shunt out of the deal.


bp
<part15sbs{at}gmail{dot}com>

On 6/15/2017 3:47 PM, George Skorup wrote:

Forrest,

Would you be willing to make a 20A shunt? Would the traces on your 
current design handle it?


Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt 
negative side of a Traco BCMU360. Didn't occur to me that 230 watts @ 
~12VDC can get up to 20A. So the shunt went kaput after about 25 
minutes and the site went down. Not a problem at most other sites 
with less load. This one happens to be the most heavily loaded with 
two Trango ApexPlus, various APs and PTPs plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[Bill Prince]

But what would the typical tolerance be? 10%. So what would be the big 
deal if one had 10% more resistance? Effectively an 18A shunt?



bp
<part15sbs{at}gmail{dot}com>

On 6/15/2017 6:07 PM, Chuck McCown wrote:
Assuming they were EXACTLY the same resistance.  Otherwise there will 
be an uneven division of currents.


I prefer to use #10 wire.  1 foot is .001 ohms.  Make your own shunt. 
Assuming 20 mV full scale is enough.
20 gauge (which is hard to find) is close to .01 ohms per foot. 
However that exceeds the ampacity.


I would be OK with one foot of 14 gauge for a 20 amp shunt. .0025 ohms 
per foot.  that would give you 50 mV full scale.
Of course this assumes you have the room for and don't mind the look 
of a coiled up foot of wire.


-Original Message- From: Bill Prince
Sent: Thursday, June 15, 2017 4:55 PM
To: af@afmug.com
Subject: Re: [AFMUG] PacketFlux shunts

This may be a bozo approach, but if you took two 10 amp shunts and
connected them in parallel, you would get a 20 amp shunt out of the deal.


bp
<part15sbs{at}gmail{dot}com>

On 6/15/2017 3:47 PM, George Skorup wrote:

Forrest,

Would you be willing to make a 20A shunt? Would the traces on your 
current design handle it?


Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt 
negative side of a Traco BCMU360. Didn't occur to me that 230 watts @ 
~12VDC can get up to 20A. So the shunt went kaput after about 25 
minutes and the site went down. Not a problem at most other sites 
with less load. This one happens to be the most heavily loaded with 
two Trango ApexPlus, various APs and PTPs plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[Forrest Christian (List Account)]

There will likely be a 20A shunt in our future.I'm in the process of
redesigning these so that they're less expensive to build since the
existing design is being sold at or possibly below cost.  I'm trying to end
up with a 20A shunt as a result but I don't know for sure if this will
happen.

On Jun 15, 2017 5:47 PM, "George Skorup"  wrote:

Forrest,

Would you be willing to make a 20A shunt? Would the traces on your current
design handle it?

Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt negative
side of a Traco BCMU360. Didn't occur to me that 230 watts @ ~12VDC can get
up to 20A. So the shunt went kaput after about 25 minutes and the site went
down. Not a problem at most other sites with less load. This one happens to
be the most heavily loaded with two Trango ApexPlus, various APs and PTPs
plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[Chuck McCown]

Assuming they were EXACTLY the same resistance.  Otherwise there will be an 
uneven division of currents.


I prefer to use #10 wire.  1 foot is .001 ohms.  Make your own shunt. 
Assuming 20 mV full scale is enough.
20 gauge (which is hard to find) is close to .01 ohms per foot.  However 
that exceeds the ampacity.


I would be OK with one foot of 14 gauge for a 20 amp shunt. .0025 ohms per 
foot.  that would give you 50 mV full scale.
Of course this assumes you have the room for and don't mind the look of a 
coiled up foot of wire.


-Original Message- 
From: Bill Prince

Sent: Thursday, June 15, 2017 4:55 PM
To: af@afmug.com
Subject: Re: [AFMUG] PacketFlux shunts

This may be a bozo approach, but if you took two 10 amp shunts and
connected them in parallel, you would get a 20 amp shunt out of the deal.


bp
<part15sbs{at}gmail{dot}com>

On 6/15/2017 3:47 PM, George Skorup wrote:

Forrest,

Would you be willing to make a 20A shunt? Would the traces on your current 
design handle it?


Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt negative 
side of a Traco BCMU360. Didn't occur to me that 230 watts @ ~12VDC can 
get up to 20A. So the shunt went kaput after about 25 minutes and the site 
went down. Not a problem at most other sites with less load. This one 
happens to be the most heavily loaded with two Trango ApexPlus, various 
APs and PTPs plus the DC-DC inefficiencies.

Re: [AFMUG] PacketFlux shunts

[Bill Prince]

This may be a bozo approach, but if you took two 10 amp shunts and 
connected them in parallel, you would get a 20 amp shunt out of the deal.



bp


On 6/15/2017 3:47 PM, George Skorup wrote:

Forrest,

Would you be willing to make a 20A shunt? Would the traces on your 
current design handle it?


Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt 
negative side of a Traco BCMU360. Didn't occur to me that 230 watts @ 
~12VDC can get up to 20A. So the shunt went kaput after about 25 
minutes and the site went down. Not a problem at most other sites with 
less load. This one happens to be the most heavily loaded with two 
Trango ApexPlus, various APs and PTPs plus the DC-DC inefficiencies.

[AFMUG] PacketFlux shunts

[George Skorup]

Forrest,

Would you be willing to make a 20A shunt? Would the traces on your 
current design handle it?


Reason I'm asking is... I'm stupid. I had a 10A shunt on the batt 
negative side of a Traco BCMU360. Didn't occur to me that 230 watts @ 
~12VDC can get up to 20A. So the shunt went kaput after about 25 minutes 
and the site went down. Not a problem at most other sites with less 
load. This one happens to be the most heavily loaded with two Trango 
ApexPlus, various APs and PTPs plus the DC-DC inefficiencies.