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.
