"DoN. Nichols" wrote in message
...
On 2017-05-08, David Lesher wrote:
"DoN. Nichols" writes:
Some -- but the worst was when I installed a current shunt in
series with the battery to the fuse block. There was an easy place
to
mount it -- a shelf on the right side just in front of the
firewall. (I
was using some aircraft instruments as displays, plus a 24-hour
wind-up
aircraft clock on a secondary panel -- removable so a passenger
could
fit in the seat.
It was fine until I hit a vigorous bump, and the bonnet (US
hood) prop rod fell down and shorted the load side of the shunt to
ground. That stopped the car rather rapidly. :-)
That's your fault, Don. You should have had the shunt in the ground
side.
Well ... the ground connection was from the battery to the
chassis, and included the starter current. What I was metering were
the
things controlled by instrument panel switches (ignition -- *not*
starter current, headlamps, instrument panel lamps, turn signals,
and
not much else. Those were grounded everywhere to the nearest
chassis
point, an d hard to put the shunt in that side without including the
starter motor.
So -- it was more my fault for not protecting the shunt from
moving parts of the car (e.g. the bonnet prop rod. :-)
As for SU fuel pumps, they were designed to save fuel. The car on
the side
of theroad uses none....
They do that, for sure. :-)
Enjoy,
DoN.
I housed a bare 100A shunt in a PVC conduit tee. The heavy current
leads pass through the straight ends and the sense leads, made from
in-line fuseholders, come out the center leg. The fuseholders restrain
the shunt so it doesn't need mounting screws that would expose voltage
on the outside.
http://www.bennys.bz/electrical/elec...prod_4111.html
For this particular combination the heavy current bolts also keep the
shunt in place because they won't pass into the round ends.
I bought another 1.000 milliOhm 100A-rated shunt that lacked the 3/8"
bolts. I couldn't find 3/8" brass bolts locally but a Diesel shop had
3/8-16 copper starter contacts that worked after I turned down the
heads to accept soldered 3/8" brass nuts for the hex.
-jsw