The old style zero center ammeters are not very desirable in my
opinion unless mounted very close to your batteries, or it has an
external shunt. Without a shunt it is necessary to run a high current
wire (large) all the way to the meter and back to your battery/engine
area. Better to get one of the new digital ammeters (with shunt) that
reads both positive and negative flow.

Correct me if I'm wrong (not being an electrical type But aren't
external shunt type amp meters milli-volt meters and the meter simply
measures the voltage drop across the shunt??

I don't see that the voltage could be reversed to operate the meter on
either side of zero.

I always assumed that this was the reason you we never see any external
shunt type 'zero center' amp meters.

If anyone knows of a 150-0-150 amp, shunt type amp meter, I would like to
know where I can get one. I could then monitor my house bank charge and
useage at the DC panel without opening the inverter/charger locker.

(Sorry, I didn't mean to 'hijack' this thread. This topic may deserves it's
own thread.)

Steve
s/v Good Intentions

On Thu, 21 Oct 2004 08:10:36 -0700, "Steve" wrote:

Correct me if I'm wrong (not being an electrical type But aren't
external shunt type amp meters milli-volt meters and the meter simply
measures the voltage drop across the shunt??

That is correct.

I don't see that the voltage could be reversed to operate the meter on
either side of zero.

The polarity of the voltage across the shunt depends on the direction
of current flow. The shunt is usually installed so that a charging
current is a positive voltage, discharge negative.

I always assumed that this was the reason you we never see any external
shunt type 'zero center' amp meters.

I'm sure they can be purchased somewhere but why bother when the price
and availability of digital meters has improved so much.

If anyone knows of a 150-0-150 amp, shunt type amp meter, I would like to
know where I can get one. I could then monitor my house bank charge and
useage at the DC panel without opening the inverter/charger locker.

Shunts are readily available from a variety of sources. Finding a
suitable analog meter to go with the shunt may take more time but they
are out there (perhaps from Grainger?).

One of the issues with a high current analog meter such as 150-0-150
is that small current values are difficult to read accurately whereas
with a digital meter it doesn't really matter.

The Blue Seas part no:8253 is a 100-0-100 ammeter with a shunt. I never see
any retailer stock them but you can order direct.

Although I have a digital ammeter as a part of my Link 20, I still like to
have a digital ammeter. Not only can I always see what is happening with
my charging circuit (without having to scroll through menu, but the output
is very "analog". By that I mean I don't have to interpret a number in my
seasick brain to determine if there is a problem I should espond to. I
also like having the redundancy of an analog instrument to back up my
digital instruments. I don't trust little wires and circuit traces in the
manine environment.


David
S/V Nausicaa



The old style zero center ammeters are not very desirable in my
opinion unless mounted very close to your batteries, or it has an
external shunt. Without a shunt it is necessary to run a high current
wire (large) all the way to the meter and back to your battery/engine
area. Better to get one of the new digital ammeters (with shunt) that
reads both positive and negative flow.

Correct me if I'm wrong (not being an electrical type But aren't
external shunt type amp meters milli-volt meters and the meter simply
measures the voltage drop across the shunt??

I don't see that the voltage could be reversed to operate the meter on
either side of zero.

I always assumed that this was the reason you we never see any external
shunt type 'zero center' amp meters.

If anyone knows of a 150-0-150 amp, shunt type amp meter, I would like to
know where I can get one. I could then monitor my house bank charge and
useage at the DC panel without opening the inverter/charger locker.

(Sorry, I didn't mean to 'hijack' this thread. This topic may deserves
it's
own thread.)

Steve
s/v Good Intentions

On Sun, 24 Oct 2004 11:18:06 -0400, "dbraun"
wrote:

I don't trust little wires and circuit traces in the
manine environment.

==========================

Good point. That seems to be particularly true for the Link 20 in my
experience. It not only has little wires and traces but embedded
computer logic as well.

"dbraun" wrote in message
lkaboutelectronicequipment
..com...
The Blue Seas part no:8253 is a 100-0-100 ammeter with a shunt. I never
see
any retailer stock them but you can order direct.


Thanks David,
I'll order that meter through my marine suppier and that should be ok for
anything except the anchor windlass (momentarily, when I'm braking out the
hook.).

I have 100 amp meter in my DC panel but as I stated I want to monitor both
charge and discharge to see the net gain. I don't have room on the existing
panel to add a digital meter, so a Blue Seas instrument should fit in one
of the OEM holes.

I have looked at the digitals and the price is a bit more than I want to
spend.. Also, I would be concerned with the power consumption if they are
LEDs and I wanted to leave them on all the time.. The LCDs are more power
conservative but are difficult to read without some suplimental lighting
(back the my dark corner of the nav. station.). To be honest, I never notice
a LCD instrument, unless I'm thinking about it. While a LED will get my
attention. I frequently forget to turn off my fixed mount GPS when I leave
the boat because the display is LCD and not 'attention getting' (and I'm 68
and....).

Steve
s/v Good Intentions