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A: METER INSTALLATION--PRELIMINARY:
Useful information to
review before installing.
Choosing meter location and some benefits of battery monitoring:
To make best use of this monitor, we recommend
that it be located where it can be readily observed in the living area where the electrical power is used, such as a kitchen
or living room. It displays the current draw or the charging current by either “amps” and “watts”. (It is designed to be
located up to a few hundred feet away from the battery bank using 4 wires.) One important use is to learn how much
electrical power various appliances draw by looking at the "amps" or “watts” readout first with the appliance off, and then
observing how much the current increases when you turn it on. This is inconvenient if the meter is located away from the
living area. After a while you will become instinctively familiar with the electrical usage of your appliances, so you won't
need to refer to the meter. Also, you can become familiar with "normal" electrical usage, and occasionally check that it
is not excessive, which would indicate some appliance has been unknowingly left on. Using the "BATTERY % FULL"
display, (or "Amp-hours from full") readout you will be able to see approximately how much energy you've withdrawn
from the battery bank. If you have "lead acid" batteries--the most commonly used type--the "Volts" readout gives useful
information about the "extreme" cases, when your batteries have gotten a nearly full charge, (which, while
charging
a 12
volt lead-acid battery will typically show voltage above 14.3 volts) or on the other hand when they are in a low charge
state (which, while
discharging
a 12 volt lead acid battery will typically show voltage 10.8 to 11.6 volts depending on
how many "amps" are being withdrawn). However “volts” is not too informative when the batteries are between 20%-
90% charged, since in this case exact voltage depends on several factors, including:
whether
the batteries are being
charged or discharged,
how fast
they are being charged or discharged, temperature of the battery, and the recent past
history of charge/discharge. For example, if they are charged at a high rate for awhile, the voltage will rise higher than
they would be after charging stops, due to what are called "polarization" effects. The TriMetric, therefore, uses the
battery voltage as an indicator for when the batteries are "charged". Then--when discharging the batteries from there, the
"BATTERY % FULL" (or "amp-hours from full") reading is a better guide for determining intermediate battery state of
charge. Voltage can again be useful for seeing that the batteries are in a state of near discharge--this is useful since it is
not good for lead-acid batteries to be too often, or remain too long nearly discharged. (Multiply voltages above by 2 for
24 volt systems or 4 for 48 volt systems)
The TM-2025 can measure two battery systems if you choose
: This meter measures one battery system
comprehensively, including
volts
and battery charging/discharging
amps
, typically for the one that supplies power to
appliances so you can measure accurately the
state of cha
r
ge
(how much energy is in the batteries.) In addition, it will
monitor
voltage only
on a second battery having a common negative connection, which could be the engine starting
battery.
Permissible battery voltage:
This meter is suitable for battery systems with nominal voltage from 8 to 65 volts.
It should
not be connected to systems which will ever exceed 65 volts.
You may choose three different operating levels from simplest to more complex:
It comes initially programmed at the
lowest Operating Level: L1 which will furnish the most important data. There are also levels “L2” or “L3” which add
more functionality, but with more complexity you will need to read more of the operating instructions.. If you are new to
this, begin with L1, and after becoming familiar with the meter you may easily advance to L2 or L3 at any time should
you need to. These levels are described in the TriMetric User’s Instructions.
Lightning considerations:
The meter has been designed with reasonably good protection against lightning.
SHUNT AND WIRING CONSIDERATIONS
A shunt (a very low resistance, accurate, high power resistor) must be wired into your battery system as described in
section B of these instructions.
This is how current (amps) and watts are measured by this meter: The “amps” shown
on the meter measures whatever current passes through this shunt. Therefore the shunt must be wired in series with the
wire which carries the current to be measured.
The shunt is almost always installed between the negative terminal of
the battery to all loads and charging sources
(as shown in the wiring diagram on page 15.) It is located near the
batteries, since the high current carrying wires must be kept short. The TriMetric measures the current ("amps") by
measuring the very small voltage drop across this shunt. Watts measured by the meter are shown by multiplying the
“volts” times the “amps”.
Shunt requirements:
There are two choices of shunts which may be used: Most systems will use the 500 amp-50 mV
shunt. For smaller systems you can use a 100A/100mV shunt (For this choice the meter must be programmed at
Opearating Level L3.)
Who might want to use the 100A/100mV shunt? (
requires Operational Level L3
)
If you have an unusually small system
that uses less than 70 amps maximum (charging or discharging) this shunt will show an extra digit to the right of the
decimal point, and resolve currents as low as 1/100 amp. But the 100A/100mV shunt can get too hot with a typical 12V
system with a 1000 watt inverter.
Technical note:
Incidentally, it is only the shunt
ratio
between amps to mV. which is important to the meter--so, for example, a
200 amp-200 mV. shunt can, from the meter's point of view, be considered equivalent to the 100 amp-100 mV shunt. The
