Blue Sea Systems 8015 DC analog Voltmeter Panel - 8 to 16V DC - Manual (Page 2)

4. Panel Mount: For thicker mounting surfaces, the meter can be mounted into a 0.125” thick
panel. Blue Sea Systems offers meter mounting panels for our standard size meters only. For PN
8003 use PN 8013 to mount a single meter or PN 8014 to mount two meters.
Installation of Voltmeter Wires
Wire the meter as shown below, making certain to attach the positive lead to the terminal on the
meter marked “+” and the negative lead to the terminal marked “-”. Use a minimum 16 AWG wire,
red for positive and black or yellow for negative (ABYC recommends yellow for negative). Install a
1 ampere fuse in the positive lead near the source. Do not connect the voltmeter in a serial
(in-line) configuration.
Use of Voltmeter
A full treatment of the subject of battery management is beyond the scope of these instructions.
However, we believe that it is necessary to alert our customers to the issues involved and urge
that the issue be studied further. There is probably no other activity that will contribute more to a
healthy electrical system than proper battery management. There are several ways to measure
the state of charge in a battery or battery bank. The three most common methods are:
1. Open Circuit Voltage 2. Electrolyte Specific Gravity 3. Net Amp-Hours
None of these methods is perfect, but the primary determinant of success in measuring battery
charge and managing battery condition is the operator’s knowledge. Voltage is an effective
method of determining charge condition when properly used with an understanding of the battery
charge/discharge process. It is not generally realized that the difference between a fully
discharged and a fully charged battery is about 1 volt. The table below shows the percent of
charge for various voltages:
Experts recommend that for maximum life a battery be discharged no more than 50%. Once a
battery has been charged to approximately 80% of full charge its acceptance rate decreases
rapidly and it can take a great amount of charging time to bring the charge to 100%. For this
reason, in practice, the operating range becomes the 50 - 80% of charge area. Voltage is a good
indicator of charge condition only when a battery’s true open circuit voltage is measured. Open
circuit voltage is obtained when a battery is neither charged nor discharged and then the voltage
is allowed to stabilized. There is disagreement about the length of time the battery is required to
rest before a usable open circuit voltage is obtained. However, the user will observe that in the
first 10 to 20 minutes of rest the voltage will settle to a figure close to its completely rested open
circuit voltage, which is generally considered to be obtained at 24 hours. Gel batteries can take
up to 48 hours. With experience, the user will learn the time required for reliable readings on any
particular system.
A particularly good treatment of this issue is presented in Nigel Calder’s Boatowner’s Mechanical
and Electrical Manual (Second Edition, McGraw Hill).
Series Installation