Page 1
DESIGNED AND
MANUFACTURED
IN ENGLAND
BATTERY MONITOR
BM-1
V
100%
A
A-Hr
100%
80
80
60
60
40
40
TIME
CHARGE
DIS
ILLUM
V&A
CLIPPER
RoHS
2002/95/EC
BATTERY
MONITORS
BM1 / BM2
Page 2
READ THIS FIRST!
BEFORE INSTALLING THE BM1 / BM2, CAREFULLY READ THE FOLLOWING
INSTRUCTIONS, ESPECIALLY THE SAFETY NOTES AND WARRANTY
CONDITIONS.
IMPORTANT
BM1 / BM2 look identical but they are different Models.
The Shunts and Shunt cables are NOT interchangeable.
CLIPPER BM1. . . . . Load & Charge
Current - 100 Amps Maximum
CLIPPER BM2. . . . . Load & Charge
Current - 200 Amps Maximum
NASA BATTERY MONITOR BM1 / BM2
Table of Contents
PAGE
INTRODUCTION
1
INSTALLING THE DISPLAY
Safety Notes
Installation of the Display Unit
BATTERY MANAGEMENT BASICS
NORMAL OPERATION
Switching the backlight
Showing the Voltage and Current
Showing the Ampere hours total
Showing the Time to Go
ENGINEERING
Setting the Battery’s Nominal Capacity
Setting the Estimated Battery Temperature
Setting the zero-current
QUESTIONS AND ANSWERS
1
1
1
3
5
5
5
5
6
6
6
6
6
8
Page 3
INTRODUCTION
The NASA Clipper BM1/BM2 is supplied complete with display unit,
current shunt (standard 50mV), and connecting cables. They are intended
for operation on 12V Lead-Acid batteries with capacities between 5 and 600
Ampere-hours (Ahr). Their own current consumption is less than 1.5 mA,
which is about 1 Ahr per month, less than the self-discharge rate of most
Lead-Acid batteries.
The NASA BM1/BM2 monitors the battery voltage, the current into and out
of the battery, the total Ahr since it was last fully charged, and predicts the
time to achieve full charge (during charging) or the time to full discharge
(during discharging). A visual indication of the state of the battery charge is
always available, and an alarm is used as an alert when the battery voltage
falls to a preset level.
INSTALLING THE DISPLAY
Safety notes - IMPORTANT
Lead-acid batteries can emit hydrogen when in operation. Hydrogen and air
forms a potentially explosive mixture. Accordingly, ensure that the area
around the batteries is well-ventilated, and douse all naked flames and
prevent sparks.
Short-circuiting a battery with a metal tool or piece of jewellery can cause
catastrophic currents to flow. Before installing any of the BM1/BM2 units,
remove all jewellery (such as rings or metal necklaces). Ensure that no
metal tool can cause a short circuit.
If you are not sufficiently skilled to undertake any part of this installation
safely, you must seek the assistance of a suitably qualified person.
Installation of the Display unit
The installation should be performed in the order specified in the following
sections.
1 Select a convenient position for the display. Cut a hole in the panel
87mm wide and 67mm deep. The site must be flat and the cavity
behind the panel must remain dry at all times. (The cable entry is
deliberately not sealed to ensure adequate ventilation. This prevents
misting of the display).
2 Bring the shunt cable through the hole in the panel.
3 Unscrew and remove the two wing nuts from the rear of the
instrument and remove the stainless steel clamping bracket.
4 Fit the "O" ring seal into the groove in the panel-mounting face of
the instrument. Ensure that it is correctly lying in its groove to
provide the watertight seal for the display before fitting the
instrument to the panel.
Page 1
Page 4
NEGATIVE
LOADS AND GENERATORS
TO ALL DOMESTIC
Cables
supplied
Original
cables
YELLOW
SHUNT
No other connection
should be made to
this post
-
DOMESTIC
BATTERY OR
BATTERIES
POSITIVE
TO ALL DOMESTIC
LOADS & GENERATORS
FUSE
+
5-metre
CABLE
WHITE
BLACK
RED
ILLUM
BM
A-Hr
V&A
ORANGE
YELLOW YELLOW
WHITE*
BLACK*
RED
TIME
* Black & White
MUS T NO T be
joine d a t thi s end.
Figure 1 - Domestic battery only
5 Connect the shunt cable to the display unit as shown on Figure 1,
below, using the terminal block supplied. Be careful to connect the
wires exactly as shown, noting that the black and white wires are
joined at the shunt connection, and are connected separately at the
instrument end of the cable.
6 Fit the instrument into the panel, fit the stainless clamp over the
studs, fit and tighten the two wing nuts finger tight only. It is
important that the O-ring rubber seal makes good contact with the
panel to prevent water getting behind the unit and entering the
cavity behind the panel.
7 It is good practice to run the cables vertically downwards from the
unit, even if they later have to rise to connect to the vessel's
supplies. Doing so prevents any water that might get onto the cables
from running back along the cables and into the unit.
8 Ensure that all loads are switched off
9 Disconnect the NEGATIVE terminal from the battery and connect to
the shunt as shown on Figure 1. Ensure it is positioned where it
cannot come into electrical contact with other parts, and ensure it
will remain dry and free from contaminants. Also note that the
shunt can get warm when heavy currents flow, so ensure it is
secured in a position where its heat cannot affect other parts. TAKE
CARE TO AVOID OVER-TIGHTENING THE CONNECTION TO THE
SHUNT.
10 Connect the Black and White wires and Yellow wire to the shunt as
shown on Figure 1.
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Page 5
11 Connect short link cable to the shunt and then to the negative
terminal of the battery.
12 If the starter battery voltage is to be monitored then connect the
orange wire to the positive terminal of the starter battery.
A 1 amp fuse close to the starter battery will aford protection if a
fault occurs.
13 Finally, connect the red wire to the POSITIVE terminal of the battery
to complete the electrical installation. The BM1/BM2 will now begin
assessing the battery state, using its factory default values. The
default values must be set to the values appropriate to the new
installation as follows.
14 Press, and keep pressed, the ILLUM key until the word "Eng" is
shown on the display. Release the ILLUM key and adjust the
capacity shown using the and keys to match the value shown
TIME
A-Hr
on your battery (see the Engineering section below for more details).
15 Press the V&A key to change to adjusting the battery temperature,
and adjust it using the and keys to match the estimated
TIME
average battery temperature within 10 C.
A-Hr
o
16 Press ILLUM to finish Engineering settings.
17 Do NOT put the battery on charge immediately.
18 Apply a load to the battery by switching on lights or instruments
and wait for a few minutes for the BM1/BM2 to "learn" the battery's
characteristics and to show a steady reading before starting
charging.
NEGATIVE
TO ALL DOMESTIC
LOADS AND GENERATORS
POSITIVE
TO ALL DOMESTIC
LOADS & GENERATORS
TO STARTER
+
ENGINE START
FUSE
Figure 2 -
Domestic
and
starter
Batteries
-
BATTERY
THIS CABLE IS NOT SUPPLIED
BM
ILLUM
A-Hr
V&A
No other connection
should be made to
this post
-
DOMESTIC
BATTERY OR
YELLOW
WHITE
BLACK
RED
BATTERIES
5-metre
CABLE
SHUNT
YELLOW
ORANGE
YELLOW
WHITE*
BLACK*
RED
TIME
* Black & White
MUS T NO T be
joine d a t thi s end.
+
FUSE
Cables
supplied
Original
cables
Page 6
BATTERY MANAGEMENT BASICS
After Voltage and Current, the most useful measurement available from a
battery condition monitor is the sate of charge of the battery. However.
estimation of the state of charge of lead-acid batteries is never exact. The
problem of making accurate estimates results from the characteristics of
the cells, the electrolyte, and the history of currents drawn from (discharge)
and supplied to (charge) the battery.
The basis for the best capacity estimates is that the starting condition is
known. The only well-established "known" state of a battery is when it is
fully charged after a long period of trickle or float charging, usually on a
shore or regulated alternator-driven charging system. Discharging a fullycharged new battery at a current 1/20 of the manufacturer's stated
capacity will discharge it fully in 20 hours. This current is known as the
"20-hour rate".
So, for example, if a battery has a stated capacity of 100 Ahr, then the 20hour rate for that battery is 5 Amps (because 100/20 = 5). Likewise, a 40
Ahr battery would have a 20-hour rate of 2 Amps (because 40/20 = 2).
If higher currents than the 20-hour rate are drawn from the battery, the
available capacity is reduced. For example, if it is steadily discharged at 10
times the 20-hour rate (50 Amps from a 100Ahr battery), the available
capacity falls to about half of the stated capacity. The battery will be flat
after about 1 hour instead of the expected 2 hours. (However, if the battery
is left to recover with the heavy load removed, most of its remaining
capacity will return after perhaps 20 hours' resting or at a discharge rate
close to the 20-hour rate.) The BM1/BM2 makes due allowance for these
effects when estimating the battery's state of charge and the expected time
to discharge the battery fully.
When the battery is being charged, the voltage is no longer a reliable
estimate of the state of charge, and so the BM1/BM2 integrates the Ampere
hours added to the last known capacity to estimate the battery's state of
charge on a continuous basis. Allowance for charge efficiency (not all
charging current results in useful charge in the battery) is also computed.
Available battery capacity is significantly reduced at temperatures
significantly below 20C. The value quoted by the manufacturers is valid at
20C. However, at 0C the capacity may be only 90%, and at -20C may be
only 70% of the 20C value. A small increase in capacity is achieved at
battery temperatures above 20C, rising to about 105% of the nominal value
at 40C.
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Page 7
The effects of cell deterioration on the available capacity are significant. If
the battery is charged for long periods, gassing takes place. The gases are
Hydrogen and Oxygen, derived from the water in the battery acid. Loss of
this water needs to be made up by topping up the cells if possible, or by
avoiding lengthy overcharges in sealed cells.
Other irretrievable effects include sulphation (encouraged by leaving the
battery flat for long periods), and deterioration of the cells' plates. If the
battery voltage falls below 10.7 Volts (for a nominally 12 Volt battery), and
charging is not started, sulphation of the plates can begin. The BM1/BM2
has an alarm which flashes the bell symbol when the voltage falls below
10.7 Volts. If the alarm is triggered, it is important to reduce the current
being drawn immediately, and if possible place the battery on charge, to
avoid permanent damage to the cells. If the alarm is ignored, the total
number of charge/discharge cycles which the battery will survive before it
loses a substantial fraction of its nominal capacity may be substantially
reduced.
All of these (and other effects) reduce the available charge after fully
charging the battery. If the effects are ignored, the BM1/BM2 will
incorrectly estimate that more capacity is available at any state of discharge
than is actually the case. If so, it is wise to alter the nominal capacity
stored in the unit to match the reality of the battery's condition.
NORMAL OPERATION
The NASA BM1/BM2 offers four normal modes of operation:
Volts and Amps;
Ampere-hours;
Time to go.
Starter Battery Voltage
In all these normal modes, the battery charge state is also displayed on the
scale on the right of the display. Also, if the battery voltage falls below the
preset alarm level representing dangerous discharge, the alarm bell symbol
is flashed.
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Page 8
The three normal modes, and the keys which activate them, are shown in
Figure 2, below.
%
C
ILLUM
V
100% 100%
DIS
V&A
100% 100%
80 80
80 80
60 60
60 60
A
40 40
40 40
A-Hr
TIME
ILLUM
CHARGE
V&A
A
h
A-Hr
r
100%
100%
DISCHARGE CHARGE
80
80
60
60
40
40
TIME
TIME TO
ILLUM
V&A
h
A-Hr
r
TIME
Volts and Amps Ampere-hours Charge/discharge times
Figure 2 - Operating modes
Switching the backlight
Press the ILLUM key to switch the backlighting on or off.
The backlight area is restricted in the top corners of the display to
concentrate the lighting in the areas of interest.
Showing the Voltage and Current
Press V&A key to show the present battery voltage and the present battery
current, as well as the estimate of the state of the battery's charge on the
scale. The maximum current measurement is 102 Amps.
A second press on V&A will display the starter battery voltage together with
the symbol ‘St’
NOTE: The open circuit voltage can indicate the starter battery’s state of
charge. However when displaying the starter battery’s voltage, the
instrument continues to monitor all aspects of the domestic battery, and
Showing the Ampere-hours total.
Press the key to show the total Ampere-hours since the totals were last
reset. Int is shown, and all the uncorrected normal total Ampere-hours
are shown in the upper numerals. They show the net charge or discharge
in Ampere-hours since the unit's counters were last reset. (A new, exfactory, instrument shows zero.) To reset the Ampere-hours integrator,
press the key and keep it pressed until 0 is shown.
A-Hr
A-Hr
A-Hr
Showing the time to go.
Press the key to show the percentage remaining battery capacity (%C),
and the up-to-date estimate of how long it will take to charge or discharge
the battery fully. As the load changes, the estimate of the time updates
continuously, reflecting the best estimate of time to fully charged or fully
discharged (0% remaining charge). Values in excess of 199 hours are
shown as 199 hr.
TIME
Page 9
If the BM-1+ is left for long periods registering little or no charge or
discharge current, the estimate of capacity may become unreliable. It is
important to switch some load onto the battery for a few minutes so a
reliable estimate can be calculated, and its value settles, before starting
charging.
ENGINEERING
Engineering is the mode for setting the nominal battery capacity, the
battery temperature, and the zero-current. Engineering is accessed by
keeping ILLUM pressed until ENG is displayed to show that Engineering
settings are now available. The first value when ILLUM is released is the
stored nominal battery capacity in Ampere-hours. Then press the V&A key
to move between capacity, battery temperature, and zero-current settings.
In any of these modes, the and keys alter the chosen setting. All
TIME
A-Hr
settings are saved by pressing the ILLUM key to exit Engineering.
Setting the battery's nominal capacity
Press V&A until the stored capacity appears in the upper numerals, and
the Ahr symbols are showing (the factory default is 100 Ahr). Now press
the key to increase the value, and the key to reduce the value. Keep
TIME
the key pressed for repeating adjustments.
The maximum capacity is 600 A-hr, and the minimum is 5 A-hr. When
the correct value has been selected, press the V&A key to finish
adjustment, store the new value in memory and to move to temperature
setting, or press the ILLUM key to exit Engineering.
A-Hr
Setting the Estimated Battery Temperature
Press V&A until the battery temperature appears and the symbols C are
shown. The factory preset value is 20 C which is the value used by
battery manufacturers to define their products' capacity. Now, if desired,
press the key to increase the value, and the key to reduce the value,
which changes by 10 C for each press. The values are limited to the range
-20 C to +40 C.
TIME
TIME
o o
o
o
A-Hr
o
Setting the zero-current
If no current is flowing into or out of the battery and a residual current is
shown on the display, the reading can be adjusted to zero.
With no current flowing into or out of the battery, press V&A until the
residual current is shown. Now press the key or the key to bring the
TIME
TIME
value to zero. (Note: eight presses of the key alter the setting by 0.1A). The
desired setting is stored when the V&A key is pressed to move to the other
setting again, or the ILLUM key is pressed to exit Engineering.
Page 7
A-Hr
Page 10
QUESTIONS AND ANSWERS
Q Why is the screen of my BM1/BM2 blank?
A Check the wiring is correct and securely terminated. Check the
fuse, and check that the battery is not completely flat.
Q Why does my BM1/BM2 show that the number of hours
remaining is high or low when a constant discharge current is
flowing?.
A The actual battery capacity is different from the value you have
entered in Engineering. The reasons for this difference have been
discussed above. Adjust the battery capacity in Engineering to
match the battery.
Q My battery is made up of a bank of several batteries. Is that a
problem?
A Not as long as the combination produces a nominal 12 volts, and
all the current drawn from the bank passes through the shunt.
Q Can the BM1/BM2 monitor my engine starting battery as well
as my service battery?
A Yes it can monitor the engine start battery voltage. The open
current voltage of the starter battery can be used to estimate its
state of charge
Q I have another voltmeter on my boat which shows a different
value to the BM1/BM2 indication.
A The BM1/BM2 very accurately measures the voltage directly
across the battery terminals. Other voltmeters may read
differently owing to volt drops in the boat's wiring.
Q Why does my BM-1+ show a higher capacity immediately after
charging than it does after a few minutes' discharging?
A This is an unavoidable feature of battery chemistry, which varies
from battery to battery, and the charging regime used.
Page 8
Page 11
Q Do I need to disconnect my BM1/BM2 when I leave the boat
for long periods?
A No. The BM1/BM2 is designed to be permanently connected to the
battery. It is independently fused, and draws only 1.5mA from the
battery. At such a low current, it would take several years to
discharge a typical fully-charged marine service battery.
Q Why does my battery seem to have less capacity than it says
on its label?
A The value on the manufacturer's label is seldom the value achieved
in service, because of the deterioration of the cells' plates and
many other factors. If it seems to have much lower than its
expected capacity, it may need replacement, or you may feel that
changing the nominal capacity from the Engineering mode will
suffice to let you know well enough the percentage charge
remaining.
Q Why does my BM1/BM2 show a large net charge after a day's
cruising?
A You have put more charge into the battery than you have used.
The amount should not exceed the total battery capacity. If it does,
it may be wise to check that the charging system is working
correctly and is not over-charging the battery.
Q When on heavy load, the time to run is lower than I expect. Is
this correct?
A YES. When heavily loaded, a lead-acid battery delivers less energy
than expected owing to electrolyte exhaustion and stagnation.
When the battery is delivering heavy currents the BM1/BM2 uses
Peukert's equation to allow for these effects and so show a better
estimate for the time to run.
Q Why is my BM1 showing incorrect readings?
A Check the connections in the terminal block are correct and that
the clamps in the block are fastened on the copper of the wires
and not the plastic insulation of the wires .
Page 12
IMPORTANT READ THIS BEFORE
UNPACKING INSTRUMENT
Prior to unpacking this instrument read and fully understand the installation instructions.
Only proceed with the installation if you are competent to do so. Nasa Marine Ltd. will
not accept any responsibility for injury or damage caused by, during or as a result of
the installation of this product. Any piece of equipment can fail due to a number of
causes. Do not install this equipment if it is the only source of information and its failure
could result in injury or death. Instead return the instrument to your retailer for full credit.
Remember this equipment is an aid to navigation and not a substitute for proper
seamanship. This instrument is used at your own risk, use it prudently and check its
operation from time to time against other data. Inspect the installation from time to time
and seek advice if any part thereof is not fully seaworthy.
LIMITED WARRANTY
Nasa Marine Ltd. warrants this instrument to be substantially free of defects in both
materials and workmanship for a period of one year from the date of purchase.
Nasa Marine Ltd. will at its discretion repair or replace any components which fail in
normal use within the warranty period. Such repairs or replacements will be made at
no charge to the customer for parts and labour. The customer is however responsible
for transport costs. This warranty excludes failures resulting from abuse, misuse,
accident or unauthorised modifications or repairs. In no event shall Nasa Marine Ltd.
be liable for incidental, special, indirect or consequential damages, whether resulting
from the use, misuse, the inability to correctly use the instrument or from defects in
the instrument. If any of the above terms are unacceptable to you then return the
instrument unopened and unused to your retailer for full credit.
Name
Address
Dealer Name
Address
Date of Purchase
Proof of purchase may be required for warranty claims.
Boulton Road, Stevenage, Herts SG1 4QG England
Nasa Marine Ltd.
Declaration of Conformity
NASA Marine Ltd declare this product is in compliance with the essential requirements of
R&TTE directive 1995/5/EC.
The original Declaration of Conformity certificate can be requested at info@nasamarine.com
THIS PRODUCT IS INTENDED FOR USE ONLY ON NON SOLAS VESSELS
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