Clipper BM1 Owner's Manual - User Manual

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DESIGNED AND

MANUFACTURED

CE:

IN ENGLAND

DISCHARGE

100%

©!LOffeJffeJ{g�

BATTERY MONITORS

BM1/BM2

READ THIS FIRST!

BEFORE INSTALLING THE BM1

BM2, CAREFULLY READ THE FOLLOWING

INSTRUCTIONS, ESPECIALLY THE SAFETY NOTES AND WARRANT Y
CONDITIONS.

IMPORTANT

BM1

BM2 look identical but they are different Models.

Tha Shunts and Shunt cables are

NOT

interchangeable.

CLIPPER BMt.....

Load

Charge

Current - 100 Amps Maximum

CLIPPER BM2.

. . .

Load

Charge

Current - 200 Amps Maximum

NASA BATTERY MONITOR BM1

BM2

Table of Contents

PAGE

INTRODUCTION

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 Nomlnal Capacity

Setting the Estimated Battery Temperature

Setting the zero-current

QUESTIONS AND ANSWERS

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

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 alr
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.

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).

Bring the shunt cable through the hole in the panel.

Unscrew and remove the two wing nuts from the rear of the

instrument and remove the stainless steel clamping bracket.

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

NEGATIVE

TO ALL DOMESTIC

LOADS AND GENERATORS

POSITIVE

TO ALL DOMESTIC

LOADS

GENERATORS

• Black & White

MUST NOT be

Joined

.t lhl8

end.

Figure

- Domestic battery only

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.

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 0-ring rubber  seal makes good contact with the
panel to  prevent water getting behind the  unit  and entering the
cavity behind the panel.

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.

Ensure that all loads are switched off

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

AVOID OVER-TIGHTENING THE CONNECTION

THE

SHUNT.

10 Connect the Black and White wires and Yellow wire to the shunt as

own

on Figure

Page2

Connect short

link

cable to the shunt and then to the negative

terminal of the batteiy.

If the starter batteiy voltage is to be monitored then connect the

orange

wire

to the positive terminal of the starter batteiy.

amp fuse close to the starter batteiy

will

aford protection

fault occurs.

Finally, connect the red wire to the POSITIVE terminal of the batteiy

to complete the electrical installation. The

/BM2

will now begin

assessing  the batteiy  state,  using  its  factoiy  default  values.  The
default  values  must  be  set  to  the  values  appropriate  to  the  new
installation  as  follows.

Press, and keep pressed, the

ILWM

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

on your batteiy (see the Engineering section below for more details).

Press the

V&A

key to change to adjusting the batteiy temperature,

and adjust it using the �and � keys to match the estimated
average batteiy temperature within l0°C.

Press

ILLUM

to finish Engineering settings.

Do NOT put the batteiy on charge immediately.

Apply a load to the batteiy 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.

Figure 2

Domestic

and

starter
Batteries

NEGATIVE

TO ALL DOMESTIC

LOADS AND

POSITIVE

TO ALL DOMESTIC

LOADS

GENERATORS

othar

connection

•hould

b9 made 7

this

post

•

Bl•ck

Whll8

llUSTNOTIHI

JolnlMI

111:

lhl• end.

I
I

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 fully
charged 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

020-hour rate11•

So, for example, if a battery has a stated capacity of 100 Ahr, then the 20-
hour 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

exam

ple, if it is steadily discharged at 10

times the 20-hour rate (50 Amps from a  l OOAhr  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 BM

/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 OC 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.

Page4

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

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

curr

ent

being drawn immediately, and

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 BM 1 /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,

the battery voltage falls below the

preset

alarm

level representing dangerous discharge, the alarm bell symbol

is flashed.

Page

The three normal modes, and the keys which activate them, are shown in

Figure

below.

Volts and Amps

Ampere-hours

Charge/discharge times

Figure

- Operating modes

Switching the backlight

Press the

ILLUM

key to switch the backlighting on or off.

The backlight area is restricted in the top comers 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,  ex
factory,  instrument  shows  zero.) To  reset  the  Ampere-hours integrator,
press the� key and  keep  it  pressed  until

is shown.

Showing the time to go.

Press the

TI":E

key to show the percentage remaining battery capacity (o/oC),

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

fully charged or fully

discharged

(0%

remaining charge). Values in excess of

199

hours are

shown as

199

hr.

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-

curr

ent. Engineering is accessed by

keeping

ILLUM

pressed until ENG is displayed to show that Engineering

settings are now available. The frrst value when

ILLUM

is released is the

stored nominal battery capacity in Ampere-hours. Then press the

VB.A

key

to  move  between  capacity,  battery temperature,  and zero-current  settings.
In any  of these  modes,  the  ;t;, and �keys  alter the  chosen  setting. All
settings  are  saved  by  pressing the

ILLUM

key to exit Engineering.

Setting the battery's nominal capacity

Press

VB.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;t;,key to increase the value, and the� key to reduce the value. Keep
the key pressed for repeating adjustments.

The maximum capacity is

600

A-hr, and the minimum is

A-hr. When

the correct value has been selected, press the

VB.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.

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 defme their products' capacity. Now,

desired,

press the ;t;, 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

+40 'C.

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

curr

ent

into or out of the

press

VB.A

until the

residual current is shown. Now press the

key or the � key to bring the

value to zero. (Note: eight presses of the key alter the setting by

lA). The

desired setting is stored when the

VB.A

key is pressed to move to the other

setting again, or the

ILLUM

key is pressed to exit Engineering.

Page7

QUESTIONS AND ANSWERS

Why

the screen of my Bl!II1/Bl!II2 blank?

Check the wiring is correct and securely terminated. Check the

fuse, and check that the battery is not completely flat.

Why does my BM1/Bl!II2 show that the number of hours
remaining ia high or low when a constant discharge current

flowing?.

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.

My battery

made up of a bank of several batteries. Ia that a

problem?

Not as long

the combination produces a nominal 12 volts, and

all the current drawn from the bank passes through the shunt.

Can

the Bll.U/BM2 monitor my engine starting battery

well

my service battery?

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

I have another voltmeter on my boat which shows a different
value to the BM1/BM2 indication.

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.

Why does my BM-1+ show a higher capacity immediately after
charging than it does after a few minutes' discharging?

This is an unavoidable feature of battery chemistry, which varies

from battery to battery, and the charging regime used.

Page

Do I need to disconnect my BM1/BM2 when I leave the boat
for long periods?

No. The BM1/BM2 is designed to be permanently connected to the

battery. It is independently fused, and draws only 1.SmA from the
battery. At such a low

curr

ent, it would take several years to

discharge a typical fully-charged marine service battery.

Why does my battery seem to have less capacity than it uys

its label?

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

remalning.

Why does my BM:l/BM2 show a large net charge after a day's

cruising?

You have put more charge into the battery than you have used.
The amount should not exceed the total battery capacity. !fit does,

it may be wise to check that the charging system is working
correctly and is not over-charging the battery.

When on heavy load, the time to run is lower than I expect. Is

this correct?

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 BM

/BM2 uses

Peukert's equation to allow for these effects and so show a better
estimate for the time to run.

Ask a Question ?