Curtis 908 Operating Instructions Manual

MODEL 908

“Fuel” Gauge

Read Instructions Carefully!

CURTIS INSTRUMENTS, INC.

200 Kisco Ave.

Mount Kisco, New York 10549

914-666-2971

www.curtisinstruments.com

53051 Rev C 9/15

TABLE OF CONTENTS

1. Model Encodement 2

2. Technical Specifications

2.1 Electrical 6

2.2 Mechanical 8

2.3 Environmental 9

3. Installation 10

4. Operation

4.1 Display 15

4.2 Reset Type/Level 16

5. Troubleshooting 17

6. Maintenance 18

7. Warranty 19

SAFETY INSTRUCTIONS

This instrument was manufactured and tested according to the
applicable technical standards. It complies with all the safety
regulations as shipped from the factory.

Installation and startup must be performed by skilled person­nel.

Failure to install and operate the unit in accordance with these
instructions may result in damage or injury.

If safe operation of the instrument can no longer be ensured,
stop and secure it against accidental operation.

If instrument failure or malfunction may cause personal injury
or material damage, use additional safety measures such as
limit switches, guards, etc.

Read the Operating Instructions carefully before startup.

Note the safety instructions marked with this
warning symbol in this manual!

2 3

Example: Model 908 R 2448 D P J A O

Case Style

Voltage

Reset

Discharge

Output

Special

Options

1 3 5

2 4 6

Artwork

7

Case Style Options:

R = Round (52mm)

1

Voltage Options:

2

Reset Profile Options

3

1. MODEL ENCODEMENT

Single Dual

12 24/36

24 24/48

36 36/48

48 72/80

72

80

Letter

Code

Volts per Cell

Open Circuit

Reset

Charge

Tracking

Reset Full

Charge

Tracking

Reset

Empty

B 2.090 2.35 2.10

C 2.135 2.400 2.10

D 2.060 2.32 2.10

G 2.090 2.40 2.10

K 1.928 2.167 2.10

N 1.980 2.230 2.10

T 2.028 2.28 2.10

Y 2.083 2.167 2.10

4 5

Discharge Profile Options

4

Letter Code Logo

O Curtis
N None

Special Options

A = (TBD)

Output Options

5

6

Artwork Options

7

Letter Code

Volts per Cell

Full Empty

G 1.97 1.75
H 1.97 1.70

J 1.97 1.63

K 2.01 1.65

L 2.10 1.92

M 2.00 1.83

N 2.04 1.73

O 2.08 1.88

P 2.08 1.98

Q 2.10 1.88

R 2.02 1.90
S 2.08 1.85

T 2.03 1.90

V 1.98 1.85

W 2.02 1.85

X 1.95 1.75
Y 2.00 1.90
Z 2.04 1.82

Letter

Code

Relay Contact Rating

J Holding

3 Amps when continuously closed,

1 Amp when opening

K N.C. 1 Amp

Y N.O. 1 Amp

6 7

2. TECHNICAL SPECIFICATIONS

2.1 Electrical Operating Voltage:

Operating Range: ±25% of nominal voltage.

Operating current at pin 7 (V+) or 8 (V++) for each

nominal and maximum voltage is specified:

Rating

V+/V++

Test Conditions

V+ or V++ (Volts)

Operating Current (mA)

Notes

Nominal Maximum

12 V+

12 (Nom) 17 —

For all test
conditions:

• V(Nom) is
the rated
value, e.g.
24 volts

• V (Max) =
V (Nom)
+25%

• J relay

15 (Max) — 29

24/36

V+

24 26 —

30 — 39

V++

36 17 —

45 — 23

36/48

V+

36 22 —

45 — 30

V++

48 16 —

60 — 22

Rating

V+/V++

Test Conditions

V+ or V++ (Volts)

Operating Current (mA)

Notes

Nominal Maximum

24/48

V+

24 26 —

For all test
conditions:

• V(Nom) is
the rated
value, e.g.
24 volts

• V (Max) =
V (Nom)
+25%

• J relay

30 — 39

V++

48 15 —

60 — 21

72/80

V+

72 22 —

90 — 28

V++

80 15 —

96 — 20

96 V+

96 21 —

120 — 27

8 9

2.3 Environmental

Temperature

Operating: –40°C to +85°C
Storage: –50°C to +90°C

Humidity

95% RH (non-condensing) at 38°C

Shock and Vibration

Shock: per SAE J 1378 paragraph 5.6

12 shocks in each direction along each axis (72
shocks total). 44 to 55g amplitude, half sine of
9 to 13 ms.

Vibration: per SAE J 1378 paragraph 5.5

2 hours along each axis. Double amplitude of

1.52mm from 10-80-10 Hz (10g max) at intervals
of 1 minute.

2.2 Mechanical

Display

Battery state-of-charge: 10-bar, tri-color LED.

Hardware Kit

Mounting bracket, thumbnuts or M4 Hex nuts (2), lock
washers (2).

Panel Cutout

52mm, 2 ¹/16” diameter

Mating Connector

Molex
Housing: 39-01-2085
Pins: 39-00-0039 (18-24 AWG)
39-00-0078 (16 AWG)

10 11

3. INSTALLATION

The Model 908 fits into a dash-panel cutout
measuring 2 ¹/16” (52mm).

Terminal Assignment (see diagram on page 14)

Pin 7 or 8 = Battery +

Single voltage models: Pin 7 to battery +; Pin 8, open.

Dual voltage models: When vehicle voltage is the

higher voltage of the 2 operating voltages, Pin 8 con­nects to battery +; Pin 7, open. When vehicle voltage is
the lower of the 2 operating voltages, Pin 7 connects to
battery +, Pin 8, open.

The discharge indicator uses Pin 7 or 8 for its battery
state-of-charge measurements. Connection are to be
made as close as possible to battery to prevent voltage
drops that will cause errors in discharge indicator
readings. The connection is not to be switched by the
vehicle’s keyswitch.

Pin 5 = Battery –

Connect to battery ground as close to battery
as possible.

CURTIS Model 908 Rear View

12 13

NOTE: Fuses and Wires

Regulations may require that the Model 908 be
fused. If installing a fuse, use a 10A fuse wired
with 1.5mm or equivalent wire. The voltage
drop across the fuse, its holder, and connectors must
be less than 1% of the nominal system voltage.

Pin 2 = Keyswitch

The keyswitch turns on and off the LED display of the
battery discharge indicator. Monitoring of the battery
continues when Pin 2 is turned off and the display
is not lit.

Pin 3 = Relay +

Pin 3 connects in series with the lift coil circuit (or the
circuit to be switched at empty). For holding relay (J), Pin
3 must be electrically closer to battery + than Pin 4.

Pin 4 = Relay –

Pin 4 also connects in series with the circuit to be
switched at empty.

Pins 1 and 6 are not used.

14 15

4. OPERATION

4.1 Display

The Curtis Model 908 combines in one instrument a

completely solid state LED battery state-of-charge
indicator and lift lockout.

The top LED is lit only when the battery is properly

charged. As the battery’s state-of-charge decreases,

successive LEDs light
up one at a time.

Here, the LED flashes
indicating “energy
reserve” (70% depth
of discharge).

The 2 bottom LEDs
flash, indicating “empty”
(80% depth of discharge).
At this point, lift lockout
occurs.

1

Connections for Typical Model 908 Application

Vehicle system voltage is the higher of the two
operating voltages of a dual voltage unit.

1

0

1/2

1

16 17

4.2 Reset Type/Level

(after or during recharge)

CTR (Charge Tracking Reset)

If the gauge is connected to the battery during
recharge, the gauge will track battery charge levels.

OCR (Open Circuit Reset)

If the gauge is disconnected from the battery during
recharge, the gauge will retain the last indication. It will
advance to full when reconnected only of the battery
voltage is above the OCR level. For standard (“B”)
reset, OCR=2.09 VPC (Volts per cell).

5. TROUBLESHOOTING

The following checklist should help you troubleshoot any
problem with Model 908.

Problem Possible Cause

No display Terminals not connected or improper voltage

Stays at FULL Instrument voltage does not match battery

voltage; B+ connected to the wrong terminal
(see page 11)

Will not reset Instrument voltage does not match battery

voltage or battery not fully charged

Reset without
charging battery

Not connected directly to battery terminals

EMPTY too soon B+ connected to wrong terminal, or

instrument voltage does not match battery
voltage, or terminals not connected directly
to battery

18 19

Curtis Instruments’ products and/or components are
guaranteed against defects in workmanship and material for
a period of one year, or as defined in the individual product
literature, from date of shipment from our factory, when applied
in a proper application within specified ratings. This guarantee
is limited to repairor replacement F.O.B. our factory. There
is no further warranty or implied representation, guarantee,
promise or agreement as to any Curtis Instruments product
and/or component. Curtis Instruments, Inc., cannot assume
responsibility or accept invoices for unauthorized repairs to
its products and/or components,even though defective. In no
case will Curtis Instruments’ responsibility extend to products,
components or equipment not of its manufacture. Under no
circumstances shall Curtis Instruments, Inc., be liable for any
special or consequential damages or loss of profits or other
damages. Returned goods will not be accepted unless
identified by a Curtis Return Material Authorization (RMA).

All specifications are subject to

change without notice.

7. WARRANTY

6. MAINTENANCE

Curtis Model 908 series is not field serviceable. Return
defective units to your distributor for warranty coverage.