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Instrumentation

www.curtisinstruments.com

Battery “Fuel” Gauge

Model 906
www.curtisinstruments.com 2

Battery “Fuel” Gauge 

Model 906

FEATURES OPTIONS

SPECIFICATIONS

▶ All principal circuits are integrated in a single chip for 

long-life reliability.

▶ A 10-bar LED displays the state-of-charge 

successively, bar by bar, from full to empty.

▶ At 70% depth of discharge, a flashing LED signals an 

“energy reserve” alert.

▶ At 80%, alternately flashing LEDs provides an 

“empty” status warning.

▶ Model 906 is compact and easily installed in panel 

cutouts as small as 36.8 X 24.1 mm, with as little as 

35 mm behind panel clearance needed, see 

dimensions of various case styles.

▶ Recognizes improperly charged battery.

▶ Keyswitch activated LED display (state-of-charge is 

monitored as long as 906 is connected to battery).

▶ Memory allows gauge to recall state-of-charge 

whenever battery is disconnected.

▶ Three possible reset methods:

1. Open Circuit Reset (OCR): Upon reconnection of 

a battery the gauge will reset if it measures 2.09 

volts/cell or higher (example “B” profile) (for units 

with memory option). 

2. High Voltage Reset (HVR): Gauge must measure 

>2.35 volts per cell for 6 continuous minutes 

during charging (example “B” profile).

3. Charge Tracking Reset (CTR): Display tracks charge 

level during opportunity charging (requires gauge 

to be connected to battery when charging)

Model 906 is an inexpensive, one piece, easy to install battery fuel gauge. It is completely solid state and provides 

a reliable, accurate, and easy to read display of battery state-of-charge. Model 906 is available in six panel mount 

packages and a printed circuit board mounted module for custom dash panel applications. This battery fuel 

gauge features Curtis patented technology and is ideal for golf cars, commercial cleaning equipment, mobility 

aids, electric bicycles, electric marine motors, medical devices, and similar equipment.

▶ The Output Signal option causes the voltage on pin 3 to 

drop from 5 to 0 volts at 80% discharge. It can be used to 

signal another component or to allow for the disabling of 

a specified vehicle function, insuring against abusive deep 

discharge conditions. The Output Signal can also be used 

to drive the Curtis 1178 Relay Module.

▶ Special models and custom panels are available.

System Voltages: 12V, 24V, 36V, 48V

Operating voltage: +/–25% of nominal voltage

Operating temperature: –40°C to +85°C

Storage temperature: –50°C to +90°C

Shock & Vibration: Meets SAE J 1378

See a 360° view of Model 906 at:

curtisinstruments.com/360view
www.curtisinstruments.com 3

Battery “Fuel” Gauge 

Model 906

DIMENSIONS mm

0 1

F Case:

D Case: 

N Case: 

Y Case: 

- +

Ø3.8 (2X)

23.8

36.7

44.5

53.2 MAX.

22.7

35.5

1.5

3.2

18.0

31.2

MAX.

28.8

3/16" (4.8mm) wide (4X)

1 2

4 3

18.0

36.5

4.7

27.5

40.6

23.8

36.7

1 2 3 4

NOTE: Equivalent to Delphi-Packard connector P/N 15336035 4-pin.

 24 

 48 

0 1

 14.4 

 14.3 

 22.0 

 21.9 

1 2

4 3

32 Max. 

14.6 ±0.3 

22 ±0.2 

4 ±0.2 48 ±0.3 

24 ±0.3 

Case Style T

Case Style D

Case Style Y

Case Style N
www.curtisinstruments.com 4

Battery “Fuel” Gauge 

Model 906

DIMENSIONS mm

Z Case: 

Module:

+ P +

+ +

COMPONENT

SIDE

33.0 Max

28 33.0 Max

2.0 

2.0

0.8±.02 Dia. 

4 Places

14.0 19.0 Max 19.0 Max

10.50 Max

13.0 Min

9.5

26.70

10.50 Max 

1 2

4 3

 906 F 24 H N A A 

 Case Styles Reset Level Option

 Voltage Discharge Profile Special Options 

F

T

J

D

Y

Z

P

R

H=2.35 V/cell HVR

 

B=2.09 V/cell OCR

 

A=No option

D=Output signal

 5 ± 0.5V above empty

 0 to 0.1 V at empty

 10K W impedance

 N=2.04 V/cell @ full to 1.73 V/cell @ empty

[G=1.97 V/cell @ full to 1.75 V/cell @ empty]

[W=2.02 V/cell @ full to 1.85 V/cell @ empty]

12V

24V

36V

48V 

27.5

23.8

18.0

28.8

4.7

27.5

40.6

23.8

36.7

1 2

4 3

1 2 3 4

NOTE: 1/4" fast on spade terminals.

NOTE: Equivalent to Delphi-Packard connector P/N 15336035 4-pin.

Case Style Z

Module P

continued

Case Style R 0 1

4 3

1 2

THUMBNUT 4MM

LOCKWASHER 4MM

SEE NOTE 2.0

“U”CLAMP FOR .8 MM TO 6.4 MM.

PANEL THICKNESS

8.9 MAX.

13.2 MAX.

28.6 MAX.

58.4 MAX.

51.5 MAX

NOTE: 3/16" fast on spade terminals.

NOTE 2.0: OEM's are supplied with hex 

nuts and lock washers only. They do not 

receive thumbnuts.

Pin Function

PIN 1 B+

PIN 2 B– 

PIN 3 Output Signal + or No Option

PIN 4 Keyswitch +
www.curtisinstruments.com 5

Battery “Fuel” Gauge 

Model 906

MODEL NUMBER ENCODING

Determine your model number by selecting the correct attribute for each item from the charts provided. Choose the 

appropriate letter that corresponds to the proper specification. Enter the code sequentially per the example below.

1 CASE STYLES 3 RESET PROFILE OPTIONS

2 VOLTAGE 

 OPTIONS

D DIN case—rectangular

F

Hex bezel 

w/1/4” spade 

terminals (enGage I)

J Hex bezel w/Packard 

connector (enGage I)

N DIN case—

rectangular, snap-fit

P Pin mount (module)

R

52mm Round 

bezel & case

(same as 700Q)

T

Hex bezel 

w/3/16” spade 

terminals (enGage I)

TX

Hex bezel 

w/3/16” spade 

terminals (old T case)

Y

Rectangular bezel 

w/Packard connector (enGage I)

Z

Rectangular bezel 

w/1/4” spade terminals (enGage I)

Profile with 

Memory 

Option

Profile 

without 

Memory 

Option

Volts Per Cell

OCR HVR CTR

Full

CTR 

Empty

K 1.928 2.167 2.167 2.10

J N/A 2.167

Y 2.083 2.167 2.167 2.10

N 1.980 2.230 2.230 2.10

E N/A 2.230

T 2.028 2.280 2.28 2.10

L N/A 2.280

D 2.060 2.320 2.32 2.10

P N/A 2.320

B 2.090 2.350 2.35 2.10

H N/A 2.350

C 2.135 2.400 2.400 2.10

M N/A 2.400

F N/A 2.416

12

24

36

48

2 4 6

3 5 7

Example Model 906 D 24 M C D A O

Voltage

Case Style Reset Output Artwork

Discharge

Special 

Options

1
www.curtisinstruments.com 6

Battery “Fuel” Gauge 

Model 906

MODEL NUMBER ENCODING continued

Note: This gauge is not intended to measure the state-of-charge of batteries 

subject to extended periods of inactivity since it does not account for selfdischarge effects. Consult factory for details.

4 DISCHARGE 

PROFILE OPTIONS 5 OUTPUT OPTIONS 6 SPECIAL OPTIONS

7 ARTWORK OPTIONS

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

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

Letter 

Code Signal

A No option

B* Both output &

memory options 

C*

Both output & memory 

options and CTR reset 

instead of HVR

D Output option only

M Memory option only

* option is for micro versions only

Letter 

Code Options

A Red LED array

G Tri-color LED array

Letter 

Code Options

O Curtis

N No Logo

is a trademark of Curtis Instruments, Inc. Specifications subject to change without notice ©2017 Curtis Instruments, Inc. 50020 Rev M 12/17

WARRANTY Two year limited warranty from time of delivery.

2 4 6

3 5 7

Example Model 906 D 24 M C D A O

Voltage

Case Style Reset Output Artwork

Discharge

Special 

Options

1