Battery Chargers

Schaefer B3700 SERIES Battery Charger

The Schaefer B3700 Series is a high-performance battery charger with a power rating of 1250W, designed to support diverse industrial and critical infrastructure applications. Housed in a 6U footprint, the B3700 Series employs natural convection cooling, ensuring reliable operation even in challenging conditions. Capable of supporting nominal battery voltages of 12Vdc, 24Vdc, 48Vdc, 60Vdc, 110Vdc, and 220Vdc, it is an ideal choice for a wide range of battery configurations. Flexible mounting options, including chassis mount, wall mount, and 19" rackmount via a 6U subrack, provide installation versatility. The B3700 Series can be easily paralleled for higher-powered or redundant systems (N+1 or A+B configurations). Optional features, such as additional electrical protection, monitoring, conformal coating, and enhanced mechanical strength, make it highly durable and resilient in demanding environments.

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Schaefer B3700 SERIES Battery Charger

Features

  • High Power Capability: Reliable 1250W battery charger designed for industrial and critical infrastructure applications.
  • AC Input: options for 1-Phase or 3-Phase supply
  • DC Output Voltages: Compatible with a wide range of battery voltages, including 12Vdc, 24Vdc, 48Vdc, 60Vdc, 110Vdc, and 220Vdc.
  • Efficient Cooling Solutions: Natural convection cooling for most models
  • Flexible Installation: Offers multiple mounting options, including wall, or 19" rackmount via a 6U subrack, and options for parallel / redundant system arrangements.
  • Durable Construction: Optional features include conformal coating, enhanced mechanical strength, and additional electrical protection for increased resilience.
Specifications
INPUT
Input voltage 1ph 115/230Vac 3ph 200/400/480Vac See selection table Units will turn off with under or over input voltage.
No-load input power 3-6W model (series dependant)
Inrush current AC input limited by thermistor
Switch on time 1-2 seconds.
Input Options Option au: Autoranging for 115/230Vac input Option pr: Power OK via relay contacts
ENVIRONMENTAL
Operating temperature -20°C to +75°C (optional -40 to 75C)
Load derating Derate 2.5% per °C, from +55°C to 75°C
Cooling H: Heatsink - natural convection F: Fan - increased airflow recommended TF: Temperature controlled Fan included See selection table
Environment Options Option c: Extended temperature range to -40°C
Storage temperature -40°C to +85°C
Humidity Up to 95% RH, non-condensing
OUTPUT
Output voltage Voltage range; 4.5 - 400Vdc See selection table
Output current See selection table.
Ripple & noise 1% + 30mVpp
Line regulation 0.1% (±10%)
Load regulation 0.2% typical, load step 10-90%
Load transient 6% typical, load step 10-90%
Response time 2-3ms typical ±1%
Temperature coefficient 0.02% per °C typical.
Holdup time 10mS at 220VAC typical
Turn on rise time 100mS typical (soft start)
Remote sensing Standard for all series
Efficiency 80%-92% typical
Output Options Option dd: Decoupling Diode for redundant / parallel operation Option cs: Active Current Sharing Option h: Remote on/off (inhibit) Option dr: DC OK via relay contacts Programming Options: See selection table
STANDARDS
EMI standards acc. to EN61000-6-4 class A, optionally class B
Immunity standards acc. to EN61000-6-2
C-Tick AS/NZS CISPR11: 2002 Group1 Class A
Safety / Construction acc. to EN60950-1 / EN50178
Protection category IP20 acc. to EN60529 NEMA or others on request
PROTECTION
Overload protection Current limited at 105%110% of full load.
Overvoltage protection OVP switches off module with automatic return to operation
Protection Options Option i: Inrush Current Limiting Option sd: Reverse polarity protection for DC input by Series Diode
MTBF 100Khrs to 140Khrs at 40°C acc. to MIL-HDBK-217E (notice 1)
MECHANICAL
Mounting See technical illustrations Eurocassette, pluggable module for 19" subrack Option w: Wall Mounting Option cha: Chassis Mounting
Dimensions See Technical illustration
Connector H15 acc. to DIN 41612 H15 and high current connectors for I > 50A, or terminals / bolts / bars
Mechanical Options Option ms: Increased Mechanical Strength Option t: Tropical protection
19" Rack Mounting Options Subrack Height 3U, 5U, 6U Wiring, Front Panels Accessories: Fuses, MCBs, Mains on/off switch Contact Powerbox for rack configuration
Selection Table
INPUT 100-240VAC ±10% WITH PFC OUTPUT AMPS INPUT 115VAC ±20% INPUT 230VAC +15% - 20% INPUT 115 ± 20% 230VAC +15% - 20% INPUT 3X200VAC +15% - 20% INPUT 3X400VAC +15% - 20% INPUT 3X480VAC +15% - 20% OUTPUT AMPS COOLING HEATSINK FAN BATTERY CHARGER VOLTAGE VOLTAGE ADJ RANGE
BP3791 65 B3761 B3781 B3791 B3761V B3781V B3791V 7 F 512 12-16
BP3792 32 B3762 B3782 B3792 B3762V B3782V B3792V 40 H 24 24-32
BP3794 16 B3764 B3784 B3794 B3764V B3784V B3794V 22 H 48 48-64
BP3796 12 B3766 B3786 B3796 B3766V B3786V B3796V 18 H 60 60-80
BP3797 8 B3767 B3787 B3797 B3767V B3787V B3797V 10 H 110 110-145
BP3798 4 B3768 B3788 B3798 B3768V B3788V B3798V 5 H 220 220-290

Cooling

H: Heatsink - natural convection

F: Fan - increased airflow recommended

TF: Temperature controlled Fan included

See selection table

Model configuration options:

Add the options to the model number, eg. B3768-dd-dr-cs

Options for Input, Output, Environmental and Mechanical follow.
19" Rack Mounting Options

Subrack Height 3U, 5U, 6U

Wiring, Front Panels

Accessories: Fuses, MCBs, Mains on/off switch

Contact Powerbox for rack configuration
OPTIONS INPUT
Option “i” (inrush current limiting): A thermistor is connected in series with the
input lines which changes its resistance from high to low when it gets hot. It does
not reduce the current surge if the input power is interrupted for a short period of
time not allowing the thermistor to cool down. Thermistors are fitted as standard
to all mains input models except for 1-phase input of models > 2.5kW.
Thermistors are available up to 45A. For higher input current an electronic inrush
current limitation can be offered.
Option “ie” electronic inrush current limiting An electronic circuit limits the inrush
current.
Option “sd” (series diode): A series diode protects the module against input
voltage of wrong polarity (additional power losses).
Option “ad” (anti-parallel diode): To avoid the power losses of a series diode a diode is
provided with opposite polarity in parallel to the input blowing an internal or external
fuse if the module is connected to a supply with wrong polarity.
Option “au” (auto-ranging) For standard dual AC input models the range of
115/230Vac is to be selected by connecting the input line to different pins on the
connector. With auto-ranging the unit senses the input voltage and provides
automatically the correct connection.
Option “p” (power fail): A signal (logic or relay) is given if the input voltage (AC or
DC) drops below the specified limit. In AC input units we sense the rectified input
voltage so that a power fail alarm will not be triggered if at light loads mains
power returns before the input capacitors are substantially discharged.
Option “r” (relay): A relay instead of a logic signal is provided for failure indication.
OUTPUT
Option “dd” (decoupling diode): For redundant operation the outputs of two or
more units are paralleled behind de-coupling diodes so that an internal fault of
one module does not affect the operation of the others. These diodes cause power
losses.
Option “cs” (active current sharing): An additional control circuit provides active
current sharing via an interconnecting wire between converters that operate in
parallel. Active current sharing should be used for multi-output units operating in
parallel.
Option “csi” (current sharing interrupt): Option "csi" will effect the removal of the
"cs" signal. Should there be an instance where a unit is not supplying the load,
then the effect of its "cs" signal is removed, and the load voltage is unaffected by
this condition.
Option “h1” (inhibit): A terminal connected to the negative input line also shuts off the
converter. This can also be used in conjunction with a thermal trip which shuts the unit
down.
Option “h2” (inhibit): Operation of the unit is inhibited if a voltage signal
(5V/10mA) is applied in reference to the negative line of the (main) output.
Option “rco” (reducing current limiting at over temperature) A circuit reduces the
current limiting level at higher temperature (to be specified).
Option “d” (DC-ok, one output): A logic signal is given if the output voltage (main
output in multi-output systems) is below the specified limit.
Option “m” (DC-ok, all outputs): In multi-output systems a logic signal is provided
if the voltage of any output is below the specified limit.
Option “ac” (AC ok) A logic signal connected to relay contacts is given if the
output voltage of an inverter is below the specified limit.
Option "y" (sys-reset): This logic signal is a combination of power fail and DC-ok
as specified for VME systems.
Option "r" (relay): A relay instead of a logic signal is provided for failure
indication.
CHARGER PROGRAMMING
Option "tc" Temperature compensated charging voltage(sensor not included)
Option "ts1" Temperature sensor, not interchangeable due to fixed resistor values
Option "ts2" Interchangeable, IC controlled
Option "ch1" Automatic selection of charging characteristic (float / equalize charge) with timer
Option "ch2" Additionally: Manual selection of charging characteristic
Option "ch3" Additionally: Boost charge operation (manually activated with
time delayed return to normal operation)
ENVIRONMENT
Option "t" (tropical protection):The unit is given additional protection by a heavy
coat of varnish on the printed circuit board(s) and components.
Option "c" (extended temperature range):The circuit is designed and tested for
operation at an ambient temperature as low as –40 °C.
Option "ms" (increased mechanical strength): Screws are secured by Locktite and
heavy components are fastened by ties and/or glue. Modules with the "ms" option
meet the standard EN61373 regarding shock and vibration.
MECHANICS
Standard mounting "Eurocassette" pluggable module for 19" sub-racks 8
Option "w" (wall mounting): Module is screwed against a mounting plate for
installation in a cabinet. The load connections are typically a terminal block.
Option "cha" (chassis mount) Module is designed for installation to a structure or
within cabinet. Screw type connectors are supplied with the module.
Option "din" (DIN rail mount) Module is designed for DIN rail mounting to a
structure or within Cabinet. Screw type connectors are supplied with the module.
Technical Illustrations
Downloads
schaefer_cb3700-AC-DC-PS-BatteryChargers-DC-DC-Converters.pdf
INPUT
Input voltage 1ph 115/230Vac 3ph 200/400/480Vac See selection table Units will turn off with under or over input voltage.
No-load input power 3-6W model (series dependant)
Inrush current AC input limited by thermistor
Switch on time 1-2 seconds.
Input Options Option au: Autoranging for 115/230Vac input Option pr: Power OK via relay contacts
ENVIRONMENTAL
Operating temperature -20°C to +75°C (optional -40 to 75C)
Load derating Derate 2.5% per °C, from +55°C to 75°C
Cooling H: Heatsink - natural convection F: Fan - increased airflow recommended TF: Temperature controlled Fan included See selection table
Environment Options Option c: Extended temperature range to -40°C
Storage temperature -40°C to +85°C
Humidity Up to 95% RH, non-condensing
OUTPUT
Output voltage Voltage range; 4.5 - 400Vdc See selection table
Output current See selection table.
Ripple & noise 1% + 30mVpp
Line regulation 0.1% (±10%)
Load regulation 0.2% typical, load step 10-90%
Load transient 6% typical, load step 10-90%
Response time 2-3ms typical ±1%
Temperature coefficient 0.02% per °C typical.
Holdup time 10mS at 220VAC typical
Turn on rise time 100mS typical (soft start)
Remote sensing Standard for all series
Efficiency 80%-92% typical
Output Options Option dd: Decoupling Diode for redundant / parallel operation Option cs: Active Current Sharing Option h: Remote on/off (inhibit) Option dr: DC OK via relay contacts Programming Options: See selection table
STANDARDS
EMI standards acc. to EN61000-6-4 class A, optionally class B
Immunity standards acc. to EN61000-6-2
C-Tick AS/NZS CISPR11: 2002 Group1 Class A
Safety / Construction acc. to EN60950-1 / EN50178
Protection category IP20 acc. to EN60529 NEMA or others on request
PROTECTION
Overload protection Current limited at 105%110% of full load.
Overvoltage protection OVP switches off module with automatic return to operation
Protection Options Option i: Inrush Current Limiting Option sd: Reverse polarity protection for DC input by Series Diode
MTBF 100Khrs to 140Khrs at 40°C acc. to MIL-HDBK-217E (notice 1)
MECHANICAL
Mounting See technical illustrations Eurocassette, pluggable module for 19" subrack Option w: Wall Mounting Option cha: Chassis Mounting
Dimensions See Technical illustration
Connector H15 acc. to DIN 41612 H15 and high current connectors for I > 50A, or terminals / bolts / bars
Mechanical Options Option ms: Increased Mechanical Strength Option t: Tropical protection
19" Rack Mounting Options Subrack Height 3U, 5U, 6U Wiring, Front Panels Accessories: Fuses, MCBs, Mains on/off switch Contact Powerbox for rack configuration
INPUT 100-240VAC ±10% WITH PFC OUTPUT AMPS INPUT 115VAC ±20% INPUT 230VAC +15% - 20% INPUT 115 ± 20% 230VAC +15% - 20% INPUT 3X200VAC +15% - 20% INPUT 3X400VAC +15% - 20% INPUT 3X480VAC +15% - 20% OUTPUT AMPS COOLING HEATSINK FAN BATTERY CHARGER VOLTAGE VOLTAGE ADJ RANGE
BP3791 65 B3761 B3781 B3791 B3761V B3781V B3791V 7 F 512 12-16
BP3792 32 B3762 B3782 B3792 B3762V B3782V B3792V 40 H 24 24-32
BP3794 16 B3764 B3784 B3794 B3764V B3784V B3794V 22 H 48 48-64
BP3796 12 B3766 B3786 B3796 B3766V B3786V B3796V 18 H 60 60-80
BP3797 8 B3767 B3787 B3797 B3767V B3787V B3797V 10 H 110 110-145
BP3798 4 B3768 B3788 B3798 B3768V B3788V B3798V 5 H 220 220-290

Cooling

H: Heatsink - natural convection

F: Fan - increased airflow recommended

TF: Temperature controlled Fan included

See selection table

Model configuration options:

Add the options to the model number, eg. B3768-dd-dr-cs

Options for Input, Output, Environmental and Mechanical follow.
19" Rack Mounting Options

Subrack Height 3U, 5U, 6U

Wiring, Front Panels

Accessories: Fuses, MCBs, Mains on/off switch

Contact Powerbox for rack configuration
OPTIONS INPUT
Option “i” (inrush current limiting): A thermistor is connected in series with the
input lines which changes its resistance from high to low when it gets hot. It does
not reduce the current surge if the input power is interrupted for a short period of
time not allowing the thermistor to cool down. Thermistors are fitted as standard
to all mains input models except for 1-phase input of models > 2.5kW.
Thermistors are available up to 45A. For higher input current an electronic inrush
current limitation can be offered.
Option “ie” electronic inrush current limiting An electronic circuit limits the inrush
current.
Option “sd” (series diode): A series diode protects the module against input
voltage of wrong polarity (additional power losses).
Option “ad” (anti-parallel diode): To avoid the power losses of a series diode a diode is
provided with opposite polarity in parallel to the input blowing an internal or external
fuse if the module is connected to a supply with wrong polarity.
Option “au” (auto-ranging) For standard dual AC input models the range of
115/230Vac is to be selected by connecting the input line to different pins on the
connector. With auto-ranging the unit senses the input voltage and provides
automatically the correct connection.
Option “p” (power fail): A signal (logic or relay) is given if the input voltage (AC or
DC) drops below the specified limit. In AC input units we sense the rectified input
voltage so that a power fail alarm will not be triggered if at light loads mains
power returns before the input capacitors are substantially discharged.
Option “r” (relay): A relay instead of a logic signal is provided for failure indication.
OUTPUT
Option “dd” (decoupling diode): For redundant operation the outputs of two or
more units are paralleled behind de-coupling diodes so that an internal fault of
one module does not affect the operation of the others. These diodes cause power
losses.
Option “cs” (active current sharing): An additional control circuit provides active
current sharing via an interconnecting wire between converters that operate in
parallel. Active current sharing should be used for multi-output units operating in
parallel.
Option “csi” (current sharing interrupt): Option "csi" will effect the removal of the
"cs" signal. Should there be an instance where a unit is not supplying the load,
then the effect of its "cs" signal is removed, and the load voltage is unaffected by
this condition.
Option “h1” (inhibit): A terminal connected to the negative input line also shuts off the
converter. This can also be used in conjunction with a thermal trip which shuts the unit
down.
Option “h2” (inhibit): Operation of the unit is inhibited if a voltage signal
(5V/10mA) is applied in reference to the negative line of the (main) output.
Option “rco” (reducing current limiting at over temperature) A circuit reduces the
current limiting level at higher temperature (to be specified).
Option “d” (DC-ok, one output): A logic signal is given if the output voltage (main
output in multi-output systems) is below the specified limit.
Option “m” (DC-ok, all outputs): In multi-output systems a logic signal is provided
if the voltage of any output is below the specified limit.
Option “ac” (AC ok) A logic signal connected to relay contacts is given if the
output voltage of an inverter is below the specified limit.
Option "y" (sys-reset): This logic signal is a combination of power fail and DC-ok
as specified for VME systems.
Option "r" (relay): A relay instead of a logic signal is provided for failure
indication.
CHARGER PROGRAMMING
Option "tc" Temperature compensated charging voltage(sensor not included)
Option "ts1" Temperature sensor, not interchangeable due to fixed resistor values
Option "ts2" Interchangeable, IC controlled
Option "ch1" Automatic selection of charging characteristic (float / equalize charge) with timer
Option "ch2" Additionally: Manual selection of charging characteristic
Option "ch3" Additionally: Boost charge operation (manually activated with
time delayed return to normal operation)
ENVIRONMENT
Option "t" (tropical protection):The unit is given additional protection by a heavy
coat of varnish on the printed circuit board(s) and components.
Option "c" (extended temperature range):The circuit is designed and tested for
operation at an ambient temperature as low as –40 °C.
Option "ms" (increased mechanical strength): Screws are secured by Locktite and
heavy components are fastened by ties and/or glue. Modules with the "ms" option
meet the standard EN61373 regarding shock and vibration.
MECHANICS
Standard mounting "Eurocassette" pluggable module for 19" sub-racks 8
Option "w" (wall mounting): Module is screwed against a mounting plate for
installation in a cabinet. The load connections are typically a terminal block.
Option "cha" (chassis mount) Module is designed for installation to a structure or
within cabinet. Screw type connectors are supplied with the module.
Option "din" (DIN rail mount) Module is designed for DIN rail mounting to a
structure or within Cabinet. Screw type connectors are supplied with the module.
schaefer_cb3700-AC-DC-PS-BatteryChargers-DC-DC-Converters.pdf

Find the Right Model

Model Number Input Voltage (Vac) Output Voltage (Vdc) Output Current (A)
product variant B3761 115Vac ± 20 % 50/60Hz 12Vdc (Adj. 12 - 16Vdc) 75A
product variant B3762 115Vac ± 20 % 50/60Hz 24Vdc (Adj. 24 - 32Vdc) 40A
product variant B3764 115Vac ± 20 % 50/60Hz 48Vdc (Adj. 48 - 64Vdc) 22A
product variant B3766 115Vac ± 20 % 50/60Hz 60Vdc (Adj. 60 - 80VDc) 18A
product variant B3767 115Vac ± 20 % 50/60Hz 110Vdc (Adj. 110 - 145VDc) 10A
product variant B3768 115Vac ± 20 % 50/60Hz 220Vdc (Adj. 220 - 290Vdc) 5A
product variant B3781 230Vac +15%/-20% 50/60Hz 12Vdc (Adj. 12 - 16Vdc) 75A
product variant B3782 230Vac +15%/-20% 50/60Hz 24Vdc (Adj. 24 - 32Vdc) 40A
product variant B3784 230Vac +15%/-20% 50/60Hz 48Vdc (Adj. 48 - 64Vdc) 22A
product variant B3786 230Vac +15%/-20% 50/60Hz 60Vdc (Adj. 60 - 80VDc) 18A
product variant B3787 230Vac +15%/-20% 50/60Hz 110Vdc (Adj. 110 - 145VDc) 10A
product variant B3788 230Vac +15%/-20% 50/60Hz 220Vdc (Adj. 220 - 290Vdc) 5A
product variant B3791 115Vac ± 20 % 50/60Hz or 230Vac +15%/-20% 50/60Hz 12Vdc (Adj. 12 - 16Vdc) 75A
product variant B3792 115Vac ± 20 % 50/60Hz or 230Vac +15%/-20% 50/60Hz 24Vdc (Adj. 24 - 32Vdc) 40A
product variant B3794 115Vac ± 20 % 50/60Hz or 230Vac +15%/-20% 50/60Hz 48Vdc (Adj. 48 - 64Vdc) 22A
product variant B3796 115Vac ± 20 % 50/60Hz or 230Vac +15%/-20% 50/60Hz 60Vdc (Adj. 60 - 80VDc) 18A
product variant B3797 115Vac ± 20 % 50/60Hz or 230Vac +15%/-20% 50/60Hz 110Vdc (Adj. 110 - 145VDc) 10A
product variant B3798 115Vac ± 20 % 50/60Hz or 230Vac +15%/-20% 50/60Hz 220Vdc (Adj. 220 - 290Vdc) 5A
product variant B3761V 3 x 200Vac +15%/-20% 50/60Hz 12Vdc (Adj. 12 - 16Vdc) 75A
product variant B3762V 3 x 200Vac +15%/-20% 50/60Hz 24Vdc (Adj. 24 - 32Vdc) 40A
product variant B3764V 3 x 200Vac +15%/-20% 50/60Hz 48Vdc (Adj. 48 - 64Vdc) 22A
product variant B3766V 3 x 200Vac +15%/-20% 50/60Hz 60Vdc (Adj. 60 - 80VDc) 18A
product variant B3767V 3 x 200Vac +15%/-20% 50/60Hz 110Vdc (Adj. 110 - 145VDc) 10A
product variant B3768V 3 x 200Vac +15%/-20% 50/60Hz 220Vdc (Adj. 220 - 290Vdc) 5A
product variant B3781V 3 x 400Vac +15%/-20% 50/60Hz 12Vdc (Adj. 12 - 16Vdc) 75A
product variant B3782V 3 x 400Vac +15%/-20% 50/60Hz 24Vdc (Adj. 24 - 32Vdc) 40A
product variant B3784V 3 x 400Vac +15%/-20% 50/60Hz 48Vdc (Adj. 48 - 64Vdc) 22A
product variant B3786V 3 x 400Vac +15%/-20% 50/60Hz 60Vdc (Adj. 60 - 80VDc) 18A
product variant B3787V 3 x 400Vac +15%/-20% 50/60Hz 110Vdc (Adj. 110 - 145VDc) 10A
product variant B3788V 3 x 400Vac +15%/-20% 50/60Hz 220Vdc (Adj. 220 - 290Vdc) 5A
product variant B3791V 3 x 480Vac +10%/-15% 50/60Hz 12Vdc (Adj. 12 - 16Vdc) 75A
product variant B3792V 3 x 480Vac +10%/-15% 50/60Hz 24Vdc (Adj. 24 - 32Vdc) 40A
product variant B3794V 3 x 480Vac +10%/-15% 50/60Hz 48Vdc (Adj. 48 - 64Vdc) 22A
product variant B3796V 3 x 480Vac +10%/-15% 50/60Hz 60Vdc (Adj. 60 - 80VDc) 18A
product variant B3797V 3 x 480Vac +10%/-15% 50/60Hz 110Vdc (Adj. 110 - 145VDc) 10A
product variant B3798V 3 x 480Vac +10%/-15% 50/60Hz 220Vdc (Adj. 220 - 290Vdc) 5A

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