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CTEK "OFF GRID" Battery to Battery Charging System 20A

CTEK D250SE Dual DC-DC 20A "OFF GRID" Charging System


CTEK D250SE Dual DC-DC 20A "OFF GRID" Charging System

If you are converting a modern van with a stop/start and/or a regenerative system and you want to charge a leisure battery, you will need a split charge system that can cope with the complexities of the new systems.

These CTEK Battery to Battery chargers solve the problem, whilst also allowing you to connect a sloar panel directly into the charger. This Off Grid version has an additional power monitor showing the number of hours left in your battery.

If you dont need the power monitor, see the CTEK D250SA Dual DC-DC Charger


Manufacturers Details.

With award winning Swedish technology, the dual input D250SE allows you to enjoy your vehicle more with maximized battery capacity as the ideal charger for vehicles without access to a mains power supply. For complete peace of mind this Off Grid version, has an additional power monitor, so you can see at a glance how much charge you’ve got left and the length of time till your batteries are discharged.

The D250SE is a fully automatic, 5 step charger that supplies up to 20A of power to any 12V lead acid service battery from 40-300Ah, including Wet, EFB, MF, Ca/Ca, AGM and Gel. It has selectable charge voltages for AGM batteries and can use power through its dual input from alternator, solar panel and wind power. When the service battery is fully charged, the D250SE will automatically redirect maintenance charge power to the starter battery. The D250SE can maintain a stable output up to 20A to vehicles fitted with smart ECU controlled alternators and also has a temperature sensor for optimised charging, regardless of weather conditions.


Schematic showing D250SE and optional Smartpass 120, for bigger battery setups.  If you require this extra power, see the additional Smartpass 120, or the OFF ROAD Battery to Battery 140A system, complete with the system monitor 





  • 20A fully automatic temperature compensated charging for batteries from 40-300Ah while you’re on the move
  • Dual input (solar and alternator in parallel)
  • Smart alternator compatible
  • Battery separation replacing diodes and VSR relays
  • Solar panel regulator with Maximum Power Point Tracking (MPPT)
  • Selectable AGM/LITHIUM option – 14.4V or 14.7V
  • Maximised charging for better battery life and performance
  • Temperature sensor to compensate for hot or cold conditions
  • Splash and dust proof (IP65)
  • Compatible with SMARTPASS 120 for the ultimate 140A power management solution
  • 2-year warranty




Manufacturer: CTEK
Input Voltage - Volts: 11.5 / 23
Output voltage - Volts:
Max. charging current - Amps: 20
Charging Ports: 1
Input from solar panel - V: 11.5v to 23v
Conventional alternator cut-in: >13.1V, for 5 sec. (engine running, alternator charging)
Conventional alternator cut-out: <12.8V, for 10 sec. (engine running, alternator not charging) or service battery voltage > starter battery voltage
Smart alternator cut-in V: >11.8V, for 5 sec. (engine running, alternator charging)
Smart alternator cut-out V: <11.4V, for 10 sec. (engine running, alternator not charging) or service battery voltage > starter battery voltage
Battery guard cut-in: 11.5V
Battery guard cut-out: 12.0V
Temperature protection cut-in: 60 degrees C (140 degrees F)
Start assistance activation: Starter battery 6V
Trickle charge starter battery: Starter battery 11.5V to12.6V.
Charging characteristic: Five-step
Suitable for battery size - Ah: 40Ah to 300Ah
Suitable for battery types: All 12V lead-acid batteries including: Wet, A.G.M, gel, calcium, lithium and maintenance free
Max. power input from solar panel - Watts: 300
Solar regulator type: MPPT
Cooling method: Convection cooled
Operating temperature range - : minus 20 degrees C to plus 50 degrees C. Automatic reduction of power at high ambient temperature.
Power reduction: 30 degrees C 16A, 50 degrees C 13A
Enclosure class: IP65 (splash and dust proof)
Notes: This charger can only be used with solar panels that have a peak voltage of 23V. Please ensure that your panel is compatible before purchasing.
Protections: Temperature compensated charging, Reverse Polarity protection
Certification: Fully certified for use in vehicles
Dimensions (L x W x H) - mm: 192 x 110 x 65mm
Nett weight - kg: 1.047
Warranty - years: 2


Compatible with Euro5/Euro6 Stop/Start & Regenerative Vehicles

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