Your Cart is Empty



Ctek D250Sa 20A Dc/Dc Battery Charger

The ultimate 12V 4WD and camping power management system

The new CTEK D250SA, 5-step charger, gives 4WDers the flexibility and ease of quickly charging up your service batteries from either traditional or smart alternators or from solar power. It will even give your starter battery a maintenance charge when your service batteries are fully charged.

Used independently CTEK’s D250SA and the SMARTPASS120 are superb, but combined, especially for service batteries larger than 100Ah, they become the ultimate power management system. Together these smart products can deliver up to 140A to your service batteries while you’re on the move.

This dynamic duo is the ultimate 140A power system that allows you to manage and control your power more reliably. So make sure CTEK is one of your mates when you head off on your next big adventure.


  • A 5-step charger to quickly charge up your service batteries from either traditional or smart alternators or from solar power
  • Smart alternator compatibility
  • Special AGM function, featuring a selectable 14.7V for AGM batteries, as well as a 14.4V option for other batteries
  • An advanced in-built Maximum Power Point Tracker (MPPT), maximising the power from your solar panels
  • Temperature compensation

Download the fact sheet | Download our starter guide

Wiring Information


  • Red Wire – wired to the 12 volt Accessories in the car ignition.
  • Black Wire – if Battery Boost voltage is 14.7v – connect to the negative of battery

If Battery Boost Voltage is 14.4v – leave off


  • Red wire can be left disconnected.
  • Black Wire – if Battery Boost is 14.7v – connect to the negative of battery

If Battery Boost Voltage is 14.4v – leave off

Wire as per D250S DUAL (with NO RELAY).

Frequently Asked Questions

1.What size should my solar panel be?
A: The solar panel should be between 150-300W ( total power of the array ), 12V panel. Maximum Open Circuit voltage no higher than 22 volts DC. A solar regulator is not required. Smaller panels wired in parallel should be matched and not exceed the above ratings.

2. What is the function of the smart pass?
A: To handle a larger battery bank typically up to 500 amp hours. It also helps manage loads connected to the battery bank.

3. What size should my cables be?
A: For a D250S Dual on its own - around 4mm diameter across the copper. Thicker is acceptable. If you have a Smartpass your cable should be at least 6mm across the copper. Thicker is acceptable.

4. What fuses should I be using in my system?
A: With a D250S Dual a 25AMP fuse is good. With a Smartpass, the fuse needs to go up to about 80 amp.

5. Where can I put my Dual?
A: The Dual should be inside of the vehicle. We recommend you don’t install under the bonnet as it will get too hot and be subject to water ingress. Likewise if a Smartpass is used.

6. Where is the best place to put my solar panel?
A: The best place to put your solar panel is where it can receive the most sun. Please note that the solar panel will not work properly if it is not in direct sunlight.

7. How do I know if my car has a smart /electronic alternator ?
A: This can be checked out with either the Vehicle manufacturer or the service centre you take your vehicle to. Voltage tests across one’s start battery are not 100% conclusive of your alternator type.

8. Who can wire up my vehicle ?
A: If your unable to wire your own vehicle, the job can be done at any competent 4WD Centre, Auto Electrician, or Trailer / Battery Place that does fitouts.