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The CTEK Dual Battery System


Long gone are the days we had to be content with the traditional solenoid dual battery system. With the current advanced modern day DC to DC systems you can now truly maximize on battery power. Batteries today are expensive and one needs to ensure that you get the most out of your auxiliary battery and prolong its lifespan.

“During the last couple of years we have seen great improvements on battery development,” says Shane Maree, head of Technical Sales at Enertec, suppliers of CTEK smart DC to DC systems and Discover batteries.

Here are some differences between the traditional deep-cycle lead-acid battery and the latest AGM or Gel battery:

  1. AGM (Absorbent Glass Mat) batteries differ from flooded cell lead-acid batteries in that the electrolyte is held in glass mats, as opposed to freely flooding the plates. Very thin glass fibres are woven into a mat to increase surface area enough to hold sufficient electrolyte on the cells for their lifetime.
  2. Extreme temperature variances can have a greater effect on the battery life of the traditional flooded battery due to the electrolyte solution inside the battery having the ability to evaporate or freeze, which will shorten the lifespan of the battery.
  3. AGM batteries present better self-discharging characteristics than conventional batteries in a different range of temperatures.
  4. On top of that, the AGM or Gel battery can be discharged down to 20%, versus the 50% of the traditional battery, and is quicker to recharge as well.

What this means is that the modern-day AGM or Gel battery is tougher than the traditional lead-acid battery when doing normal duties in a vehicle. The standard lead-acid battery reads full at 12.7 volts whereas the AGM or Gel battery reads full at 13.1 volts. This is what gives AGM or Gel batteries their longer runtime.


The new D250SA has dual input (solar and alternator in parallel).

Solar Panel Regulator with Maximum Power Point Tracking.

Fully automatic temperature compensated charging up to 300A while you are on the move.

Smart alternator compatible.

Battery separation and automatic higher voltage charging for advanced AGM batteries (14.7V).

As with lead-acid batteries, to maximize the life of AGM batteries it is important to follow the correct charging specifications. A voltage regulated (smart) charger is recommended. This can easily double the runtime compared to what a standard lead-acid battery of the same amperage can produce.

CTEK battery chargers, combined with the new Discover AGM battery from Enertec, definitely gives the end user an advantage over the competition. Award-winning Swedish technology is behind the performance of the CTEK D250SA, which can detect the difference between a standard lead acid and an AGM or Gel battery, and will then charge at higher voltage (14.7V) to ensure maximum battery performance.

The right system
Well known 4×4 specialist, André de Villiers, has chosen to fit the CTEK D250S system to his two Amarok vehicles. André represents the popular KYKNET television series Safari 4×4 Roetes.

Says André, “I run two fridge-freezers in my Amarok and I am more than happy with the results the D250SA produces, when combined with a Discover AGM 115A/h battery. With the added runtime the AGM battery provides, I now do not need to worry about the fridges requiring a top-up when camping for a day or two.”

A recent test showed a standard 70-litre fridge set at minus 2 degrees Celsius can draw up to 7 Amps when exposed to the harsh conditions encountered in Namibia and Botswana when ambient temperatures are around 40 degrees Celsius, he explains. “Even when high temperatures cause the fridges to draw more power than usual, I feel comfortable.”

Power consumption of the two fridges running off a Discover 115A/h battery in André de Villiers’ Amarok.

CTEK also has top-up charging covered. “When my vehicle is stationary and there is electricity available I run my system off a CTEK MXS10A unit built into my Amarok.” André is no newcomer to CTEK battery chargers. Since CTEK first came to SA he was one of the first to test and try this technology, and is satisfied with the results.

To complement his dual battery system, André makes use of the CTEK Battery Sense which enables him to see “inside” the auxiliary battery. By having this detailed information at his fingertips, André can make a decision on when to provide a top-up charge with solar power when his vehicle is stationery. The CTEK Battery Sense is a small unit fitted to a battery and read by the CTEK App, which is downloaded from the Internet to your smartphone. It provides a real-time battery capacity reading by means of a Bluetooth connection to your smartphone, plus is able to store three months’ data on a graphic display.

André de Villiers.


CTEK D250SA: R5495

CTEK Battery Sense: R1395

Discover AGM Battery 115A/h: R5899

Enertec supply a complete range of Discover batteries ranging from a 33A/h to the top-of-the-range 140A/h unit via its many outlets. To contact them, fill out the form below.

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