How to

Power Up!

Innovative Swedish technology can save you from flat battery issues while out on the water. Jim Harnwell reports.

MODERN sportfishing boats now feature a bewildering array of electronic devices. All these gadgets put pressure on battery systems. And sometimes these systems fail.

I found this out the hard way. Like many offshore fishing boats, the Fisho Bar Crusher 670 is loaded up with electronics. I’ve got a big Simrad NSE 8 sounder/plotter, GME 27 meg and VHF radios, a Stress Free anchor winch, a variety of lights, three separate pumps, trim tabs and a Fusion stereo complete with sub woofer.

Combined, all this stuff draws a fair bit of power from my twin battery set-up. Exactly how much power drain was revealed at the end of a long day spent drifting over broken reef jigging plastics. I had the sounder going, both marine radios on and the Fusion stereo pumping full blast. This resulted in both my batteries going flat. I had to call the local marine rescue guys to give me a jump start. Not a good look, especially when you have FISHING WORLD emblazoned on the side of your boat …

The boat came standard with a switching system that allowed me to select either or both of the 12 volt starter batteries fitted as standard under the transom. On the day in question I had both batteries on and, unbeknownst to me, the current draw from the sub woofer, combined with all the other equipment, was enough to completely drain them. If I’d been driving around or trolling there would have been no prob – the E-TEC’s powerful alternator would have kept the batteries topped up. But eight hours of drifting with no charge from the engine and constant power drain was too much for the batteries to handle.

This was a problem. I do a lot of drift fishing and I really love how I can plug my iPod into the Fusion and crank it up. What could I do to play my music without draining my batteries?

At the 2009 Sydney International Boat Show I explained my problem to Jason Marshall and Pete Blume from Queensland-based Baintech, distributors of the innovative Swedish CTEK products. The Baintech guys showed me a couple of new CTEC devices – a Smartpass and a D250S Dual – that they reckoned would solve my battery issues once and for all.

The idea was to create a system that separated the starter battery from the house battery so that I would always be able to start the engine, regardless of what electronics I had running. As I felt the original batteries were now compromised from going flat, I decided to obtain a serious heavy duty start battery and also a specialist deep cycle battery to power the sounder, radios, stereo and so on. Start, or cranking, batteries and deep cycle house, aka service, batteries are two very different beasts. A start battery needs to be able to belt out lots of power over short periods to turn your engine over; a deep cycle, on the other hand, produces power over long periods to run devices like lights, sounders, radios and even fridges.

After a bit of looking around I ended up with an Exide MS700 as the start battery and an Exide DC12V105 as the house battery. Once the new batteries were sorted, it was time to talk with the Baintech guys about the CTEK gear they were recommending.

As mentioned above, the idea behind the system is pretty simple – the starter battery does its job and its job alone. The house battery does everything else. In a worst case scenario of the house battery going flat, no probs – I can still get home because the starter battery is always at full power.

The D250S Dual has three inputs, two of which connect to the starter and house battery; the third is designed to be used with a solar panel on moored boats. When my trailer boat’s not in use, the Dual is connected to a mains powered CTEK Multi XS 4003 battery charger which automatically keeps both batteries fully charged and maintained through.

When the engine is running, the alternator charges the start battery as per usual but the Dual jumps in to maximise alternator output to also fully charge the house battery. Most outboards don’t generate enough voltage to fully charge a big deep cycle battery but the Dual fixes that by processing the output so that voltage is increased for maximum deep cycle battery charging efficiency. So whether the boat is in the shed connected to mains power or underway out at sea, the Dual ensures optimum charging for both batteries at all times.

The Smartpass, which is designed to work in conjunction with the Dual, enables maximum efficiency of the house battery by automatically sensing input from the engine’s alternator when underway. When the engine is running, the Smartpass provides power to the boat’s electronics directly from the alternator, thus allowing the house battery to charge more efficiently through the Dual. Without the Smartpass the battery is being charged by the alternator but at the same time is losing power by also trying to run all the electronics. The Smartpass enables maximum charging efficiency by taking the load away from the battery and letting the alternator do the work. When the engine is turned off, the Smartpass diverts power use back to the house battery as per usual.

It’s pretty clever stuff and as far as I know the Fisho Bar Crusher is the first trailerboat in Australia to be fitted with this CTEK gear. When you consider how much a decent battery system costs, the investment in a Smartpass and Dual (they retail for $439 each) makes a lot of sense. These units will maximise battery life and efficiency.

Both the Dual and the Smartpass are designed to be DIY installed. Anyone who has a basic understanding of electronics will have no problems fitting out a boat with these units.  Lights and diagrams on the face plates of the units (which are each fairly compact at about 170mm long and 90mm wide) tell you that the appropriate power sources are working or if there are any errors. The Smartpass will also warn you if the house battery is running low.

Make sure you use appropriately sized cabling if you run the units any distance away from the batteries in order to reduce power loss. When Baintech’s Peter Blume did the install for me he used 10mm tinned cable so use that as a basic guide if you’re planning on installing these units in a 6-8m vessel.  

Refer to the diagram by Fisho illustrator Chris Palatsides published opposite to see exactly how the system works. Contact Baintech  at or by calling (07) 3821 3333 to find the location of your local CTEK stockist. There’s an interesting video at the Baintech site that explains how the Dual unit works, which is well worth a view. For more details on CTEK and the products it makes, go to For details on high quality Exide marine batteries, go to

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