We have set up the back of our MU-X wagon with an MSA fridge slide to mount a 12V fridge in for camping trips. While a fridge will run off your vehicle’s main battery when you are driving and the alternator is keeping the battery charged, the battery won’t last long once you have stopped in camp for the night or longer.
Add in a few other electrical accessories such as camp lights and music players to the power draw on the car fridge and you’ll probably wake up to a flat battery after the first night.
This is why we fit dual-battery systems to our 4x4s, to provide a second battery in the car that is used exclusively to power accessories. The second, or auxiliary battery is also charged off the car’s alternator when the engine is running but is isolated from your main starting battery, so that any accessories being used do not drain the main battery and you are able to start the car when it’s time to move on.
Smart charging
For many years these dual-battery systems were relatively simple, but as our vehicles have become more complicated and loaded with computers and so-called smart charging systems, fitting a dual-battery system has also become more complex.
DC-DC chargers have become the standard practice for dual-battery set-ups in recent times. Not only do they work with modern vehicles’ complex charging systems, but allow smart charging of your auxiliary battery via staged charging as required.
Modern DC-DC chargers are also compatible with lithium batteries which have their own specific requirements, so you need a specific charger for them. Lithium batteries are becoming more popular in 4×4 battery systems as their prices come down and they’re suitable to use as an auxiliary battery.
Quality gear
For our MU-X, we’ve gone with a charging system from Swedish battery charging specialists CTEK, and one of the new Lithium Pro batteries from Australian battery manufacturer, Century Batteries.
The CTEK hardware starts with one of its D250SE DC-DC chargers which is boosted by a CTEK Smartpass 120S. The D250SE is a 20amp DC-DC charger, but by partnering it with the Smartpass, the charging output is boosted up to 140amp as required.
The Smartpass also acts as the battery isolator to protect the main battery from draining when running accessories, gives us an input to take charge from solar panels, and is suitable for lithium batteries, allowing us to use the new Lithium Pro slimline from Century.
Installation
While this is a relatively simple dual-battery set-up that many would be able to instal at home with the right tools, we went to the team at Autobarn Bayswater where the store’s touring and 4×4 manager, Torin Petty, has experience with the CTEK gear.
After talking with Torin and telling him what we needed and where we wanted to mount the components of the system on the back of the MSA Fridge Barrier, he was able to ‘build’ the system on a board ready for the installation before we took the car to the workshop.
The Smartpass and D250SE were mounted on a board along with a Narva fuse box, Narva 3x outlet panel and Anderson plugs for the solar input, and another power output.
The mounting board was cut to size to fit on the fridge barrier directly above where the battery was mounted on the MU-X’s false rear floor.
Wiring the system up meant running cables from the Century Dual Force main battery in the engine bay, back through the firewall and under scuff panels to the system. A fuse and new earth leads were also fitted in the engine bay.
With everything in place, it was just a matter of attaching the positive cable and firing the system up. This has to be done in a sequence described in the CTEK owner’s manual to avoid any problems, and there were none on this occasion.
Torin put a meter on the system and found it to be charging the Lithium Pro up as it should, and by the time we drove the MU-X back to work it was fully charged. Using the Century Lithium Pro app on your phone, you can check on the state of charge at any time and the rate of charge when the engine is running or a solar panel is plugged in.
The CTEK combination uses a five-stage charging process to ensure maximum charging without overcharging the battery:
• The first stage checks the state of charge and if the battery can accept a charge.
• Once the battery is found to be okay and can accept a charge, Stage 2 employs maximum charging until the battery is at 90 per cent of its capacity.
• Stage 3 is an absorption stage where the charge reduces the charging current to bring the battery up to 95 per cent.
• Stage 4 again employs maximum constant charge.
• Stage 5 delivers a pulsing charge to maintain the battery at 95 to 100 per cent, keeping it at its optimal state of charge.
Both the Smartpass 120S and the D250SE have a temperature sensor, which are placed close to the battery and monitor ambient temperature, so that the units can deliver optimal charging according to the conditions.
The CTEK products are IP65 rated as splash- and dust-proof, which is not a problem for them where they are mounted in the car but good to know if you’re mounting them in the elements. They are also covered by a two-year manufacturer’s warranty.
Century Lithium Pro battery
When we made the call to go with a second battery, we wanted it to be a lithium unit and our timing was perfectly in-line with the Century Batteries’ launch of its new Lithium Pro products.
There are three batteries in the Lithium Pro Range: a 100Ah/1280Wh N70 sized unit, a 100Ah/1280Wh slimline unit, and the big 200Ah/2560Wh unit. We went with the slimline battery as it met our requirements and would fit perfectly in the space we had behind the back seat.
Lithium Iron Phosphate (LiFePO4) batteries are perfect for deep-cycle applications where the unit might be drained and recharged regularly, such as in recreational application where they are running accessories.
Century Batteries says its Lithium Pro Deep Cycle batteries are designed to provide long-lasting power in recreational application, delivering more than 3000 cycles (at 80 per cent DOD) with a longer service life, more usable energy and up to 10 times faster recharging. With claims like that, you can see why they are so popular in 4×4 applications.
The Century Lithium Pro can be monitored via a free app that shows you the state of charge, condition of the individual cells and the rate of charging. Unfortunately, this is a separate app to the regular Century battery monitor app, so we now have two apps to monitor the two different Century batteries in our MU-X. First world problems, eh?
The Century Lithium Pro is covered by a 36-month warranty.
With thanks
A big thank you to our suppliers at CTEK and Century Batteries for this system and a big thank you to Torin, Chris and the crew at Autobarn Bayswater for such a professional installation.
I must admit that Autobarn wouldn’t have been my first choice for fitting 4×4 accessories, but the guys at Autobarn Bayswater own and drive 4x4s and knew exactly what was needed here, doing a first-rate job on our 12V instal.
For more information, visit: www.autobarn.com.au/ab/store/31BW
Available from: www.ctek.com/au; www.centurybatteries.com.au
RRP: CTEK D250SE $469; CTEK Smartpass 120S $549; Century Lithium Pro Slimline $1399
Keyword: MU-X build: C-TEK system and Century Lithium Pro battery installed