If you are thinking of installing a dual battery system for your camping rig the most important consideration is protection of your cranking battery. You don’t want to be stuck out in the sticks with a dead battery and no means of starting your vehicle. This article looks at one way to prevent this by utilizing an intelligent battery isolator.

With the most basic of dual battery installations such as that shown below, if you are camping without mains power for a considerable time, you run the risk of flattening your main cranking battery (a big no no). This diagram illustrates that when the vehicle is stationary (alternator not charging the batteries), the main and auxiliary batteries are effectively connected in parallel and will both discharge under load. Even if you add a manual isolation switch between the main and auxiliary batteries, chances are that at some point you will forget to throw the switch. Then the next time you want to start the engine, you don’t have enough power.

So now let’s add some protection for the cranking battery, and in this example it is the Redarc ‘SmartStart®’ intelligent battery isolator. Look how easily it slots into the basic diagram between the main and auxiliary batteries.

The SmartStart® is a microprocessor controlled continuous duty solenoid that acts to allow charging of your auxiliary battery while traveling, but protects the main cranking battery when stopped and under load. Out of the box it is configured to close the solenoid and switching contacts when the main battery voltage reaches 13.2 volts. This places both batteries in a parallel connection for both to receive charge from the vehicle alternator. If for any reason the main battery voltage drops below 12.7 volts the solenoid will drop out and the switching contacts open, thus isolating the main from the auxiliary. Any switching voltage spikes are also suppressed by the advanced circuitry in the isolator.

If for any reason your cranking battery does fail to start the vehicle, an extra connection on the SmartStart® allows an over-ride switch to re-connect the auxiliary battery to assist with starting. The isolator takes very little current from the battery when energized (approx 0.15 Amp), so no worries there. It also comes in four models – 100 or 200 Amp continuous load for 12 and 24 volt systems. If you are into serious off road driving and camping you cannot do without a SmartStart®.

I have two SmartStart® isolators in my vehicle. One feeds two AGM auxiliary batteries in my pop top camper to keep them charged whilst driving. The other feeds the three way refrigerator in the camper when it is switched to DC for traveling. I have used this system for over three years now with no problems whatsoever and never a flat battery.

Of course there is much more to this that simply adding a battery isolator and I have covered the installation of such a system in a How-To guide you can access here.

Please Tell Your Friends

• 

Filed under: General Tips, Smart Ideas