Batteries - Deep Cycle or Hybrid.

Terry : looks like you have the wrong battery as a second battery, depending on how your rig is set up of course, but I reckon your second battery should be a 'Deep Cycle" version, they are very different from a 'Starting Battery' ....why not set your rig up correctly before you run out and spent an arm and a leg on a fancy battery which may be an overkill....I have the same vehicle. fridge and lights and have not had aworry in over two years... this includes charging razor, and the boss's electric toothbrush !! the inverter we have is not a big one, just enough to blow dry her hair.. Suggest you get in touch with an Electrical Tweaker to confirm your requirements as i only speak from experience..

While deep cycles are best for running fridges and such, there are other factors that will affect your decision.

Deep cycles (apart from spiral types) don't charge well from an alternator alone. You'll either need to use a main battery charger or solar panels to keep them running happily long term. They also don't like being charged at more than 10% of their amp hour capacity - ie a 60 Ah battery should be ideally charged at 6 amps (10 amp RMS) not at 40-60 amps that an alternator puts out. Also the output voltage of an alternater is set for starting batteries, most deep cycles need higher voltages.
Your choice may depend on the type of isolator you have for your second battery. There are many potential problems here, such as parallel charging different types and ages of battery may reduce battery life.
Many cheap deep cycles are designed for stationary applications and will die in a 4WD. If you go for a high capacity deep cycle then stick with good brands like Federal or Trojan.
The Century Marine Pro 600 is a reasonable compromise in a 4WD if you don't want to have to worry about slow charging a true deep cycle. Optima give the same result at a dearer price but with a claimed longer life.


I personally use a Federal 90Ah deep cycle to run the fridge (in Far North Queensland I get 56 hours from fully charged to 11.5 volts). I try to charge it up on an Arlec 10 amp charger ASAP after a weekend away.

Hope this helps

One more thing to add:

A reply to a previous question made mention of a charger than converted the alternator output to higher voltage/lower current to be compatible with deep cycle batteries. See http://www.12volt.com.au/htlm/dualbat.html for the details. I intend to find out more about this system myself.

Terry,
I've had an Exide Extreme (N70EX) in my GU Patrol for eighteen months now, and its still runs fine (but I guess you'd expect that!). The research I did at the time suggested to me that this was a slightly better option than the ZZ style battery. We tend to spend up to five nights in one location (but still use the car during the day), and have never had a power loss problem. We run a Waeco fridge and an inverter to power lights, music etc.

All the best
Andrew

We tend to camp out in remote locations a lot. If I were to replace my second battery with a deep cycle type, (Currently a cranking battery) and the main battery failed, would the deep cycle be able to start the motor...a Toyota 4.2 diesel.