SECOND BATTERY ????

I run 2 x Century Overlander 700cca cranking batteries in parallel through a basic solenoid with a dash switch.

Battery around $150, wiring around $20, solenoid was free from EO forum mate but would cost around $40. Install self.

So you should do it for around the $200 mark.

Cheers

I have a Deep Cycle battery as the second battery, after destroying 2 cranking batteries running the 110L Waeco. Charging is done via a Rotronics unit, having fried 3 other brands previously. My current setup is working brilliantly, but I suspect the 16-page instructions with the Rotronics charging isolator may have helped. I was earthing the auxilliary battery and accessories through the body/chassis - now I have the battery earthed to the engine and all accessories earthed to the negative terminal on the battery.

Good luck with your setting up.
John
Hermannsburg

I use the Exide Extreme Battery, great 2 year warranty, costs between $130-$150. I have killed 2 of these batteries due to lack of charging. I have the ARB Dual Battery System, the car doesn't get much use during the week hence the lack of charge. The Engel 40L is running all the time.

Batteries have been swapped out under warranty both times at KMart.

The main battery is also the Exide Extreme.

Crakaphat

Crakaphat

I've got a 60 series cruiser with dual batteries my brother in law( auto electrician) and myself (electrician) installed dual batteries in without any of the fancy gear, much like old mate in the first reply. About the only exception was we wired the cut out solenoid to the accessory active at the wiper motor so the batteries would parallel on starting. We used VERY large multi stranded conductor to replace all wiring between batteries and negatives to earth,motor etc. I run a 60 litre Engel and lighting. The main start battery is a Yuasa Overlander which is 9 years old ( completely true- still have the purchase receipt) and the other is a deep cycle calcium battery. Stationary we get about 3 days with the fridge on refridgerator only .

I have also an 80 watt solar panel permanently mounted of the roof of the old girl which charges the deep cycle through a permanently wired regulator, I have rigged up some diodes so there is no back charge when the motors running. With this setup we have no power supply worries unless it rains for five days or more and we do not start the car. I am not an expert by any means however, the setup I am running is proof you do not need to spend a fortune just to get a workable dual battery system in there. Contact me if you wish and I'll send some pics, its very simple you could do it yourself.

Cheers

Gday Crakaphat
I have a similar setup to a few above, Simple solenoid like Darkman, with Exide extremes similar to Phil P, so I suppose I'm a combination of a few setups here. It works well, and I get 48 hours running an 80l waeco off it.

Willem, I think it was you who I asked if there are any issues with starting if you completely flatten the aux, (sorry if it wasn't, but I'll waffle on a bit here anyway), as it may suck all the power out of the starter when they go into parallell when you turn the ignition on.

You, (or the person I asked) said they had no problems to date. Well I sort of tested the theory the other day, but in reverse. I copmpletely killed the starter battery (leaving the headlights on for 7 days will do that). I hooked a jumper lead across +ve to +ve, as the solenoid won't work with no power from the starter battery, and it started instantly! I now have full confidence in my setup.

The starter was tested and was completely dead, but 3 1/2 years out of a starter up here isn't bad. It was mistreated a couple of times, so I'll stick with the exides for now.

Cheers Andrew

"What second battery to use"

As big as you can fit. An 80 A/h deep cycle battery is about the limit for most installations due to the "footprint size".

The best type of battery to use is a SEALED deep cycle battery, preferably an AGM type. Being sealed, you don't need to remember to keep topping it up with distilled water, something that is not easy when the battery is mounted high and against the firewall in the engine bay.
An AGM battery will change quicker and more completely from the vehicle alternator and you can discharge it lower than any "wet cell" battery.

A dual battery system should be managed by an Isolator to protect the two batteries from total discharge should one or the other malfunction.

What Isolator you use is up to you. You can get away with a simple solenoid and a dash switch, if you remember to use the switch, or you can select a smart Isolator that you can install and "forget".

Redarc and Piranha are two worthy brands of Isolators.

Alternatively, you can use a portable battery system that comes complete with an in-car charging unit. Such a system will give you about 80 A/h of supply.
The cost will be similar to a standard dual battery system, but gives you more flexibility of where you place your fridge when camping.

I use both an in-car dual battery system and a 75 A/h Thumper portable battery system which is the "ants pants" for flexible travelling and camping.
The portable battery system also allows for your future "smart charge items" such as a solar panel when you can justify it. It simply plugs in to one of the 12 volt sockets on the sealed, waterproof housing.
HomeOf12Volt

Go to the battery web sites and read the information posted there - by them, after all they spend squillions of $$$$ researching these things and just for you.

Look at the reasons different batteries work and some don't at running low drain accessories. I won't sugest you ask Telstra why they don't use cheaper Cranking batteries as 'standby' batteries in their phone systems instead of AGM batteries, that would be an insult to intellegance :)

Even this post has some interesting relevant information.

Yes, I'm biased, but you can't get better performance than an AGM Deep Cycle battery to run a fridge, yes they supply power for longer period of time and cost more money, (about $270 retail for 100ah) but do the maths and you can see it's worth it to spend the money now, rather than have no battery power while on holiday.
They have a life expectancy of about 10 years v the cranking battery that you can read about here lasting a few years only.

Why not believe the "profesional" that's their job ,they have to give you a warranty.