Generator vs dual battery help please!

Submitted: Tuesday, Mar 20, 2012 at 15:49
ThreadID: 92659 Views:4752 Replies:8 FollowUps:3
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So I am pretty new to all this, but i have a land cruiser ute with a canopy on the back that i am gearing up to go around aus in. I have space under the hood for a second battery to go but am not sure if its the way to go?

Pretty much I don't have a heap of money to spend, but i want to be able to power some lights and an 80 litre waeco fridge as I go, possibly charge a phone and a laptop etc., but will be tapping into mains as we go as well. I don't have any of the wiring for a dual battery so I will be starting pretty much from scratch - so i can go any which way.

So please treat me like a child, help me out because I am clueless and my girlfriend is even worse!
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Reply By: Member - Troll 81 (QLD) - Tuesday, Mar 20, 2012 at 16:44

Tuesday, Mar 20, 2012 at 16:44
I would go for a good quality dual battery setup. Put yourself out in the middle of nowhere and think what if you wake up the next day and your starting battery is dead for what ever reason? and there is not a soul insight.

If you already have the space and a battery tray then you can easily do the job yourself by following the instructions. There are plenty of DIY kits out on the market.

Once you have a good system then you can run your lights and your fridges and what ever else you want. I have had to jump start people's cars way to many times on Fraser Island or other remote camping spots because they forgot to turn off a interior light or something simple.

AnswerID: 480912

Reply By: Gadget X10 - Tuesday, Mar 20, 2012 at 16:45

Tuesday, Mar 20, 2012 at 16:45
Hi Kieran,
Yes I would put a second battery under the hood at a minimum, perhaps one in the back of the canopy as well, you will need it to run the 80lt, if funds allow consider a Redarc 12v DC/DC charger. this is well worth finding the money for.
This will keep your batts strong and doubles as an isolator, it has 40amp capacity so in theory you can run your truck for a few hours and get say 40+ amps into the system.

Redarc dual battery link

I have spent the last 8 years traveling and the gen set is nice to have but 2k+ it's a lot of cash.
Your fridge will draw down about 3 to 4 amps per hour ( not continuous ), so say 50 to 70 amps per 24 hour period out of a single 125 amp battery ?? you will have to keep your eye on it ( 2 x 125's = 250 amps would be safer ).
AnswerID: 480913

Follow Up By: Kieran R - Tuesday, Mar 20, 2012 at 19:37

Tuesday, Mar 20, 2012 at 19:37
Hi Gadget
So if i got two 125 amp batterys, and say a DC batter charger 24V to 12V (is this the same thing?) that has an output of 20 amps, this would be enough to power my fridge and a few extras, like laptop, phone, lights?
Does the battery charger thing act as an inverter? so you run both batteries back to this, and then onto the tray? Im sorry if this is basic camper stuff, but I really am such a rookie!
FollowupID: 756315

Follow Up By: Gadget X10 - Wednesday, Mar 21, 2012 at 09:04

Wednesday, Mar 21, 2012 at 09:04
Hi Kieran
First off the Redarc 12v DC/DC charger only works when your truck is running, its power comes from the alternator.
Redarc make two sizes a 40 amp and a 20 amp
No the Redarc I described is not an inverter.
Yes you can bye 240v /12v Battery Chargers that are inverters.

IMHO I always go with the highest output charger I can afford, this can result in shorter charging times.
Just because is says 40 amps dose not mean it will pump 40 amps all the time.

In my Ftruck I have a Redarc DC/DC 40 amp for my 2 x start batts and 3 x 125 Aux batts, to run 2 x 40 lt Engels, I also run a 50 amp 240v Xantrac charger off my gen set and I can bring low batts back up very quickly.
My kit is in the silly end of the scale but I bush camp for weeks at a time with no issues, solar for the van with another 5 batts.

(Please don't pick on me for some simple logic shown below)
Kieran as an example 2 x 125 amps = 250 amps ( usable say 100 amps )
now a 10 amp 240v charger should take 10 hours to re charge, a 50 amp 240v charger 2 hours, in theory, but it's not quite that simple in the real world, but for the example OK
Most good charger's start with a heavy hit perhaps there stated max output, then they lower the charge rate to a point that you may only be getting 1.5 amps per hour.
So perhaps you can get the idea of why a higher output charger can be beneficial.
Again the Redarc ONLY needs you to run your truck to work, no 240v required.

FollowupID: 756356

Reply By: ken triton - Tuesday, Mar 20, 2012 at 16:57

Tuesday, Mar 20, 2012 at 16:57
Hi Kieran,
I have been 4wd and camping for over twenty years and would thoroughly recommend a dual battery set up first. A good dual battery setup will let you sit, run your fridge and some led lighting for a minimum of 2 days without staring the car. The key is to make sure all your appliances draw as little amounts of power as possible. When you stay a caravan parks or have access to power take the opportunity to charge your batteries fully using a good quality battery charger. As far as the dual battery setup is concerned you will receive all sorts of advise and opinions as to which is the best, I would have a talk to a couple of different auto electricians or 4wd outlets and then make a decision, the most expensive is not always the best. My system has worked fine for many years and I just have the two batteries connected together with battery cables on marine terminals and if I am sitting for a couple of days I just disconnect from the main battery. I have never had a flat battery and the system works great. All it costs is the battery cables and the battery, a couple of hundred dollars and the job is done. Both of my batteries are exactly the same and that is quite important.
Hope this helps
AnswerID: 480914

Reply By: Member - Keith Berg - Tuesday, Mar 20, 2012 at 17:02

Tuesday, Mar 20, 2012 at 17:02
One cheap option might be to connect your auxiliary battery or batteries in parallel with the starter battery. But in the positive lead that goes from the auxiliary to the starting battery, you fit a voltage controlled solenoid. This is a heavy duty switch that is turned on and off by a signal from an outside source that is a little higher than battery voltage. That source is the charging voltage from the alternator.

The effect is that your auxiliary battery can go flat when the engine is not running, but your starting battery is always good and can start the engine no matter how flat the auxiliary is. When the engine is running, it will charge both batteries - provided they are of the same type.

I have not seen this system on 4WDs but it worked a treat on my boat, which had a big auxiliary battery bank. You may have to talk to a marine electrician about this kind of solenoid. The only downside is that it can take quite a while to get a flat auxiliary up to full charge. But supplemented by a solar panel on the roof of the ute, it might be a cheap solution.

I'd be interested to hear of any comments from wiser heads on such a scheme.
AnswerID: 480915

Reply By: Sand Man (SA) - Tuesday, Mar 20, 2012 at 20:23

Tuesday, Mar 20, 2012 at 20:23

Assuming your fridge will be in the tub/canopy area or your ute, this is where you should place your auxiliary battery.

Speaking from personal experience, a great all round solution is to invest in a Sidewinder Flyer and add a battery of your choice.

The Flyer comes complete with all cabling, Anderson connectors and a built-in Isolator to protect your starting battery from running flat.

I have a Flyer installed in the tub/canopy of my dual cab with a 100Ah Remco inside.
You can go to a higher capacity AGM battery if you wish. The choice is yours.

The Flyer has a 12 volt DC socket for your fridge and you could easily add a 240vac/12VDC charger to recharge the battery when in a caravan park. Simply add a 50 amp Anderson connector to the business end (12 volt end) of the charger, then you can disconnect the alternator cable feed, (also a 50 amp Anderson connector) and plug the charger in.

I wouldn't worry about the phone/laptop charging from the auxiliary battery. This can be achieved by plugging into the original cigarette socket on the dash. These are low current drawing devices and can be run while driving. When you turn the ignition off, the circuit is disconnected so you will never drain the primary battery.

The Flyer is a great all-round solution in my opinion. Derek is an advertiser on this site.
You could also add a solar panel input and dc-dc charger to further enhance your setup for long term camping away from 240VAC power, or prolonged stoppage without the alternator running, but just the Flyer (and an AGM battery) wired up to the included cable kit is all you should need up front.


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AnswerID: 480928

Reply By: JR - Tuesday, Mar 20, 2012 at 20:38

Tuesday, Mar 20, 2012 at 20:38
Can I suggest you look at an independant dual battery system. works just like all the others as far as isolating main from Auxillary but charges each one individually
More expensive but way more usable recharging second battery in a fraction of the time using your engine. Rotronics make a good one.
Watch DC to DC chargers, they are often low amperage capacity and charge slowly. Big ones are $$ but available
AnswerID: 480932

Reply By: Mick O - Tuesday, Mar 20, 2012 at 21:04

Tuesday, Mar 20, 2012 at 21:04

this is probably the most important decision after the selection and purchase of the actual vehicle. If you intend travelling and camping out bush, then a dual battery system is a must. These can be done quite cheaply but as the old adage often says, "you get what you pay for"!

Dual battery systems can be as simple as a battery isolator and switched solenoid system up to a proper dc-dc charger which will charge your battery in the optimum configuration the manufacturer intended. Do not scrimp on dollars when selecting a dual battery. Look at what your power needs are and ensure you get a good capacity AGM or Hybrid AGM (This still provided a high level of cold cranking amps to start your vehicle). AGM’s require a high rate of charge to ensure optimum performance so a DC-DC charger is a great option. Someone above posted a link to teh Redarc version. These are a great option but there is a smaller model that would be suitable for you, namely the 12/20. It’s a couple of hundred bucks cheaper (Anew model is due out in April that will have an inbuilt MPPT solar controller as well meaning you can plug your solar panels directly into it). Visit their site to read about what each product does. They also have wiring diagrams to show you how to prepare and install the systems yourself from the basic solenoid type, upwards.

Visit John and Vals blog to learn about DC power needs and how to judge what is best for you. If you want to see just how seriously a keen outback traveller takes provision of 12V DC power, visit my ute build blog.

Cheers Mick
''We knew from the experience of well-known travelers that the
trip would doubtless be attended with much hardship.''
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AnswerID: 480938

Reply By: ross - Wednesday, Mar 21, 2012 at 11:15

Wednesday, Mar 21, 2012 at 11:15
I have a landcruiser ute with dual batteries and a deep cycle battery in the back for the fridge.
I bought a Yamaha generator some years ago but its sits there gathering dust.
If Im driving most days I never have to plug into the mains and if Im stopped,my 80litre Waeco can go for 2-3 days on the deep cycle battery with careful use of the fridge.
AnswerID: 480982

Follow Up By: ross - Wednesday, Mar 21, 2012 at 11:20

Wednesday, Mar 21, 2012 at 11:20
I plan on getting a small solar panel,they are becoming so cheap these days. For few hundred dollars ,you can get one that would run that 80 litre waeco and still have a bit left over for lighting at night(via a battery)
FollowupID: 756378

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