dual battery setup confusion

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I'm a good boy Dave I don't want to offend people with such filth. Besides it wasn't in capitals so it wasn't offensive (not matter how much smart arse was involved).

Thats right back on topic.

1 battery 3 wires and 12 fuses hooked up in series with parallel connections and your radio will work.
 
Nathan96 is spot on the money, I forgot a big fuse on the big cable side of the aux battery.

I don't need one in mine, because mine's electrically isolated:

main battery -> 30A fuse -> cable -> inverter -> charger -> battery -> fuse -> fridge

Kudos to Nathan for spotting the oversight. I won't go back and fix it, because that would make 90% of this thread look weird.
 
Luckily I know Krafty is crafty

12 fuses wont work because its an even number it will invert you polarity across the popularity over the length of the inverted cable meaning the radio wont work. Use 13 and it'll be all sweet.

But seriously another option is what old.tony has posted above.

or if doing the "usual set up" you can use manual resetting circuit breakers in place of fuses
 
Yeah but one of my fuses was a double and I failed to mention it to fool you into thinking I'd made the mistake.

I actually use a self resetting fuse off my main battery, would never know how many times it's tripped or if in fact it has. Sure some people might like the idea of knowing if fuses trip and replacing them but I'm fine with the auto fuse and it's never stopped my fridge working.
 
My fuses are "thermal resetting" fuses. I presume that they are just circuit breakers that trip when hot and as they cool down they set themselves again.

Sorta glad I also have a relay in there so that power only goes down the back when the ignition is on.

The system I described is one that I put in our caravan first, and now have in the Navara tub. I wouldn't do it any other way. While we're driving, not only is the battery being charged by a proper multistage battery charger, but the fridge is switched over to 240V and isn't drawing on the battery that's being charged (which makes the battery look like it's undercharged).
 
enough about fuses ay!?

so i understand that when camping i'll need to wire up all new plugs/cables to the aux battery.

so obviously i'd wire up a new engel plug to the aux...

i have 2 roof work lights, spread beam 100w hellas, which are brilliant for camping as they light up the area, but i'm not keen at all to leave them constantly turned on through the night. so that means i'd have to wire those lights up to the aux battery, would i also be right in saying that when the car is running and i turn the lights on they will still work whether or not the isolator has 'connected' the aux battery for charging or disconnected it once the isolator sees the battery is fully charged?

the main thing now is that i'll have to rewire my car radio, as i tend to leave in on for hours when just sitting at camp at night. yet when the car is on and running i'll still be able to use it? would i just have to rewire the radio so that it gets the positive feed from the aux batt? and then again, how would i get the aux feed to power the radio when i have to put the key to ACC which is still connected to the main batt?

and yes i know i'm making this sound very hard and confusing haha, sorry
 
100W at 12V is about 8.3A. Two of those = 16.6A. Overnight (say in summer, 9pm to 5am = 8 hours) that's 132amp-hours. You need a battery of at least 260Ah capacity to do that without doing too much damage to the battery - and that's without running anything else!

I'd seriously look at LED lights, or do what we do - solar garden lights for around the site and hand everyone a torch!

As for your car radio, that's a nasty job. I wouldn't be mucking around in there - the radio taps into the ACC power as well as the vehicle lights. If you've got a system like mine, it also taps into the reverse wire and handbrake switch too! That's so messy, I actually recommend a cheap solution: a boom box.

You can get 'em that run off 12V (8 'D' size batteries = 12V). Some even come with car power cables, so it's a piece of cake to hook it up in the tub.
 
i got a landcruiser remember!

no fancy stereo to reverse lights crap haha

i did think about getting a seperate radio instead and hooking that up to a 12v socket or something a little bit custom so i can actually have the sound pointing to where i'm sitting, not just blaring out of the car til everyone can hear it haha

looks like car radio is off the charts.

so isolator + wiring + new deep cycle battery = lot of cash to power an engel over night and to have a few lights on. i dont keep the work lights on for too long, maybe 5 hours max? and in between i would always start the car and give it a few revs for a few min to recharge.
 
Be sure to give Challenge Batteries in Jandakot a call when you are ready to buy one, I just bought a 120AH AGM for $264

Also, have a look at the ABR (not ARB) Sidewinder electronic isolator and battery monitor
DB-120 Controller
ABR Battery Monitor

I love them and with this battery monitor connected to their isolator, you can link the batteries up at the flick of a switch. They will be automatically linked once the main voltage is above 13.2v, it will then isolate the aux from the main once the main goes below 12.4v. Linkign the batteries is useful if the main dies, I know deep cycles shouldnt be used to turn the starter motor but if im stuck in the middle of the desert with a dead main battery, Im bloody well going to get the car going again using the aux!
 
No matter what car it is re-wiring the radio is still one of those jobs that doesn't always have benefits, we found years ago that it was far easier to use portable radios or cd players. You can spend a bit of money and by a decent radio made for getting reception in the bush or just a cheap compact unit and as long as it's powered by batteries you can easily set it up to run off your 12V supply of either the main or the aux battery.

We use a 9v battery lead from the two terminals in the battery compartment of the radio hook that to a box that converts the 12V to 9v and plug the box into any cig lighter. $20 build it yourself box, a bit of work and power on the go anywhere you need it for a battery driven radio without using the inverter or having to carry D cell batteries.

We also use this set up around some of the sheds at the farm where it's most effective for us to solar charge a small car batteries to give us 12 volts all the time and we just take the radio and the laptop from shed to shed depending on where the work needs doing.
 
heres a thought...

what if you hooked up the cars main positive power wire to the AUX battery, but connected the starter motor power wire to the main battery?

that way you can run all existing stuff off the aux battery, but have the car start up on the isolated main battery?

surely that would work?
 
There'd still be an active electrical connection between aux and main batteries, so what you did to one would immediately affect the other.

That's what the isolator does: it removes the permanent connection so that one battery can't impact on the other unless it's in a good way. This means:

* Starting the car will only draw power from the starter battery
* Aux battery can't draw too much power from starter battery
* Items run from the aux side can't drain the starter battery
* Starter battery gets charged first, ensuring you can always start the vehicle

It basically leaves you in the best position possible: you are always able to start the vehicle and drive it.

Safety first. Don't ever live-connect your starter battery to the aux, or run items from your starter. That should only ever be used for running the vehicle.
 
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