Dual battery wiring set-up question

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Ideally keep the isolator as close to the battery as possible because that is what Redarc recommend. I guess this is because you can get significant voltage drop in the cable if it is too small and as the Redarc isolator senses input voltage to switch on or off Redarc are just making sure the isolator will work as planned. However one way or another you will be running heavy duty cable to the battery so it shouldn't matter. There are a few voltage loss calculators on the web so you can see what will happen at the blunt end of your 8B&S when pulling 50A. I ran 6 B&S from the main to the DC DC charger and will run that or larger to power out the back when the time comes.

What ever way you do it make sure you have a circuit breaker or fuse in line near the battery that can handle the current flow and give you some protection. I go for a manual circuit breaker than doubles as an isolation switch. Right next door to the main battery and between the battery and Redarc isolator / DC DC charger.

http://www.redarc.com.au/images/uplo...ion_Manual.pdf

Not sure letterboxman what you mean. If you are suggesting running all the standard OEM ancilliaries off the auxiliary battery I don't see the point. There was another thread on here not so long ago about doing that and none of us usual PPers could work out why you would bother. Typically the auxiliary battery is for running new bits and pieces and having these isolated from the main battery so that if the auxiliary does go flat you can still start the car and drive away. So these things are usually fridge, CB radio, power sockets and or extra lights. Things you want power available for when the engine is off.

Redarc and the other similar isolators usually have provision for starting off two batteries or winching off two batteries. To be honest if that is what you want to do then go for the biggest capacity isolator you can find because the current draw momentarily can be huge and burn out wiring quite quickly. That lets the smoke out of the electrics and we all know that is a bad bad thing.

[letterboxman Junior Member Find all posts View Profile Close letterboxman]

I agree with you Mj, seams like a lot of stuffing around... My confusion is if that is the question from the original post...

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

Ok the question, I think, was whether the OP could wire his aux fuse box to the Redarc aux terminal rather than coming off the +VE terminal of the aux battery. I guess so the fuse boxes could be close while the aux battery is further away. As stated Redarc say not to connect anything to these terminals. I suppose again this is so the Redarc isolator can correctly read main and aux battery voltage without a parasitic load on the Redarc. Maybe. I can understand why you would want to if you had the aux in the back and wanted to run lights or something up the front. In my experience Redarc have been brilliant replying to questions about their products and installs and they also have a blog/forum with installs. Any questions about doing something different to the standard drawings just ask Redarc I reckon.

[Jon Avid PP Poster! Find all posts View Profile Close Jon]

I have wired my auxiliary fuse box directly from the positive terminal of the auxiliary battery (through an in-line fuse). I believe Redarc are correct in stating this is the way to go. There are some very technical issues due to current flow, voltage drop, reference voltage and other things that makes the charging and load connections to be done as per specifications.

[D4D Addicted PP Member Find all posts View Profile Close D4D]

There are some very technical issues due to current flow, voltage drop, reference voltage and other things that makes the charging and load connections to be done as per specifications.

Can you elaborate Jon?

[Dune Buggie Junior Member Find all posts View Profile Close Dune Buggie]

Sorry, hadn't had time to get back on PP for a while, thanks for that MJ, ended up placing the smart isolator in the battery box in the rear as I have already ran some cable to the rear for constant power to run my waeco. I only use the battery box for trip away, so if I need the fridge for day trips I can run it off the starting battery without the isolator cutting in.