Dual battery & camper trailer - guidance please!

[Bagheera]

I have some parts already, and now I need to hook it all up. Looking to do it all myself, but would like some guidance on the finer points.

I am looking to set up a second battery under the bonnet, with an Anderson plug to connect to my camper trailer battery (100AH AGM) for those longer family trips. Not too concerned about isolating the 2nd battery and camper battery from each other, unless it can be done easily/cheaply.

So what I have currently:
Battery tray & marine battery (N70ZZ equiv)
Several 50A Andersen plugs and a towbar mount to suit
The ability to solder and access to a decent soldering iron

I'm about to order the rest of the gear, but want to make sure I get the right parts.

Which isolator to use? I've had various recommendations of the Redarc SBI12, ABR DBi-140R, Projecta 140A unit...can't see any significant differences between them, but I could be missing something.

I am planning on using 6B&S cable throughout. Will use individual cables from +VE to isolator to +VE 2nd battery, but was looking at using the twin 6B&S cable to run to the rear plug point. Is this ok?

How do I handle -VE? I've seen various setups which either join -VE between both batteries in the engine bay, or connect the 2nd battery to a chassis earth. Knowing the earthing problems on GU Patrols, should I be linking -VE between the two? What do I do with the camper -VE; chassis at rear or link back to 2nd battery?

Fuses vs circuit breakers for the main links? Planning on fusing either side of the isolator, close to the batteries, and both ends of the camper feed. Will 100A be enough on the main links? I'm assuming 50A for the camper feed, giving I'm using 50A Anderson plugs?

Finally - is soldering and heat-shrinking the lugs sufficient? Or do I need to borrow a crimper/find an auto sparky to make up the various leads after I cut to length?

I had planned to leave this until I had more time after Christmas, but I've been given a fridge to lug around the provisions for our extended family, so I'm fighting against a deadline to get this sorted.

Appreciate any input or constructive criticisms.

[MudRunnerTD]

For a start here is some really good info for you mate

second and third batteries (http://www.nissanpatrol.com.au/forums/showthread.php?2880-DIY-Installing-a-Second-or-Third-Battery)

Hope that is of some help. There is a fare bit written in the DIY and Electrical sections too.

Cheers MR

[gu8 patrol]

gday mate,i have an anderson plug at the rear of my patrol to charge battery in the camper,you need to put a 50 amp circuit breaker as close to the vehichle battery as possible,you also need to run minimum 8b&s from the battery and breaker all the way to the rear plug otherwise you have too much voltage drop over that distance,hope this helps.

[philfree]

Hi What i generally do here is hook up a sbi 12 between the main and the underbonnet 2nd battery and then run a lead from the 2nd battery to Anderson plug at rear. If you want to isolate the Anderson plug then you could use a extra sbi 12 ( also if you have solar redarc make a sbi12d witch charges both ways eg when the solar is charging the aux battery and the aux battery is nearly full it will link the main battery in so both get charged) if you intend to be able to jump start off the aux battery then i would run solid loom tube and no circuit breaker with cable no smaller then 2 b & S with the battery earth on the engine somewhere. If you are not going to use the jump start feature then you could use the 6 b & S cable. I would use 100amp circuit breakers for main battery cable to isolator and another between isolator and 2nd battery and just a 50a circuit breaker between 2nd battery and anderson plug keeping in mind that the battery in the camper should have some sort of protection for the cable going to the hitch. I hope i explained it well.

[Yendor]

I have some parts already, and now I need to hook it all up. Looking to do it all myself, but would like some guidance on the finer points.

I am looking to set up a second battery under the bonnet, with an Anderson plug to connect to my camper trailer battery (100AH AGM) for those longer family trips. Not too concerned about isolating the 2nd battery and camper battery from each other, unless it can be done easily/cheaply.

So what I have currently:
Battery tray & marine battery (N70ZZ equiv)
Several 50A Andersen plugs and a towbar mount to suit
The ability to solder and access to a decent soldering iron

I'm about to order the rest of the gear, but want to make sure I get the right parts.

Which isolator to use? I've had various recommendations of the Redarc SBI12, ABR DBi-140R, Projecta 140A unit...can't see any significant differences between them, but I could be missing something.

I am planning on using 6B&S cable throughout. Will use individual cables from +VE to isolator to +VE 2nd battery, but was looking at using the twin 6B&S cable to run to the rear plug point. Is this ok?

How do I handle -VE? I've seen various setups which either join -VE between both batteries in the engine bay, or connect the 2nd battery to a chassis earth. Knowing the earthing problems on GU Patrols, should I be linking -VE between the two? What do I do with the camper -VE; chassis at rear or link back to 2nd battery?

Fuses vs circuit breakers for the main links? Planning on fusing either side of the isolator, close to the batteries, and both ends of the camper feed. Will 100A be enough on the main links? I'm assuming 50A for the camper feed, giving I'm using 50A Anderson plugs?

Finally - is soldering and heat-shrinking the lugs sufficient? Or do I need to borrow a crimper/find an auto sparky to make up the various leads after I cut to length?

I had planned to leave this until I had more time after Christmas, but I've been given a fridge to lug around the provisions for our extended family, so I'm fighting against a deadline to get this sorted.

Appreciate any input or constructive criticisms.

I like the RedArc isolators but the other units will work just as well.

The 6B&S cable is fine.

For the earth I would run a main battery cable something like 2B&S from the negative of the 2nd battery to the engine block (if you ever need to jump start yourself just connect the positives of both batteries together with jumper leads) and a small earth strap to the body as well.

It's up to you if you use fuses or circuit breakers in the link between the 2 batteries. The 50amp circuit breaker for the camper feed is fine.

Crimping would be better. If you are confident in soldering then that will be fine, just don't allow the solder to run up the lead.

To get maximum performance and life out of your AGM you would be better off using a DC-DC charger in between your second battery and your AGM.

[Cuppa]

I think Yendor has covered it well.
I have a used SBi12 you can have for $40 plus postage if you are interested.
Can't see much advantage to isolating the two aux batteries unless the one under the bonnet will be used for winching & you want to 'save' the one in the camper.

Cuppa

[Reddave]

In mine, I ran my Anderson plug wiring directly from the auxiliary battery using 6b&s cable.

Negative straight to the battery, positive from the battery to a rotronics isolator, then to a 50a manual reset circuit breaker, from the circuit breaker to the Anderson plug at the back of the patrol.

I only used a manual reset circuit breaker so there is only power going to the Anderson plug when I set it. Once I hook the camper up, a flick of the bonnet, you know to check all those things that you should be checking, oil, water etc.
It's just a simple flick of a switch and the camper battery is charging.

Once I get home, pop the bonnet and turn the circuit breaker off