Camper van dual battery electrical diagram


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Old 04-24-19, 07:58 AM
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Camper van dual battery electrical diagram

Hi all,
New to this forum, and to electrical work in general. I am currently converting a Nissan NV 2500 cargo van to a camper van for cross-country traveling. The van currently has a 130a alternator powering the starter battery, and I have purchased a WirthCo 20092 Battery Doctor 125 Amp/150 Amp Battery Isolator (smart isolator) to charge a AGM Deep Cycle 12v 125ah SLA rechargeable Battery. I plan to hook up a vent fan, LED lights, and some 12V outlets to start (all via a fuse box). I may add solar at a later point, but for now, want to see how if I can get by with just charging the auxiliary battery off of the existing alternator with a smart isolator.

Since I am new to electrical work, I want to make sure everything I am doing is safe! I plan on using all 4AWG wiring between starter battery>isolator, isolator>aux battery, and battery>fuse box, and then all 12AWG wiring accessories to fuse box. I am also planning using 150a fuses at each battery connection, but am unsure if I should use in-line or a fused terminal for the auxiliary battery.

Please see the attached diagram (apologies for it being hand drawn...) for further explanation.

Questions I have:
  1. Is my current diagram safe/functional?
  2. What would be an affordable charge monitor (would a voltmeter suffice) for the battery in this setup, and where would I connect it?
  3. Should I use in-line fuses for the auxiliary battery (from the isolator and to the fuse box), or can I use one fused terminal on the battery to fuse both of these wires?
  4. Any other tips/advice?
Thanks!!

PS please let me know if there is a more appropriate thread/forum to post this in, our another website entirely.

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Last edited by PJmax; 04-24-19 at 07:44 PM. Reason: enhanced/enlarged diagram
  #2  
Old 04-24-19, 07:43 PM
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Welcome to the forums.

A lot of info here...... posted and needed.

I owned a mobile electronics shop for many years. Installed a lot of dual battery systems.

Pass on that isolator. Go with a continuous duty solenoid. It gets mounted out near underhood battery. It gets connected to an ignition source in the fusebox that is on only when the engine is running. A 100% connection method. No isolator loss. When the key is off.... the batteries are not connected.

Use two ANL fuseholders and fuses. The wiring goes from main battery thru one fuse to the solenoid to the second fuse and then to the aux battery. The wiring is protected at both ends from catastrophic shorts.

#4 wiring is ok. Locate a multiple fuseholder near the AUX battery for smaller loads.
Something like this.
 
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Old 04-26-19, 11:38 AM
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Thanks for your help! I know, lots of info. I tend to over-research things and provide too much detail. But figured electricity is one thing not to screw around with.

I did already purchase the isolator, but could return via Amazon Prime. And I'm not sure if with my minimal knowledge/skill I would be able to connect the continuous duty solenoid to the ignition source... Would it essentially function similarly to the isolator? Any tips on that? I should also mention that I may eventually hook up a solar panel or too to charge the secondary battery. I had figured the isolator would be best for this.

I have wondered about potentially taking the vehicle to a mobile electronics shop to have them hook up a secondary battery instead of me. About how much would that run me, if you happen to know?

Thanks again for your time!!!
Matt
 
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Old 04-26-19, 11:55 AM
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It's been a while but the job usually ran about $200. That was all parts and wiring except for the battery.

The isolator you bought wires just about the same. Battery in - battery out - power from ignition.
An isolator is just a switch. When the engine is running..... it's closed and when the engine is off it's open. A solar system connects directly to the aux battery.

Many of the isolators offered now and in the past were nothing more than diodes that allowed the current to flow in one direction. They ran hot, used power needlessly and didn't allow full voltage to reach the battery so the batteries were never fully charged. I use a basic continuous duty solenoid that connects both batteries together and directly to the alternator.

It can be argued that batteries charge at different rates and using a solenoid is harmful but I have never run across one problem.
 
 

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