Dual Battery Setup

WHY?   Power.  It takes lots of it to operate all the gadgets I'm hanging on this beast and the stock battery and stator aren't always up to the task.  One solution that's been used by off-roaders for years is to add a second battery to handle the load, so I decided to go that route.  There is plenty of spare room under the Rhino's front compartment and several aftermarket manufacturers produce battery boxes to fit there; I chose a nice-looking unit that I found on eBay.  This box fits between the top frame rails and is sized to fit a group 24 battery.  Here's a shot of the box:

To carry the electrical load I chose a group 24 deep-cycle battery; it's not designed for a starting load, but should carry all the accessories I'll add and will withstand the rigors of regular charging and discharging. 

Next I needed to add a battery separator/isolator and I chose the Sure Power #1314.  This unit allows the two batteries to be charged from one source but separated when they are not charging.  When the primary  battery is attached to a charging source and reaches a charge of 13.2 volts the isolator sends the charge to the second battery.  This prevents the primary battery from being discharged when the auxiliary battery is under load.  To round out the system I picked up a fuse block with relay; this unit enables me to power four accessories with switched power and three with constant hot.  After picking up various cables and wiring terminals I was ready for installation.

SERVICE. Not an issue here--I'm just evaluating several individual pieces.

INSTALLATION. I'm a minister and not an electrical engineer, but I finished this job in a little over an hour.  It shouldn't be too difficult for the average mechanic with a set of tools and some experience in working with 12v wiring.  Here's how I proceeded:

1.  Install the battery box; this one dropped in place like it was made to go there.  I installed the battery and held it in place with an aftermarket clamp.

2.  Mount the battery isolator.  I placed it on the frame cross-rail behind the radiator (see pic below).

3.  Mount the fuse block and relay.  I placed both on the top cross-rail (see pic) because that location seemed to offer at least some protection.  Now to get everything hooked together...

4.  Connect the positive terminal on the auxiliary battery to the auxiliary terminal on the battery isolator then connect the positive terminal of the primary battery to the primary terminal on the isolator, using at least 6-gauge cables for both connections.  Connect the negative terminals of both batteries.  Run a ground wire from the Battery isolator to a good ground on the Rhino's frame.  When you make this connection you will hear the solenoid on the isolator click.

5.  When you mount the fuse block to the frame it will ground itself; connect the 10-gauge positive connection to the included relay and connect the relay to the positive terminal on the auxiliary battery and the small-gauge wire to a source of switched power (a fuse tap is included with the fuse block).  Any accessories you wish to power can now be connected to either switched or always-hot power via the leads on the fuse block.  Now my winch and accessory lights are powered by the auxiliary battery with no danger of over-taxing the primary battery.  Here's how the setup looks:

Here are most of the working parts

Here's a look at the new fuse block

RESULTS.  Fantastic!  Now I can operate all my accessories with no fear of dragging down my primary battery.  When my Rhino's not in use I leave it connected to a battery tender, so both batteries are always charged and ready to go.  All circuits are protected with fuses and relays.  As an added bonus the Sure Power isolator has a feature that joins the two batteries when the engine is started, effectively allowing you to carry your own jumper system with you.

WORTH THE MONEY?  Absolutely.  This entire setup cost me about $300--not cheap, but it definitely was a bargain for me.  The system should be rock-solid reliable and provide power for any accessories I wish to add without stressing or damaging the stock battery and charging system.  Money well spent as far as I'm concerned!