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I’ve had several requests to write a 'How-to' for my Dual Battery set up and I finally got it put together. Thanks to ChrisHaynesUSA for keeping my Butt to the Fire, and the others that have encouraged me to write it up. I hope this helps!

A Couple of Things to Keep in Mind:
1. This project is really two projects in one, moving the power steering fluid reservoir and adding the additional electrical.

2. The electrical changes are not particularly difficult but anytime you work around batteries there is a hazard associated with it. Be careful.

3. Because I’m that kind of person, I installed a high-end version that is completely unnecessary, so I will try to differentiate what is really important vs what is actually necessary.

4. Because there are about 40 pictures associated with this write up, I had to link to my Photophucket Album instead of interleaving the pictures with the text. Sorry. That also made it easier for me. Go here for the pictures: Dual Battery Install by Dave Croker | Photobucket > Corrected: Old Navy inserted photos where required.

OK, let’s get to it….


1. Remove the Battery.

2. Lift the PSFR off the Bracket. It is tight, but it should go. I forget if I had to remove any tabs or ties.

3. Unclip Voltage Monitor from Bracket. That let’s you remove the bolt from the top that holds the main Battery Ground Bracket to the Reservoir Bracket. Remove Ground Bracket from Reservoir Bracket and remove the Ground Bracket from Main Ground Cable, (leave the Clamp on the Cable) - (All 10mm).
4. Remove the 3 bolts that hold the Reservoir Bracket, and save them, (All 10mm).

5. Time to remove the PSFR and Hoses. You’ll need to have two empty 16oz Water Bottles handy to collect the Power Steering Fluid that will leak out. I removed the Supply Hose, (the smaller of the two), from the Reservoir first. Quickly place a bottle under the Reservoir Nipple and let it drain, meanwhile holding the Supply Hose up so it doesn’t leak. Once the Reservoir is mostly empty, I put a piece of Duct Tape over the Nipple to prevent more dripping. I then removed the Return Hose, (the larger of the two), from the Reservoir and added a piece of Duct Tape to that Nipple too and set the Reservoir aside. Next I removed the Supply Hose from the Metal “Hose” coming from the Pump, (just to the right of the Battery Tray). This effort is the first place where 'swearing might occur', because it is a tight fit. I had my wife help by holding the free end of the hose while I worked on getting the hose free. I had the other empty Water Bottle down inside the Engine Bay nearby so I could quickly throw it on the Metal Hose End once the Hose was off. A few drops of fluid came out the newly freed end of hose before we could turn it up to prevent more leaks. Then we emptied the Supply Hose into the first Water Bottle and set those aside. The second bottle remained on the end of the Metal Hose until I was ready to install the new hose. Eventually there was about 2-3 ounces of fluid drip into it before I was done. The last step is to remove the Return Hose from the Engine Block. I had no fluid drips with the removal of this hose. I then placed another piece of Duct Tape over the Metal Nipple on the Engine so no foreign particles would accidentally fall in. The two hoses cannot be reused. I don’t have any pics of this step because;

a) I was too occupied with hoses leaking fluid
b) my hands were too slimy


6. Find the unused Slotted Bracket by the Manifold and drill it out to ¼”, (circled in photo below)

7. Find a Bracket that you can use for a Riser for the PSFR Bracket about 1.5” to 2”. I used a Simpson Strong Tie Bracket I had laying around, (see photos and others later). Drill out the Riser Bracket to hold the PSFR Bracket and so it can also attach to the Slotted Bracket from Step 6. Install as in;

So that you can measure for another Support Bracket shown in the Step 8 photos.

8. Cut, drill and bend additional Support Bracket.

I used a Plated Steel Strap 1” wide by 1/8” thick by 4 1/8” long. One end attaches to the PSFR Bracket and the other end to a Threaded Hole that is not being used closer to the front of the vehicle.

This hole accepts 10mm bolts.

9. Assemble the original PSFR Bracket, the Riser Bracket, and the additional Support Bracket with ¼”-20 SS bolts, (mostly 1” and ½” long). Mount Bracket Assembly to the vehicle using a ¼”-20 bolt at the Slotted Bracket from Step 6 and one of the 10mm bolts you removed in Step 4. Final Bracket Assembly here;

10. Remove the large Wiring Bundle from the Restraining Clamp shown in;

and the Bracket that holds it in. You’ll use this same hole (from the Bracket) for your own Hose Clamp in Step 12. Also remove the Ground Lug, (two Black Cables from large Wiring Bundle—also in photo above). Bend the Wiring Harness back to give you more room to route new hoses.

11. Attach the new Return Hose, (9/16” ID, 15/16” OD; P/N Gates 85965F—difficult to find—which is actually Hydraulic Fluid Hose), to Reservoir and measure length allowing for bends and clamps. Mine was 21”. Attach the new Supply Hose, (3/8” ID, 11/16” OD; P/N Gates 350010F which is regular Power Steering Hose), to the Reservoir and measure the length allowing for bends and clamps. Mine was 29”. Note: I allowed for slack in both hoses to allow me to still slip the Reservoir out of the Bracket for future access to the Engine. Cut hoses to length. Once the hoses are the correct length, put Reservoir in its Bracket and feed the hoses through a final time. The Return Hose will slide on easily, but the Supply Hose will not. Lube up the Supply Hose with a little Power Steering Fluid and get ready to 'swear' again. The Metal Hose is loose enough I blocked it with a Wood Block to allow me to push harder without damaging the Metal Hose. Note: Make sure you have the Spring Clamp on before you do this! Secure all Hose Ends with the original Spring Clamps and secure the Reservoir in its Bracket, (I used one long Tie Wrap around the whole Assembly to get it to sit down).

12. Secure the new Hoses to the Frame with Rubber-insulated Clamps, (1” size for return hose, 5/8” for supply). Use the 10mm bolts that you’ve saved to attach the Clamps to the Frame.

13. Protect the new Hoses with Flex Tubing where necessary to avoid unwanted Rubbing.

13a. Refill the PSFR! It took about a bottle and a quarter for me.

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14. Make room for the Aux Battery Tray. Remove the Flange where the Battery Tie Down J-bolt in front used to attach. I don’t have a cut off saw, so I just used brute force, a Chisel, and a Hammer to essentially rip the Flange off. It was held on by a couple Tack Welds. If you have a Chop Saw, that’s probably the way to go.

15. Drill a new hole in Frame for the new Battery Tie Down J-bolt.

Because the drill will be at an angle to the smooth metal and a Hole Punch is difficult to get through the hole, start with a Small Bit and work your way up to a 5/16” hole. The Bit will go through an existing hole, (see above photo). Of course if you have an Angle Drill, this step will be easier as you can come at it from the outside. The new J-bolt will only be ¼”, but a 5/16” hole makes it easier to slip the bolt into.

16. Install the inside Battery Tie Down Point. I used a 2” Plated Steel Angle Bracket and cut one side down to 1”.

The holes in the Bracket were already basically 1/4”, but I reamed them out by another 1/16” or so. Attach the Bracket to the Frame through the existing hole near the Relay Box. You’ll have to drill a ¼” hole in the Plastic Wheel Well Lining. Use ¼” Stainless Steel Bolt and hardware.

17. Fabricate new Battery Trays. NOTE: If you use different Batteries, your dimensions will be different. Follow along for the concept. I used an Optima Yellow Top for my Main (Starter) Battery and an Optima Blue Top for my Auxiliary Battery. Turns out using the Optimas was advantageous due to the rounded corners that allowed for Support Bolts in the corners and ends of the Trays. Other Batteries can work, but you’ll want to spend A LOT of time figuring out if there is room for your style/size of Battery and the Support Bolt System I describe will probably have to be worked around. I suspect a Red Top will fit just as well as a Yellow Top for the Main Battery. The material I used for the Trays was 1/8” Thick Stainless Steel Plate from a local supplier.

17a. Main Battery Plate: Dimensions are 10” x 7.5” on the outside.

Refer to above photo to see how I marked the plate to cut the corners out and then rounded the remaining corners and filed all edges to eliminate sharp edges.

Bend up the sides as shown in the pics. Drill 4 holes: 2 for attaching to the Frame and 2 for Support Bolts.

The Support Bolts are ¼” x 1 5/8” long. Step 21 shows the Tray Mounted, but you don’t want to mount it permanently just yet.

17b. Auxiliary Battery Tray: Dimensions are 11.75” x 7.75” on the outside.

Refer to above photos on how I marked, cut, bent, and drilled the Plate. The Support Bolt is ¼” x 5.5” long, which goes in the front left corner. I also added an Angle Bracket to the right side of the Tray on the underside to help support the right side of the Tray. The Bracket just rests against the Frame to the right of where you drilled the new front J-bolt, and just helps keep the right side of the Tray from bending so much. This may not be necessary, but I think it also helps hold the Tray in place.

Refer to above photos on how the Aux Battery Tray assembled. Step 23 shows the Tray Mounted to the Frame, but don’t do that yet.

18. Trim back Split Loom Tubing on large Wiring Bundle that goes to the Positive Battery Terminal to allow more slack on the two Ground Wires that are part of the bundle. Cut a 9” long Piece of #4 AWG Wire, and add ¼” Lugs to both ends. Add new Split Loom to both the new #4 Wire and the original two Ground Wires. Use a ¼” x 1” long Stainless Steel Bolt to connect the original Ground Wires and one end of the new #4 Wire to the Angled Ground Clamp on the Negative Battery Lead.

Use one of the 10mm Bolts you’ve saved to attach the other end of the new #4 Wire to the Frame, (I cleaned up the bolt hole area with a Wire Brush on a Dremel to ensure a good Electrical Contact). Cut off the very end of the 'cheesy' Negative Battery Terminal and crimp on a new #4 x 5/16” Lug. This lug will fit on the new Negative Main Battery Terminal that you purchase. (see Step 23).

19. Follow the Main Negative Lead back to the Engine Block and unbolt the Main Bolt (12mm). Install a new #2 AWG Wire with a 5/16” Lug on one end, (to fit over the 12mm Lug), to that Main Engine Block Ground Point and bolt the two Ground Leads under the one 12mm Bolt, (make sure the OEM Lug is shiny clean and clean the bolt). The length of the new #2 depends on whether you do the simple install or the high-end install that I did. I used a piece about 24” long to thread between the two Batteries to the Negative Power Post. For the simple install, the other end of the wire can go straight to the Negative Terminal on the Aux Battery.

20. Remove the Positive Battery Terminal from the Large Harness that includes all of the Fuses, (cheap piece of crap). I had to soak the bolt for a while to get it to break free. Thoroughly clean the Plate that it attached to.

(For high-end install only) - Remove the Alternator Lead from the Positive Battery Fuse Harness, (it’s the one on the left that feeds the 140A Fuse). You’ll need to cut the Alternator Wire back an inch or two and add a new #2 x 5/16” Lug.

21. Install the Main Battery Tray.

22. (For high-end install only) - Build a Wood board as shown in Step 23 to attach the Negative Power Post and, (if wanted), Shunt. My pictures show a Solenoid Attached on a piece of wood in the vertical position. The Solenoid is part of the Warn Quick Connector Remote Cut Off Switch that Mounts inside the Cab. If you don’t have one or don't care to install one, ignore that part of the build. I protected the wood with a couple coats of Clear Acrylic. This board and the Aux Battery Tray share the same hole in the Frame.

22a. (For high-end install only) - Install Negative Power Post and, (if wanted), Shunt to board, (this Shunt is used to Monitor the Current Flow to or from the Aux Battery). Install Copper Strap between Power Post and Shunt and protect it with Shrink Tubing. If you have a Solenoid like me, install it now.

23. Install Aux Battery Tray and, (if used), Wood Block from Step 22. This requires drilling a ¼” hole through the Frame into the Wheel Well. After drilling the hole, I used that as a guide to cut away more of the Plastic Lining inside the Wheel Well with a Utility Knife so that the bolt head, (1/4” x 1” or 1.5” depending on whether you installed the Wood Block), and a nice big washer can sit flush with the Frame.

At this point, it is hard for me to describe what to do because everyone will have a different reason for adding a Second Battery. I wanted an Aux Battery mainly to run accessories like a 12V Fridge, CB/Ham Radios, and my Air Compressor. I also added the Shunts for Monitoring Current and Voltage and a Solenoid to Remotely turn 'ON' and 'OFF' my Warn Quick Connectors front and rear.

These photos will show the Final Electrical Hookup that I did.

Wiring Diagrams 1 and 2 show my Wiring Diagram and a Simplified Wiring Diagram respectively.

Wiring Diagram 3 shows the Alternate Grounding scheme that I’m considering trying due to the Variable Voltage Monitor complication, (have not tried it yet). The wiring diagrams have fairly complete parts lists, at least for the major items. I know they are missing some things.

I will, however, describe the Battery Tie Down that I came up with because that will apply to everyone:

24. Buy new 8” and 10” J-bolts. The 10” is for the front and the rear is 8", (the measured length of the rear bolt is 6.25” after I cut it down, so you might be able to get by with a 6” J-bolt instead). I used Double-slotted Closet Shelving Rails that I had laying around, and they worked great. Cut two lengths, one 6.75” long and the other 9.25” long. The 6.75” piece goes over the Aux Battery, labeled “Blue Side”, (in pics 36 & 37). Drill one hole at each end of each piece to accept the J-bolts. Then drill 2 holes in the other ends of each piece that line up with each other. Note: The orientation of the Brackets in the pictures as they are opposite each other. Use 1.5” long ¼” bolts with extra nuts and washers to bolt the two pieces together (pic38). Lastly, I had to cut and drill a short piece of Metal Strapping for the wing nut on the rear J-bolt (pic36).

More Notes below. Cheers!

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Additional 'How-to' Notes:

1) You’ll need a big Wire Crimper for Lugs of this size. Don’t cheap out—it’s not worth it. They’re expensive, so borrow one from a friend or neighbor like I did.

2) I ultimately decided on using the Battery Isolator from Hellroaring Technologies, (P/N 95150B). I liked the Solid State quality and the Low Current Draw and clean power that it provides. But just as importantly, it is at least half the size as any store-bought Isolator, and under the hood of the Xterra, there’s not enough room for anything larger, (I first bought a Warn Isolator, but just laughed when I held it up to the Engine Compartment). Solenoids are also commonly used for Battery Isolators. The best that I found was from National Luna. I forget exactly why I decided against it. If you are willing to do the simple install and don’t want to have a piece of Wood Floating on your Fuse Box, you could probably install the Solenoid where I installed mine for the Warn Quick Connectors. That could make for a nice compact install.

3) Through communications with the kind folks at Hellroaring, it was clear that their Isolator is not capable of the Currents that could be produced by the Alternator in most of the 2nd Generation X’s, so self-jumping and winching are not recommended through the Isolator. That’s why my Warn Winch Connectors come off of the Main Battery and one reason why I installed the Heavy-duty Battery Switch which Bypasses the Isolator. The Switch also allows you to isolate the Aux Battery from the Main Battery which can add a factor of safety during Battery replacements and other wiring operations.

4) I also found out that the Blue Sea Shunt-shifters are being discontinued, (the little board attached to the side of the Shunt in (pic35) that allows you to install the Shunt on the Positive Lead instead of the customary Negative Lead that you see in (pic34). Customer Service couldn’t tell me if they were being replaced by something else, or what. That could be a real problem if you want to Monitor Current from the Alternator.

5) I bought all my Cable from my local West Marine Store. I prefer their cable as it’s made for the Marine Environment and it’s high quality, (and pricey!). And you can get it by the foot. However, choose whatever wire you want. Nissan uses #2 AWG for the Positive Lead from the Alternator and #4 AWG from the Engine Block, but I used #2 on both. Reading the various charts on Current/Wire Gauge/Length, I feel confident that #2 is plenty good enough (overkill) for all the connections.

6) I also bought all my Wire Lugs at West Marine for the same reasons. Likewise, most of the other parts are from Blue Sea.

7) The Copper Straps were used to simplify the installation in places where wire would be far too short, difficult to work with, or expensive. I bought a piece of 1” wide, 1/64” thick solid Copper from the same supplier where I got the Stainless Steel Plate. I only used about half of a 3’ long strip. It’s easy to work with using tin snips.

8) I’m still trying to gauge how the OEM Voltage Monitor affects the charging of the Second Battery. I have used the system with and without the Voltage Monitor installed as shown in Diagram 1 with different results, neither of which seems ideal. I have one more idea to try, and that’s shown in Diagram 3.

9) Use Shrink Tubing and the Split-loom Tubing liberally. In all my pictures, Red is Positive and Black is Negative.

10) The labels you see in the pictures are actually from Radio Shack. They are sold in a small package. You write on one end and then wrap a clear flap around the cable to cover the writing. Slick. (Radio Shack P/N 278-1616).

11) And, if you have any doubts about the robustness of the install as a whole, it survived a week of running around northern Death Valley, including the Lippencott Road and miles of washboard on the Saline Valley Road without moving a peep.

Have fun with it!


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Nice, I've been waiting for this; thanks for writing it up. I haven't gone through it yet, so I'm responding mostly just to get subscribed. I need to take some time and go through your write up and pictures.

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On the cable crimper, something I ve done for years in the absence of a crimping tool is
heat the lug in a vise with propane or any torch. melt solder in to fill halfway up. with the cable prep done already(stripped, and heat shrink slid back on the cable, I prefer the watertight glue variety) stick the cable in the lug with the molten solder. then useing a center punch. punch (as needed to tighten the lug) the lug which will crimp the cable very tight too. Everyone do yourself a favor and use the correct size lugs and cable either way you build the cables. then slip up the heat shrink, shrink it and your done. this also makes a no ohm (no resistance), water tight, strong cable end also and is a great field or shop repair.

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Discussion Starter · #14 ·
How long did this install take you?
Good question. I debated about whether to say in the write up, but couldn't decide what to put. So many of the steps took research, and then add in the 400 trips to the hardware/autoparts/marine store (in my wife's car since mine was conveniently missing a battery), it's really hard to say. It also depends on what version of the build you want to do.

My guess is that if you had all the parts and tools ready and just wanted to do a simple install, you might finish in a weekend. Or if you are someone who lives by the mantra "measure once, then wing it" you might get it done in one weekend. On the other hand, I could see this easily moving into the full two weekends realm. This build took me at least 2 months of weekends, but that also counts installing the multimeter in the cab and making some other wiring adjustments at the same time.

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Discussion Starter · #20 ·
Thanks XJ-TERRA and Randwulf. My wife gives me a hard time about some of the projects I do, but then is quite appreciative when we pull a cold soda and lunch out of the fridge. :D

chrishaynesusa has taken the dual battery setup and simplified it and professionalized it. Take a look at his thread for more ideas.
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