LR3: My dual battery / auxiliary battery install
 

I will update this thread as I finish this project. Today I just fitted the battery into the second bay. This is a US LHD model LR3 - 2006.

The first thing was to get a battery that would fit. Many threads, many comments. Some battery sizes I could not locate in the US. I ended up with a 40R. The size, 40R, has the "euro" top which works with the factory hold-down. And while this battery is physically smaller than the main battery the capacity remains pretty much the same. 800CS, 650CCA. So I have matched batteries. NAPA Auto Parts carries the 40R for $125 USD. If you have a Sam's Club, you can pick up a 40R from Duracell for just $100 USD. You can also use a regular group 40. The R means reverse terminals, which for how I am positioning the battery and routing wires was ideal. This battery is a wet cell lead acid starting battery. Its NOT a deep cycle. Because I dont camp much this works fine. I usually stay at a place for just one night. And even if I stress the battery enough to kill it, I should get at least three years out of it. Battery has a 75 month warranty. I assume the is some prorated coverage after the first year.


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But the battery will be wired for jump starting, winch assist, and house power via 4awg lines to the rear. To assist in charging and switching power for jumping/winching the main batter I have a Blue Sea ML-ACR (model: 7622). I bought this particular kit after looking at the popular Traxide solenoid for a couple reasons. First the Blue Sea solenoid was about the same price since I will be making all my own cables. Second, its IP67 rated. This means it can take pressurized water, like from a pressure washer, just fine as well as be submerged for 30 minutes. Traxide fails to mention any IP rating. Third it can operate up to 500amps continuous. I will never push the amp rating that far, but the Traxide is rated for only 160amp and I dont believe continuous. This may not be a big deal, but if I am winching and want all the power I can get I want to be certain its there safely. The best price for these was from Amazon for about $200. It includes a remote switch, standard carling style. I will have to extend the cable.
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INSTALL:

So today I deiced to at least get the battery fitted into the second bay. If you are going for the largest battery that will fit, like I did, you need to make some minor modifications to the battery compartment base. On the forward end there are some support ribs that must be removed. I removed half the base and with careful Dremel work took them off. For the three remaining on the other half base, same deal. I just did so with the base installed. Make sure you smooth things out. The plastic is very hard and I feel its possible burs could cut into the battery shell. Before final install, I will be placing some compression foam to support the battery and snug it up.

As you can see in the pics, there is still about a quarter to half inch gap between the battery and master cylinder. I will be installing some dense foam on that side of the battery. I may even insert some studs in the compartment base to prevent the battery from sliding backwards into the master cylinder. But for now I am happy with how much clearance there is. I test fit the cover and there was no issue, plenty of room. The one mistake I made was to purchase a battery hold down for an LR3 that stated it was for the second bay. They are not the same, you need different holders for each side. So I am off to purchase the proper one now. I know I could make my own but I much prefer the security of the original design.

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The battery hold-down is YJF500100R. Some people sell them with the long bolts, some not. On eBay a kit is a whopping $50. Total rip-off. But there are not a ton of reliable sources in the US. Im still looking around for a better price.

edit: Bought the one on eBay. They have several available. All new with bolts.

Using that part number, I found a listing that I had seen earlier at BPUtah for the bracket and both bolts for LHD for $40 plus shipping. Is that same thing you Found on eBay?
British Parts of Utah

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So while I was waiting for my exhaust to cool, I took a few minutes to install the battery itself. Thus, not much to report right now. The battery is shorter than stock, so I picked up a couple thick nylon washers that worked perfectly! I also installed a bit of foam. It compresses a lot. So it sorta acts as a cushion pad but also to prevent the battery from shifting. So now the battery is very well secured. I dont feel it would hit he master cylinder at all. Coming up soon will be the solenoid and cable installation.



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If you are handy with basic metal work and can find metric threaded rod, I have seen some use a simple piece of flat metal. Inch or two wide. Drill a couple holes and then just a couple nuts on the top end of the thread. Paint it black to look pretty. Simple but effective and very low profile.

You know that the CCA rating means little when using it as an auxiliary, what is the amp hour rating of the battery ?

Yes, I know what I am doing.

20% off at NAPA for AAA members this month brings the out-the-door price down to <$100

when I installed my aux battery I got the 'reversed' battery hold down from the LR dealer.

Install complete and working. Although I have one more wire to connect for engine start isolation. Upon starting, it will delay connecting for 3 to 5 minutes. Right now it connects after about 30 seconds. Really no real reason to add this function other than to get the starting battery a head start on charing. This feature is more designed for boats where engine cranking takes longer and can result in power fluctuations that may harm equipment on the house power.

Another thing I want to go back to is removal of a bit of plastic on the lower section of the battery tray. The relay is mounted up against here and the bottom portion bumps out for the upper secant to sit into. This extra plastic is pushing the bottom of the relay out about 1.5mm and in turn pushes the relay against the battery holder. I think if I remove this bit things will fit just a little better. That white connector holder was of course removed.


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Cables:

I am using 1/0 (0 awg) copper welding cable. Its very flexible and not terribly expensive. Its designed for high temp and high voltage. Its often sold as automotive battery cable. I purchased a hydraulic crimper from Amazon for about $40 USD. It works brilliantly! Just be certain to get one with the sized fitting you need, some only have fitting for smaller diameter wires. With each lug end I installed two layers of glue-lined shrink tubing. One small piece at the connection, one longer piece that is the appropriate color (negative/positive). The tubing I bought has a high shrink rate of 3 times, so it will accommodate 0 awg down to probably 6 awg. Certainly works on 4 awg.

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First piece of shrink tube.

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Second pice of shrink tube.

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Complete cable with shielding. Using shrink tube for securing shielding works great and looks factory.

Mounting the relay:

The Blue Seas 7622 relay is rather bulky and water sealed, but I wanted it in a place where it was somewhat protected for water and heat. I also did not want the over-ride switch on top to get full of fine silt, dust making it difficult to operate if needed. The only location I could find was this small back cubby in the second battery bay. The fitment is incredibly tight.

I had to actually cut two small holes to accommodate the remote wire connection. One hole for the cable to go straight down and a second to bring the cable back into the battery box. Only one hole pictured here. CAREFUL when drilling as your AC lines are right behind this area. Putting something behind is recommenced.

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For final fitment I had to Dremel away the upper right corner of the relay, where a mounting hole is, to accommodate the vacuum line seen above. Also you will need to install a ground wire from the relay harness to your aux battery ground point. This is part of the voltage sense, so it's required. If you look below you can see a pic of the ground wire with eyelet on the chassis ground point.

Cable install/routing:

The relay cables were the hardest and room was tight. Keep in mind with this install setup there is virtually no room to get to the studs on the relay. So you must attach and secure the cable before mounting the relay. Although I found I can snap the housing loose and lift the relay a little to work the nuts. Both positive leads had to be run towards the firewall. For the left stud I used a standard flat cable lug and one hex jam nut (a thin nut) to act as an extra spacer on the stud. Then another jam nut to secure the lug. For the relay's right lug, I used a 45 degree cable lug to direct the cable upwards. When tightening both cables, I made sure there was room between them to prevent contact.


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The negative lead simply connects to the second ground point form the factory. Its a dead match for the one used on the main starting battery.


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The primary positive lead runs along the cowl to the main starting battery. I covered it in shielding mainly to keep the engine bay look clean. A little Dremel action on the plastic battery box separator to run the cable through.
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And that is pretty much it for the main part of the project. Once all was fitted I used a single metal rivet to secure the relay in place. The remote switch install, which is optional, has LEDs that give status of the system. That install involved a larger project for accessories and I will cover it in another thread. But you only need to really run three wires into the cabin. If you look above you can see I ran a 12-wire cable. In that bundle I ran the red wire and yellow wire from the relay harness. Then a third wire that gets positive power from the aux battery. You can not use positive power form anywhere but the aux battery. If you try, the switch many illuminate but it will not function properly.

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Here are some large, random pics to give some extra details:

Remote switch location:

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I like that switch panel. Custom?

Not custom, but no longer made. Sold out pretty much since they made the first batch or so. And I really like these. You can find other brands now, but they switches are straight up and down. What that does it make for an INCREDIBLY tight install behind the switches. These are angled a bit, the bottom of the switch panel kicks out. This helps by giving more room in back for wires. I you google search "rover LR3 switch panel" you can probably locate other sources. I think Proud Rhino is one brand.

https://carrs4x4.com/products/lr3-6-...b-charger-4-2v