As many have done above, I could do away with the large foam insert and build a false floor for the system and mount the battery in the lower left space (remove bracket and relocate towing module)... or I've measured and created templates for the electronics and found a slightly more compact LiFePO4 battery, so I'm thinking I could fit everything into the storage compartment of the foam insert. Thus allowing me a little less "permanent" solution for future resale or "too much modification" for the dealer to gripe about if it needs to go in for service. I don't know how much heat all of this will produce and if being contained in the foam tray will build up considerably more heat than the false plywood floor solution? I could cut some "vent holes" in the sides of the foam insert, especially near the fans to all a little heat to escape. This you-tuber did the foam insert installation and claims to have no heat problems ( ).

 

Loving this thread!! "One Day" I'll start putzing around with either putting better storage in that area or a dual battery. Seen lots of great attempts, but nothing that really "fits" my MHEV and my needs/wants. So, keep at it and love to see how it turns out!

 

Have recently been reading this thread and trying to set up my own dual battery system in my p400. When comparing with other images in this treat I seem to have two of this box circled in green which really limits my space for the battery. Does anyone know what this is for? Can I move it out of the way?

Will post more pictures as I troubleshoot this project. Am trying to use the ultramax 100ah battery but it’s absolutely huge! I think the renogy smart battery without Bluetooth may have fit better for anyone trying this in the future.

 

Hi all,

So I’ve been following this thread for a while and have been working on my own dual battery set up. Used the mild hybrid 12v on the rear and connected it to a ctek 250SE and then my lithium battery. It works amazingly and didn’t need to connect the alternator cable as the mild hybrid battery turns the voltage down from 14V to 12V when the engine is off so you don’t drain the starter battery. Am really very happy how it’s turned out.

 

I just saw this. I might be too late, but I have P400 and simply moved it out of the way.

 

thanks very much for this! In the end I went for a different location for battery which seems to have worked for me but eats a lot into space for storing other things such as the jack. Have found a solution by sticking the jack on the place where the air pump is in some models as I don’t have an air pump.

Have also tried out a Wi-Fi relay switch to control my side lights which has worked out very well! Highly recommend if ppl don’t want to screw into panels to put switches in.

 

Haven't seen any activity on this thread lately. I thought I would post what I did for my dual battery system. The main reason for the dual battery is so I can run a fridge and have a couple of extra 12vdc outlets that don't drain the main battery.

1st I had to remove the third row in my defender. Nothing special here to do that. There are a couple of threads already posted about that from others. My Defender has the mild electric hybrid system, so I needed to make a platform to go over that. Because I had a third row there were some bolts holes that I could use. In the bottom of the picture you can see some aluminum brackets I made. I just took some aluminum flat bar stock and bent them to fit. At the top of the picture I have some threaded rods that were used to temporary hold everything in place. Those have since been replaced with the factory bolts and the AC duct put back. Also I removed the platform area near the compressor to make room for the battery.


After I got the platform right I covered it in carpet and then preceded to install the electronics for the dual battery system. As others have done I connected to the output of the 48v to 12v system that is part of the mild electric hybrid system which is located immediately below the platform. The grey anderson connected on the right side of the picture is the disconnect for that wiring. The negative wire in that connector goes directly back to the battery. From that connector I go to a circuit breaker and then split the wires. One wire goes to the renogy 50a DC to DC charger. I got this supper cheap on facebook marketplace, $75, brand new. The other wire goes to a relay that I can turn on and off to control a 50a anderson connector mounted next to the 7pin for my off road trailer.

The renogy charge controller also has an input for a solar panel. I have that connected to a cascadia hood mount 75 watt solar panel. From the renogy I go through another circuit breaker and the to the battery. I also got that battery for cheap on facebook marketplace. The battery is mounted in a similar place as other have mounted it. I had to move the trailer wiring control box. The battery then goes to another circuit breaker and low load disconnect and eventually to a distribution block ( red horizontal piece at the top of the picture). The distribution block feeds a blue sea fuse block and Auxbeam switch controller. The auxbeam switch controller control panel is mounted to the left of the steering wheel and controls the relay for the trailer charging circuit and a light for the rear area. Eventually I will use remaining switches for exterior lighting.

The fuse block is used for some auxiliary usb chargers and 12vdc connectors. The vertical distribution block on the top right is used to distribute a 12vdc ignition signal, coming from a fuse tap, to various devices that require that signal. The three relay blocks in the middle of the picture are used for two things. One block is used to only enable the relay for the trailer charging circuit when the ignition is on. The other two relays are used to allow me to turn on a light in the back from either the cars battery (when the doors open) or from the second battery.



For the time being I have cut out a piece of plywood to cover all this. I am looking for something better. Considering the goose gear platform system, but not entirely sold on that.

 

This is a really nice set up! The platform is great and you’ve managed to get a lot of things going on. I also recently bought a hood mounted solar panel but am struggling to find a way to route the cable from the hood of the car to the back where my CTEK is. How did you manage to run that cable from the hood of the car to the trunk?

 

Thanks. I wanted to go with the redarc redvision system like other have done but when the renogy device popped up for sale i couldn't resist. All in, including the battery, I maybe spent $1,000. The redarc system starts at $2,300 and no battery or other ancillary equipment. Though it would make the install cleaner and have more space available. Not sure what I am going to do if I want to add an inverter.

I looked long and hard for a place to get through the firewall. I did notice there was a rubber grommet on the left side of the driver footwell way up high. Looks like it comes out near the engine air intake. I couldn't figure out where it came out in the engine bay though. In the end I went through the steering column grommet like others have done. This is a huge grommet. It is probably 10" high and the steering column is down in the lower half. In the picture below taken from the engine bay you can't even see the steering column. The picture from the inside is taken from about the brake pedal. You have to peel back the flooring and the insulating material to get to the grommet. I just poked a hole through the top part of that. Be careful when doing that, I pushed a little to hard and popped the rubber out of the plastic plate holding it on. In the picture you can see daylight where the grommet should be. I had to loosen the bolts for the plastic plate in the engine bay to get the grommet to reseat properly.

Once in the footwell I routed the wire over to the side and ran it down along base trim to the back. There is a nice channel below that trim to run the wire.

 

As a thank you to everyone who posted all of this excellent information, I am reviving this thread. I finally got my second battery system installed into my storage space. I will admit that it took a lot longer than I expected. I went with the Redarc TVMS, Manager30 and 2000w Pure Sine Inverter, and added a BigBattery Owl Max 228aH lithium battery. With the additional size of the battery and the inverter, I had a challenge ahead of me, as I wanted to maintain enough room to store my jack and recovery kit under the load space flooring. Figuring this out took a lot of trial and error. I am embarrassed at how many failed attempts I made, but I learned a ton along the way. One thing I learned, the hard way, was that the depth is not consistent from from to back. At one point I had the inverter mounted next to my battery and it turned out that it was like 1mm too tall there!
In my past, I have built some server racks and came up with the idea to get 2 ventilated rack shelves 19”x8” and 4 4U rack posts and build a mini rack. This allowed me to use some vertical space.

TVMS on top shelf with Manager30 underneath. I chose to use some Anderson connectors for the house battery and the inverter to make it easier to remove, if needed.

I mounted the positive and ground blocks to the side, and put the Redarc battery monitor and 80amp fuse on top with the TVMS.


The final install, with battery and inverter.




Still more to do,to wire in the starter battery, ignition trigger, and my solar panel inputs, but I am very relieved to have this part completed!