neverEnoughRice's Dual Battery Mod

Hey everybody! I recently finished my dual battery mod and I wanted to post my write up. I will start with the parts list and schematic:


This list does not include the extra tools or hardware I had to purchase. Now for the write up:

I first started with drilling the blank Powertray so I could place the Victron DC-DC Charger and the 30 Amp circuit breaker in the engine bay in between the fuse box and master brake cylinder. The tray is 5052 Aluminum so it was relatively easy to drill with titanium bits, this video helped (I later had to drill another set of holes after putting the tray in the engine bay and realizing that the hood strut was making contact with the Victron when I closed the hood. After making the adjustment, no more interference with the hood strut.): https://www.youtube.com/watch?v=Fu6Mdrp8fy8

Once I placed the charger and circuit breaker on the tray, I put them to the side so I could move the relay box over to make room for the tray. I followed this guide on the Powertray website (https://www.powertrays.com/pages/2020-4runner-relay-box-relocation).






Once that was complete and made sure the tray fit, I began to run the 6 gauge wires through the gasket. Using a metal wire hanger as a fish, I poked a hole through the gasket after reading that it would be more waterproof than drilling a hole and some sealant. It took a good amount of pulling the wire through and pushing the gasket back in to get the desired result but eventually it was completed in about 10 minutes for each wire.





I then began to install the tray where the small relay box was, which was much more difficult than I first expected. I ended up having to buy a set of universal socket joints in order to tighten the bolts to the fender. I would also recommend having a magnetic pickup tool just in case you drop one of the bolts/nuts, I’m glad I had one on hand. After everything was tightened down, I stripped the wires that I just pulled through. The black wire was directly attached to the Victron and the red one was prepped to be attached to the 30 Amp breaker using the 6 AWG, 1/4” hole lugs. I used heat shrink with adhesive inside to form a watertight connection.





Moving on to the starter battery, I placed the 40 Amp breaker on the fuse box cover. Using the 6 gauge cables and the matching 5/16” and 1/4” lugs, I connected the starter to the DC-DC. With that complete, everything I needed to do in the engine bay is done.






Up next I start to route the cables under the driver side trim all the way to the trunk by the bottle jack and terminate them with a set of the Anderson Plugs. This was by far the most difficult part compared to the rest of the mod. I originally thought to use a split wire loom for the entire run but the parts of trim where the door steps were had issues with extra plastic pieces that were supposed to hold the existing wire harness in place. Instead of cutting these pieces off, I just fit the wires right next to the harness, under the “clamps;” I did have to remove the wire loom in that area though. In order to get through the B pillar, I had to unscrew the seatbelt bolt and pull off the trim slightly. All I had to do to get it off was press in from the sides which released some tabs holding it in place. There was a small wire in this area that I had to be careful not to damage.










Once through and wired under the passenger area door step trim, the biggest hurdle was in front of me. Originally I planned to fish the wires through the trim and pop the storage tray to help it along. After reading forums( ) and watching a video from Think Adventure in which he showed that there are screws that hold it in place. I decided against it as I did not want to break the brackets: https://www.youtube.com/watch?v=i5h66oVnEdk

I watched another video, this time from Overland Engineer, for an idea of how to get the trim off: https://www.youtube.com/watch?v=X5TecFoA_Y4

Unfortunately in the process I damaged a plastic pin that was holding the trim to the body. It worked out in the end because the door step trim kept the part in place when I put everything back together. There were a couple of these trim-to-body pins and I didn’t have an good way to get them out without damage so I decided not to try and take the whole rear trim off but instead try to fish the cables through with the wire hangar. There are also a few small wires in this area that I had to be careful not to damage, one of which I assumed to be part of the air bag. It was easier taking off the door frame gasket to give myself some room between the trim and the body. I also found and better way to remove the seat adjustment lever; instead of trying to pop it out with a tool, just push it to the left with some steady force and it should come out easily.







After fishing the cables around the seat adjustment rail and through the empty area behind the jack, I was finally able to bring the wires out into the trunk space. The black cable is longer because I used some of the red cable on the 30 Amp breaker next to the DC-DC Charger. I considered cutting it off but decided against it. I then crimped on the Anderson Powerpole terminals to the ends and installed them into the housing. Hardest part of the mod was complete!

Moving on to the battery, I originally used approximately 1 foot of 6AWG wire to install on to the battery terminals but I had to move them elsewhere when I realized I had no way to measure the current battery capacity. I ordered and installed a Victron SmartShunt 500A, placed it as close as possible to the negative terminal and installed the black charging wire to the ‘System Minus’ end.

After setting up the devices from the VictronConnect App on my tablet, the system is ready to get charged from my car. After a few rounds of driving, it looks like everything works excellently and the aux battery is fully charged! It was now time to order the inverter and I move on to building a setup to hold the battery and inverter out of spare wooden slats I had from a previous bed frame. The planning took longer than I thought, with a few modifications after putting it all together but it works perfectly (i.e. I had to shorten the vertical blocks because the trunk tonneau cover case was interfering with the inverter going in all the way). The battery is removable and the inverter is screwed in at the top. The wiring is a bit messy at the moment but that will be fixed once I buy the bus bars and cut some of the 1/0 cable down to size. The setup is held down with some Husky ratchet straps.















Total weight is about 60 lbs but so far it is stable when lifting it from the wooden “handles.” I would say it took 12-16 hrs for me, spread out over 2 weeks, from assembling all the materials to finishing the battery “container.” Values in the Victron app show a <1% voltage drop (~0.08V; 29.2V at charger, 29.12V at battery) from the charger to the battery and the inverter is able to run all of my AC devices without problems (Laptop chargers, instant pots (3qt & 8qt), rice cooker, electric skillet, 1500W space heater, and more). Each outlet says its 1500W max but it has stayed around 1600-1700W without shutting down. I will probably attach a receptacle or high current power strip to the hardwire output to safely use >1500W devices in the future, so far only one appliance would use that much. I considered placing the battery + inverter setup in a Plano trunk but I will see if I need to. As a note, the inverter input terminal studs are 1/4” in size. I looked all over for that info but I wasn’t able to find it, thankfully I had a few extra terminals since the circuit breaker studs were the same size. The inverter is grounded to chassis using the 14AWG wire that came with it, I just terminated it with a 14AWG, M6 ring terminal that I purchased online. The eye bolts are M6 plain steel that I also purchased online. I ran the remote power on/off cable via the passenger side floor area to the center console so I could easily turn it on and off from the driver's seat.

After a few months on use from March to July, I can safely say that I have encountered no issues from the system. The DC-DC Converter works perfectly inside the engine bay, even on hot days, and I have not seen any de-rating. I haven’t encountered too much freezing weather so I can’t comment on that performance yet, but from my research it seems the only thing I can’t do is charge it under 32 degrees F. The double sided tape on the circuit breaker in the engine bay also seems to be holding up.

Concerns:

- Since the circuit breakers are thethermally responsive bi-metal blade type, there could be an issue placing them in the engine bay. (So far 30 minutes of driving in the <50 degrees F are fine but I will have to see how they perform in the summer.)

- The DC-DC charger is only rated IP43 as well as a max operating temperature of 55C and derates current above 40C which could be an issue being located in the engine bay as well. (After driving a few times in heavy rain, it looks like no water is intruding into the engine bay that would cause concerns.)

- Currently using double-sided tape with the 40 Amp Breaker in the engine bay, I’m not sure it will hold up in that environment. (Some issues so far with the tape not adhering to the fuse box cover, the 6AWG cable helps to keep it from moving too much though.)

- It takes about 6.6 hrs total to charge the battery from empty, I’m not sure how much this would stress the alternator but I will probably have a solar set up before I use the battery enough to consistently drain it to empty.

Future Plans:

- Solar + its components

- Add socket for 3000W inverter output

- 24V to 12V converter

- Fuse blocks for DC accessories

- DC fridge

- Upgrade to Redarc DC-DC if the Victron can’t handle the engine bay

- Add heating pads to battery for below freezing temperatures

- Drill holes and add grommets for trunk wires, and a general prettying up of cables.

- Migrate the setup to a Plano Box

Hope this helps some people with their own dual battery mod!

 

This is a really good write up. Thanks for taking the time to share with the forum!

 

Nice setup, I have a similar but 12v SOK and Redarc BCDC and if I was to do it again I'd pick Victron DCDC+Solar controllers vs the Redarc.

The seamless integration and monitoring of each of those components is nice, I have a Victron shunt and can see the amps/volts in and out but being able to see how much solar I am producing independently of the house battery usage would be better its all a blackbox with the redarc, and be able to adjust the bulk and absorption rates.

6 awg is prob perfect, I used 4 awg and do see it gets warm but my charger is more than double your amps.

I don't believe those Orion water protected so I would keep watch of that. I don't believe heat is gonna be too much of an issue but I seen the engine bay reach go past of the Orion's operating temp ranges (I have a spod in the same spot and it has temp monitoring). You could just move next to your battery (that is preferred the charge being closer to the house battery vs starter).

 

Wow!! What a great piece of work.

 

What’s going on with that yellow wire bolted at the cargo area dry cleaning hook…..

 

Inverter ground i am thinking.

 

Curious why it’s up there and not black?

 

Dang good question, I wondered the same thing.
Possibility that he hasn't finalized the wire routing at this point.
Kinda like a dry run.

 

Sorry, it looks like the edit must've updated late. I put the answer in the second to last paragraph:

"The inverter is grounded to chassis using the 14AWG wire that came with it, I just terminated it with a 14AWG, M6 ring terminal that I purchased online. The eye bolts are M6 plain steel that I also purchased online."

Yes, I would say this is in the late beta stages as I have not made any holes through the plastic in the trunk yet. When I do, I'll be sure to update the post.

 

Not something I'm going to do, but that's a hell of a writeup man. Hat tip.

 

Thank you! That is good to know about the Redarc. I'll update if I see any problems with the system this summer.