Moving Battery Inside on a 2023 320S Boondock

dpj895

Hello all,

First let me thank all of the folks who contribute to this forum, it has been invaluable to this first-time trailer owner.  

So here's my question.  There have been many discussions on moving batteries and switching out to lithium, but there isn't one that matches my situation exactly.  Here's what I have:

• 2023 Tab 320S Boondock which came with a AGM battery from the dealer. 
• 100Ah Lithium drop in replacement. I did manage to get the WFCO to auto adjust and give us the magic blue light.
• After a few trips and not knowing the state of the battery, I added a shunt in the tub.  This is in a water-proof box with bus terminals.
• After a few more trips and knowing the state of the battery, I added an external solar suit case.  We camp in New England, mostly where there isn't shore power, and there are usually trees so the flexibility has been invaluable. Currently the Solar Controller is in the tub in a water-proof junction box. The 2023 doesn't have an external solar port so I have a set of plugs to connect the suitcase to the controller.

This is a diagram on where we stand now:


So my big winter project is to move the battery inside. We could use the space in the tubs, and I would feel better with battery inside and more secure.


This is what I plan to do

I would prefer not to have to run new wires, so my plan is to reuse the runs that exist. Note that for the 2023 the battery switch is right inside the door, not in the tub which is where it seems to be on older models. Most discussions that I have seen on this move were on older models, so I need to adjust accordingly.  My plan:

• Install the battery, shunt, and the external solar controller under the passenger-side seat.
• Run a single wire from the negative bus behind the WFCO to the shunt.
• Run a new pair of wires from the factory mounted solar controller to the shunt and the positive terminal, with a 30 Amp fuse on the positive wire. The factory-installed controller is under the driver's side seat.
• Use the wires that were going from the factory solar controller to the tub for the external solar controller.  I will splice plugs onto the tub side with a 30amp fuse, and also do a splice inside to a pair of new wires that I will run to the shunt and positive terminal. There will also be a 30amp fuse inside as well.
• Determine which wire from the switch is going to the battery; remove it from the switch and instead run a new wire to the positive terminal with a 30amp fuse.  The other wire I will not touch and will still run to terminal 6 in the tongue junction box.
• I will abandon two wire runs...  the positive run from the switch to the tub, and the negative run to the tub. 
• I will use a bus terminals under the seat for both positive and negative runs to make it cleaner and easier to deal with. 
• 10 AWG for all runs

Am I missing anything, or does this seem like a reasonable plan?  Thanks in advance for any comments and suggestions.

SLJ

I'd add a positive buss bar at the battery for those three connections. Battery should have it's own fuse. Breaker accomplishes that. I put a marine breaker/switch between the battery positive before the buss bar to totally disconnect the battery from everything without having to pull a bunch of fuses.

I went a different route and left all the original connections in the tub (in a new waterproof box) and ran new +/- lines from the tub inside under the bench for the battery move. (older '21 320 with the on/off switch and both solar connections already in the tub).

dpj895

Thanks for the response.  Your web site is where I got the original idea ;-).  I thought about running the new wire, but had concerns about pulling the cover off the bottom as well as introducing a new hole in the floor.  I trust myself more with the electrical rather than a good water/critter proof seal of the floor.

I see what your are saying about the battery and its own fuse.  The three positive runs will end at a buss bar, so can add a breaker between it and the battery.

Yoshi_TAB

Hi,  In addition to the positive busbar comment, I would also suggest one for the 3 negative wires at the shunt so there is only one wire connected to the shunt.  Cleaner and less likely for a failure of stacked connections.  

I would suggest a second switch and fuse between the WFCO and battery (which I've done).  That way, the switch going out to the junction box is never turned off.  I really dislike the current design where if you turn off the battery switch (for maintenance or what ever)  and forget to turn it on before traveling, your emergency electric brakes would have no power.  I use to do chemical plant hazard analysis and that failure scenrio would need to be addressed for a safety device.

Maxcamp

Another perspective, understand you'd rather limit re-circuiting.
You don't necessarily have to pull the undertrailer Scrim for wire routing. 

In 2021 we mounted batteries in passenger wheelwell compartment along with Victron monitor.
I too left the original shutoff switch in the front box and removed the battery.  Ran an 8awg SOOW cord from 7-pin box to front trailer box and across to passsenger wheelwell.  Drilled through midsection of C channel frame crossmember, tywrapped along inside of C channel frame on passsenger side, and drilled up into  inner front corner of passenger side wheelwell storage compartment.  Sealed floor with rubberized roofing cement from below and above, with plastic escutcheon cover.  No issues.
Victron battery monitor is wall mounted just below See-Level factory monitor, homerun in wire loom down to wheelwell.

Truck really does not charge our batteries, preparing to add DC to DC converter in trailer, homerun with Anderson connectors and a battery isolation relay.

bjn2

I ran new wire, but did so through the seating bays inside the trailer. The run doesn't take much wire and I was able to use existing holes for routing. I used some nylon clips to secure the wire run. I disconnected and insulated the existing wires to the cutoff switch and use that switch with my new wire to the converter's power connection. I left the hot lead connected that runs to the tub since that splits off to provide power to the electric brake's junction box. I secured the converter wire to an insulated terminal I added to the tub. I also ran new wires from the Victron converter under the seats to the battery/shunt. I'll reuse the original solar wires to the tub to install a second controller and a solar port for suitcase solar connections, again adding some wire to make the additional battery/shunt connection.

dpj895

Thanks everyone for comments.  Based on these and some further consideration, this is my revised plan:

I plan on running three pairs of wires from the under the driver's side seat to under the passenger side seat

• Pair 1:  Positive WFCO to Interior Switch; The switch will then be connected to the Positive Buss.  I will also connect the Negative Buss to Negative Buss
• Pair 2:  Factory installed solar controller to respective busses
• Pair 3: Spliced to existing solar controller wires from tub, to the newly installed solar controller, which will then be connected to respective busses

The positive wire that currently goes from the interior cutoff switch to terminal 6 in the tongue junction box will be connected to the positive buss. This will ensure that the emergency brakes are connected even if the switch is off.

The cutoff switch will now only isolate the WFCO from the battery.

I will abandon the Positive wire from WFCO to Terminal 6 and  the Positive from the cut off switch to the tub. I will remove or abandon the negative wire from the tongue junction box to the tub(not in the drawing).

I will install a breaker between the positive buss and the battery.  This will allow me to totally isolate the battery if need be.  I plan on using 6 terminal busses, so that if I want to add second battery in the future I have the capacity to do so.

Thanks again form your help and comments.

Yoshi_TAB

Hi,

Another suggestion from what I did for the 12V wire going to the junction box for the trailer brakes.  I wanted a way to confirm I always have power past the fuse.  If for some reason the fuse blows, you would not know that power was lost to the E-brakes (making them unusable).  I installed a small indicator light (next to the newly installed battery switch) after the fuse.  I know...who needs another light in the TAB.  But I used below that come in colors of your choice.  So during my pre-departure routine, I take a quick look at the light to confirm the fuse did not blow.  It can be mounted anywhere with a small drilled hole.

https://www.amazon.com/gp/product/B01AF5THFS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The other thing to consider, w/o a switch on that circuit,  the only way to disconnect the power to the E-brakes is to pull the fuse.  I do not have a switch, and find pulling the fuse ok.  I occassionally pull the hitch plug for the e-brakes to test them.  For that reason or if they activate by accident, you need a way to disconnect power.

Good luck with your install...