2021 320 Lithium and Inverter Install (Complete)

Yoshi_TAB

Hi,

As I begin to undertake a lithium and inverter install, I look for any comments, suggestion, questions on my proposed install.  I used information I found in this forum.

My first question is does anyone see any issue with the placement/location of the batteries and inverter next to the Air8?

My second question is on my proposed wiring and fuse size.  Anything I should change?  It's a 2000W inverter and two 100 AH batteries.  I plan to keep the OEM wiring in the front tub  and run a single positive and negative back to the new install.  

Thank you,

AnOldUR

Shouldn't the inverter negative be after the shunt to measure its usage?

Yoshi_TAB

AnOldUR said:

Shouldn't the inverter negative be after the shunt to measure its usage?

You mean on the load side?

AnOldUR

@Yoshi_TAB someone with more knowledge will come along, but from the research I've done in planning a shunt install, my understanding was that all negative connections (including solar) had to pass through the shunt before attaching to the negative battery terminal. Seem to make sense that to know the state of charge, it would have to have all the loads and power sources run through it.

elbolillo

Yoshi_TAB said:

AnOldUR said:

Shouldn't the inverter negative be after the shunt to measure its usage?

You mean on the load side?

Your negative from the inverter needs to connect to the loads side of the smart shunt. Then the battery negative side of the smart shunt to the negative of your battery.

Regarding the size of the wire, I used 1/0 AWG to connect the inverter to the batteries (I did however have a longer run, about 6') And I connected the batteries to each other with 2/0 AWG wire.

Yoshi_TAB

elbolillo said:

Your negative from the inverter needs to connect to the loads side of the smart shunt. Then the battery negative side of the smart shunt to the negative of your battery.

Regarding the size of the wire, I used 1/0 AWG to connect the inverter to the batteries (I did however have a longer run, about 6') And I connected the batteries to each other with 2/0 AWG wire.

Hi,

So if I understand correctly, the negative 1/0 AWG wire from the inverter gets connected to the smart shunt?  Seems like a large cable to be connected?  

The inverter comes with 4 AWG wires.  These would not be used?

Thank you, 

Denny16

If the Inverter came with 4AWG cables, than these would be fine for a short run less than 5-feet.  I would use No 2 AWG cables to connect the two batteries together, for extra safety.  

Cheers 

kottum

Denny16, do you mean 2/0 AWG wires to connect the two 100 AH batteries to ensure virtually no resistance between them? Together, they are acting as a single 12v battery?

Doug

Yoshi_TAB

Denny16 said:

If the Inverter came with 4AWG cables, than these would be fine for a short run less than 5-feet.  I would use No 2 AWG cables to connect the two batteries together, for extra safety.  

Hi,

What are your thoughts on the wire size from the OEM battery location up front to the new battery location in the back?

The wire sizing is very confusing, you get different answers depending on which website you check.  

Thank you

Denny16

Doug, two DC batteries wired in parallel do act as a single 12VDC battery, then the jumper wires should be rated for the max Amp output.  AWG no 4 is rated for 100 amps, but two 100 amp batteries in parallel gives you a 200 amp battery, which would normally need a 2/0 jumper to cover the 200 amps max amp draw the battery could put out, as an extra safety measure.  

In the TaB Using a AWG No 2 wire would work, since the biggest draw is the inverter, (2000watts inverter would be around 125-150 amps at max output), but one would need to check and see what size fuse the inverter uses (shown as 125 amps in Yoshi’s drawing, which AWG no 2 wire would be correct) and choose an appropriate wire size, based on the fuse.  

If the fuse is 150-160 amps, then a AWG no. 1 wire would be needed for both the inverter and battery jumpers.  With a large inverter, a no, 4 AWG wire is too small, and runs the risk of overheating, and/or dropping the voltage below 12VDC.  As you pointed out, using a 2/0 cable for the jumpers would  insure a no voltage loss connection, and would be best to be safety.  That said, nüCamp does not appear to be using 2/0 cables in their new lithium install package from the photos I have seen. 
 Cheers 

Denny16

Yoshi, a No. 4 wire in a  20-foot run is rated for 40 amps using a 25-30 ft run, which for a two wire circuit is a max of 15 feet from battery location to the load source (original battery box).  That said, the only reason to connect the new battery bank to the tongue box, would be to power the brakes in an emergency. 

 I would just connect the new battery bank to the trailers power converter buss, where the OEM wires from the tongue box battery connection run to the WFCO unit.  The existing wires from this bus to the battery box would still power the brakes.  Just remove the original battery cables from the box, and leave the rest of the front box wiring intact.  

Cheers 

Yoshi_TAB

Hi @Denny16,

Thank you the input.  Hmm,   Let me run a few other things by you (or others) to make sure I understand.  Bold and italic are highlighted with my questions...so they are not lost.

In the attached wire diagram from a 2019 (thank you to who ever did this), which I would guess is the same as a 2021or very close;  are you saying run a new wire from the new battery bank to position #6 in the junction box?  or  (I don't think this is what you are saying) connect the new battery bank to the 30A fuse wire in the WFCO inside the TAB?


I also would have to:

1.  Relocate the battery disconnect switch

2.  Connect negative from new battery bank to position #7 or to ground bus bar in TAB?  I'm a bit fuzzy on this.  Need to get the negative from the TAB loads to the smart shunt?  Which wire would this be?

3.  Connect existing positive Victron solar battery connection to the new battery bank and ground

4.  I also use the external SAE solar plug .  I need to get these wires into the TAB and connect them to the new battery bank and ground.

Also, based on some reading I've done, I updated my wire sizing and fuse.  Did I go a tad to big?  From what I read, the inverter should have 2/0 wire and an appropriatew 200 amp fuse to go with that size.  Is 1/0 too big for the battery jumpers?  As see you recommend a 2/0?

thank you
Stuart

Bayliss

@Yoshi_TAB, I'm tied up on another project, so I can't be real helpful right now (plus I have a single lithium battery and no inverter, so a different setup.)  However, since you already have my diagram of the wiring for the junction box in my 2019 320 S, I am including below a discussion thread that may help you with the wiring.

I moved my battery and disconnect switch from the outside tub to inside the trailer, as others have done and discussed in different posts on this forum.  My specific modifications (again, different from your setup) is discussed in the second page of the discussion and includes a diagram of how I wired everything (12V, solar and the Victron BMV-712), so maybe the diagram will be of some value to you.  I would suggest that you review the whole discussion in the below link to see if it helps with your questions.  Hopefully, others will chime in as well regarding your specific setup.  Good luck!

https://tab-rv.vanillacommunity.com/discussion/10532/lithium-or-agm-battery-mounted-inside-a-320-cabin/p1

Yoshi_TAB

Thank you @Bayliss,

I believe I now understand.  I used your drawing and made a mark up (just positives):

1.  The 12V wire inside the TAB going from the WFCO 30A  position to junction box #6 cuts spliced/cut.

2.  The cut end from the WFCO goes to the new switch

3.  The cut end from the #6 junction box goes to the battery.  This will allow the brakes to always have power independant of the battery switch position.

4.   The other side of the new switch goes to the12V battery.  This will allows the switch to turn power on/off from the battery.

5.  The negatives (battery, trailer and solar loads) can be attached to the ground bus behind/next to the WFCO.

This would eliminate having to run wires from the OEM front box, but I still need a way to get the external solar plug wires inside.

Do I have this right?

Per standard wire charts and the short runs,   10 AWG seems  sufficient?  

Thank you,

R/

Bayliss

@Yoshi:

1. Yes
2. Yes
3. Yes
4. Yes
5. Conceivably, Yes, except that the wiring diagram in your original post indicates that you have a smart shunt (Victron?)  Assuming that is accurate, I agree with the comments by @AnOldUR and @elbolillo.  If you look at the wiring diagram of my Battleborn battery/Renogy solar suitcase connections (included in the other discussion thread I linked to), you will see how the negative wires from the (-) bus bar and solar negative are connected to the "B2" terminal on the shunt; the (-) from the battery is connected to the "B1" terminal on the shunt.  Take a close look at all the connections to the shunt, including for its power and digital display (if you have one), and also take care to review and follow the documentation and connection instructions provided by the manufacturer of the shunt.

CAVEAT: I do not have an inverter and therefore no experience with wiring one as part of the overall electrical system.  I also am unclear if you actually have a separate (+) bus bar, but it appears so, which is different than my connections.  Therefore, I am also not sure what is the appropriate wire gauge size to recommend for your particular setup (i.e., two 100 Ah batteries, solar, inverter, and smart shunt.)

As far as the  solar connection from the front of the trailer, that is a separate issue.  You will either need to find a way to route those wires into the trailer and on to the battery compartment, OR create a new entry point through the sidewall of the trailer (or other appropriate location) for the external solar port, similar to how I installed the Furrion port on my trailer.  If you go that route, you can use the same type solar port you currently have, or explore other options.

Good luck!

Yoshi_TAB

Hi, @Bayliss,

Appreciate you taking the time to look at my proposed design.  This certainly will be easier (and a bit cheaper) than running new wire and cutting a hole in the floor to run the  new wire. 

A couple of quick follows ups:

1.  Just to confirm, the12V charge line will still charge the battery with no additional changes?  Since it's tied into #6 position on junction box, which is tied directly into the battery, it appears so.

2.  I do have a smart shunt.  Connecting (wire) the B2 load side of the shunt to the negative bus bar will capture all the 12V loads in the TAB?  Essentially, this is the same as OEM ground wire   in the front tub that gets connected to the battery.

3.  Did you install a DC to DC battery charger to boost the voltage for the lithium battery? 

I'm on the fence.   Not so much to charge the battery or cap the amps as I travel down the road, but to eliminate any possible damage (or over heating) to the tow vehicle's alternator or wiring from sending to much current to the lithium batteries.  I have read conflicting information if this is true (the damage).    Victron has a video showing it can happen but BB batteries in a blog says it only required if using 3 or more lithium batteres. But it does say to use another device to protect the alternator.  

Re: Wire Gauge.  I'm pretty confident of the battery jumper and inverter wire connection sizes.  Since the new wires for the switch and ground are on the low 30amp 12V side, I would think 8-10 AWG is fine..just looking for someone to confirm.

tks again,

Bayliss

@Yoshi_TAB:

1.  Yes.  The charge line from the tow vehicle is also connected to terminal #6 in the junction box, so that sends power back to the battery.  When you are plugged in to 120V AC at a campground, your power to charge the battery is coming from the WFCO power center/converter.

2.  Yes, that is how I did it.

3.  No, I have not installed a DC-to-DC charger.  I may consider doing it in the future, but it hasn't been an issue for me.  I have a 150 amp alternator on my 2007 Toyota Tundra and am only using a single 100 Ah lithium battery, so my current configuration has been adequate.  My understanding is that a DC-to-DC charger is advisable for tow vehicles that have a "smart" alternator, which you very likely do.  There are articles and videos online that describe how to determine that, which is simple to do.

Here is a helpful article about the purpose of a DC-to-DC charger and how it works, but you can search for similar articles and videos online to help you decide whether you should add one to your system:

https://www.doityourselfrv.com/dc-to-dc-charger/

Use the search box at the top of the forum page and search for "DC-DC" and you will find some discussions by other forum members who have installed a DC to DC charger.  You can also search for "lithium battery installation" (or "install") to get an idea of the wire size that others with multiple batteries have used.

Also, although you have different lithium batteries, here's some info on wire-sizing by Battle Born:

https://battlebornbatteries.com/electrical-wiring-essentials/



 

Horigan

Another key benefit of a DC to DC charger is that you can fully charge a lithium battery using a lower voltage lead acid/AGM charging system (alternator or non-lithium converter).  Just charging with a high amperage alternator will only get you to ~80% SOC due to the lower voltage of the alternator.

Yoshi_TAB

tks so much for all the info..I'm off ordering wire and a few other parts.  

I'll post pictures of the install when I'm done, probably in a bunch of weeks.  My install is a bit weather dependant.  I'm in the mid Atantic.  

On a side note, I figured out how to avoid a new mounting location for the external solar plug.  I will re-purpose the existing Victron Solar Controller pos. and neg. wires that run to the front tub as I need to run new wires for it to the new battery location and negative bus bar.

R/

Bayliss

Sounds good, @Yoshi_TAB.  You may want to consider running the negative wire from the solar port directly to the shunt, as I did, rather than to the negative bus bar.  I haven't really thought about it, or specifically why I did that (except that is how it was connected by others when I was researching how to approach the wiring), but it may make a difference.  I believe my thinking was that I wanted the most direct connection between the solar panels and the battery to obtain accurate readings from the Victron BMV-712 monitor.  Brighter (solar) minds on this forum may chime in and educate us both as to whether connecting the (-) wire to the negative bus bar effectively accomplishes the same thing, which is to be able to monitor the charge from your solar panels.

Denny16

@Yoshi_TAB, you got it in one.  But instead of splicing into the wire that goes from no6 terminal to the WFCO, cut it and insert a two connection buss bar to connect the battery cable to and the battery switch, then the switched leg of the battery switch can be connected to the wire going to the WFCO, so the WFCO only get power when the battery switch is on.  

Cheers 

Yoshi_TAB

Attached is a newer revision of my proposed set up.    

Yoshi_TAB

Hi,

For those interested, attached are photos of the final install.  Everything is up and running as it should.  Thank you to all who answered my questions.  

Spectre9

Quick comment on this transfer switch - I do not know if required on your 2021 converter  but on my 2018 320 I installed a split breaker with both  30 and a 15 to replace the double-width 30a master breaker and split off my converter onto its own 15amp circuit so I could turn off the ac to dc converter by flipping off the 15amp breaker.  

In my planned setup though I’m using transfer switch only on the gfci outlets not powering the entire converter box.

I actually use this so I can run camper off generator to power my ac without heating up the cabin further from running power converter. It gets hot in Texas so controlling extra heat helps (and we have solar)

Yoshi_TAB

Hi,
That was an option I was considering, but the transfer switch had a built in contact for the converter so it only is powered when on shore power.  So I took the AC lines from the converter and wired them into the transfer switch.  I’m on my first outing with the setup and I’m getting some power draw from the batteries while on shore power and the charger/converter comes on sometimes and other times it doesn’t.  I’m trying to get my head around why that is.  I think it may have to do with it being a lead acid charger and the program inside the WFCO says not to turn on until it gets to the voltage for a lead acid battery.  Solar is keeping it at 100%.