Dual BB LiFePO4 Battery Setup

corunner

I recently finished my install & securing of my new dual battery setup on a 2021 320S BD.  Thought I'd share what I did here in the event someone is thinking of doing the same.  I'm a bit of novice, but tried to do my homework by reading as much as I could in these forums.

I went with (2) Battleborn 100Ah batteries wired in parallel with a Victron Smartshunt.  I plan to use the pre-installed SAE port with a suitcase panel when needed.  Given the cost of the batteries, securing them was a very important concern, as well as protection from the elements.  I really want to get my 10+ years out of these!

My original intent was to have both batteries in the main storage compartment, but learned quickly they both will not fit if they are placed in battery boxes.  The battery boxes were important to me for two reason.  Protection from the elements, but they also hide the type of battery inside of them.

I decided to mount one battery in the main compartment and the second battery in the "David Hess" side storage compartment.  Both batteries are secured with a thick Master Lock security cable.

Here is the first battery in the main compartment.  I would have liked to have the security cable a bit closer to the battery, but there were pre-existing holes in the platform, and I didn't want to also drill through the utility platform, so I only drilled into the storage compartment.  It would be very challenging for someone to wiggle the battery out with how tight the cable is and the battery box is wedged into place.





With the cover/cable removed.  The cables to the second battery thread through the back hole.  Don't be alarmed by what looks like a positive battery cable connected to the negative terminal.  I used a red cable to connect to the SmartShunt and tried to color it with a black Sharpie marker (but didn't get all of it!).



Smartshunt in my Rubbermaid waterproof container.



The second battery in the side storage compartment.  There's still room on top to store other things.  I drilled three hole in the back (2 for battery cables and 1 for the security cable).  Also drilled one hole in the front bottom for the security cable.



I mounted the side storage boxes about 2 inches forward so that I could run this cable around the utility platform bar and also to access the SAE port in the back.



Back of side compartment view.  With the boxes mounted forward about 2", I can access the SAE port and use the pre-existing hole to run the cable through the platform.  



Second battery w/ cover/cable off.



I make no claims that this setup is the best one out there - but it works for us and my hope is that there will be minimal need to access them based on how we plan to keep them charged.  If anyone sees something I've missed - please let me know!

Marceline

corunner said:

Here is the first battery in the main compartment.  I would have liked to have the security cable a bit closer to the battery, but there were pre-existing holes in the platform, and I didn't want to also drill through the utility platform, so I only drilled into the storage compartment.  It would be very challenging for someone to wiggle the battery out with how tight the cable is and the battery box is wedged into place.
...

I make no claims that this setup is the best one out there - but it works for us and my hope is that there will be minimal need to access them based on how we plan to keep them charged.  If anyone sees something I've missed - please let me know!

FWIW I went a slightly different route. I used 4 heavy duty furniture feet (like these) under the battery box. The battery box and feet are through-bolted to the bottom of the aluminum tub. Putting the box on top of the feet gives about 1/2" clearance to thread a cable. I went to a hardware store that sells plastic-coated cable by the foot and had them make me a cable of the exact correct length with swaged loops at each end for a lock. It fits very snugly to the box and would be impossible to open the box without cutting it. 

I also considered getting a nasty looking rubbermaid tub, labeling the top "sewer supplies" and putting the battery in there. I still think that might be the better way to go.

corunner

It fits very snugly to the box and would be impossible to open the box without cutting it. 

Thanks for sharing.  That sounds good too.  You definitely accomplished what my goal was.....making the theft of the batteries a major hassle.

Denny16

@corunner nice job, but the Smart shut is basically weather resistant, and needs  some air circulation to cool.  Located in a sealed box, it could overheat.  You need to drill small holes in the sides and bottom to get air circulation in that box.  The top cover will keep any direct water leaks off the shunt. 

The front of the new TaB aluminum box is water tight at the front (no direct water leaks or splashing I have seen) and you could just eliminate ate the plastic box, and screw the shut to the inside front of the box, and tape over the electrical connections and Bob’s your uncle... 
cheers

4ncar

Where your battery cables pass through the boxes...highly advisable that you use a rubber grommet.  That diamond plate will chafe those cables in  time... also, wrap the red cable that is now a negative with black electrical tape on both terminal ends. This is a “proper” way to ID a colored conductor being used not for its intended purpose.

Denny16

Good catch.
cheers

corunner

...the Smart shut is basically weather resistant, and needs  some air circulation to cool.

Interesting - I feel like I've seen posts here where the shunts are in waterproof boxes.  Maybe that was the full battery monitor and not just the smartshunt.

I'll remove the duct tape that I place around the holes.  I drilled them a little too big, so there should be some airflow through both of those.  I'll keep an eye on it.  Thanks again.

corunner

4ncar said:  Where your battery cables pass through the boxes...highly advisable that you use a rubber grommet.  That diamond plate will chafe those cables in  time... also, wrap the red cable that is now a negative with black electrical tape on both terminal ends. This is a “proper” way to ID a colored conductor being used not for its intended purpose.

Yes, the grommets are part of the plan.  I wrapped both cables in duct tape until I could get a more permanent solution in place to protect them against the sharp edges.

Good call on the black electrical tape to cover up all of the red.  I'll do that soon!

Denny16

You do not need o cover all the red, just a 1 or 2-inch band at each end of the cable. 

Cheers

DelZMan

Apologies for asking for repeat info: Can someone provide a picture of their dual BB install in battery area of 2021 400BD, please? I can’t find it with search function. Thanks in advance.

Polanskyster

DelZMan

Champion!  You went with the GC version, which is what I was leaning toward.  Thanks very much.

CharlieRN

Great setup - and one I hope to move on to down the road. I have a couple of questions for you if you don't mind..

You mention that you have the "David Hess" boxes and in fact, use one for battery storage. I see from the photo that the SAE port in the factory storage box has not been moved - how do you access it with the additional storage box adjacent to it? I also have the additional Bradley box and have been ruminating over where to relocate my SAE port.

Regarding the BB batteries, did you go with the standard or the heated variety?

Since you now have LiFePO4 batteries, did you also add a DC-DC charger?

MarkAl

I like what Jenn G did for her 320 / 2021 moving the Li batteries into the AC area BUT I'm wondering about tongue weight if you don't replace the weight on all the trips. Probably not a problem for most people as the tongue probably gets too much on a longer trip. We don't tend to put much on the tongue - we seem to be still hiker/campers and don't bring much extra.

corunner

CharlieRN said:

Great setup - and one I hope to move on to down the road. I have a couple of questions for you if you don't mind..

You mention that you have the "David Hess" boxes and in fact, use one for battery storage. I see from the photo that the SAE port in the factory storage box has not been moved - how do you access it with the additional storage box adjacent to it? I also have the additional Bradley box and have been ruminating over where to relocate my SAE port.

Regarding the BB batteries, did you go with the standard or the heated variety?

Since you now have LiFePO4 batteries, did you also add a DC-DC charger?

I didn't relocate the SAE port, but rather left it where it was originally installed.  Instead, I mounted the side storage boxes forward a couple inches so the SAE port was accessible.  I think you can see that in the last two photos.  I did the same on the other side and like having them forward a bit.  At camp, I find myself sliding various things behind the one without the battery just for "in camp" storage.

I went w/ the non-heated batteries.  I just don't see myself camping much where daytime temps are below 32 and where I'd need to charge.  I won't hookup the suitcase panel in below freezing temps, and I'll find a way to disconnect the factory solar (pull fuse or disable the controller).

The operating/discharge temps for the batteries are much lower (low single digits).  Again, I just don't see myself camping in those kinds of temps.  My main concern was using the batteries at night when temps could drop into the lower 20's or upper teens.  The standard BB batteries can handle that just fine.

Seems like the heated batteries are important if you need to charge below 32 or if you need to draw on them below 0.

So far, the factory solar + 200W suitcase panels have topped off the batteries very quickly.  With 200ah capacity, I'm less concerned about charging from the TV.  That may change in the future, but I'm going to go with this setup for a few months and reassess.

Denny16

Corunner said: “I'll find a way to disconnect the factory solar (pull fuse or disable the controller)...”

You could always add a small battery cutoff (on/off version) between the controller and the battery connection, to control power from the factory solar going to the battery.  

Cheers

Dutch061

Denny16 said:

Corunner said: “I'll find a way to disconnect the factory solar (pull fuse or disable the controller)...”

You could always add a small battery cutoff (on/off version) between the controller and the battery connection, to control power from the factory solar going to the battery.  

Cheers

You would be far better off to go under the "Battery Setting" in the MPPT and turn charging off since that function already exists.

Brad

corunner

@Denny16 - good suggestion.  

In the Victron App, one of the Settings under the Smart Solar controller is to toggle off/on "Charger enabled".  When you toggle it off, you get a messages stating, "Charger will be disabled and battery will stop charging.  This is intended for maintenance purposes only."  Hitting okay produces a banner at the top of the Settings page indicating the charger has been disabled.

Seems like that could also be a simple option if it works.  Anyone have experience using this? 

I know BB batteries have a BMS that prevents charging below freezing temps, but it would be nice to have a second simple solution like yours or toggling this off in the app.  It would be good not to have a single point of failure with costly batteries.

corunner

Dutch061 said:

You would be far better off to go under the "Battery Setting" in the MPPT and turn charging off since that function already exists.

Brad

Sorry @Dutch061 - I should have refreshed the page before I posted my reply.  Thanks for sharing.

Travelin3D

I am planning a lithium upgrade and seriously considering two of the BB GC2's if I can work out the fitment in the aluminum tub. My question is, will my factory solar panel plus a 100W portable panel be enough to keep up with the 200ah BB's?

dragonsdofly

@Travelin3D, the most common wisdom is that you need at least 1 watt of solar charging to 1 ah of battery capacity. Thus a 100ah LiFePO battery will need 100 watts of solar to charge it in a reasonable amount of time. On the solar system of my other trailer, we are at 2.3 charging watts per 1ah of battery capacity. We have 1,400 wats of solar to 600ah of battery bank. That is probably overkill and your 100 watts of solar panel should be just fine for a 100ah battery or battery bank.

corunner

Travelin3D said:

My question is, will my factory solar panel plus a 100W portable panel be enough to keep up with the 200ah BB's?

@Travelin3D - I think that depends on a few things.  I'm not sure how much you'll draw them down and thus need to charge back up.  And also the amount of sun the panels receive.  And the type of controllers you have (MPPT being more efficient).

My experience so far was that I've been using about 30-40ah per day and with 300W of panels (100 factory, 200 portable) - I was topped off in about 2 hours with decent sun.

I think the general rule of thumb is 200W of solar per 100ah battery.  But I'm guessing that is to fully charge a battery in one day of full sun. 

So far so good with 300W solar with (2) 100ah batteries - but I haven't drained the batteries down much, so I'm not sure how long it will take if I drop down to below 25% capacity.

I'm really appreciating the 200ah capacity as I know I'll hit a stretch of cloudy/rainy weather, and for when I camp in thick tree cover.  When that happens, I'll trust the extra capacity will see me through and then try to harvest whatever solar I can with the factory and portable panels.

Denny16

The nüCamp factory install for a 200-224 amp hr batter bang is 193-watts of solar panels.  We have this setup on our TaB 400, and the solar recharges the overnight drain using the AC/DC feindge on DC, lights, and Alde for evening heat.  So Traveling, your factory 100 watts is good for a draw down of the battery bank to. 50%, if it discharges more than that, you may need to add the extra 100-watt portable panel, which is a good idea anyway to use when the trailer solar panel is shaded.  I would get both.

That said, you should consider getting one 100 amp.hr. Lithium battery to start, to go with your 100-watt solar, which is correct balance, and see how much battery power your  are using.  If you keep drawing down the single 100 amp.hr. battery down to 80% discharge, or feel you need more battery power, then add the second battery and a portable solar panel.
cheers

Travelin3D

Thanks for the replies, you've all confirmed I was thinking along the right lines. At this point I am definitely adding a portable 100W panel, smart shunt and additional matching 75/10 Victron controller. I will have to decide whether to go big on the amp-hours now, or wait and see as @Denny16 suggests. If I can figure out a way to make the 2 GC's fit, I feel like it's best to just tackle the whole job at once. 

N7SHG_Ham

@Polanskyster were the GC2 a direct drop in for the space available in factory 400 space? I am looking at the GC2 also because my understanding is that is exact form factor of the OEM batteries. I have a 2019, so would like to fit replacement in factory space under black astic cover.

DelZMan

To the best of my knowledge the sizes are:

BBGC2:   10.31 × 7.28 × 11.02 in

Harris 6v: 10.2 x 7.1 x 10.8

dragonsdofly

@corunner, @Travelin3D, I stand corrected. Misread the OP as 100ah BB battery, not 200ah battery bank, however, current wisdom still holds at 1 solar watt of charging per 1ah of battery or battery bank capacity. In the case of 2 100ah batteries with a total rating of 200ah capacity, 200 watts of solar charging will do nicely. Some experts will say that more solar watts will be wasted money because there will not necessarily be more efficient battery charging when it comes to recouping expended costs for perhaps faster charging. I tend to agree about exponentially  increasing the cost of charging your batteries with little change in the result. In most cases, your batteries will be recharged by the next day. Good luck.

Dutch061

DelZMan said:

To the best of my knowledge the sizes are:

BBGC2:   10.31 × 7.28 × 11.02 in

Harris 6v: 10.2 x 7.1 x 10.8

Please see the attached cut sheet for the Harris AGM, slightly different dimensions. 

Brad