Yet another lithium battery installation

CharlieRN

Edit: I should have acknowledged the many helpful threads on the topic of battery installation on this forum that played important roles in helping my project to be successful. Thanks also to the folks who responded to my many questions. With that said, the focus of this post is to share some information and observations on my nearly complete lithium battery installation on my 320S BD.

I was lucky enough to find Battle Born 100 Ah batteries on sale late last year. While they will fit in the outside storage box, for various reasons, I decided to relocate them inside the 320. The location is under the right-hand bench (door side). 

This first photo is of the batteries in place with the wiring nearly complete. What is missing is the 12v line needed to energize the Renogy DC-DC charger. I also plan to add a small 12 v fan for aux cooling, and that is missing as well. All of the wiring to/from the charger, batteries and forward to the battery connection on the TV (via Anderson connector) is 6 AWG.

You can also see in the photo that there is a connection in place for the AC charger (the lighter gauge wires that terminates in the blue plug). If you're wondering why there is a mix of yellow and red for the positive wires, it's because I could only find tinned marine grade 6 AWG in yellow at my wire supplier of choice, Greg's Marine Wire Supply. They sell US-made wire and for the most part, are less expensive than the Asian suppliers on Amazon. Shipping's not free but it's reasonable (they use the USPS) and your order is generally on your doorstep in two days.

 

The interior wiring for the batteries is relatively easy, made more so if you have a hydraulic crimping tool. Harbor Freight has one that is in the $60 range and does a decent job of cold soldering lugs. All of wiring terminations in the photo above, and in fact in the whole project, were done with the crimping tool,

Wiring the DC-DC charger to the TV system battery is a bit more challenging, mostly due to how you need to run things. I decided to leave the existing camper wiring that is in the cargo box in place, so used bus bars in hobby boxes. The first photo below is of the negative bus box; you can see how using a bus cleans things up. The positive bus is similar and mounted next to it in the cargo box. You can see both in the second photo, but with the tops of the boxes on. Both buses connect directly back to the battery bank (using 8 AWG marine wire), with all the existing factory runs maintained and connected to their respective bus bars.

Bus - photo 1

Bus - photo 2

The toughest part of the project was the wire run from the cargo box to the battery bank. It required removing the corrugated plastic splash shield under the T@B. The shield is held in place by metal strips attached to the frame with self-tapping screws. Removing them was a huge PITA and several were corroded enough that they simply snapped off.

You also need to remove the front Bal leveler. Though my camper is a 2021 that has only been used a few times, and never in cold weather when there is road salt, the bolts holding the leveler were already starting to rust & corrode. I replaced them with stainless bolts and nylock nuts when I put the leveler back on. I also took the opportunity to spray the threads with some lithium grease lube.

In order to get the wiring from the interior bench area out and forward to the cargo box. I drilled a hole in the floor in the adjacent compartment to the immediate rear (the one with the Air 8 unit). The reason that I chose this location was that there is already a penetration, so I was sure there was not issue drilling next to it. Once I drilled the hole, I used a piece of PVC electrical conduit for the wiring. It is held in place by PVC couplings that are half-height (simply sawn in half). The bottom coupling is solvent-welded to the conduit, but the top is not. Instead, the coupling is a simple friction fit, though with a hole drilled through the diameter of both the conduit and half-coupling. To ensure it will stay in place, I ran a piece of 12-gauge copper wire through and folded the ends. My thought was that doing things this way would make it easier to remove the conduit if I ever needed to; if it was glued, it would be a real project to get it out of there.

On the left of the photo, which is the outside wall of the camper, you can see a 30 amp breaker. This is the 8 AWG run to/from the battery bank to the positive bus in the cargo box. As far as the runs themselves, they exit the camper at the penetration, then head forward. I was originally going to run them through a short section of conduit (I have quite a bit in various sizes from previous projects lying around). After some research, I decided not to do that because the recommendation for wire sizing changes if run through conduit. I was still worried about chafing, so I used four ~2" sections to run the wire through where it would have been in contact with the water storage tank supports. The four pieces are screwed to some small dimensional scrap wood that is then zip-tied to the tank supports. There is a second set on the support behind the axle, and not visible in this photo. One of the tubes carries the 8-gauge run to/from the battery bank to the buses, the other carries the 6-gauge run that terminates in an Anderson connector at the 7-pole plug.

By the way, the red wire that is wire-tied to the axle is the brake line. As it came from the factory, there was a lot of excess wire that can easily work its way through the grommet on the frame. If that happens, the wire will likely eventually touch the tire and get worn through, rendering the brake on that side useless. My solution was to zip-tie the excess to the tank frame, so this hopefully is no longer a potential problem. You may want to check to see where your brake line is and if it's getting close to the tire, at least push it back a bit.

Hope this helps somebody considering a similar modification.

Yoshi_TAB

Hi @CharlieRN,

I have two new lithium batteries I plan to install in my 2021.  I plan to mimic your install by keeping the OEM wires in the front box and running a single new positive and negative wire back to the new batteries.  I have a couple of questions:

1.  You used 8 ga wireback to the Lithium batteries?  How did to you decide on 8 ga. vs 6 ga.?

2.  Why did you select the storage area by the wheel well as opposed next to the Air 8?  I'm leaning toward the Air 8 location because we use the storage area by the wheel well.

3.  Did you fuse the new wire run back to the new batteries or is the existing 30 amp on the OEM battery wire sufficient?

Thank you

CharlieRN

Yoshi_TAB said:

Hi @CharlieRN,

I have two new lithium batteries I plan to install in my 2021.  I plan to mimic your install by keeping the OEM wires in the front box and running a single new positive and negative wire back to the new batteries.  I have a couple of questions:

1.  You used 8 ga wireback to the Lithium batteries?  How did to you decide on 8 ga. vs 6 ga.?

2.  Why did you select the storage area by the wheel well as opposed next to the Air 8?  I'm leaning toward the Air 8 location because we use the storage area by the wheel well.

3.  Did you fuse the new wire run back to the new batteries or is the existing 30 amp on the OEM battery wire sufficient?

Thank you

1. While I would have preferred to use 6 AWG throughout, at the time, supply chain issues made it difficult to get tinned marine wire in that gauge. 8 AWG was available, and is more than adequate for the shorter run in the camper from the bus bars to/from the battery bank. I was originally going to run that wire in conduit, but since that could decrease load capacity (due to increasing ambient air temp), did not do so, though I did run individual lines through short sections at potential chafe points. All of the longer runs are heavier 6 AWG.

2. The battery location was an issue of space and ease of installation. The space in the Air 8 compartment is constrained because of the factory floor penetration and the air supply lines. I also needed to do an additional floor penetration for the battery wiring, which was easier to do near that existing factory penetration. It was simply easier to put the batteries in the adjacent compartment. If you can fit them in the Air 8 compartment in your 320, there's no reason not to put them there.

3. Yes, I added an additional breaker - it's actually visible in the shot of the Air 8 compartment, on the exterior side, just below the factory AC duplex box.

Yoshi_TAB

3. Yes, I added an additional breaker - it's actually visible in the shot of the Air 8 compartment, on the exterior side, just below the factory AC duplex box.

Hi, I see it.  What size is it?  Why a breaker vs. a fuse?

Thank you

CharlieRN

Yoshi_TAB said:

3. Yes, I added an additional breaker - it's actually visible in the shot of the Air 8 compartment, on the exterior side, just below the factory AC duplex box.

Hi, I see it.  What size is it?  Why a breaker vs. a fuse?

Thank you

Believe it's 30a but I honestly don't recall and need to check my notes. It was leftover from another project, and I have plenty of lugs and connectors for the terminations, as well as a crimping tool, so an easy installation too. While fuses are less expensive, I would have used a breaker even if I had to buy one, since they have a long service life and can be reset after tripping, so don't require you to carry a replacement fuse.