Simple LIFEPO4 for 2670MK

[Lhinaz71]

I went to my trailer last night and took measurements. My converter to battery wire is 8awg. I've seen elsewhere where 6awg is mentioned, but they seem to have reflection 5th wheels. I suspect those of us with Imagine trailers all have 8awg.

[Lhinaz71]

My plan is to put my battery in the storage compartment. When I was making my measurements, I'm thinking I can connect the positive on the battery to the battery side of the switch. I'll route the negative to the existing bolt on the frame.

This should keep all battery, converter, switch functionality the same as stock. Therefore not interfering with ebrake power.

I'll end up adding about 3 foot wire to negative side. But, positive side will be about 4 foot shorter to the converter.

[humunuku]

My plan is to put my battery in the storage compartment. When I was making my measurements, I'm thinking I can connect the positive on the battery to the battery side of the switch. I'll route the negative to the existing bolt on the frame.

This should keep all battery, converter, switch functionality the same as stock. Therefore not interfering with ebrake power.

I'll end up adding about 3 foot wire to negative side. But, positive side will be about 4 foot shorter to the converter.

Hello Lhinaz71,

As you mentioned in original post, my biggest concern with storing RV was the security of the batteries on the tongue. For this reason I have moved my batteries to the pass-through storage. In the future I will be replacing all of our slam-latches to match the new RVLock for the door.

Coincidentally, I just completed moving one lithium(BB 100AH) from the tongue to the pass-through storage. At same time, added a second battery(BB 100AH) and installed a Victron battery monitor (Smart-Shunt).
Prior to this project I replaced the stock inverter with WFCO: WF-9855LIS to properly charge the single battery on the tongue in a battery box.

For this project I purchased:

1 Package 6 AWG Gauge Red + Black Pure Copper Battery Inverter Cables Solar, RV, Car, Boat 7 feet 3/8 + 5/16 in Lugs ($34)
2 Package 6 AWG Gauge Red + Black Pure Copper Battery Inverter Cables Solar, RV, Car, Boat 12 in 3/8 in Lugs ($24)
1 Unit. Victron Energy SmartShunt 500 amp Battery Monitor (Bluetooth). ($130)

To keep the install simple, I found the connection terminals for original battery cables by following the cables. Both the ground and positive connect under the chassis near the tongue. (picture added). From the exposed terminals all of the system cables, wrapped in plastic/split conduit follow the chassis to a hole that comes though the 3/4" floor into the water valve bay. Once I peeled away the stuff-it installation the hole was very exposed and easy to feed the new 7-ft battery leads up into the storage space with enough length to place the batteries behind the water valve enclosure. This was very easy routing and did not require any electrical knowledge. I secured the two batteries by building a wood box and strapped it down to the 3/4" flooring. The box protects the batteries and monitor from any other items moving about in the pass-through storage.

I chose to add the Victron because the Lippert One control APP did not work well nor did it provide enough information for me to know our daily use.

In summary, the install was not complicated. It did require some time on my back, and also laying in the pass-through to make all the connections. Lastly, I added a solar charging port as part of this but did not want to make the answer too off topic.

If you have any further questions, I will be glad to provide more detail.

Regards,

[RockingKCranch]

I have ordered and will install the replacement wfco 8955-AD-MBA converter/charger section to the power center to make my system automatically detect and charge LiFePO4 300 ah batteries that I'm moving into the passthrough. My system install wiring will look like yours Humunuku and like what the original poster, .Lhinaz71 wanted to accomplish. I am hoping to install a simple, specific use 2000 to 3000 watt inverter running to 2 specific locations- one outlet in the bath for a hairdryer, and a run of about 20 ft back to 2 outlets serving the TV and Microwave for those rare instances when we want to use them when boondocking. I am concerned about how much heat the inverter will generate in the pass through with my batteries and the Solar Charger in there also making some heat. Thoughts about that? Also I'd like to visit with someone who has run 8/3 house wiring from the inverter to the various 120 plugs I'm wanting to install. Where and how to run these is the question. Enjoying the forum and all of your thoughts/expertise/experiences.

[Lhinaz71]

humunuku Thanks for all the details. I'm planning something very similar and this just helps reinforce that I'm on the right track.

I've been building my box and mounting a board on the back of it. I'm also attaching a Victron shunt Bmv700, and also an ANL fuse.

I've already run a feeder string through the hole behind the docking station where the existing wires go to the undercarriage your pictures show. That should make it real easy for me when I go to run the wires now.

I'm hoping to mount it all this weekend.

[humunuku]

humunuku Thanks for all the details. I'm planning something very similar and this just helps reinforce that I'm on the right track.

I've been building my box and mounting a board on the back of it. I'm also attaching a Victron shunt Bmv700, and also an ANL fuse.

I've already run a feeder string through the hole behind the docking station where the existing wires go to the undercarriage your pictures show. That should make it real easy for me when I go to run the wires now.

I'm hoping to mount it all this weekend.

I think you'll do fine. It took me about four hours for all the electrical connections and battery monitor. I spent the second day building the box.

All in all, we will both sleep better knowing our trailers are much more secure in storage. Funny story: Each year we end up in a different location for the winter months of February and March. When we find a short term storage location, I look at all of the rigs to see if their batteries are intact. Now I can skip this worry and get on with more important items.

Good luck.

PS: Here are a couple quick thoughts:

1. Your original plan of connecting battery directly to the battery disconnect had me concerned. By placing the positive lead of the battery directly to the disconnect, you would have bypassed the 30/50 amp inline fuse. Remember this, fuses are sized to protect the wires from overheating. They generally are not there to protect end-use devices.
2. After installing new battery monitor, I found a 6 watt drain on my batteries. When I throw the disconnect the drain goes away. This tells me its internal to the rig. My guess is that its the Radio and CO2 monitor. Everything else is off (including fridge). When in storage, my estimate is the radio would drain a 100AH battery in approximately 8 days. Thus, using the battery disconnect is very important.
3. One of my favorite accessories is the VIAIR air compressor. However, I do not like having to open the hood of the truck to power it off the truck battery. So part of this installation I added a solar plug to the side of the trailer near the pass-through door. The solar plug has two purposes. I can directly plug my VIAIR (30amp) into it. This will use my lithium battery for inflating tires. Secondly, like you, I have portable solar panel with controller that I can now directly connect to the batteries without opening the pass-through door.
Xaugiry 2 Pack 1ft 10AWG SAE Connector Extension Cable, SAE Quick Connector Disconnect Plug SAE Automotive Extension Cable, Solar Panel SAE Plug

[Guest]

Wonderful systems but want to add that Fuses or breakers in a modified system should be placed as close to the power source as possible (battery) so there is no issue in directly connecting to the switch as long as the circuits are protected.

Jim

[Lhinaz71]

Today I completed my project. I just wanted to thank all for their ideas and suggestions.

In the end, I used 4awg wire and routed both the positive and negative to the underbelly where the factory battery connects. I have a ANL fuse and a Victron shunt with display which I mounted on the docking station.

I ended up keeping the existing battery box on the tongue (removed the battery) and put a 2 prong busbar in there. I connected my tire pressure monitor relay in here. And, I'll use it to connect my portable solar panel as well.

I did not upgrade the converter at this point. I'll see how it does. Since I have factory solar, in theory, the solar controller should have the smarts to top off the battery. And, I've also read it's not necessarily good to keep your battery at 100%. I don't know the right answer, but I'll see how it goes, and upgrade the converter if needed.

And, of course, none of this happened unless there are pictures.

[uwskier]

I've been considering this exact upgrade. Hoping to do 200ah battery in a year or so. Thanks for the follow up!

[Guest]

Nice job! Its true that Lithium batteries will have increased longevity if they are kept away from the extremes. So 0% soc or 100% soc where the ideal range would be between 20% and 80%. Some however do not want to give up that much capacity. It is important to top off the battery once in a while so the cells can balance. These batteries top balance toward 100% soc.

Battery longevity is also increased by storing them at 50% soc.

Jim

[Paul & Deb]

I did not upgrade the converter at this point. I'll see how it does. Since I have factory solar, in theory, the solar controller should have the smarts to top off the battery. And, I've also read it's not necessarily good to keep your battery at 100%. I don't know the right answer, but I'll see how it goes, and upgrade the converter if needed.

Your factory solar panel should in fact help keep the battery fully charged but remember to change its setting to Lithium.

[Lhinaz71]

After a five day trip dry camping, I'll be purchasing a new converter after all. The problem with the non-lithium converter is that it only outputs about 2amps when you are above 40% (I don't have exact numbers).

I'm no battery expert, but I suspect it has to do with the higher voltages of a lithium battery, the converter thinks it's almost fully charged and goes into float mode.

The problem with this is that you have to run a generator all day if you are dry camping or boondocking to charge up your battery unless you have sufficient solar and sun.

Fortunately, I had my Victron charger with me.

[Country Campers]

After a five day trip dry camping, I'll be purchasing a new converter after all. The problem with the non-lithium converter is that it only outputs about 2amps when you are above 40% (I don't have exact numbers).

I'm no battery expert, but I suspect it has to do with the higher voltages of a lithium battery, the converter thinks it's almost fully charged and goes into float mode.

The problem with this is that you have to run a generator all day if you are dry camping or boondocking to charge up your battery unless you have sufficient solar and sun.

Fortunately, I had my Victron charger with me.

That is good info to share. This has been debated for quite some time and the info in this post will surely give the nod to going with a Lithium charger to replace the non lithium charger.

Brian

[mboehk]

I can confirm the issue with the WFCO 8955 when using LiFePO4 batteries after a lot of testing last weekend. While docked I unplugged and then swapped out my lead acid with the LiFePO4 battery with full bluetooth monitoring of charging, drain etc. The battery was at an SOC of about 35% and initially started charging around 6-7 amps, within about 20 minutes though, it had dropped to 3-4 amps and an hour after that 2-3 amps and the battery SOC was around 43%. I gave up an hour later as the battery was only getting about 2-3 amps of charge. I connected a single 100W solar panel and it jumped up to 4.5 amps, so it's definitely an issue with the WFCO not providing enough voltage for the LiFePO4. A few hours later with the SOC at 60%, I reconnected the WFCO and flipped the breaker on and off hoping it would go into a higher level charge mode, but no - it didn't seem to be charging at all.

I'm in the process of buying a Lithium converter and then I'll pretty much follow this thread to permanently mount the battery in the internal storage with all the fuses, tips, and wiring guides provided here.

The one difference is that I'm going place the new converter next to the battery in the storage area.

Thanks to everyone for contributing to this thread - it's definitely a keeper for those of us just starting out and looking for a simple, yet safe and effective Lithium battery upgrade.

Mike