DIY Lithium RV Battery Build - Part 3: Battery Box, Installation, and Converter Replacement

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In Part 3 of this video series, we're wrapping up our Lithium RV Battery Upgrade project (for now!). Today we'll:
- Build a solid, weather proof RV battery box for our custom LiFePO4 battery
- Install the battery box and batteries in our travel trailer and wire everything up
- Upgrade our RV converter to a Lithium converter
We might even build the second battery (hint!).
The result is a super compact 200 Amp Hour (AH) Lithium pack that looks better than anything that comes equipped on an RV from the factory, and will work in almost any trailer, motorhome, or van conversion. Impress your friends and fellow campers. Dive in, follow along, and build your Lithium battery pack!
DISCLAIMER:
Undertake any project at your own risk. I'm being as safe as I can be and making that judgment for myself. I'm sharing my knowledge as I go, but I could be incorrect or miss something, and do not know about every possible unexpected issue that could arise. I try to push myself, but I also know my limits and don't exceed them. Before you embark on a project, you should too.
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PARTS and SUPPLIES
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Case:
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Monoprice 20.3 Liter battery box (QTY 1) (www.amazon.com...)
Wiring:
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MSI Speedware through panel terminals (1 black, 1 red) (www.amazon.com...)
Silicone sealant (www.amazon.com...)
8-32 x 1 inch long stainless socket head cap screws (QTY 4)
8-32 flat washers (QTY 8)
8-32 nylon lock nuts (QTY 4)
Red and black Terminal covers (www.amazon.com...)
12 inch red 4 gauge x 5/16 lug battery cable (www.amazon.com...)
12 inch black 4 gauge x 5/16 lug battery cable (www.amazon.com...)
24 inch red 5 gauge x 5/16 lug battery cable (www.amazon.com...)
Kydex sheet (for insulating panel) (www.amazon.com...)
Case Mounting:
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Polyethylene packing foam (for retaining battery within case)
1.25 inch square tubing x 8 inches long [your quantity and dimensions may vary] (QTY 4)
5/16 x 3.5 inch carriage bolts [your length may vary] (QTY 4)
5/16 stainless fender washers (4)
5/16 nylon locknuts (4)
adhesive backed ratcheting cable clamps (QTY 2) (www.homedepot....)
Converter:
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WFCO 8950L2MBA (Only applies to replacing WFCO converter. Consult with your manufacturer for your best replacement option)
-- or --
WFCO 8950LIS-MBA (has switch to change between Lithium and Lead Acid charging)
Tools:
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1 inch hole saw (www.homedepot....)
5/32 drill bit
5/16 drill bit
7/16 drill bit
Philips screwdriver
Other Supplies:
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Black Paint
heat shrink tubing
Wire nut
Electrical tape

Опубликовано:

8 сен 2024

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Комментарии : 45

@davidthurman3963 2 месяца назад

I subscribed just based on the quality of the solutions. This allows me to build my 48volt with 2 cases since I was trying to figure out how to do a split case for moving the batteries. All I need to do is now is figure out the bms pass through but that should be relatively easy. I think. Lol.

@bennettburns3507 Год назад

That is the cleanest home-built battery I've seen! Beautiful. We just ordered cells and BMS for two batteries for our fifth wheel after having the same first night lack of juice blues. I'm looking forward to the process. Your level of finish is first rate and sure sets the bar high. Thank you for the added growth challenge!

@QuintBUILDs Год назад

That battery case is sweet! Perfect fit for the trailer too.

@thegregbase Год назад

Thanks! You can find similar cases in just about any size to fit the number and shape of batteries that work best for you.

@MrButuz 3 года назад

Thats a great build I am using the same kind of camera/gear cases off amazon as they're so well built and sturdy for the money - and using nissan leaf cells in there - done a small 14v 60ah one and doing a larger 14v 120ah one at the moment. Each one is self sufficient with small victron 75/15 charge controller, and multiple usb and 12v outputs. The bigger one is going to have an 800w inverter bolted to the outside too.

@thegregbase 3 года назад

Nice! Sounds like you built an awesome self contained and portable unit. If I had more room inside, I would potentially have put more electronics inside.

@jasonbroom7147 3 года назад

Continued excellence in this video. That box could be a commercially sold unit, it's done so well. 200AH @ 12v or 100AH @ 24v would both be very useful.

@thegregbase 3 года назад

Thanks! Super happy with how it turned out. 24 volt is intriguing for the future too!

@jasonbroom7147 3 года назад

@@thegregbase - It's not particularly relevant for your application, but as voltage goes up, so does inverter efficiency. So, for emergency backup power in your home, 24 or 48 volt batteries, with corresponding inverters, can make a lot more sense.

@jeredcox3605 11 месяцев назад

Nicely done

@thegregbase 10 месяцев назад

Thanks!

@thomash7573 3 года назад

What a great build! A work of art. Thanks for the video.

@thegregbase 3 года назад

Thanks! Looking forward to sharing the results of some real life use!

@RVTA 2 года назад

Enjoyed the travel trailer battery install. Super useful information. I have no plans to build a battery though. Congrats!

@thegregbase 2 года назад

Well, thanks for watching even still!

@RVTA 2 года назад

I learned a lot.

@Sanwizard1 2 года назад

Thanks for the upload. You should add fuses, and battery pack cables are supposed to be the same length to prevent unequal voltage drop. Nice box though. I think the CALB's, with their plastic cases are perfect for mobile applications. If you plan to head out in cold weather, you may want to also add a 12v heater in the box. (Glue on tank heater or silicon heater with built in thermostats work well)

@thegregbase 2 года назад

Yeah, your advice is good advice . Will looks at some revisions in the future.

@russellriggan2088 6 месяцев назад

I always said,I would replace the marine battery on our trailer once it died. Well, it died. I don't think I'll build a lithium battery or mount it back on the trailer tongue. I do plan on mounting inside under the bed. Thank you for your research.

@loucinci3922 3 года назад

Nice box. Super build. Did you consider a breaker @ the box? I saw the cut-off switch inside, but I think a fuse or DC breaker there at the box would be a plus. Nonetheless, awesome build. Thanks for sharing.

@thegregbase 3 года назад

That's a good idea. I should never see dangerous current with normal loads, but if something went really wrong, a breaker would add some additional protection. Guess I do need up to the next size of box :)

@dougg8280 2 года назад

Well done! Have you thought about adding a heater? You already added insulation.

@thegregbase 2 года назад

I have thought about, but wanted to get comfortable with having enough power before adding the additional load. So far in Oregon we don’t get a lot of icy days during our camping season. In other climates I think that would be a great addition!

@van_dutch 3 года назад

Nice! You're a pro at editing. I know ohms law, and how to throw capacitors at people, and make them pop, but this is next level learning. I was happy to see the strap around the box at the very end, I know battery theft is huge business, and would hate to see that work of art stolen! Do you also put locks on the box?

@thegregbase 3 года назад

Ha, thanks! Definitely learning as I go on all of this. There's a padlock on the security strap tucked behind the box where it's extra hard to get to.

@gunningopher 3 года назад

That installation looks awesome. I have a 12v 200AH LiFePo4 that I purchased complete for about $1000 delivered. Yours looks way better, has better user controls/information and I bet it cost much less. It would be helpful if you put together a build sheet for it. I wanted to build my own but I didn't feel like having to justify it to the wife and I was surely going to hear about it if things went south!! I'm glad you put a strap and lock on it. I'd consider that a must for any that was accessible from the outside. I'm curious to find out how your converter worked. I couldn't tell if you bought a multi-stage one. I assume you did because single stage chargers are garbage. It wouldn't make sense to go through all this and short yourself on the charging end. Are you disabling the charger from your tow vehicle? As you probably know, there are some concerns about charging lithium using the alternator but there are a some solutions that can alleviate those concerns.

@thegregbase 3 года назад

Thanks! I really liked how it turned out. I'd say 200AH for $1000 delivered is not bad at all (compared to some of the off the shelf units that are closer to $900-$1050 per 100AH). Mine was in the same ballpark as yours, but I also enjoyed the heck out of building it. I'll have to put together a build sheet. Great suggestion. Converter worked okay, but that led me to discover some areas where I dropped the ball, and other shortcomings of the trailer that are limiting its performance. All in all, though, it worked great, and all of the other stuff is just tweaking the frosting on the cake to make it even better. I'm putting together a video following a trip with the batteries (they take a surprising amount of work to edit), and will get something together with what went well and didn't go so well, and what needed tweaking. I hear you on the alternator. Haven't addressed it yet, but will need to soon.

@Bryster51 2 года назад

I'd be concerned about placing cells on it's side for use. Bet the small amount of liquid inside does not like it long term.

@thegregbase 2 года назад

Great note. Generally speaking, flexibility of mounting orientation is one of the advantages of LiFePO4 batteries. That said, each cell type (and manufacturer) has its own recommendations and limitations. As I understand it. for prismatic cells with a safety valves on the top, it is preferred to orient the cells with the vents facing upward. Most manufacturers say laying on their sides is fine, though, with having them on their edge like I have them being preferred to laying them on their flat face. Upside down is a no-go. The concern is about the electrolyte pooling in the safety valve and rendering it non-functional. If you make your battery from cylindrical cells, on the other hand, this doesn't apply, and the sky's the limit as far as I can tell.

@thegregbase 2 года назад

@ovchannelag5238 Год назад

👍👍

@azizz8151 2 года назад

Question great job by the way! I was wondering aren’t lithium heat sensitive I ask because with other installs there always putting fans in. This method seems simpler I rather do this.

@thegregbase 2 года назад

Thanks for the question. Lithium Iron Phosphate (LiFePO4) aren’t as prone to thermal runaway as Lithium Ion chemistries used in electric vehicles, for example. Not sure if that’s where you were seeing the use of fans. LiFePO4 gives up some energy density as a trade off for this stability, but worth it in this case. If you look at the off the shelf 12v lithium replacements, they are the same types of cells I’m using for that same reason, sealed in a case that just happens to look like a car battery. So essentially I’m doing the same kind of thing. If I was building a really big bank of batteries, I might do it differently and consider some active cooling as an additional insurance policy, though.

@buckbiggs1602 2 года назад

Great job! Makes me consider building my own batteries. Have you further checked the wfco charger? I'm in the research phase trying to decide on the wfco replacement or one of the other brands that offer a lithium compatible converter charger that fits the wfco box.

@thegregbase 2 года назад

The WFCO charger is okay. I get about 35A peak charge current out of it. But I have about 25’ of factory 6 ga battery cable and wiring between the batteries ( front of the trailer) and the converter (far back end of trailer) , so this is probably playing into things. There is more efficiency to be extracted from the overall system before I would invest in a different converter. Though I don’t have personal experience with them, there are some other options from progressive dynamics that are well regarded. At the time I bought my WFCO, the price and availability difference was kind of significant, but now that prices on cells have dropped, that’s not as much of a concern. But again, it’s about the whole system. Getting a mega converter will expose the next weak link.

@buckbiggs1602 2 года назад

@@thegregbase Are your batteries getting to 100%. I had heard some complaints the 8950l2 voltage output was less than the recommended 14.2-14.4v. That's why I was considering one with adjustable output. Yes, lifepo4 batteries are getting cheaper 👍

@EBKRV412 2 года назад

Once the Installation was complete did you have to do anything to your 7 pin connector from your tow vehicle? Does the charge from the 7 pin work ok with the lithium batteries?

@thegregbase 2 года назад

I didn’t have to do anything to the seven pin connector on my tow vehicle to get it to start charging. That said, different vehicles may output different voltage levels, so not all alternators or charging systems may successfully charge a lithium battery. I also understand that there is some danger in charging directly to your lithium battery from your alternator. Because the lithium batteries can take as much charge current as your alternator can probably output, you could blow a fuse in the charging circuit. Also, when the BMS shuts off charging suddenly, that can be bad for the tow vehicle’s charging system. I have not experienced this myself, but every vehicle is different and there are known concerns.

@badactor3440 2 года назад

What guage cable would I need if my batteries are separated by 4' ? I know this is a unusual question but I have a set of 2 batteries and a set of 3 batteries that I want to combine together into a single bank.

@thegregbase 2 года назад

The size of your cables will be dictated in part by how many amps of current you’re going to push through the cables. Voltage affects it too, but I’m assuming you’re talking about a 12V system. You can find cable size calculators online that will let you plug in values. I used one at wirebarn.com and assumed max 150A at 13.8V. They say you can get away with 4 gauge, but 2 gauge might help you sleep better at night. Doesn’t cost that much more than 4 ga either. If others have other opinions, feel free to weigh in.

@ronaldrogerson5724 2 года назад

is that a 67 or 68 cougar behind you?

@thegregbase 2 года назад

Good eye! That’s a 68. Been in the family since it was new, and undergoing a VERY slow restoration/modification.

@richr6416 Год назад

What was your final cost?

@thegregbase Год назад

Here's a bit of a breakdown. This is effective cost for parts used. For example, in some cases, I bought a case of heat shrink tubing. So technically, I might have spent more than shown, but I ended up with excess. I ended up using the extras on the second battery, or other projects, so not accurate to attribute all of the cost to one battery. First Battery, band, bms, bus bars, connectors: $699.00 Second Battery, band, bms, bus bars, connectors: $567.11 Case, internal cables, terminal blocks, hardware to mount to trailer: $179.04 Converter/charger: $157.70 This was all circa 2020/21. I went back and looked at current prices, and today, the same battery would cost $354.31 to build with the exact same cells, BMS, and pieces. The case assembly would cost $167. Thanks!