48v RV Build Plan

[CarlCruzin]

Hey guys, I am in the planning stage of my RV solar and lithium build. I just purchased the RV about a month ago and I really want to be able to camp without hookups and not need to run my generator. I am trying to stay within a $5k budget and would like 5kwh+. From what I've been finding, this is a realistic goal for a DIY project. So far, the bulk of the items I am leaning towards (listed below) come in around $4k for a 13kWh 48v build.

Am I on the right track? Does this look like a good compatible setup? I am getting ready to start buying, but this will be my first project of this type and looking for some confidence in my setup (or alternate, better recommendations) before spending the $$ and getting the project rolling.

- DIY 48v LifePo4 Battery bank (still looking for 16s BMS)
- All-in-one off grid inverter/charger/transfer 3kw
- 1280w Solar Panels
- 48v to 12v 30a converter for 12v coach accessories

- 48v 280ah LifePo4 Battery bank (overkill for my needs, but the price is good):

2344.36US $ 6% OFF|16PCS/Lot LiFePO4 3.2V 280Ah Cells for 48V Camping RV Battery Pack With Bus Bars|Rechargeable Batteries| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

- All-in-one off grid inverter/charger/transfer

Growatt 48V SPF 3000TL LVM – 3kW 120Vac Stackable Inverter 4.5kW MPPT Charge Controller Split Phase 120V/240V capable with two or more units + free wifi – Watts247 Wholesale watts247.com

- 1280w Solar Panels

Longi Solar 320W Solar Panel

Longi Solar 320W LR6-60HPH-320M Solar Panel with Black Frame Established in 2000, LONGi has produced photovoltaic cells since 2007 and is the world leader in photovoltaic cell production. The LR6 lineup is a low LID monocrystalline PERC 60-cell with Half-cut technology module, with excellent...

www.solartechdirect.com

- 48v to 12v 30am converter for 12v coach accessories

Amazon.com

 

[Craig]

Not a bad start at all. You can do better with the cells though buying in one of the group buys on the forum. Around 1600. Check santan solar for prices on panels you may be able to shave a few more bucks. I like the growatt

 

[berksrunner]

Are there any decent/tested/reliable/affordable 48V/16S bms's out there yet?

 

[CarlCruzin]

Not a bad start at all. You can do better with the cells though buying in one of the group buys on the forum. Around 1600. Check santan solar for prices on panels you may be able to shave a few more bucks. I like the growatt

I will check those out, thanks for the advice!

 

[CarlCruzin]

I ended up placing an order with Michael for 16x 280Ah cells! ? ??

Now I just need to make sure everything else is good to go by the time the batteries come in!

 

[CarlCruzin]

Are there any decent/tested/reliable/affordable 48V/16S bms's out there yet?

You are asking the wrong person, Lol. I guess I assumed that there would be some good options out there. Have you had difficulty finding one?

 

[berksrunner]

You are asking the wrong person, Lol. I guess I assumed that there would be some good options out there. Have you had difficulty finding one?

I haven’t searched much since I don’t have a 48v system, but I would think this would be a major downside to trying to assemble 48v unless you’re willing to a. Take a risk on alibaba or b. Pay $$$ for a super-lux BMS. I have a 24v system and am loving Overkill Solar.

 

[CleanEnergyGuy]

Hi, I hope that you guys don't mind me jumping in on your conversation, but it looks like I'm in a very similar position to Carl in that I'm wanting to put a solar system with lithium battery backup for my 31' Class A motor home.

My goal is to be able to boon dock in a hot environment and to not have to use my generator too much (or as close to not at all as possible) for multiple days. I realize that this is difficult, but I want to come as close to accomplishing it as I and my budget can get.

So, here's my battle plan. Please let me know what you guys think.

Step One: Replace 13,500 BTU Carrier AC Unit with a Senville Senl-12cd mini split ac/heat pump. It pulls 1260 watts per hour when cooling, slightly less when heating. I plan on leaving the propane furnace in place as heating back up.

Step Two: Install 8, 250 watt Santan used solar panels for a max total of 2000 watts

Step Three: Install a Growatt 48 V SPF 3000 TL LVM - 3Kw 120 Solar Charge controller

Step Four: Install 4 100Ah Battle born Lithium batteries wired in series

Step Five: As time goes on and I can afford it, I'll add another bank of 4 100 Ah Battle Born Batteries

I also have purchased a Bluetti AC200 solar power station that I will be able to use to power my freezer chest, computers, etc. if I'm pushing things.

So, what do you guys think? Does this sound like this system will allow me to run my ac at least most of the night?

Also, when I talked with the rep at Battle Born, he suggested that I consider going with a 24 volt system, so I would greatly appreciate your input on if 24 is better than 48 vice versa or something else.

Thanks!

Bob

 

[John Frum]

Hi, I hope that you guys don't mind me jumping in on your conversation, but it looks like I'm in a very similar position to Carl in that I'm wanting to put a solar system with lithium battery backup for my 31' Class A motor home.

Step 1 is an energy audit.
Will you be integrating with an legacy 12 or 24 volt systems?
Will you ever by using shore power?

 

[CleanEnergyGuy]

Hi Joey:

My biggest concern is to be able to run the AC off of the batteries for at least 8 hours. The mini-split that I"m looking at pulls 1260 watts when the compressor is fully engaged (which isn't all of the time). The rest of our electrical usage will be fairly minimal...house lights, a lap top, a 40 inch tv. I am expecting my Bluetti AC200 to arrive any day and I plan on using it for things like phone charging, running the freezer chest, etc.

So, I basically need to be able to run the mini split AC during the overnight when it will basically be the only thing running off of the house batteries.

The existing system is a 12V system and I plan on putting a DC to DC converter in to step the 48 down to 12 to run the DC bus. I'm still getting use to using some of these terms, so forgive me if I'm not using them 100% correctly).

As far as shore power, I'll use it when it's available, but our plan right now is to boon dock most of the time.

Thanks for replying and I appreciate your input!

Bob

 

[John Frum]

Hi Joey:

My biggest concern is to be able to run the AC off of the batteries for at least 8 hours. The mini-split that I"m looking at pulls 1260 watts when the compressor is fully engaged (which isn't all of the time). The rest of our electrical usage will be fairly minimal...house lights, a lap top, a 40 inch tv. I am expecting my Bluetti AC200 to arrive any day and I plan on using it for things like phone charging, running the freezer chest, etc.

So, I basically need to be able to run the mini split AC during the overnight when it will basically be the only thing running off of the house batteries.

The existing system is a 12V system and I plan on putting a DC to DC converter in to step the 48 down to 12 to run the DC bus. I'm still getting use to using some of these terms, so forgive me if I'm not using them 100% correctly).

As far as shore power, I'll use it when it's available, but our plan right now is to boon dock most of the time.

Thanks for replying and I appreciate your input!

Bob

See my signature for a link regarding energy auditing.
Skipping this step 1 is a bad idea.
How much current can the legacy 12 volt system draw?
If its a wfco panel most of them have ~15 10 amp circuits which is far from trivial.
Are the components expecting ~12 volts or ~13.6 volts?

 

[CleanEnergyGuy]

Hi Joey: We haven't done this enough to be able to do a true audit. The current house batteries (2 6V deep cycle lead acid batteries wired in series) are shot, so I'm having to replace them one way or the other. My end goal is to build a big enough system that I could run my ac unit as much as I like and still avoid using my generator unless there were several cloudy days in a row.

I figure that with a 48V system with 2000 watts of panels on the roof, plus my Bluetti to power the other items that I will need to run, that it should come down to how many battery banks that I will need. I plan on starting with 4 100 Ah batteries (wired in series) then adding additional banks of 4 100Ah batteries as I can afford them.

I'm not totally opposed to adding some additional flexible panels that I would run in parallel that I could put out into the sun if I needed some extra opph!

Regarding the current that the existing system can handle, I don't have the foggiest. I've got a really good HVAC guy who is helping me with the install and he understands the nuts and bolts and with him, I'm not nervous about upgrading any components that we might have to upgrade.

My biggest question right now is if the system that I outlined above will at least get me started towards my goal and be able to support adding the additional panels and batteries if it doesn't. Does that make sense?

Thanks again,

Bob

 

[pangrande]

I haven’t searched much since I don’t have a 48v system, but I would think this would be a major downside to trying to assemble 48v unless you’re willing to a. Take a risk on alibaba or b. Pay $$$ for a super-lux BMS. I have a 24v system and am loving Overkill Solar.

I am in the same position. I have purchased components to build a similar systems using 48V but finding a 16s 48V BMS is proving difficult. The ones I find that are in the US are usually for 18560 based cells and not the prismatic cells and their different voltage reqs. (I almost ordered one and then quickly realized my newbie mistake). At this point I think I will be in a holding pattern as I think I now need to order from China and wait over a month. I debated going with 24V instead but then realized that the 24V all-in-ones (Growatt and MPPSolar) have a 2000W limit on the PV input and I have 3000W so 48V it is (or buy a second all-in-one and put in parallel).

 

[CleanEnergyGuy]

I am in the same position. I have purchased components to build a similar systems using 48V but finding a 16s 48V BMS is proving difficult. The ones I find that are in the US are usually for 18560 based cells and not the prismatic cells and their different voltage reqs. (I almost ordered one and then quickly realized my newbie mistake). At this point I think I will be in a holding pattern as I think I now need to order from China and wait over a month. I debated going with 24V instead but then realized that the 24V all-in-ones (Growatt and MPPSolar) have a 2000W limit on the PV input and I have 3000W so 48V it is (or buy a second all-in-one and put in parallel).

It's amazing that for something that in theory is so simple, just how complex it can get once you go into the weeds a bit! I suffered a really bad flair up of my sciatica, so was side lined for several weeks. Then there was a death in the family that required my attention out of town, so my whole project has been put on hold.

Now, just today, I'm back to work on it (sorry for the delay in getting back to you). I'll let you know what I find out, but thanks for the heads up on the BMS.

Bob

 

[CleanEnergyGuy]

I am in the same position. I have purchased components to build a similar systems using 48V but finding a 16s 48V BMS is proving difficult. The ones I find that are in the US are usually for 18560 based cells and not the prismatic cells and their different voltage reqs. (I almost ordered one and then quickly realized my newbie mistake). At this point I think I will be in a holding pattern as I think I now need to order from China and wait over a month. I debated going with 24V instead but then realized that the 24V all-in-ones (Growatt and MPPSolar) have a 2000W limit on the PV input and I have 3000W so 48V it is (or buy a second all-in-one and put in parallel).

Hi, an update if you're still interested. I decided to go with the Growatt 48 V system with 2000 watts of solar panels on the roof and 4 100 Ah Battle Born lithium batteries.

The batteries were expensive, but you can't argue with the warranty and come with their own BMS.

I ordered everything except now I'm trying to figure out what all accessories that I"m going to need such as the wiring kits from the batteries to the MPP, the cables connecting the panels, etc.

I'm still feeling a bit lost, but from what everyone who I've asked has told me, this system should work just fine. When I go to add an additional battery bank, I might get more creative and either build my own or utilize an electric car battery bank. I figured that it would be better to walk before I crawl though!

Let me know how your system comes together and I'll keep you updated on what I experience.

Bob

 

[berksrunner]

Hi, an update if you're still interested. I decided to go with the Growatt 48 V system with 2000 watts of solar panels on the roof and 4 100 Ah Battle Born lithium batteries.

The batteries were expensive, but you can't argue with the warranty and come with their own BMS.

I ordered everything except now I'm trying to figure out what all accessories that I"m going to need such as the wiring kits from the batteries to the MPP, the cables connecting the panels, etc.

I'm still feeling a bit lost, but from what everyone who I've asked has told me, this system should work just fine. When I go to add an additional battery bank, I might get more creative and either build my own or utilize an electric car battery bank. I figured that it would be better to walk before I crawl though!

Let me know how your system comes together and I'll keep you updated on what I experience.

Bob

Are you planning to charge via an alternator?

 

[CleanEnergyGuy]

Are you planning to charge via an alternator?

I've thought a little bit about it, but haven't really researched it yet. Have you looked into it already and if so, what did you find out?

 

[Thafella]

Hi folks. I’m building something similar and hadn’t realized yet there was a shortage of 48v BMS out there. I’ll have to investigate and consider 2x24v bms in series.

 

[pangrande]

So I decided on a two-step plan to address my needs for a 48V 16s BMS.

Step 1 (option for the impatient): Bought a DALY 48v BMS for LiFePO4 cells (watch out because many are for 18650 cells and if they arent programmable you will have voltage issues) off eBay from a US shipper $55. That gave me a BMS withing a few days so I got up and running.
Step 2 (or Step 1 if you are more patient than I): Ordered an ANT SMART BMS w/Bluetooth and LCD for 10S-24S setups. This BMS is programmable, has the lovely LCD and has 4 temp sensors. Pretty slick setup and cost was about $125 for the 200A setup. The downside was that it took over a month to get delivered from China. Hence why you may want to opp for Step 1.

 

[Thafella]

the overkill 48v BMS is now available (recently is my understanding)

16s BMS 100a for LifePo4 with 12″ 8ga Wires – Overkill Solar

overkillsolar.com

Just for the benefit of anyone reading this in the future.