DIY LiFePo4 24v battery bank???

[Nord]

Hi,

I'm new to solar but am diving in headfirst. I don't want to spend $4k on 4 100ah battle born batteries. I've been watching Will Prowse's youtube channel and learning heaps. He talks up the cells you can buy off Alibaba.com and I want to get your opinions on the pros and cons of buying 8 or 16 of these cells and stringing them together for a cheap battery bank. I'm thinking of doing either a 24v or 48v system. I'm building a school bus into an off grid adventure mobile and I want it to be capable of running a/c and power tools etc....I know it's going to be expensive but I'd prefer it not be $4k-$8k in batteries alone.

Thanks y'all,

Matt
Instagram @elchanchoamarillo if you'd like to follow along on the bus build.

 

[Pacer]

I pursued the same thing for a 24v pack. Purchased 8 cells from Xuba on Alibaba. They’re currently en route. With this cost I saved so much, it was absolutely worth the time and effort when it’s all said and done.

 

[GMB]

I purchased (16) of the 3.2volt 280 amp hour cells (making two 24volt batteries) for less than 2k shipped to my door. This would equate to about 10k in Battleborn batteries. I am very happy with my purchase. They are being discussed in this thread if you would like to read about them further and do some research: https://diysolarforum.com/threads/xuba-electronics-deal-280ah-lifepo4-cells-purchase-review.3850/

 

[Nord]

I purchased (16) of the 3.2volt 280 amp hour cells (making two 24volt batteries) for less than 2k shipped to my door. This would equate to about 10k in Battleborn batteries. I am very happy with my purchase. They are being discussed in this thread if you would like to read about them further and do some research: https://diysolarforum.com/threads/xuba-electronics-deal-280ah-lifepo4-cells-purchase-review.3850/

Thanks for the info! I'm starting to read Will's book now. As soon as I grasp that I'll start shopping. I still need to understand how to configure my set up for what I need it for and whether I need 48v set up or can get by with a 24v. Can you tell me about your set up and what you plan on running with it?

 

[GMB]

I am using my system to run a 12,000 BTU air conditioner to keep a room cool for my dog at an off grid property I own in Arizona. The system is way bigger than needed, but I will be adding more uses for it in the future.

This is my third system and my first two were very small and used AGM batteries. My first was for a camper van I used to travel in for a year with my dog and live out of (mostly West Coast states and we moved with the weather so no AC was needed). Your schoolie adventure mobile sounds right up my alley. It was one of the funnest years of my life and I will eventually get back to that traveling lifestyle once I get this piece of property developed and sold.

This is my schematic - however 2 of the bus bars aren't actually needed but I wanted to keep it easy to understand since I will be selling it with the property and the next person might not have any solar knowledge so it's easy to follow each wire to its location and understand what is going on. I have roughly about $6000 into the system.

 

[Steve_S]

24V is good for supporting up to the 4000W / 5000W (excluding surge value) after that, it's usually better to go up to 48V for 6000W and up.
Note that for 24V you need 8 cells for one pack, 16 cells for 48V.
The 280AH example provided above are cells that I also have, so I feel I should mention that the cells are 5kg / 11.0 lbs each.
Simplest would be to build 24V 8S (8 in series) packs and add parallel packs to add 280AH per pack.
8 Cells with S&H to USA: Total $1,093.52
16 cells with S&H to USA: Total$2,178.84
Source: Xuba Electronics on Alibaba
In a mobile application, the cells should be secured & "boxed" to prevent movement / vibrations etc...
A decent BMS (Battery Management System) start @ $100 (basic) and up depending on features, capabilities & functions. It really depends on how much you want to be able to do and if you want to be able to monitor, adjust tweak & control or not.
** Keep in mind that the bigger the battery bank the more amperage will be needed to charge said bank, this will of course need to be addressed with your Solar Charge Controller (SCC) and Inverter / Charger system.
For a robust Mobile Application which allows for Shore Power, Auto-Switching IF shore power is available and flexibility overall, I'd suggest the Samlex EVO series of Inverter Charger (see links in my signature) I use the 4024 (24V / 4000W) for my offgrid cabin that I live in FT. But there are other good ones out there too. The devil is in the details, low standby power use, configurability and capabilities.

24V - 8S "Block Pack"


Hope that Helps,
Good Luck
Steve

 

[Nord]

Thank you both! That helps so much. I'll be studying up on this over the next month and then start building my system ?

 

[gdpetti]

Can I ask, after this DIY battery is built, do you setup separate terminals or just use the black-out wire from the BMS and the red direct from the main positive battery connection?