Budget 90ah 48v lifepo4 battery build (under a grand)
 

So I had good luck building a lifepo4 battery this spring for my solar popup camper setup. This got me thinking since I found an old electric yamaha g8 cheap enough that I would build a solar charging 48v lithium powered cart. This started as a bare bones cheap thing but keeps expanding it seems.

Anyway heres is my progress thus far. the cells I ordered here from aliexpress came today after a 2 month wait.I got them on sale during the 11:11 yearly sale for $623 shipped.
The cells all look good with a charge of 3.22v and they are not bloated. I went with these "90ah" cells specifically because they are rated at 3C (270amps) continuous discharge output with higher peak ill likely never need, even with the used SR72500 alltrax controller I scored on ebay.

https://www.aliexpress.us/item/22518...andl_shipto=US

I bought (ebay) a used hoffman steel electrical enclosure (14x16x10) for $63 shipped which with a little shimming and a thin layer of closed cell foam fits the 16 cells perfectly and keeps them compressed which is ideal for longer battery life. I also purchased a few flexible dollar store cutting mats which I cut into insulation strips and put between each row of cells. The material is very thin plastic. this it between the cells and the metal enclosure on the one side of the inside of the box that isnt lined with the neoprene type foam or the floor underlayment I have on two sides as shims. (classy I know) but this all adds to the layer of protection from shorts as the aluminum case of the cells under the blue wrap is grounded to the negative terminal of each cell.

Unfortunately the 300a continuous JBD bms has not arrived yet. I did receive the touchscreen bms interface though.
https://www.aliexpress.us/item/32568...andl_shipto=US

I ordered these terminals to the enclosure im waiting on.
https://www.aliexpress.us/item/32568...andl_shipto=US

(RS485 touchscreen)
https://www.aliexpress.us/item/32568...andl_shipto=US

I also scored a new open box 58.4V 22a charger on ebay for $90 shipped the other day that im waiting on.

At this point im going to start top balancing all the cells to 3.65v while I wait for the bms. I will post pictures tomorrow of this.

Re: Budget 90ah 48v lifepo4 battery build (under a grand)
 

Looking good. Looks like you are going to have the lowest cost solution out there.

Re: Budget 90ah 48v lifepo4 battery build (under a grand)
 

There's cheaper solutions with used/reclaimed cells. Honestly time will tell how well this setup with perform but it "should" be an excellent pack with the capability and ratings on the cells and BMS.
I just finished stringing the top balance leads and have it top balancing until the bms arrives next week. Top balancing is optional (especially since I have the active balancer) but I have the time while I wait and it will only improve performance.

Tonight I plan on making the bus bars out of a copper bat I bought.. After reading about the oxidation that often occurs between the aluminum Posts on these batteries and the copper or nickel plated bus bars that are often used I am convinced a lot of these battery issues reported here are from terminals heating up from oxidation I bought some antioxative electrical coating that's supposed to help prevent this I saw a YouTube video today showing with a heat gun how much resistance the oxidation can cause on what otherwise looks like a clean connection. This also causes cells to wander out of or appear to be out of balance as well

this is the stuff I got.

https://www.ebay.com/itm/134339514805

I am really tempted to just say the hell with making the bus bars and buying 16 of these https://www.aliexpress.us/item/32568...d=8meZITgUyg8X

But I already spent $50 on the 1/4" x 3/4"x 36" copper bar to make them.

Re: Budget 90ah 48v lifepo4 battery build (under a grand)
 

Would like to get my hands on 16 of these for a build.

https://batteryhookup.com/products/4...39785286664354

Re: Budget 90ah 48v lifepo4 battery build (under a grand)
 

Those are very old. They havent used those plastic housings in years.. I have been looking there for weeks. They get deals that typically sell out in hours. shipping can be a killer though. I'm happy so far with the cells I bought... I may buy more from that seller. they are CATL cells.

Re: Budget 90ah 48v lifepo4 battery build (under a grand)
 

Yea I ran into the shipping cost issue on one I was looking at earlier this year.

Re: Budget 90ah 48v lifepo4 battery build (under a grand)
 

I have that screen on one of my batteries. It comes in handy for checking SOC without having to fire up the phone app as I don’t have a dedicated SOC meter connected to it. It works very well.

You should end up with a very good battery there Augiedoggy.

Re: Budget 90ah 48v lifepo4 battery build (under a grand)
 

Still waiting on terminals and I decided to splurge for flexible tin plated bus bars. Im using the whimpy ones that came with the cells for now... Got the Bms connected and charging now.. Almost done. Still waiting on the charger so I improvised and connected the $40 mppt boost solar charger to my 30v 10a power supply... Surprisingly it worked to charge with almost 10 amps. I had it charging at 3.65v for a couple days in parallel but I didnt use heavy enough wire with good enough connections as I have the cells under compression in correct order now and knew there would be some normal swelling once charged up and there would be no rearranging then.

Re: Budget 90ah 48v lifepo4 battery build (under a grand)
 

Well balanced cells you have there. Is the active balancer connected?

Re: Budget 90ah 48v lifepo4 battery build (under a grand)
 

Very nice work auggiedoggie! Someday I want to do this so I'll be watching your progress. Just in the reading and learning stages now.