New to lithium building

[Capt. Lenny]

So I've read a lot of posts on building a lithium battery here on BGW and thought I should build one. Why? Because I love a good project and I have more time than money. My current juice box still has about 3 years life on it so I didn't need to hurry.

With the help of Pat911, I set out looking for some good cells to use and was originally thinking about some EVE 105's but they were only 1C continuous. Then I got thinking about EVE 90's that augiedoggy was building a pack with that had a higher C continuous discharge. Anyhow I remember reading a post from augiedoggy about these Japanese cells being a good option for a pack. These things I think are really pack a punch @74ah they have a 180 amp continuous and pulse of 600 amps for 10 seconds! After conferring with Pat911 I settled on these cells and I think they'll be alright for my use. Bought the cells from batteryhookup.com. Bought some 40 mil PVC shower pan liner from Home Depot to put between the cells.

Trying to decide what to put them in was next. Thought about building a box out of plywood or PVC and then decided on an electrical enclosure. Found a brand new 16 X 20 X8 stainless steel enclosure on EBAY for about what it would cost me to build a PVC enclosure. Found some compression plates w/all thread from Jag35 (could have bought the cells here too but found them later).

The charger? Well because the cells are a little different voltage, I needed a charger that was CC CV but variable to suit my charging needs. After looking on EBAY and Amazon and not finding what I was looking for, Pat suggested AliExpress and buying the one pictured. Never looked or bought anything from AliExpress so this was a challenge with a learning curve. Finally got comfortable with it so I bought busbars, 300 amp main connectors, a JK BMS and screen but because I was unorganized in my build I bought these at different times so I had to wait on several slow boats from China.

Finding busbars for these cells was a challenge. I didn't like the ones available from Jag35 because you have to stack them for higher current situations and I didn't like that idea, too many connecting points. Liked the flexible ones that augiedoggy pointed me to but couldn't find the right size. The studs on these cells are 8mm and are 55mm center to center and there's quit a bit of contact area on the cells. I bought some with oval holes 56mm apart but only 6mm and couldn't figure out how to enlarge the oval hole so it would look/work right. So I ended up buying some C110 copper bar 1/8" X 3/4" and made my own. These are 3.12mm thick so 50% thicker than what I could buy.

So I've come a long way with the guidance of Pat911 and am nearly ready to dial in the correct parameters and do the initial charge and balance before the install. Good news is I have a guy that wants to buy my FLA batteries!

[Capt. Lenny]

More pictures of my build.

[Volt_Ampere]

Nice job! Best part about a custom build is that you learn how the thing is put together so that you can maintain it. (and the low cost) Drop-ins are good for most folks that don't want to or can't build their own pack. Yours is well thought out and very well executed!

[Capt. Lenny]

Thank You Volt_Ampere! My thoughts exactly. Feel free to comment if you see anything I'm doing wrong.

[TheCartBoy]

Looks clean and well thought out. How will you retain the cells inside the enclosure and is the lid also stainless? Wondering what prevents the studs shorting out, in the case of a roll over.

[Capt. Lenny]

The cells are compressed together with plates that I bought from Jag35. They make them just for these cells and they have a flange on them which can then be bolted to the bottom of the old battery tray, one is on the inside and one on the outside due to internal space limitations. On top of the cells there is a clear piece of plexiglass and the BMS will sit on that using command removable strips. I used the 40 mil PVC cut into strips in between all the cells on all side and the bottom. The all thread has tubing over it to prevent any possible chafing or rubbing. All in all it's makes for a pretty tight package. I have not rolled the cart over in 9 years and if I did I don't think the plastic hold downs for the FLA batteries would have done much good to retain them. The lid is also stainless and on a hinge.

Still trying to decide how much compression to put on the whole pack of cells.

[Pat911]

Very nice execution there Lenny, I’m very impressed. You’ve come a long way since we started discussing this almost 2 months ago. The cells that Augiedoggy found should serve you very well. Love the plexiglass top. You can hardly see it. I had to go looking for it as it looks like the BMS is sitting directly on the cell terminals. I was a little worried there for a second. :)

As for not rolling a cart in 9 years, don’t forget that with less battery weight your centre of mass is higher now. Still will be difficult to roll but just be aware.

[Volt_Ampere]

Center of mass is higher but mass is lower so the force to roll it may not be worse. Carts can roll quite easily if you drive them across a hill rather than up or down. One must be aware of that potential and drive accordingly!

[Capt. Lenny]

Thanks Pat, I am aware of that, that's why I don't like lifted carts. My father-in-law was on a stock cart in the back seat with 2 women driving and they rolled it. The batteries came loose and acid all over the 2 women and they had to be life flighted off of an island.

[Pat911]

Oh wow, I’ve never thought about acid burn as a consequence of a cart accident, just blunt force trauma and laceration/amputation. But it makes sense thinking about it now.