DIY 91v 26s LEV60F Pack

[copper]

Posting this to help others with ideas for builds and to say in 2025 your probably better off buying a pack.

The change to greater than 60 volts required a new reducer that could handle up to 92v and a new contractor is recommended.

I charge it with a cheap Variable DC Power Supply from amazon, 120VDC 3A Adjustable Switching Regulated DC Bench Power Supply. I don't use the cart a lot and I don't need to charge it fast. Its so cheap I wont post a link, but if you need a good charger try this one https://batteryhookup.com/products/m...e-power-supply

I wanted a pack that could keep up with the controller 650A for 30 sec and 250A constant. Assuming that’s rated at 48 volts that would be 31kW & 12kW. 31,000 watts at 91v is 340 amps and the cells are rated for 600A for 10 sec. I went up 91 volts bc the controller max is 92 and the higher the volts the less amp draw. (safer on the cells).

*Rants. I am surprised at the number of packs (DIY and manufactured) without fuses on the cell leads. I am surprised at the number of packs with underrated bus bars. Yes, I have been guilty of both in the past. I live in Texas and I know I am going to draw high amps (generate heat) in 100+ deg heat weather. Heat kills batteries. Resistance creates heat, beyond ratings creates more heat. To reduce the heat created from draw and not spend 400$ on copper I designed bus bars and had them made by sendcutsend.com (and the end plates).Links below. Related to heat, I also recommend carbon grease or something similar. I probably should add a contactor and not use the cheap BMS and MOSFETS for main power draw but I wanted to keep it simple and I like the monitoring without adding a shunt.


Battery Cells
https://batteryhookup.com/products/n...rismatic-cells

Volt Meter
https://www.amazon.com/dp/B0BN1J13FY

HDPE Sheet
https://www.amazon.com/dp/B0CXP7BSHX

Epoxy Sheet Resin Fiberglass Plate Insulating Plate
https://www.amazon.com/dp/B0CQXGYMLT

400A T Class Fuse
https://www.amazon.com/dp/B000MMH1JO

Fuse block
https://www.amazon.com/dp/B001VJ03LA

3A Pico Fuse.
https://www.amazon.com/dp/B082S77X66

Contactor
https://www.amazon.com/dp/B0B9M98MH6

Reducer
https://www.amazon.com/dp/B0C5WV1XKJ

Carbon Conductive Grease
https://www.amazon.com/dp/B005T8ROWA

BusBars
https://cad.onshape.com/documents/c0...f7384573de4a62

End Plate
https://cad.onshape.com/documents/6b...c1627a8ae6c321

[copper]

More pics

[Capt. Lenny]

Those are great cells, I have not had any problem with them. I actually thought about that carbon grease but decided against it due to the cost and how much I would need. Great build anyway, good job! I often wish I would have went 72 volts but this was my first build and not sure of what I was doing. I have to say I prefer copper busbars and the only thing better is silver or gold which are out of the budget. Very nice work, Great post!

[davros]

Thanks for sharing, very interesting, would love more posts like this.
Why the HDPE (very heavy ) vs aluminum plate?

I have a set of LEV60s waiting for my next build. I need to outsource/simplify, an all metal enclosure done with ~woodshop tools was very time consuming, sooo much drilling tapping....

I will take some scrap sense wire and see what it does when treated as a fusible link, I may be unhappy with the result.

[copper]

Originally Posted by Capt. Lenny

I often wish I would have went 72 volts but this was my first build and not sure of what I was doing.

Thanks! #metoo This is my third pack, after figuring out that 48-60v @ 600+amps is more of a pain than 72-96v @300

Originally Posted by davros

Why the HDPE (very heavy ) vs aluminum plate?

..I need to outsource/simplify, an all metal enclosure....

I will take some scrap sense wire and see what it does when treated as a fusible link, I may be unhappy with the result.

1.Cost 2.Conductivity. I came very close to plywood but water and splinters. With 124lbs in cells and stock suspension made for the extra weight of the lead batteries, the HPDE is not on the weight radar. An all metal enclosure can be done a few different methods with sendcutsend. All options end up STARTING at 300$ so I quickly decided I don't want to trap the heat ;) *When the cart is not in use I keep the pack covered in a lipo blanket.

Someone who understands they are all fusible links that glow. Just one of those 28+ fiery electron daemons ready at any time to set off a chain reaction.

If this was a battery backup on the shelf that's one thing. The cart gets driven off road and has a high chance of rolling over (again). Then its gets stored in my garage after use by people who would never bother to check it (kids) or will forget(me). If the cart burns to the ground while in use that's a minor problem...if the cart burns my house down after a day of fun in the golf cart (intended use), that's on me.

[Capt. Lenny]

Tell me more about these fusible links, I’ve never seen anybody use those before.

[TheCartBoy]

Since they are only on the sense wires I guess the idea is if they become open circuit, the BMS would see a 0V cell and shut off.

But why would you need a fuse on the sense wires? If a wire gets cut or shorted, that thin wire is going to be vaporized and the BMS would see a 0V cell.

[copper]

Originally Posted by TheCartBoy

...why would you need a fuse on the sense wires? If a wire gets cut or shorted, that thin wire is going to be vaporized and the BMS would see a 0V cell.

Safety.... wire may of may not vaporize fast enough and/or damage something in the process. For a few cents & seconds of time its worth it to me.

Originally Posted by Capt. Lenny

Tell me more about these fusible links, I’ve never seen anybody use those before.

sarcasm...when you run more amps than rated, all wires are fusible links.

[jasonojordan]

Originally Posted by copper

Safety.... wire may of may not vaporize fast enough and/or damage something in the process. For a few cents & seconds of time its worth it to me.


sarcasm...when you run more amps than rated, all wires are fusible links.

and all machines are smoke machines if operated wrong enough.