Build Thread - 120Ah LifePo4 - 40 mile range for less than $1200?

[AussieInSeattle]

Here's the update to my build. 5 pics attached with the completed pack all wired up and then wrapped up and lifted into the cart with a couple of straps I simply wrapped under the plywood base and tied at the top. My pack is an extremely tight fit into the space. Ignore the 120Ah capacity shown on the meter in the final pic - the meter is not calibrated. The pack was at 53.4V resting voltage when I put it into the cart with a 6mV difference between the 16 cells (3.337 - 3.343). Pics here show prior to hooking it up to the cart cabling.

[AussieInSeattle]

And a few more pics

[AussieInSeattle]

For an update on my build and the "issue" I ran into I posted a new thread here on how I managed to short my pack during installation:
https://www.buggiesgonewild.com/show....php?p=1803450

I'll be continuing this thread though once my 2 new cells arrive in a couple of weeks.

[reiter284]

Originally Posted by AussieInSeattle

Those BMS's look pretty sweet - what Amp version did you go for?

I bought the 60amp Bluetooth smart BMS with a common port. Going to wire it up like Sergio.

Thanks for you other responses. I just wasn’t convinced that the C rating on these lower end batteries mattered. I haven’t seen it becoming an issue anywhere. Definitely going to monitor temps (via BMS) and amp draw. It’s flat here in Houston and I’m just using the cart for pavement cruising. I have the navitas more for the OTF governor than anything.

[reiter284]

Originally Posted by AussieInSeattle

For an update on my build and the "issue" I ran into I posted a new thread here on how I managed to short my pack during installation:
https://www.buggiesgonewild.com/show....php?p=1803450

I'll be continuing this thread though once my 2 new cells arrive in a couple of weeks.

Thanks for the lesson learned story. Definitely could see myself doing the same thing. I rewired a side by side fridge so I could control the temperatures of the freezer and fridge to whatever I wanted. Very last step I made a nice spark show and needed a change of underwear.

[WC53]

Very detailed thread and the safety concerns. Looking over at dyisolar.... it seems like everyone is putting 280ah into mobile setups.. in talking to the battery guy at the, cough, local marina. He swears the lithium rep told him no +200ah cells in mobile situations as the extra mass from volume isn’t supported well. They recommend 100-160 for applications with fuses at each P block. Is that good guidance?

I’m about to go down this road, so it is great reading this and the other threaf.

[AussieInSeattle]

Originally Posted by WC53

Very detailed thread and the safety concerns. Looking over at dyisolar.... it seems like everyone is putting 280ah into mobile setups.. in talking to the battery guy at the, cough, local marina. He swears the lithium rep told him no +200ah cells in mobile situations as the extra mass from volume isn’t supported well. They recommend 100-160 for applications with fuses at each P block. Is that good guidance?

I’m about to go down this road, so it is great reading this and the other threaf.

I'm not educated enough on the larger cells to know whether what you were told is good guidance or not. I thought most were going for those 280aH cells as the cost per wH was the lowest, the ali vendor was easy to work with and the cells were capacity testing as promised. Most people it seemed were putting them into service for home storage solutions. 14kW (280aH cells) of lithium capacity in a golf cart is way over what I need - I'd size your cells so they are large enough for the distance you desire while also having appropriate continuous discharge specs. My 120Ah cell pack weighs about 100lbs (estimated) and was difficult to transfer from workbench to cart - with 280Ah cells you'd likely have to build it into the cart or split the pack which is more of a hassle - like anything there are ways to get it done, but making any aspect of your build easier is a win in my opinion.

[WC53]

Thanks!

I think I will stay about 120 just for weight and intended use. I just need to figure out which cells to use.

My google ** just found this, http://nordkyndesign.com/assembling-...ne-house-bank/

Which briefly touches on size but I don’t know how much is old vs updated info or if it is all bs.

[AussieInSeattle]

Originally Posted by WC53

Thanks!

I think I will stay about 120 just for weight and intended use. I just need to figure out which cells to use.

My google ** just found this, http://nordkyndesign.com/assembling-...ne-house-bank/

Which briefly touches on size but I don’t know how much is old vs updated info or if it is all bs.

If I was to do it again I'd go with the EVE 105Ah cells - the dimensions make them easier to fit into a cart in a 2x8 setup - the dimensions of my 120Ah cells make it a really really tight fit which makes building a case or finding an off the shelf one a lot harder. When I had to order my additional cell due to my shorting issue they (XUBA) said they could do metal boxes for $75 that were W500/D280/H250 - from my calcs they would fit the 105's easily but you'd have 20cm of extra room on one side - I'd get a custom box made and mount the bms etc externally:
https://www.alibaba.com/product-deta...7a0c3e5fNdNnEl
Yet another option would to have them build a pack to your specs with no bms and just provide a 17 pin connector through the box for you to hook up your own.

[WC53]

Originally Posted by AussieInSeattle

If I was to do it again I'd go with the EVE 105Ah cells - the dimensions make them easier to fit into a cart in a 2x8 setup - the dimensions of my 120Ah cells make it a really really tight fit which makes building a case or finding an off the shelf one a lot harder. When I had to order my additional cell due to my shorting issue they (XUBA) said they could do metal boxes for $75 that were W500/D280/H250 - from my calcs they would fit the 105's easily but you'd have 20cm of extra room on one side - I'd get a custom box made and mount the bms etc externally:
https://www.alibaba.com/product-deta...7a0c3e5fNdNnEl
Yet another option would to have them build a pack to your specs with no bms and just provide a 17 pin connector through the box for you to hook up your own.

I had originally planned to use calb or fortune but the prices are staying high, 120x16 oh my. I have been looking at the eve and lischen as they seem more reasonable right now. Have too see what is available after the Chinese new year. Also did a 60ah build with 32650 cells that has been performing well. But that is 320 cells for 120ah. It would keep the cog lower though.

Thanks for the info on the steel box. Thats is reasonable.