New member, first cheap commuter build

[Bbbbrass]

Hey all, I’ve been into the 18650 second life power wall scene for a year or so and ended up with a ton of tool cell batteries. I figured out how to fix many of them, especially the Ryobi 40V packs. During this time I also rebuilt some Headway packs to power my golf cart and got comfortable with spot welding, BMS wiring, IR & capacity testing and lithium charging/discharging safety. So I decided to build a little e-bike to use these cells! I’ve recently transitioned to my DIY pack instead of using those Ryobi packs and adaptors wired into a fuse block.
I had an old (2006ish) steel hard tail Diamondback Outlook. I’ve never done more bike maintenance than change tires, but away I went with a $200 kit off Amazon. https://www.amazon.com/Electric-Conversion-Brushless-Controller-Freewheel/dp/B097YXPFV7 I found a cheap rack at a bike store; it didn’t really fit but some leftover hardware from a TV mount and it was ready. I’ve used this bike to commute 4-7 miles on bike paths and lanes pre conversion, but my newer location would require 16 miles including some heavy traffic roads with no shoulder or path. Here is where I’m at so far, with under $250 spent total….

 

[amberwolf]

Just as a caution, I would point you to this thread regarding Daly BMS:
https://endless-sphere.com/forums/viewtopic.php?f=14&t=118344

 

[Bbbbrass]

Thanks AW. I have been following that thread with interest. Methods is doing some great work! I have a Smart Daly for a LiFePO4 prismatic build that works well, but mainly use JBD BMSs. I have a few of these small Daly (one each 24V, 36V, 48V) and only tested them for short circuit protection so far. They did work for that. I use fuses, LVC, and CCVC charging so I’m not too concerned about how much else they do. I think of lithium cells like cans of gasoline. You need to be cautious, but as long as you aren’t stupid there won’t be problems!

If anyone is interested, here are the specs from my pack.

 

[LewTwo]

I think of lithium cells like cans of gasoline.

That is not that far off. The "fuel" in a lithium ion battery fire is the organic solvents in the electrolyte.

 

[electric_nz]

Love those dyson packs! I managed to get a dozen near new vtc6a 21700 packs and over 100 loose Vtc5d cells from a battery recycler for cheap. My guess is they had real problems with their BMS engineering in the early packs, and repair wasn’t an option; as the cells perform just fine.

The plastic case means the packs are rugged too- I’m about to run a small 1p pack in a e-mtb- here it is mid build before wrapping and case goes on This particular pack had one dead cell so I have removed it for this 13s pack.

Anyway happy commuting. The next trick will be how to hide all the wires!

 

[Bbbbrass]

Anyway happy commuting. The next trick will be how to hide all the wires!

Thanks! That small pack looks great for a full suspension build. I do like the tough plastic case. The wiring I’m going to clean up after installing a real headlight and my larger 25R (10S5P)pack. Need to figure out how I want to secure it to the triangle….

 

[spinningmagnets]

Welcome!

Years ago (decades?), it was difficult to find high-amp battery packs, so two things were experimented with. Series two 36V packs for 72V, and also harvesting cordless tool cells. I recall buying a few packs, and just as advertised, one cell out of five had gone bad (for whatever reason) and the remaining four cells typically had 3/4ths of their capacity intact.

When I did this, you got a good price for buying a certain minimum, which was easy to accomplish because ebikers typically wanted 80 cells, in order to make a triangle pack with 13S x 5P = 65 cells. I seem to recall that all of this effort got me high-amp cells at $1 each. I'm sure its much more now. Now I have to pay to have my tire pressure topped off, and the attendant shrugged and said "it's inflation". (here's a thread from 2008...https://endless-sphere.com/forums/viewtopic.php?f=14&t=7569)

Since you mention having a spot-welder, I would suggest you take a quick scan of the "copper nickel sandwich" thread.

https://endless-sphere.com/forums/viewtopic.php?t=108006