48V powerwall with parallel ebike packs

[mschaus]

Hey everyone, I wanted to share what I built this past year, a little different than many I've seen here. Big thanks for everyone's informational posts and YouTube videos (especially Will) I learned so much from.

I had a bunch of 13s ebike packs with 18650 cells. I decided that since they were already nice packs I would use them the way they were assembled rather than harvesting the cells and building one giant pack. I ended up with 19 packs in parallel, all together adding up to 13s89p and about 280Ah @ 48.1V = 13.5kWh.


I replaced the BMSs with 20A Daly models and tidied them all up in shrink wrap.


And built them all into a large aluminum case. Fuse blocks with ATO fuses rated to 58V were used to tie them all together.


Combine this with a 1500W pure sine inverter and manual transfer switch (the one sold by Goal Zero with 4 circuits) and I have an awesome backup power plan!

I have the full writeup on my personal blog: https://mschausprojects.blogspot.com/2023/01/diy-powerwall-parallel-ebike-batteries.html

Excited to share and hear what people think! I'm working on adding a few more packs now... Cheers!
Mike

 

[KITROBASKIN]

Wow!
Where did you get the battery packs?

 

[KITROBASKIN]

Would that be a 13S19P configuration?

 

[MisterSandals]

I had a bunch of 13s ebike packs with 18650 cells. I decided that since they were already nice packs I would use them the way they were assembled rather than harvesting the cells and building one giant pack. I ended up with 19 packs in parallel, all together adding up to 13s89p and about 280Ah @ 48.1V = 13.5kWh.

Looks like each pack is 5P13S ? Each pack with a BMS?

Would that be a 13S19P configuration?

5P13S19P

 

[mschaus]

Yup there are currently 19 packs in parallel (adding some more probably), each with a BMS. 6x 4p packs and 13x 5p packs. 6x4+13x5=89, so equivalent to having 89 cells in parallel. I'm lucky to have a source of packs through my work; I saved them the cost of paying someone to haul away to recycle.

As for current sharing between the packs, I'm doing some experiments, but I'm not concerned because each one has such a low discharge rate, only up to 2A each or so. There is some variation through the discharge curve, but on average, the current is proportional to each pack's capacity.