LiNMC 18650 in 7S build idea

[Supervstech]

Ok, I have a TON of 18650’s and the typical 6S Tesla uses is a weird voltage, 7S puts it near inline for my 24V inverters…29.4V max, and 21V minimum
I ordered a pair of 7S BMS boards to tinker with when hey arrive, I’ll post results.

 

[NVS]

I've done the same. I used 840 -18650 cells to build a 7s 316ah battery. It is work but fun too. I built a welder from a car battery a timer and a solenoid. Now I have to buy the inverter.

Have fun!!!

 

[curiouscarbon]

I've done the same. I used 840 -18650 cells to build a 7s 316ah battery. It is work but fun too. I built a welder from a car battery a timer and a solenoid. Now I have to buy the inverter.

Have fun!!!

nice looking work. commendations, thank you for sharing.

any concerns about damage from soldering ends? probably such a short time. i have no experience with building packs with multiple parallel cells, and the curiosity struck me. thanks again for sharing.

 

[Ampster]

Ok, I have a TON of 18650’s and the typical 6S Tesla uses is a weird voltage,

I do not know how Tesla decided on that 6S design but that is no longer the situation anyway. It might have been an early decision before they had confidence in how well their packs would hold up. More recent vehicles have the pack as an integral structural par of the car and I doubt packs will become avaialble in the secondary market. The typical Tesla pack is 400 to 600 volts so 24 volts is irrelevant

 

[NVS]

nice looking work. commendations, thank you for sharing.

any concerns about damage from soldering ends? probably such a short time. i have no experience with building packs with multiple parallel cells, and the curiosity struck me. thanks again for sharing.

You'll need a high wattage soldering gun. Trick is hot and fast soldering. I bought a Weller 260/200 watt gun. You should also fuse each cell. I bought this from battery hookup.

NICKEL FUSE 2P-6P WIDE CONTINUOUS ROLL BY THE FOOT! 18650 CELL LEVEL FUSING

Each foot equals 15 cell connections long by 2, 3, 4, 5, or 6 wide. For example 2p wide would be 30 cell connections per foot (2 wide x 15 long) and 6p would be 90 cell connections per foot (6 wide x 15 long) Introducing custom cell level fused nickel design that can be spot welded with ease...

batteryhookup.com

I spot welded it in place. On on battery pack before I built the spot welder. I did solder thr fuse strip in place which seems to work as well. I first melted a small dab of solder on each cell then laid the fuse strip on top and press the tab down onto the solder until it melted removed the heat while holding it down with a small screw driver.

 

[curiouscarbon]

thank you for the insights! hot and fast, then the heat can’t propagate into the cell material, i see.

fusing per cell important.

battery hookup has supplied me with some decent cells before.

thanks again for educating me.

 

[NVS]

Fusing is important that way if you have a bad cell it will blow the fuse and disconnect itself from the pack, instead of over heating and catching on fire. This is what they do on the Tesla batteries as well.