Stackable 18650 boards - why do people use them?

[Sverige]

I’ve been looking at some of the stackable 18650 boards which are sold complete with battery clips, so you can assemble a board and add 14 x 18650 size Li-ion cells for a 7S2P arrangement per board (boards are double sided). Here is an example and here is an assembly video in case it’s not clear how the product works. Once assembled, the boards stack up vertically with conductive metal standoffs to form a larger battery, with ribbon cable via the header connectors on the side carrying the cell balance voltages so a BMS can be connected.

My question is why are people doing this, in the age of cheap prismatic LiFEPO4?

The supplier I linked to is selling these boards for $25 each, and with recovered medical pack cells from Power2Spare costing around $1.15 per 2,000mAh cell, my rough sums tell me it will cost around $550 to build up a 50Ah 7S 26V battery using 12 boards.

I just don’t see the application and why people wouldn’t use LFP prismatic, but maybe I’m missing something. Surely prismatics are not just cheaper, but much cheaper and certainly much less work.

 

[DThames]

Most people favor what they are familiar with. There is also a bit of enjoyment making something. I have an electrical/electronics background so I can easily learn one or the other, but I started messing with batteries by making small packs from old laptop batteries. Last year I purchased about 250, 3 cell modems and salvaged batteries while watching TV. I have some 280ah Eve cells ordered for a house emergency system but I also bought more small packs (2 cell Ring doorbell) to salvage as winter is on us again. Lots more in the house evenings with the cooler weather and fewer daylight hours.

Yes the price for building on those boards and the lack of good positive connection on the cells makes me wonder why anyone would use those.

 

[Sverige]

Thanks. I guess I understand some people want the satisfaction of building from scratch and maybe for smaller capacity batteries they are ok. I agree they wouldn’t be great for high currents. The header connector is soldered to the back side of the board, but the PCB traces are on the front side, so you’re relying on solder wicking its way thru the hole and you can’t check the quality of the joint as you can’t see it (covered by the header connector!)

 

[DThames]

The batteries are not soldered in but just held by spring tension. Vibration and other issues can lead to poor contact. I am building a portable (small wheeled toolbox) 7s 24v battery from 18650s but they will be welded.