DIY 10ah 4s LifePo4 without a BMS V1.1
I had been toying with the idea of more power - either for longer operations or more power or even more devices which such as portable digital operations.
I could have gone the simple Zippy 8400mah blue brick that seems the next step up from my 4200 or.. there is the homebrew route.
Using headway 38120 lifepo 4 cells that are used in E-bikes, and some simple balance extension leads I made Big Bertha v1. 10AH 13.2v. This version does not have a Battery Management System (BMS) and for all intents and purposes, it is seen by balance chargers and even the little cell monitoring beepers that many use, like a big 4s pack.
8486 - a partially built 4 cell pack comparing size with a 4200 zippy
8532 - I might have snapped up another 2x 4 cell lot on ebay that a company was getting rid of. The orange holders snap together giving the cells rigitiy
8577 - sitting on the bench testing connection to the balance charger - I took extension leads, clipped the socket end off and soldered ring terminals to the ends and connected to the negative of each cell, with one being positive - just the same as the zippy packs
8578 - v1 covered in packing foam, covered in light head shrink bags (x3)
8580 - testing my other balance charger to confirm 12v charging.
Possible improvements - increase the current handling of the load/charging cable for possible QRO operation of the 857.
Coming versions might will likely have a BMS going forward to auto cut off on low voltage.
Cells, cell holders, bus bars : https://www.evworks.com.au/
The rest was either junk box or ebay