this is what i came up with for the battery wiring. i used automotive 10awg wire becuase the insulation is soft and easy to work with. this connects 8 cells together, and then i have 4 of these wires parallel. each 10awg conductor can conduct 30amps, so that's 120amps continuous current flow. which i figure is less than the 110amps DC 48v the 4400w inverter will draw at full power.
i put the little glass fuses on each cell so that if i shorted it out, it would not cause a fire. the cells were very hard to spot weld to i'm not really sure what black magic goes into getting strong spot welds on these because i have a good spot welder and even with 2,000amps the first weld was the only strong weld, after the first weld the second and third welds were weak and i can pull the nickel strap off with my bare hands.
the soldering is not easy either. the metal of the battery sucks the heat out of the iron, and the smooth finish of the cell metal prevents solder (88pb10sn2ag) from sticking, so hitting it will a stone or sanding drum got the solder to stick, but it took two irons at full power to flow the tinned solder around the fuse leads. but once its on, i cannot pull it off. on the negative side i used a small U shaped bare tinned copper 16awg wire to connect the cell to the 10awg wire.
then once i have these all done, i'll use 30amp rated terminal strips to connect each of the 4 + leads to the next modules 4 - leads. that way if i ever want to i can easily rewire it to 12v or 24v. also the BMS wiring will be really simple since all connections are pulled out on terminal strips. it would have been alot easier to buy 4x $900-1500 12v 200ah lifepo4 batteries and just used 3 jumpers to hook it up, this way i'm showing is not the easy way to do it.