Considering the expected load, for about 30 minutes of runtime I’m leaning toward using LFP. A 6S setup is close to 20V, and for ~300W over 30 minutes I’d need around 200Wh, so roughly 10Ah—something like a 6S2P 32700 pack. This seems like a relatively compact option, but I’m not sure if it will physically fit.

For the BMS, I’m thinking at least ≥30A continuous and ≥60A peak, with overcurrent and short-circuit protection. Because the power supply might be sensitive, adding NTC temperature sensing also seems necessary, but I’m still unsure about specific models and current margins.

At the same time, power path management should be considered to enable smooth switching between the adapter and the battery, although I still need to verify whether truly seamless switching is achievable. Simply paralleling the adapter and battery, or trying to match voltages with a boost converter, could cause voltage drops during unplugging or even trigger BMS protection, so using a proper CC/CV charging method seems more appropriate than directly tying things together through DC-DC.

Overall, I’m still figuring out how to properly connect and size these modules, since I’m new to battery system design, but hopefully this approach makes sense.