Do I need to worry about Seagull battery degradation over 2 years?

Do you even care if it's a lease and going back? It should be fine, also it ideally needs charging to 100% on an A/C charger every few weeks to balance the cells and calibrate the BMS as it's LFP and has a quite flat voltage curve. Leaving the car sitting at high/low SOC for a long time is worse than charging it to 100% or letting it run low, so what you want to avoid is charging to 100% then leaving it sitting for a week or more without driving it.

> It should be fine, also it ideally needs charging to 100% on an A/C charger every few weeks to balance the cells and calibrate the BMS as it's LFP and has a quite flat voltage curve. Every few *weeks*? I heard this was recommended every few *months* (or someone else said 6 months).

Nope, the great thing about LFP batteries is you can charge them to 100% and they're fine. If you plan to leave it lonely and undriven for weeks on end it's recommended to leave it at a lower charge but other than that just charge up to however much is convenient.

Yeah, 6 monthly.

I thought I saw somewhere the car would start moaning if it's been more than a month but perhaps i'm mistaken. Don't think mines been made it that long between charges.