I didn't fly for a few months, when testing my lipos seem to have died?
I got 2x 2200 15C-rated 3cell packs, never discharged under 9V (under load) , always used a balancer etc etc. The max discharge is about 12 Amps static (well below 15C).

Before I put them away I charged the pack about 50% and it has self-discharged next-to-nothing over this time. Before testing I charged the batteries ofcoarse.

Problem I got is that under the slightest load, the voltage drops to about 9.5 V (and esc cuts off), In short, they can't handle any current anymore. both packs behave the same.

What did I do wrong? Any remedy for recovery ? These batteries have only about 10 cycles on them.

Thanks in advance,
GJ