I think these are 5000mah packs. I flew a longer than usual flight and put them on charge. The Cellpro indicated 12% capacity at the start and I put in almost 4100mah. So, its is more likely these are 5000 than 5800. I could put them on the TP1010 discharger but that will take a while. The IR dropped to 2.5 but it still seems high for a new pack.