I usually fly until my (uncalibrated) osd says I’m at 3.3 to 3.5v per cell. Typically after landing they level out to storage voltage.

I’ve been paying more attention to my chargers while charging, and I’ve noticed that both of them (imax b6 & venom pro duo) are showing that it’s put more into the battery than the stated capacity before it finishes charging. In the pictures attached, I’ve got a 4s 850ma attached to the b6 and it hit 915mah before saying full, and the venom hit 684mah on a 650mah battery before saying full.

Do I need to calibrate my chargers? Obviously I need to calibrate the voltage meters on my flight controllers, but if the battery is leveling out after flights at storage voltage I don’t think I’m over discharging them?

I think your setup is within the ballpark. I would not bother.

Most FC's have reasonable voltage readings and so what you see in the OSD is very close to actual. The first few FC's that I tried calibrating with the multimeter ended up being fairly spot on and I have never done this on any of my latest FC's.

With regards to chargers, unless you see a huge difference then do not waste much time calibrating them. Usually they are fairly close to actual voltage/current readings.

The additional mAh you see on chargers is usually also the result of balancing the cells.

Thank you! I always balance charge- it didn’t even cross my mind that it would have an effect on the final numbers.

As kafie said, 100% it’s going to be balance charge that’s tripping the capacity of the battery. When the cells are at 4.2 pay attention to which cell isn’t, that will be your dead cell if the pack ends up going south.

I ditched my original 80 watt 4 button charger for a Hota d6+ at the time because it wasn't able to charge a 5000mah 6s (monster truck) battery at a full 1C. I noticed that even batteries that the old charger could charge at 1C took much longer than the Hota. That's where the spec "balance current" comes in with a much faster overall charge time without upping C rating for the charge cycle.