Hmmm... Sounds like a subjective question. I got to the point where I just left my aircraft and support stuff in the back of my enclosed truck overnight. I ran a HD 12V constant power line to the back and plugged in a small inverter to which I plugged in walwarts. When I got home I just plugged everything in and let it go till the next day.

There is an interesting point here though. The packs I was charging were between 600 and 1100mAH. Charging these packs at 50mA for 8 to 18 hrs , regardless of their current state, was harmless and topped them off nicely. I have peak charged these and other packs in my vehicle on the way to the field but I wouldn't recommend that after flying in place of an overnight charge.

To you, Rotten40851, I will say that it IS best to play it safe and fully charge before heading to the field. Once you are past the initial few cycles of your packs it is safe to charge them at any residual state. Always check with a loaded DVM before the first flight. Cycle your packs every couple months or when you feel it's needed.

I guess what you choose to do will depend on the size of your packs and your charging versatility.

Pretty much all of the advice you get here is going to be good advice. Find yourself a baseline and go from there.

Good Luck!!