So I charged up some packs yesterday and hit the field. After the first three batteries I noticed they were really hot. Quad was a fine. So out of caution I packed up and went home. I can't imagine the hot battery temperature being good on them.

Question: What's too hot of a temperature to fly? It was in the low 90° range with a slight breeze.

This also brought up another question I'll address in another thread.

Deal

How hot is hot? Can you keep your finger pressed on them without feeling a burning sensation?

Even when I've been caning it, my batteries have come down warm to the feel but nothing I would call "hot". However, temperatures around here are only currently around 18 degrees Celcius (~65F) max, so nothing like you have there at the moment.

Not got enough to burn you or anything, but definitely hotter than I've felt them. I thought maybe I fried a battery, but it was the same with all three I used.

I've worked with my hands my whole life, so my fingers /hands are poor temperature gauges, hehe. Probably too hot for my wife to hold for very long, but she's in the dental field and has delicate hands, hehe.

Deal

So lipo operational temp range is 0-50C (32F-122F). It is really a judgement on your part when to fly. For me, any temp above 90F, I am staying indoor. It is probably safe to fly at 90F.

Basically if I can stand it, it's good to fly. Thanks.

Deal

Coming from the desert SW where daytime temps get pretty excessive in the summer, I can tell you those temps stop me from flying even in the early morning.  Early morning temps typically are around 85-90.  The main reason the temps stop me is because of the VTX, not the battery.  I fly with my VTX on 800mW or 1W depending on the VTX.  Both put out lots of heat.  Even though they are TBS Unify VTXs, and won't burn up as they have an auto shutdown for over temp, you lose your video when they shutdown, which is bad as well.

With all that said, remember when the battery is in the sun, it's getting a lot hotter than air temp.  Depending on the color of the battery, 90* air temps could be subjecting the battery to temps as high as 130*.  If the battery is kept cool until the flight, and the flight is short, like 5 or so minutes, I'm guessing you should be ok.  But if you are flying with a battery that gives long flight times, you may want to reconsider.

Thanks for all the replies.

Deal