I'm not changing anything- or guessing. You have some belief that that elevated temperature introduces no additional risk of LiPO battery failure or performance degradation which is incorrect.
Elevated ambient temps, yes.... as they don't adversely affect the charging temp of the battery itself.
I don't have any documentation on hand but feel free to do your own research.
So I did. Below is one chart showing charging temps that are safe (again, this was what my comment was about):
As noted, safe charging temps are as high as 45C/113F. I've not looked in awhile but you state Phantom batteries won't charge above 50C. This is actually DJI's recommendation on the upper limit of the _environment_ to use the battery in, not the upper charging limit. I'm pretty sure the upper charging temp is around 40C-45C. DJ recommends that the battery not be charged when hotter then 40C so I don't see why their automatic cut off would be any higher then that amount.
So if the DJI battery is safe to charge up to 45C and it won't charge when any hotter then that, they it is not any more safe to charge at that temp regardless of the ambiants air around it. The ambient air could be 20C, it could be 70C.... as long as the battery is under 45C it is just as safe to charge.
Just to be clear, here is the statement that I initially commented on:
"because it makes sense that it's safer(er) to charge batteries in 70*s-80*s air than at 90*s-100*+..."
I then needed to go on and keep explaining that my statement was nothing about the temp of the battery or any possibility of reduced cycles, etc. It was simply that the ambient air temp does not matter as the battery itself won't charge when it's temp is a safety issue. It is no less safe to charge based on ambient air temp.
This is only affected by the battery temp and the battery won't charge when that is an issue.
You might start with the JEITA (Japan Electronics and Information Technology Association) guidelines on safe LiPO charging. They recommend significant reductions in charge voltage above 40 degC, i think down to 4.1V at 45. This is for safety. This would get us nowhere near full charge on a phantom pack that uses HV LiPO cells.
Interesting.... but do they also state that a battery is less safe to charge it is at 40C and/or more safe to charge at temps under that amount? After all, this is the _only_ thing I've been talking about. Or even more on point, do they state that it is more save to charge a battery when the surrounding/ambient air is cooler? Again, the only thing I mentioned. If DJI's batteries won't charge at 40C or higher then you are simply agreeing with my one and only statement that I have been making. I'd argue even if they are set not to charge at 45C then this still applies.
I understand your argument works when you change this to a reduced life of the battery or an issue with batteries charged above the recommended temps but you are simply changing the conversation from what I was discussing.
It is no
more dangerous to charge a DJI battery when ambient air temputure is higher as the battery will stop charging based on its own temp if there is _any_ type of risk.
