TheJANG from URC shared his experience when LiPo technology was first introduced and very little information was available at the time. He bought several brand new batteries and charged them inside his house which was a cool 72°F. He then packed all his RC gear into the trunk of his car on a hot summer day with temps around 100°F, we can only guess how hot temps were in the trunk! He then drove 2 hours to the beach and when he pulled out his gear to install the freshly charged batteries into his RC he discovered that every single LiPo had swollen up into balloon shaped sausages! Never got to use a single battery and they were all destroyed.
Since then, we have learned that heat will increase voltage and it's best to charge the batteries at about the same ambient temperature that they will be used. You also want to minimize the amount of time that the cells are away from storage voltage, more info here:
https://batteryuniversity.com/article/bu-808-how-to-prolong-lithium-based-batteries
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As a battery ages, the IR of the cells become mismatched any many low quality chargers do not have a respectable "Balance Current" to keep the cells properly balanced so charge times extend 2-3 times longer than when the battery was new. A trick to get around this issue is to use the "Fast Charge" mode which bypasses the CC/CV algorithm... you won't get the proper saturation charge, but you'll get close to 95% of the capacity you need rather than waiting an unacceptable amount of time for the battery to charge.
A better way to deal with charging older packs is to invest in a quality charger with as least 2A of balance current, more info here:
https://www.rcgroups.com/forums/showthread.php?3496127-Which-charger-is-the-best