I’m curious if I have a legitimate concern or if I’m just being overly paranoid.
I have a rechargeable Lithium-Polymer battery (prismatic shaped) rated for a max charging temperature of 45 °C.
The battery rests against a circuit board that I know can generate some heat when charging the battery (500 mA current via an MCP73831 IC). It can get up to around 49 °C in a single location on the board (say about 1/4”x1/4” in size) and a dissipated temperature around that (I even measured 63 °C once on the hot spot but haven’t been able to reproduce it). That is for the back of the board where the battery rests (the front side can get up to 80 °C at the charger IC).
Is there any legitimate concern that this will heat the battery during charging? There is nothing between the LiPo and the board. Using a thermal camera, it doesn’t seem like any heat really transfers well to the battery, so it seems like it should be okay, but I’m no expert in heat transfer, especially if it remained in the described state/position for a few hours. The battery and board would sit inside a plastic enclosure.
Best Answer
Lithium-Polymer service life is seriously degraded at high temperatures, especially when fully charged. The cooler you can keep the battery the better. I suggest using a more efficient switch-mode charging IC such as the TP5000.