Background info:
I am working on a project that uses Arduino Fios as the brains of four model wireless windmills. The rotation of the windmill hubs generates voltage (less than 2v) that connects to a shield. The shield consists of a rectifier, capacitor, and pulldown resistor, and sends the windmill voltage to an analog pin. Every few milliseconds, each Fio wakes up from sleep, measures the voltage from the windmill, and compares it to the previous voltage. If the voltage is different, it wakes up the attached Xbee radio, transmits the new voltage value, and then puts itself and the Xbee back to sleep. The windmills operate wirelessly during the day, powered off an [Adafruit 328 Lithium Ion Polymer, 3.7V, 2500mAh battery . At night, they are charged in parallel to a 5v, 2.0a power supply via barrel plugs connectors in the bottom of the windmills. Those connectors are plugged into JST connectors at the CHG 5v + and – through-holes on the Fio board.
https://i.imgur.com/jP3xfqT.jpg https://imgur.com/GkYCL8T.jpg https://imgur.com/4HrqEI8.jpgThe Incident:
I have been having some trouble with charging reliability. After significant discharging, the windmills sometimes fail to charge the batteries. When I have taken them out, the microcontroller still works, but the charging circuit is dead. Frustratingly, it tended to start working again after a few hours or days, so I hadn’t pinned down the source of the problem. However, the other day, I opened a malfunctioning windmill, and there had been a small fire, originating at the LiPo charge management controller ( [datasheet).
https://i.imgur.com/CxC0o9A.jpg https://i.imgur.com/88tmIRE.jpgUpon closer inspection, the other Fios all show some degree of bubbling or scorching at the same location.
https://i.imgur.com/TKBvP1J.jpg https://i.imgur.com/TPYf4dD.jpgSpeculation:
It seems that there is some circumstance in which there is a rapid discharge/short circuit at the charge controller. I would tentatively link it to charging after heavy use i.e. the battery is more discharged than usual. Could there be a conflict between the batteries’ safety logic and the charge controllers’? Did I improperly spec the battery for this board? Has anyone else encountered this? And how can I go about fixing this? Should I upgrade to the V3? I don’t mind spending the money, but I don’t want to drop $150 if it won’t solve the problem.
Any help would be greatly appreciated. Thanks!](https://cdn.sparkfun.com/datasheets/Components/General%20IC/33244_SPCN.pdf)](Amazon.com)