Since the original car charger is unusable for me due to the fact that it requires high input voltage, I opened it up hoping for some "easy" mod to change the threshold voltage. There was not... but it is a high quality construction.
The circuit in the 12V-socket contains a fuse and possibly an over-voltage protection, but it does not control the shutoff voltage.
The charger itself is basically a huge heatsink around the dc-converter, which is controlled via I2C-bus by an STM8S 8 bit microcontroller. There is an unpopulated header for gnd/3v3/tx/rx. Just ask DJI to publish their sourcecode for it and we can mod it easily , hehe.
The DC-converter itself is operating as current limited on the input and it works at least down to 7 volt! The charger can be tricked to continue charging by first starting the charge, then prohibiting I2c-communication so that the microcontroller can't turn of the power.
I tested the battery also. Just connecting + and - and providing at least 12,6V starts the charging, and the current is limited by the source (make sure the source is current liminted!).
12,6V is enough to charge about 84%. With less than 12,6V the battery can be charged by turning it on, and it will detect that the current is flowing into the battery. It would be very convenient to use a charge voltage to automatically charge the battery to 60-65% for storage/ready to top up before flight! Of course 3-4 simultaneously.
The circuit in the 12V-socket contains a fuse and possibly an over-voltage protection, but it does not control the shutoff voltage.
The charger itself is basically a huge heatsink around the dc-converter, which is controlled via I2C-bus by an STM8S 8 bit microcontroller. There is an unpopulated header for gnd/3v3/tx/rx. Just ask DJI to publish their sourcecode for it and we can mod it easily , hehe.
The DC-converter itself is operating as current limited on the input and it works at least down to 7 volt! The charger can be tricked to continue charging by first starting the charge, then prohibiting I2c-communication so that the microcontroller can't turn of the power.
I tested the battery also. Just connecting + and - and providing at least 12,6V starts the charging, and the current is limited by the source (make sure the source is current liminted!).
12,6V is enough to charge about 84%. With less than 12,6V the battery can be charged by turning it on, and it will detect that the current is flowing into the battery. It would be very convenient to use a charge voltage to automatically charge the battery to 60-65% for storage/ready to top up before flight! Of course 3-4 simultaneously.
