Yaesu FT-727R lithium-ion conversion part three

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Battery electronics and final assembly

In part two the batteries’ body was printed and test fitted together. In part three the electronics are installed and the battery pack completed.

I highly recommend using a spotwelder to add tabs to your lithium batteries. Most consumer grade soldering irons will pump too much heat into the battery which can cause undesired side effects. The chassis’ electrical contacts were removed from the old battery and transferred to the new chassis. The battery status indicator is a pretty easy to come by schematic utilizing zener-diodes. These are easy to make and I’d suggest adding one to projects that lack a standard indicator. Kapton tape is your friend here. This radio will see high vibrations so it’s good to have a secondary layer of protection ontop of a fuse.

The connector is handy for taking the cover off and getting into the workings of the battery:

To initialize the charge controller, simply plug it into a charger and it will allow output. This is the first test of the radio powering on with a new battery pack:

From here, slide the cover on, install, and transmit!