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  • cyfus commented on cyfus's instructable Baofeng USB mod1 year ago
    Baofeng USB mod

    I'm glad you found my guide useful! Your idea of using the inputs on the board from the base charger is excellent. I used a diode to save the pins from a short circuit but using the regulator board itself is a more elegant idea. I've been meaning to revise my instrucable for sometime, so I'll include your suggestion!

    One more thing I forgot to mention. Make sure to check the output from the baofeng base charger, it is rated for 5 volts but because its normally wired directly through the battery it might (should) have some battery regulation built in for 3.7. I'm not sure if wiring the USB regulator input through the base output would upset it (by being under volt) or if the voltage from the base is expected to fluctuate by the return voltage from the discharged cell. It could be set for constant 5V (as printed) at first and reduces its voltage to compensate but i'm not sure at the moment. I know that it does backfeed but I haven't investigated this behavior over time. When I added a diode to the cell it stopped the backfeeding and didn't upset the base charger's logic so i'm not exactly sure how it ...

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    One more thing I forgot to mention. Make sure to check the output from the baofeng base charger, it is rated for 5 volts but because its normally wired directly through the battery it might (should) have some battery regulation built in for 3.7. I'm not sure if wiring the USB regulator input through the base output would upset it (by being under volt) or if the voltage from the base is expected to fluctuate by the return voltage from the discharged cell. It could be set for constant 5V (as printed) at first and reduces its voltage to compensate but i'm not sure at the moment. I know that it does backfeed but I haven't investigated this behavior over time. When I added a diode to the cell it stopped the backfeeding and didn't upset the base charger's logic so i'm not exactly sure how it senses the change in charge and when to refuse the current when blocked. I will have to reverse the layout of the charger board and figure out exactly what is going on. I figured it was better to omit the passthrough on the usb input (mine didn't have solder pads) because of this unknown. And finally the battery itself is lacking a thermal resistor as well as the contact pad to connect it to the charger base which also is lacking the resistor element sensing. The usb charger board however is able to use a thermistor (does yours have it? I can't see the pads in the image) so the last goal of this project will be to acquire the proper component and test it under stressful conditions.I haven't had the focused time to fully complete this project. If you want to spend time investigating these questions further please let me know.

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