All of the hugen version NanoVNA devices have the same redesigned IP5303 charging circuit. The original edy555 charge circuit only provided 3.7v output to charge the battery and power both the CPU and mixers. As the battery voltage dropped, the dynamic characteristics of the mixers changed. hugen's design charges the battery but then converts the output to 5v which drives a 3v regulator AND the mixers maintaining stable 5v power for the mixers.
Please read up on the original edy555 design notes in the files section.
You can stick any 3.7v LiIon battery in the unit like I did as long as it has the protection board attached. Even an 18650 will work, it will just longer to charge but at a typical 2200mAH, will last a looooong time.
Larry
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On Sun, Aug 25, 2019 at 07:33 PM, starbuck5250 wrote:
On Sun, Aug 25, 2019 at 06:40 PM, Peter Mulhare wrote:
Please be aware, that the charging chips (x2), are mounted on the Battery.
Actually within the transparent heatshrink wrapper of the Battery itself,
not
on the nanoVNA Board! Or at least on my unit they are.... when
considering
the number of variations there are of these units.
edy555's schematic calls for an optional MCP73831 Single Cell,
Li-Ion/Li-Polymer Charge Management Controller.
hugen's schematic calls out an IP5303 which performs that function and more.
My board has a USB-C connector, and came with a battery and an IP5303
near the rocker switch. It's the only 8 pin device on that side of the
board.
If this (or equivalent) is present then I'd feel comfortable putting
my own 3.7v battery in, as these chips handle LiIon and LiPo charge
management.
--buck
