2025.11.28 panel and lipo charge board testing
2025.11.28 panel and lipo charge board testing:
I've acquired several smaller solar panels, intended for use making a "solar node" for Meshtastic. That's a
node that will be in a place that's inconvenient to run power to, and since Meshtastic doesn't require any
other connection like coax, it can run on a rechargeable battery that's kept charged with an attached solar
panel.
This will require a soler controller that can handle low voltages (as far down as 4.5v) and a battery management
system for a 3.7v lithium battery. Several new boards have hit the market recently that handle the solar panel,
Lithium battery management, and load attachment with cutoffs. I decided to give the panel and board a test with
my new solar lamp. I don't have a proper fixture for the bulb yet so this will have to do.
A friend gave me the battery he found at a local DaBin store, originally designed for a Kindle Fire batt swap.
IIRC it's 3.7v at 4,500mAH. Pretty good capacity and very flat. (5mm?) Perfect for a large enclosure. I also
connected a solid-state load to pull on the battery a bit to make sure the charge controller had a battery in
need of charging so as to max out solar collection. The controller is FPVR (not MPPT), but is configured
for a 6v panel (which this is) so it should track decently.
After discharging the battery down a bit I put full light on the panel and got 180mA into the battery from
the solar controller (around 4.2v charging), so over 7 watts into the battery.
I had to dig into my JST box for the JST-2.0 connectors, and also was very rudely surprised to see that most
of them needed the wired swapped, since I like to keep my red (+) and my black (-).
Of course no JST can be trusted to be sturdy. I'm convinced these were designed to be plugged in and then NEVER ever unplugged. The pulling force required to rip the wires out the back of the connector is almost
always less than what you need to pull the two connectors apart. I reminded myself of this the first time I
tried to unplug something, and so had to splice on another conector. Always pull on the connectors, not the
wires. (which for a JST-2.0 can be a bit challenging - hope you don't bite your fingernails!)
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