I’m using a 19003 Baseboard with a solar battery charger providing power to the VBat input.
The spec sheet states a max input of 4.3V for VBat… per the schematic, the VBat input supplies a voltage divider to allow measurement of VBat, and to 2 chips that both have 6.5V max inputs.
Can anyone tell me what is driving the 4.3V absolute limit per the data sheet.
Thanks in advance.
The Battery input is for batteries, not for external solar battery chargers.
Once you connected the external solar battery charger to the Base Board, you had two chargers working against each other. There is a risk that something gets destroyed.
If you want to use an external solar battery charger, it needs to have a 5V output and you can connect it to the other connector on the Base Board, called “Solar”.
Thanks for the reply.
for more context, The charger I’m using provides a “load” output that mimics a battery and as far as the base board is concerned it looks like a battery. I have this configuration running and the only issue is that the battery “output” can go to 4.5v on the VBat versus the spec’d 4.3v.
On the 19003 schematic, D2 and D3 “switch” between the solar and usb inputs and provides voltage to VBUS_D. D3 clamps the voltage on VBUS_D to 5.6V,
VBUS_D feeds the TP4054 VCC input. if neither the solar or usb connection is there, the charger chip is not activated as there is no VCC to pin 4. The charger will not turn on. The data sheet for the TP4054 states it will draw 2uA from the battery in that state.
My question is, the VBat connection goes to ICs that allow 6.5-7V max inputs and the 1.0M/1.5M voltage divider that is driving the ADC for battery measurement ( it will be about 2.7v @ 4.5v VBat)… why is max spec for VBat 4.3v?
VBat goes to
If you destroy the WisBlock Base Boards power supply implementation by connecting something else than a Li-Ion battery, your warranty is void and we cannot help in any way.
Wow…
I seem to have hit a nerve here… I understand that this configuration is non-standard and will commit not to do a warranty claim for 15$ worth of components. lol.
Thanks for confirming that I read the schematic correctly.
I was more curious if the 4.3v spec limit had an engineering basis or was a leftover from “generic” or earlier boards.
I will do some testing with my configuration for the benefit of possible future engineers… if it melts the board I will change the circuit and give RAK some more business.
Stay tuned.
Following this one. I am sizing a solar setup for a remote gateway and the input limit changes the panel math completely. Are you seeing the limit as a hard cutoff or does it just throttle charging above the threshold?
im using the Adafruit bq25185 USB / DC / Solar Lithium Ion/Polymer Charger… it allows for a wide range of inputs to charge single 3.7V cell Lipos… this is connected to the LiPo battery input on the 19003.
I am not connecting to the solar input or the usb input on the charger to prevent any issues with the charger IC… The 4.3V is the input rating for the battery input.
Just to clarify… I am not using the onboard charger at all.
To make it clear.
The power supply system on the WisBlock Base Board is designed for the following scenarios:
Anything else connected to these connectors to supply the WisBlock System might or might not work. It might or might not destroy the voltage supply and battery charging circuits on the WisBlock Base Board.
Anything else connected to these connectors does void your warranty and it is not our responsibility if your WisBlock system is destroyed, catches fire or burns down your house.
Update after two weeks of logging: the dips line up with the nightly backhaul sync, not with sensor traffic. Moved the scheduler window an hour later and the morning battery floor came up noticeably. Sharing in case anyone else chases phantom drain — check the gateway logs first.
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