I suppose it's ok to use a small solar panel as the charging for the power shield but thought I would ask here first..
My setup:
5V 250mA solar panel connected to a micro USB cable -> power shield micro usb
Bout power shield -> moteino
1200mAh Lipo 3.7V -> power shield
I suppose it should be ok, looked at Adafruit and their poly charger uses the MCP73831 just like the power shield. Anyhow, let me know if you have any concerns w that setup..
thanks!
xavier,
Typically and ideally you would not want a heavy load (anything more than a few mA) to be shared with a cell charger.
The reasons are explained in this Microchip app note (http://ww1.microchip.com/downloads/en/AppNotes/01149c.pdf).
The gist of it is that the charger has a specific sequence based on the bus load that determines how the charger evaluates the charging state of the battery, when to switch to the next charging phase and when to stop charging. A significant load can throw off the battery charging and it may seem like it's charging forever.
The charger on the PowerShield is shared with the load. So depending on the load conditions of your Moteino or whatever else you use, it may not be ideal to rely heavily on charging from a solar cell. The MCP73831 may not be very suitable to be charged from a solar source either. BUT this is not to say it wont work at all, i just wanted to make you aware of the limitations of MCP73831 and the implementation on Power Shield. The app note explains how you can achieve load sharing.
Thanks Felix for the answer and link! I'll try it out with the understanding this may destroy my battery at one point if it keeps overcharging. Maybe this could be an enhancement to power shield for a future rev... Thanks again for the help!