Hi,
I want to make my heating pad to work, when battery stops charging its getting cold, how to make it work on battery?
And how to add on/off button?
Help if You can.
Best regards,
Dan.
It looks like you are using the Adafruit LiPo charger? Not sure why you’re using it with a heating pad (battery out). You can connect it directly to a battery and on/off switch to make it work. You should leave the battery charging as a separate circuit.
If you want a charger module with an on/off switch, we would recommend the SeeedStudio LiPo Rider Pro, however this module isn’t compatible with the Sparkfun batteries that you bought because the polarity of the connectors are inverted.
With your current module, have you tried unplugging the heating element and charging the battery entirely, and then unplug the USB and plug in the heating element? Does the heating element work this way?
I think the problem is that the heating element consumes something like 0.7A but the charging circuit is configured to supply at most 0.5A. In this situation, the battery will never charge and the charger is only really powering the heating element.
You can configure the charger to supply more than 0.5A by changing the R1 (Rprog) resistor, however it will require an external power supply (such as this one) instead of USB since the USB itself is only able to provide 0.5A.