Inkplate 6COLOR power with 3 AA NiMH batteries instead of LiPo

TECHNICAL SUPPORT Inkplate
1

Customer:

I’m building a digital picture frame that downloads a picture via WiFi once a day and goes into deep sleep afterwards. I’d like to power the Inkplate 6COLOR with 3 AA NiMH batteries (1.2 Volts 2300 mAh) without charging them on the device - only using them as a power source.

I’m concerned about fire risk with LiPo batteries in a gifted device I won’t be able to monitor. My idea is to connect 3 AA NiMH batteries to the JST input of the MCP73831 charger with a Schottky diode to prevent accidentally charging while USB is plugged in. The batteries would only be charged with an external battery charger.

My calculations: a single Energizer NiMH AA-2300 mAh (HR6) provides up to 1.4V when fully charged and 1.2V on average. Using 3 AA in series would provide a max voltage of 4.2V and 3.6V on average. The MCP73831 is rated for an input of up to 6V according to its datasheet.

Would this work? Can I power the Inkplate safely this way? Is there anything I should be aware of?

Originally submitted via email support on 10 November 2022. Migrated to the forum for community visibility.

2

Soldered Support:

You can safely use this method with your batteries. If you remove the MCP charger you don’t need to use a Schottky diode. If you are going to remove the charger, please be careful when desoldering because temperature can easily damage the e-paper. Don’t use hot air for desoldering.