My three year old NEO-M8N module doesn’t start on hot mode anymore. It appears that the VBkp voltage is too low to maintain data when the module is powered off (less than 1.5V). I temporarily connected a coin battery that solved the problem. Could you tell me the reference (or type) of the backup battery that is on the board so that I can replace it? Thank you.
Despite its shape, the component we’re using is called a supercap (a big capacitor for short), not a coin cell.
This allows the capacitor to be charged and discharged when needed.
By the way, here is the reference we are currently using : https://www.digikey.com/product-detail/en/elna-america/DSK-3R3H703T414-HLL/604-1165-1-ND/3283567
Hope this helps
Ok, thank you very much for the info. I saw some other designs with a small Li-Ion button battery as backup power, likely to keep data more long time. As the supercap value is 70mF , it won’t maintain data more than a couple of hours (NEO-M8 datasheet says 15µA as backup current value). Though sufficient to assure a hot start anyway. But as I would like to experiment with AssistNow Autonomous aiding, I will provide another backup power source (tie the Supercap to my system vdd through a diode).
Thank you again for your support.