Operating fish finder using lithium battery

[dubob]

Also, when i went to try out the new app on my cell, for the lithium batteries, it could not detect the batteries, when hitting scan

Since you didn't buy the batteries recently, it's possible that they are not 'smart' batteries and don't have a Bluetooth functionality.  Gather up the battery serial numbers and call the manufacturer and ask them if they are Bluetooth or not.

If it turns out that your batteries are bad, make sure you buy 'smart' replacements.  My Li Time Gp 31, 12v, 140aH batteries are lasting 4 to 5 trips to discharge down to 20% and then get charged back up to 100%.