Quote Originally Posted by Dixie Boy View Post
Brand new Optima d34m. Going with the d31M and see if that works. How do you charge the batt for the depthfinder, 3 bank charger or relay the cranking batt to the depth batt & let the altinator charge them both?
Your question is unclear.

If you add a separate "electronics" battery and bridge( parallel) this battery with the start battery, you only increase the amp hour rating. Note that if you decide to do this, you should match batteries of the same type and ratings.