That’s why the battery doctor is superior to a perko switch;
It allows the main battery to be charged first and then charges the secondary battery but if you drain the primary you press a button and it allows it to be “boosted” by the secondary battery. I have all my stereo on the secondary battery and the rest of the boat runs off the primary. With this setup both batteries get charged but you can never drain both batteries.
https://www.ebay.com/p/Wirthco-20092...1548ccff8c5c58


Sent from my iPhone using Tapatalk