Onboard Charger Question

[weedeater]

I bought a boat with a 2 bank charger for the t/m batteries and I know the the engine is "suppose" to charge starter battery but I have heard horror stories of it not working all the time, I am wondering if any of yall have a single bank charger for start battery that yall use or just take the chance with the engine charging it. A guy I work with has had issueswith his 90hp not keeping up and was told that if you have a 150hp or bigger not to worry, I have a 200hp but want to hear what yalls experience has been.