Old Bank - New Bank

[belizesailor]

My current house bank is getting older and has diminished capacity so I've ordered new batteries to replace it. However, the current batteries are still serviceable, just diminished in capacity (happens to all of us over time...). They still "get me through the night", but that's about it.

Given that they are still serviceable I hate to just toss 'em. So, I'm thinking of ways I can incorporate them. Conventional wisdom has it that mixing old and new batteries is a bad idea. Combining them with conventional blocking diodes causes significant voltage drop. Splitting them into two banks and using them for different loads seems to be the most straight forward solution (combining them for charging only), but of course this requires me to do some clever re-wiring of loads.

Anyone have any better ideas?