John and Sue Hansen just recently undertook such an exercise on their Hanse 43 called Imagine.
As John outlines, that while exchanging the battery bank is an expensive undertaking, it provided them with the opportunity to increase the previous capacity of their battery house bank quite significantly.
They’ve changed their previous bank of 3 100Ah lead acid batteries with a total capacity of 300Ah to 6 smaller AGM Batteries 80Ah (1 x starter battery and 5 x house batteries) which boosted their house bank capacity to 400Ah; all fitting nicely into the existing space. That is a very substantial increase of 33%.
The change over from lead acid to AGM batteries also provides the boat with a hazard free environment since the AGM batteries are full sealed and can be tipped on to their sides without any ill effects. Additionally, the fact that all batteries are the same (starter and house) they provide easy interchangeability in the unlikely event that one should prematurely fail.
The batteries were installed very professionally by Paul of Kuringai Marine Electrics who made sure that the charging system was adjusted to AGM requirements. And the batteries have been supplied by Clive from Battery Business, Warriewood NSW.
All up a very successful transition with everyone happy with the end result.