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Moving the batteries - plan

The house battery bank was quite old and placed in the bilge, which we didn't like. I started by removing the old batteries from the bilge and cleaning the area. There is still some work to do, like removing the plywood to reveal the keel bolts. Unfortunately the structural members were also cut out to be able to fit the batteries there, so we're planning to reinforce them later this year.


The previous owner left two “new” batteries that he didn't install. It's a Euroglobe EG200-12 AGM (12V 208AH), 416AH in total, with dimensions of 52 x 24 x 22cm and 63Kg each. As they're larger than the old ones, they wouldn't fit to the bilge even if we would want to. So we need to find a good place for them.
There are three locations that can be considered:


1. Engine room. The starter battery is also there (need to be replaced too). The starter battery would stay in its current location behind the wheel/rudder pole and we would build a shelf above (behind the diesel tank) to accomodate the new large and heavy batteries. We already have a weak shelf there used for storing various bits and bobs.
Pros:
  • All batteries would be in one location in the engine room.
  • Shorter battery cables can be used
  • Not in the "living" space and would not take up useful storage space in the saloon
Cons:
  • With the shelf the weight would be positioned higher
  • Adding more weight to the same place where the engine and diesel tank already weights a lot, which is aft.
  • Would make the access difficult to the stuff behind/under the battery shelf (waste tank, diesel heater, various cables, cockpit drain seacock, etc). We need to come up with a clever shelf design.
  • Placed more to starboard, not that close to the center line of the boat

2. Under saloon settee.
There is a storage space at side of the saloon settee, which is large enough to fit the two new batteries.
Pros:
  • Relatively close to the center line of the boat
  • Weight located closer to the keel
  • Easy access
  • Easy to install, no shelf is necessary
Cons:
  • Takes up the best saloon storage with the easiest access
  • Longer battery cables needed

3. Under the starboard bunk in the saloon. Fortunately the bunk is wide enough to fit the two batteries.
Pros:
  • Weight located close to the keel
  • Easy access
  • Easy to install, no shelf is necessary
Cons:
  • Located more towards the startboard side, might need to be balanced on the port side
  • Takes up a very good storage space in the saloon
  • Longer battery cables needed

I'm not that sure about some of the cons. The two batteries weights 126 kilograms in total. Does the elevated height due to the shelf really matters that much? What about the weight placed off-center?
I'm leaning towards option 1 at the moment, but we need to make some plans for the shelf first to see if we can do it in a clever way. We would make new shelves for the engine room anyway to make it more useful and tidy. We'll see how it goes.
Which option would you pick and why?

Update: There were changes in the plan, as it turned out that the batteries were not in a good condition and we decided to buy new batteries and put them in a 4th location, to the aft cabin.

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