Reserve/starter battery location and mounting

[Ekutney]

I am going to install a dedicated starting battery.  I have done a search and reviewed all the previous posts but am now looking for pics as well as more specifics on EXACTLY where others have mounted theirs.  I am trying to stay as close to the engine as possible and would like to place it an accessible but hidden location:
Under the aft berth.

[DaveBMusik]

The PO put it in the port locker, as far forward as possible with a dedicated switch under the head sink.

[SPembleton]

I use two 12v flooded cells (Duracell SLI31MDC from Batteries Plus) for house and 1 12v flooded  cell (SLI24MPH) for start. They are all located under the aft dinette seat, just in front of the sink. That might not meet your desire to have them close to the engine. See pic below

[kwaltersmi]

I'm using the same setup as SPembleton and it works fine for us.

[Geoffreykwright]

I have a year 2000 34 mk II (hull 1494).  I am not sure how much on my boat was after-market, but I have two house batteries under the aft dinette seat (close to the water heater) and a dedicated engine start battery in the engine compartment under the aft-bunk close to  the stuffing box.  I have managed to completely seperate them so that the house can be fully drained without pulling on the start battery.  hope this helps.
I can supply pictures if you like?

[Footloose]

Ed

I mounted by starting battery under the seat in the aft birth.  It made the wire run slightly longer than mounting neat the stuffing box but access is much better.  I made some wedges from some maple that I had and epoxied them into place.  I used a Group 41 battery as they are only 6 5/8 inches tall.  Strapped the battery down with a 3/4 in wide piece of steel from the hardware store.  It is held down by 1/4 inch bolts at each end and blind nuts in the back of the shelf that went on top of the wedges.  I placed the on/off switch right next to the door after using a hole saw.  Happy with it so far.

Sorry, but I don't have an pictures memorializing the process.

[Stu Jackson]

Having the reserve/start bank close to the engine is much less important than it's cracked up to be.  The connection between the two is a wire and connections.  Assuming the number of connections is the same, regardless of the switching methods one chooses, then the only difference is the distance and, therefore, the wire size.

While Maine Sail & I have had discussions about the wire sizing, I can agree with him that the old OEM #4 gauge may have been too small.  The next size up is #2.

My reserve bank is in the battery box.  I have been running my boat for the past 18 years with the OEM #4 wire.  I usually start my engine on the house bank anyway (as discussed in the Electrical Systems 101 topic posts on switching).  I increased my alternator output wire to #2 when I installed a higher output alternator.

Just to be clear:

House bank to 1-2-B switch --- #4
Reserve bank (in battery box) to 1-2-B switch --- #4
C post of 1-2-B switch to starter --- #4
Alternator output to house bank --- #2

My alternator output goes nowhere near the 1-2-B switch! 

I have three batteries in my house bank, one in the OEM tray and the other two under the forward section of the saloon settee on a nice plywood support that the PO had built.

If you choose to put your reserve bank in the aft cabin because you can't find another place for it, that's fine.  Being close to the engine, in and by itself, shouldn't be one of them.

[mark_53]

Ed
My starting battery is a group 24 GM style battery with the connections on the side. it's mounted just aft of the shaft log on 2 wooden wedges glued to the hull with 4600. I used a standard battery box modified by cutting it down to the 7" hight of the battery and cutouts for the #4 wire and terminal mounted fuses. Use #2 wire if you like but #4 for that little engine and short distance works fine. The battery box cover fits nicely and is held down by the strap that comes with the battery box attached to the wooden wedges. This provides easy acces to check water level. The aft berth cover completely covers everything. The wire runs are 3 or 4 feet to the engine and run along the same harness as the engine wiring. Mounting closer to the engine looked like it would make access more difficult and may interfere with access to engine or HX. The on off switch is located under the head sink on the engine side so when I open the through hull for the engine, I can turn the switch on at the same time. 
My house batteries are 2 grp 27 inside the battery box. There would be no room in there to put a start battery.
The Blue Sea ACR is in the house battery box with start isolation wire and remote LED run to the engine panel. The LED is useful in telling what mode the ACR is in during starting, charging, isolating, or lockout from the cockpit.

[Footloose]

I agree with Stu in that it is probably more about the connections than we want to believe.  Shortly after doing this modification my engine would not start from the start battery.  When trouble shooting it I found a poor joint to one of the ring connectors.  Thankfully, my teenage son had been helping me, so I had a scape goat!  Keeping the electron jumping distance to a minimum really does make a difference.

[mtmaksim]

We have 2 Group 27 batteries under the aft section of the settee (in front of the galley sink) as well as a group 24 battery for starting, all crammed in the space.  The three needed some coaxing to fit - but they all fit in there.

Luckily, the wiring is pretty easy to run!

[Ken Juul]

Not sure why easy access is an issue.  About the only thing that needs to be done to the start battery is a monthly water level check.  I was worried about stuff from the area to starboard under the bunk from sliding into the shaft alley.  Added a 2x4 or 2x6 don't remember fore and aft as a fence.  Fastened my plastic battery box to that.  Can check the levels by holding up the mattress with my head and sliding the hatch board out of the way.

[Noah]

Love the mattress on the head maneuver!

[Jon W]

Access to fuses is another consideration.

[Ekutney]

Thanks everyone for the description of reserve/starter battery locations, you have provided me a number of options.  My criteria and reasons are as the following:

• Out of the way
• Access to check the water level

DOES ANYBODY HAVE PICTURES?  If so can you post, please.

[Noah]

You might rethink "the need to access the water" if you buy a "maintenance free" seal top flooded battery. Even with overpriced WM pricing I got mine for $79 -- if I get 3-4 years out of it is worth it in my value calculation.