ODay 40 Battery Wiring

[DonEvans]

Hi everyone,

I’m trying to understand the wiring on my O’Day 40. I have two dual-purpose Group 27 batteries mounted together in the main battery box, and then a single smaller battery mounted just aft of that box which seems to power only the icebox.

Each of the Group 27 batteries has its own positive and negative main cable, plus I’m seeing multiple smaller-diameter positive leads connected directly to the batteries rather than coming from a single fused feed or distribution bus.

Is this a typical way to wire these boats? Shouldn’t all house loads normally route through the breaker panel from one main feed instead of several smaller leads?

Does anyone have pictures of how their O’Day 40 (or similar boats) battery banks are wired for comparison?

Thanks in advance!
Don Evans
Port Dalhousie, Lake Ontario

 

[Tally Ho]

I have an O’Day 322 (1988). I have had several battery configurations over the past 10 years:

1) 2 12-volt batteries, each wired to one of the 1-2-both-off switch. In this configuration, each battery can run the house systems and start the engine. Or I can use “Both” on the switch and use them in tandem. Each battery was about 100ah, so I had a 200ah total capacity.

2) 2 6-volt Golf cart batteries, wired in series. This gave me a single 215 Ah house bank at 12 volts, this bank was wired to the #1 post on the battery switch. This bank also started the engine. The downside was I had no extra battery to start the engine should I run this battery too low.

3) same as #2, but I added a 12-volt starting battery. This was wired to Battery 2 on the selector switch. I really only used it if bank #1 would not start the engine.

4) This year, I replaced the 2 golf cart batteries with 2 12-volt 100Ah LFP batteries wired in parallel (giving me a 200Ah bank). I also changed the start battery to be dedicated to the engine starter. So, I have a dedicated house bank, and a separate dedicated starter battery. This was done mostly because I needed to charge the new LFP batteries differently than the Lead Acid start battery.

As far as other things wired to the battery, it is not uncommon for batteries to have wires for things you want “always on” regardless of the battery switch position…bilge pump, stereo memory, power for a shunt, etc. I have never seen a separate battery for a fridge, but I guess it could be done. My fridge is powered from the house bank.

Here is my current battery compartment…you can see the 2 LFP batteries towards the top, wired in parallel and with a fuse on the pos terminal. A few other wires there too as I mentioned. The bottom is my starter battery, which now goes to a new switch and to the starter.



Greg