Setting up a house battery system

[Jay B.]

Hi All! I am getting ready to install a new house battery system into my CD25 (no need for a starting battery) and want to set it up with 2 each 6 volt golf cart batteries and an onboard charger. I currently have a Tohatsu 6hp outboard with an alternator as well as a solar charger panel. I have a dealer nearby that sells Trojan 105 batteries so I was thinking I would use those. I will probably purchase a charger from West Marine and was looking for recommendations. I was also wondering if I need to do anything special to ensure the batteries charge equally. Any advice...experience...and general discussion on the topic is welcome!
Thanks,
Jay

[Jeff Barnes]

Jay,
Obviously you will be connecting these two in series, so there is nothing you need to do to ensure equal charging. I am not familiar with the outboard's alternator, but I suspect it's small (in terms of output capacity in amps) compared to the 200+ Ah capacity of the batteries. Even though only half of the battery capacity is really usable, charging these batteries will take a while if you run them down halfway. A three stage regulator would also help significantly, but I'm not sure if your Tohatsu alternator is compatible with such a device. It's not necessary, but would help.

Jeff

[Andy Denmark]

Hi Jeff,

I like this project as it's one that will serve you well for a long time.

T-105's in series are among the best of the battery choices. My only suggestion is to use an equally good charger. Check out Charles Industries for that. IMO, the 20 amp 2000 series model is the best on the market today. It costs a bit more but you will more than offset the extra cost with greater battery life over the long haul. Charles chargers have a charging algorithm that is kinder to flooded batteries than anything else on the market.

As for location, you will want to keep the significant battery weight as low and as centralized as possible. I had a CD-25 customer who did this same project and made a battery box that lived under the step into the cabin. The batteries were side by side and a simple teak top served as a sturdy cover. This is an ideal placement of the weight. It took a bit of engineering but the end result was well worth it.

The very last place to put these heavy batteries is in a cockpit locker as the boat's trim is very sensitive to weight aft and performance will suffer significantly.

Hope this helps,

Andy