Hobie TI in hull battery setup to power a Lowrance Elite 4 GPS fish finder.

Note that the battery that is often used for the TI is around 9 amp hours (ie, it will supply 9 amps for 1 hour at 12 volts).  Since the Lowrance Elite 4 uses only about 0.19 amps when in the map mode, the battery I picked is only 5 amp hours. I did this for less wieght and I just dont need the extra capacity at the moment. Some of the larger screen chart plotters use up near .7 or .8 amps and in that case, the larger (and heavier) battery is a better choice.

How long will the 5 amp hour battery last?  If I limit the discharge of the battery to 1/2 of capacity to prolong life, I can only use 2.5 amp hours. At a load current of .19 amps, the 1/2 capacity will last

2.5 amp*hours / .19 amps =  13.5 hours.  At the moment with primarily day sails, over 13 hours is sufficient and in theory if I got into a pinch, I would have nearly 13 hours of reserve.

Monitoring at least voltage is necessary for any battery electrical system and the Lowrance Elite 4 can be set up to display voltage.

 

Figure below - wiring diagram.

Below Chart plotter mounted just behind the front seat so its easy to view from the rear seat. Top number (1.6) is speed, Bottom number (17) is depth. Also displayed is odometer (.29), water temp (73.9) and battery voltage (12.8)

Below.. easy to remove

 

Below - looking towards the rear of the boat through the front hatch. I am charging both the main battery plus the VHF hand held battery at the same time using the Battery Tender Jr. Boat is in my garage, I just run an extension cord over to the front hatch. The battery tender charger stays inside the plastic box when its not charging the battery.

The 12 volt "cigarette lighter" is also used with a USB adapter for charging Bluetooth speaker, MP3 player or cell phone

On off switch over to the side.

Below - total weight of everything in the box is about 4.6 pounds. The box should keep the inside contents dry with up to about 5.5 inches of water in the hull.