Battery Installation Plan

A total of twelve lithium ion (Li-ion) group 31 batteries have been purchased. The selection of batteries and types purchased is described on the batteries web page. These batteries will be used to create three battery banks: 48V 300Ah (14.4kWh), 24V 150Ah (3.6kWh), and 12V 200Ah (2.4kWh). The 48V bank has 8 batteries, the others have 2 each.

Aft of the mizzen mast support batteries can be mounted in a space that is 28" inches wide. This leaves very little room for space between batteries. The footprint of the 48V battery bank can be accomodated using the ability to stack batteries two high behind the mizzen mast support and forward of the low bulkhead in the hull supporting the cutlass bearing fin.

Two locations for the 24V and 12V battery banks are being considered. One space is immediately behind this extending under the steering pedestal and steering cable pulleys. The 24V and 12V battery banks cannot be stacked in this space. The second space is forward of the electric motor mounted on the engine mount stringers.

Available Space for Batteries

The LBP 24V 75Ah batteries are 12.7" long and 6.7" wide. They are 8.5" high and therefore could be stacked two high if enough height is available. The floor and underside framing add height to the assembly. Space for terminal posts used to make external connections to the batteries add height if the posts are above the batteries.

The recessed area behind the mizzen mast support is 28" wide. About 22" is available between the bulkhead supporting this post and interference with the steering cables which extend down into this area. The 28"x22" area is at least 21" in height at the shorter aft end. Aft of this is an area under the cables that is another 20" long and 28" wide but about 14" height. This is no where near enough to support stacking batteries but enough of room for one high.

Batteries Modules

Battery modules will be used to group two batteries together into a wooden open enclosure for the purpose of securing and easily connecting batteries. Each enclosure will use two Blue Sea Systems Dual PowerPost Cable Connectors for easy installation and removal. Each module will have one charging circuit connection and one load circuit connection. One cable connector will have the two positive connections, load and charge, and the other will have the two ground connections. This is so that charging can never be connected directly to loads without a battery bank being connected.

Three different types of battery modules will be built: 12V, 24V, and 48V. In the figure to the right the 12V, 24V, and 48V modules are illustrated left to right respectively. All modules will be the same size but with differing connector arrangement and mounting details such the the wrong voltage module cannot be installed in any given location. The one 12V module will have two 12V 100Ah batteries in parallel. The one 24V module will have two 24V 75Ah batteries in parallel. The four 48V modules will have two 24V 75Ah batteries in series.

Batteries will be tied together within a module with AWG #2 gauge wire. The charging cables to the battery will use AWG #6 gauge wire and lead to 150A bus bars or directly to a circuit breaker for charging positive and DC ground. The load cables to the battery will use AWG #2 gauge wire and lead to 600A bus bars or directly to a circuit breaker for load positive and DC ground. Each 48V module will have two MRBF fuses mounted on the positive battery post, one for the charging circuit, and one for the load circuit. Each 12V and 24V module will have four MRBF fuses, one pair for each battery. Additional detail on these interconnections can be found in the Battery Charge and Load Wiring section of the Battery and Electrical Wiring web page.

Batteries Module Placement

The mizzen mast support post under the cockpit sole is supported by a 6" wide but short bulkhead. This bulkhead straddles the prop shaft entry into the hull and provides a barely adequate limber hole. Just forward of this bulkhead is the stuffing box, soon to be replaced with a dripless seal. Further forward is the coupling and then the area where the electric motor will be mounted. The space beneath the bulkhead will be filled and the space aft of the bulkhead will be partially filled with coring material, resin, mat, woven roving, and glass and new limber holes drilled. This is the area where the 48V battery bank will be installed.

The 48V battery bank will be located a few inches aft of the The mizzen mast support post and bulkhead. There is more than enough height here to stack modules two high, and enough room for two athwartship. The somewhat soggy plywood storage area base will be partially sawed out and modified if width is needed and to provide better drainage and wide cable channels below the newly installed storage area floor.

The 12V bank (single module) and 24V bank (single module) will be installed a few inches aft of the 48V battery bank. There is 28" of width further aft but if the area is widenned the width will be carried aft. The hull slopes up and above this is below the binnacle and therefore the steering pulleys and cables. Batteries can't be stacked but there is plenty of height to mount one high. These modules will sit higher than the lower pair of 48V modules but below the upper pair of 48V modules.

Installation will be from the port side sail locker which has plenty of room to climb into. The starboard side modules must be installed first, then the port side. Since the 12V and 24V battery modules are furthest back these can be installed and connected first, starboard side first, then port. Then the lower 48V starboard side module can be lowered in place and connected and then the upper 48V starboard side module slid in above it and connected. Then the same can be done for the port side 48V modules.

After installing and connecting the modules some wood blocks will be installed and screwed in place to lock the modules in place.

Batteries module connections and wiring

All battery wires will be run to the port side where the breakers, battery switch, and fuses described in Battery Charge and Load Wiring section of the Battery and Electrical Wiring web page will be located. This space in near the existing shore power connector. A panel will be built within an enclosure with forced ventillation to aft dorade vents. This area will also contain the solar charge controllers, shore power charger, and serve to concentrate charge side connections.

The primary grounding bus bar will be near the battery modules with individual ground wires to each battery module. Grounding is discussed in greater detail in the Grounding and Bonding section of the Battery and Electrical Wiring web page.