Electric Yacht

Battery selection

The size and type of batteries chosen depend on a number of variables. Many options exist. The best system for you depends on:

• Size and displacement of boat

• Desired usage/range

• Pocketbook

Battery Type:

• Flooded Lead/Acid

  • Lowest cost

  • Require upright mounting and periodic maintenance

• AGM (Absorbed electrolyte in Glass Mat)

  • Mount in any position

  • More costly than flooded

  • More charge/discharge cycles than flooded

  • Require smart chargers, not tolerant of over charging

• Gel (Gelled electrolyte)

  • Mount in any position

  • More costly than flooded

  • Best charge/discharge performance in deep discharge usage

  • Require smart chargers, not tolerant of over charging

Capacity:

Following are some general guidelines. Typically a 100AH system will consist of 12V group 27 or 31 deep cycle batteries. A 200AH or larger system may consist of a series of 6V “golf car” type batteries or large 12V batteries. They can be flooded, AGM or Gel

36V/48V 100AH System:

• Race boats under 30’ and smaller lake sailors

• Used mostly to get out to starting line or on lakes where motoring distance never exceeds a few miles

• Cruise current should normally not exceed 50A, can go higher for short distances

• Cruise range limited to 1 – 1.5 hours, longer at slower speeds

• Total system weight 260 - 320 lbs

36V 200-250AH System:

• Light to medium displacement boats up to 32’

• 2 - 2.5 hour cruise at 75A*

• Up to 120A available (4.5 shp) for maneuvering and short dashes

• Reduced speed range can approach 15nm

• Total system weight around 425lbs

48V 200-250AH System:

• Light to medium displacement boats up to 35’

• Heavy displacement boats up to 32’

• 2 - 2.5 hour cruise at 75A*

• Up to 120A available (6shp) for maneuvering and short dashes

• Reduced speed range can approach 20nm

• Total system weight around 550lbs

 * - This is a deep discharge rating.  For example, the popular Trojan T-105 battery lists a 115 minute 75A rating.  The slightly taller T-145 lists 145 minutes.  It is good practice to only discharge batteries to 50% on a regular basis.