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.
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