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Terrapin is supplied by six 12 volt, heavy duty, deep-cycle, sealed lead acid gel batteries of 95 ampere-hours (AH)
The batteries are connected in series-parallel to give a total of 285 AH at 24 volts. They are housed underneath the front seats, arranged across the beam. It would be perfectly practical to reduce the number of batteries to four, or even to two, if the main use of the vessel was short, single-day, trips.
The photocells are not expected to fully replenish the batteries. They are intended to provide top-up charge only. If, for example, the boat is used over a weekend (say 3 to 4 hours running time) and then left exposed to
continuous sunlight over the the next few days, the batteries will be topped up ready for use at the weekend.
The fully-charged batteries will deliver 10 A for 20 hours without exceeding 70% of battery capacity. This current is sufficient drive the vessel at about 3 knots (i.e. a relaxed cruising speed). At 5.5 knots (the maximum speed) the ammeter shows the motor drawing 40A, less than 20% of capacity
How do I select the right size of battery for my chosen design? What types are suitable for electric boat usage? Answers to those questions on this page