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Do I need a second battery if using a prawn pot puller?

W

wild.coast

New member
18ft RIB zodiac with 2014 50hp Yamaha outboard, currently have just one battery used for starting + electronics.

Got a prawn puller, which has a 3.4-30amp load range. I definitely don't want to drain my only battery and be stranded, wondering if I should be wiring up a secondary battery? Space is at a premium, so I'd rather only do this if I have to!

Curious if anyone has any advice?

Details on my current setup:
My current battery is a NAPA 24RVS deep cycle (link)
  • Cold Cranking Amps: 575 A (makes me think this is technically a 'dual purpose' deep cycle considering the high CCA?)
  • It has a 130min reserve capacity (54Ah)
    • I understand that reserve capacity is how long a fully-charged battery can deliver 25 amps of current in an 80°F environment, before the battery is discharged down to 10.5 volts.
    • I understand 130min to mean that I can operate the prawn puller for just over 2hrs, correct?
Thoughts/questions:
  • Prawn traps are not super heavy (2 traps per line, some chain to weight traps down), so I'm assuming it's not actually drawing the maximum 30amps, more likely 20-25?? But I have no idea
  • On a given outing I'm usually pulling 3 traps @ 400ft of line, which usually only means the puller will be running for ~5min x 3 = ~15-20min
  • Any way to calculate how much 15-20min would drain down the battery?
  • Would my outboard still start if battery is at 10.5v assuming I do in fact run puller for 2hrs?
  • I'm assuming if my outboard is idling the alternator would also be charging the battery while the prawn puller is operating, so less total drain on battery
 
you really cant say without knowing the current the puller requires....you can go worst case to see if you need to refine the estimate...here goes:

30 A for 20 minutes yields 10 AHrs - so if you make sure the battery is fully charged before each trip, you should be ok...

So if you have the outboard running at idle (while pulling pots) it will generate some charge but not much...

now, from a security point of view, a spare battery is a good idea, as long as you have room...if you go where nobody else is, it becomes essential and a no-brainer...if you fish where there is frequent traffic, and you have a decent reputation, it could easily become optional...
 
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