jamesndrumcondra wrote:thats funny , i was in halfords and they said the 75amp would be too much for the motor since it says maximum amps is 54 ?
The advice they have given you is entirely incorrect. The 54 amps you have quoted above is presumably the maximum draw of the motor. A 75 amp hour battery might supply this current for a little over an hour before it would be fully discharged.
75 amp hours means that the battery can supply 1 amp for 75 hours or 75 amps for 1 hour. The larger the battery in amp hours, the longer it will last in providing motive power between charges.
As I said before I have used electric outboards since 1999 for motive power in lake boats for trout fishing. I am on my third battery. All of them were 110 amp hour batteries and the last one sufficed for nine years powering a 36lb thrust motor.
Buy the 75 amp hour if you must but the 110 amp hour would last longer in terms of range and overall life provided it is maintained.