Posted 12/16/2018 4:49 PM (#926035) Subject: What size battery?
Posts: 200
So I have a small boat and I want a small 12v battery to power my fish finder. I am going to purchase a Garmin 7cv. Would like to use one of the small 12v batteries, but I am unsure of how much power to finder will draw. It says 500w rms/4000 peak. How many amp/hour would I need to power the finder all day? 8ah? 15ah?
So an 8 Ah battery would be severely depleted after about 15 hours operating just this. An 8-hour day would use up half the capacity. I think I'd get something bigger than that. Unless it's a deep cycle battery, it wouldn't be a good idea to discharge it deeply on a routine basis.
Posted 12/16/2018 11:34 PM (#926059 - in reply to #926053) Subject: RE: What size battery?
Posts: 200
I saw a 15ah deep cycle battery. So after a 8-10 hour day that would draw about 5 amps. How far can I safely discharge a deep cycle before really hurting the longevity of the battery?
Posted 12/17/2018 1:45 PM (#926083 - in reply to #926059) Subject: RE: What size battery?
With a deep cycle battery, I don't like to go beyond 20% left, and then only in a pinch. AGM batteries are better than conventional deep-cycle batteries in this respect.
Posted 12/17/2018 3:14 PM (#926092 - in reply to #926059) Subject: RE: What size battery?
Posts: 4269
Location: Ashland WI
Bigbucks1985 - 12/16/2018 11:34 PM
I saw a 15ah deep cycle battery. So after a 8-10 hour day that would draw about 5 amps. How far can I safely discharge a deep cycle before really hurting the longevity of the battery?
I wouldn't worry to much about the longevity of the battery. Those small ones are not that expensive to replace if need be.
What size battery?