how much can I run off a single deep cycle battery?

[bowfisher8967]

The primary purpose of my deep cycle battery will be to run my trolling motor, but it will also power my nav lights and bilge pump. Generally speaking, how long would the battery last if i also add a standard car/marine radio that would power four 25 watt RMS speakers? The way I see it, you could leave your car radio on at medium volume all night and it would probably still be playing in the morning (though you wouldnt be able to start your car), so a larger deep cycle should last longer? I dont have the deep cycle yet, need suggestions on how big of one I need, without getting too heavy (i have a 14' jon boat).

 

[JB]

Re: how much can I run off a single deep cycle battery?

There are deep cycle batteries and there are deep cycle batteries, bowfisher.

A pair of those giant 6v batteries that run golf carts would last a long time if they didn't sink your boat. There are also small deep cycle batteries for running lamps that you could kill in a few minutes.

My choice for your boat would be a premium Interstate-made battery. . .the Wal Mart "Yellow one", Everstart Marine Maxx (dual purpose if you have an elec. start outboard or deep cycle if your outboard is pull start.)

If you don't have one, I suggest that you get a 15-20HP, electric start outboard that charges the battery. It will make life a lot easier and maintain your battery while traveling from spot to spot.

I think your proposed radio is too much of a power hog for a small rig. It would use more power than your troller at low speed. Go for a much more modest audio system.

 

[fucawi]

Re: how much can I run off a single deep cycle battery?

I would be supprised if your radio draws more than 1 amp ... 4 x25 W speakers is what they are rated at not what they consume .if you put 100w into them you would deafen yourself ..Test dont guess ..measure the current with an ammeter ...bet the radio got a 1 A fuse ..

A small outboard would take about 3 days to charge your battery so wont help much .just get a big battery say 110 AH ( 20 hr rate) and a voltmeter and it is fully discharged at 10.8v ..but if you can re charge onece it starts to drop below 12v ..say 11.8v for max life expectancy.

your trolling motor probably draws on average about 25 A so about 120 min on the suggested battery .

 

[fishrdan]

Re: how much can I run off a single deep cycle battery?

I agree, go with the biggest battery you can get. The Walmart dual purpose marine battery would fit the bill, though your usage is kind of vague. The stereo won't put a huge dent in the battery if played at moderate levels, though I wouldn't be playing it all day long and expect the trolling motor to run for ever. For the TM, how are you going to use it, what # thrust is it and is an inexpensive speed coil one or an expensive "digital" TM? The nav lights could suck some juice if left on all night long, but if you replace the bulbs with LED replacements, that will cut down the power draw significantly.

I also have a 14' jon boat (1436 Tracker) and had a 42# MinnKota TM on it. 1 Group 29 battery would last about 4-5 hours of constant trolling on speed 2-3. I replaced that TM with a 50# digital and 1 battery would last all day+. The digital motors are 2-3 times as efficient as the older speed coil motors, well worth the money.

A group 29 battery weighs around 65#. I have 2 of them in my jon boat since that's what was required for a full day of trolling with the old speed coil TM.

 

[John_S]

Re: how much can I run off a single deep cycle battery?

I have the group 29 from walmart. As he says, heavy. I think that is the largest they stock on the shelves.
If you are placing this under a deck or other out of way place, highly recommend getting an onboard charger. You want to charge them as soon as you return, and if you have to move them to do so, a big pain.

 

[bowfisher8967]

Re: how much can I run off a single deep cycle battery?

Thanks for the input guys. Fishrdan, i'm not sure of the thrust. Its an old foot pedal mercury Thruster II. From the 80's maybe? I'd like to think I could get out there and plow around on the troller for at least 4-5 hours (and moving to different spots with gas here n there). If I knew of a cheap dc-powered radio, cd or ipod player I would just get that, but I already have leftover parts from car stereo installs. I figured i'd customize a boombox from the head unit and speakers I have and make a project out of it. Or even mount the speakers in the seats to get some surround sound!!! Lotta work for a 14' jon boat. Fun project though. Anyone wanna talk about the acoustics of aluminum? hehe

 

[fucawi]

Re: how much can I run off a single deep cycle battery?

PMP I bet not RMS