# One battery or two?



## chavist93 (Jan 8, 2011)

I have always, and still do use just one 29 series battery in my boat. All I have to power is a 12v 45# trolling motor, navigation lights, bilge pump, and to start the engine. I have never had any problems with this setup, but I am rewiring the boat and thinking about adding a starting battery. Could anyone tell me what advantages there are to running the extra starting battery? My engine is a 25hp Mercury with electric and pull start.


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## PartsMan (Jan 8, 2011)

Reliability through redundancy.

Having your trolling motor and main power use separate batteries 
gives you the security of running one even if the other is dead.

Run your trolling battery down and you still have lights and electric start.
Run down your cranking battery trying to start your failed motor and the trolling motor still works.
You also have the ability to swap them or use them to jump each other if need be.

The down sides are the added weight and maintenance.


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## po1 (Jan 9, 2011)

For me I keep it simple with one main battery. I've got my Nissan 18hp electric start, trolling battery, and both fish finders hooked to the one battery. This allows me to keep the battery topped off when running the motor for extended weekends at the lake. My navigation lights I hooked up to 8amp 12 volt battery. This setup hasn't failed me yet and in the worst case if it did faill me, I could pull start the engine or use the 8amp battery.


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## JonBoatfever (Jan 14, 2011)

would a cd player wear down the battery alot or just next to nothhing liike a fishfinder


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## redbug (Jan 14, 2011)

a cd player will draw more that a depth finder


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## russ010 (Jan 14, 2011)

If you just use the radio, it won't drain much. If you play CDs, then you burn a little more in the radio's I've had on my boat.

Right now, I have the following coming off one battery, and it drains my battery verrrrry little throughout the whole day. When I start the day, it reads 12.6v, when I go home it reads 12.1v and this is with all of the accessories below running.

Battery - Duralast Marine 24 group (from Auto Zone)
1 - Jensen Radio (with Satellite Radio) on all day long
1 - Lowrance HDS 7 (color)
1 - Lowrance HDS 5 (color) These color screens pull more amp than the black/white do
1 - Livewell pump (on continuously)
1 - Livewell fill pump

My nav lights are running to my trolling motor batteries... they don't pull that much, but I am using LED lights too for navigation


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## KMixson (Jan 14, 2011)

The advantages of running two batteries would be
1. Having backup electrical power.
2. Piece of mind that you have backup power.
3. Being able to run your trolling motor longer hours.
4. The ability to add more electronic gadgets at a later date.

The Disadvantages of running two batteries would be
1. Weight
2. Space
3. More wiring
4. In your case since you have not had a problem with your current setup it would be overkill.


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## redbug (Jan 14, 2011)

one other thing to think about if you plan on running them in parallel you would need to start with 2 fresh batteries
Having one older than the other isn't good it will shorten the life of your new battery


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## Quackrstackr (Jan 14, 2011)

If you ever have a motor problem far from the ramp, you will figure out the answer to your question in a hurry. :mrgreen:


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## JonBoatfever (Jan 23, 2011)

thanks russ


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## rusty.hook (Jan 31, 2011)

I have always used two batteries. Because you never know when you are going to need it. One time one of my friends just got on the the water and his battery went dead. I was going in, so I loaned him one of mine so he could keep fishing. I just bought 2 onboard battery chargers, one is a Motorguide model 6 amp for the troll motor, and the other is 1 1/2 amp for the big motor, come in, plug them in and they are are both auto shut-off models, therefore I am always ready to roll out on a spur of a moment because here on the Gulf Coast we fish year round, sometimes twice a week.


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## BaitCaster (Jan 31, 2011)

I have one big battery that runs my trolling motor, bilge pump, livewell aerator and nav lights. I have a seperate small battery which is dedicated to my sonar/GPS unit.


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## tripleup05 (Jan 31, 2011)

What sort of battery do you use for your sonar and GPS, BaitCaster?


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## BaitCaster (Jan 31, 2011)

tripleup05 said:


> What sort of battery do you use for your sonar and GPS, BaitCaster?



This one from Cabela's - https://www.cabelas.com/product/Cabelas-Rechargeable-12-Volt-Battery/700551.uts?Ntk=AllProducts&searchPath=%2Fcatalog%2Fsearch%2F%3FN%3D%26No%3D40%26Ntk%3DAllProducts%26Ntt%3Dbattery%26Ntx%3Dmode%252Bmatchall%26WTz_l%3DHeader%253BSearch-All%2BProducts%26WTz_stype%3DSP%26form_state%3DsearchForm%26search%3Dbattery&Ntt=battery&WTz_l=Header%3BSearch-All+Products


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## tripleup05 (Jan 31, 2011)

This one from Cabela's - https://www.cabelas.com/product/Cabelas-Rechargeable-12-Volt-Battery/700551.uts?Ntk=AllProducts&searchPath=%2Fcatalog%2Fsearch%2F%3FN%3D%26No%3D40%26Ntk%3DAllProducts%26Ntt%3Dbattery%26Ntx%3Dmode%252Bmatchall%26WTz_l%3DHeader%253BSearch-All%2BProducts%26WTz_stype%3DSP%26form_state%3DsearchForm%26search%3Dbattery&Ntt=battery&WTz_l=Header%3BSearch-All+Products[/quote]

So thats a 12v, 8Ah battery. 

That means it will last for 8 hours if one amp is being drawn, or 1 hour if 8amps are being drawn, right?


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## redbug (Jan 31, 2011)

I used to use a lawn mower battery it would last all day running my depthfinder and LED lights and at [email protected]% bucks you couldn't go wrong


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