Looking to add a second battery

[CrewCabMax]

I am currently only running one 105AH deep cycle battery at this time. I am looking to add another battery(115AH), b/c i'm going to be adding some extra stuff to my boat. I'm wanting to add a bow mount trolling motor, FF, and a stero. Will it be ok to add a brand new battery with a battery that is about 3 years old. The battery i have now is in great shape, and holds and takes a charge just fine. I have never had a problem with it, but i want to make sure with running them in parallel that its not going to affect my new battery. I'm looking to be able to hook these both up to my main power source, so it can draw off of both batteries for anything on the boat. Thanks in advance!

 

[russ010]

The only thing about connecting the 2 together like that is what the charge and amp rates are... it's always best to try to use the same age and size battery when hooking in parallel. The main reason being the older battery may try to rob power from the newer battery which will result in 2 damaged batteries.

I have a radio, fish finder, and livewell aerator hooked to one battery, and with all 3 running all day long, it has almost no power draw. With that being said, I would move the new battery to the front and run just the trolling motor off it.

Run all of your accessories off the older battery... it's cheaper to run more wires than it is to replace a battery if the worse were to happen.. just my opinion

 

[Zum]

I'm with russ.
Although your old battery seems to be like new...it isn't.
Plus, it's not the same ah,attaching them together will shorten the life of your new battery.
Whats size TM are you using?

 

[BLK fisher]

I agree also. Keep with the same two type batteries and you should be fine.

 

[CrewCabMax]

The only one i have at the moment is a 50# transom mount. I'm looking to add a bow mount, but not sure what i'm going to be going with. I appreciate the information fella's! I'll use the old battery for accesories and the new battery for trolling motors. Thanks again guys!

 

[russ010]

If you're planning on using the front and rear trolling motor off the same battery - don't!!!

The best thing to do is run all your electronics off whichever trolling motor will receive the least use. OR... add another new battery that is the same as your newest (even though the dates won't be the same) and run your radio off that. Depending on what kind of fish finder you have (color or black & white) you can run it off it too, but I would really run all electronics off the rear trolling motor battery.

I've got a 71# motor on the front of my boat, with 2 batteries in series (24 volt). The only electronics running off that setup is my color fish finder, and that thing pulls some amps, but it doesn't affect the voltage readings of my batteries when I disconnect them to check their charge. The only other electronics that would run off of that would be the front navigation light, but I hardly fish at night so that's no problem.

In the rear I have 2 55# trolling motors, each with their own dedicated battery. I used to have them wired parallel, but found out they last longer and the motors are stronger if they are not connected together. I do have the rear light hooked to one of these batteries.

I have an extra 24 series deep cycle to run the rest of my electronics - radio, livewell, 12v adapter, and it stays charged when out during the whole day fishing. Each time I come in, it's at 95% charged. (I run an 800gph livewell aerator the whole time without cutting it off).

So... I have 4 - 29 series deep cycle batts, and 1 - 24 series deep cycle... Don't know how much room you have, but if you are planning on an electric only boat - the more batteries you have, the more you can stay out on the water with all of your equipment running at full power.

 

[LarryA]

If connecting two batteries together, both need to be the same battery in the same condition. otherwise you're going create problems betwwen both with charging & discharging. If one is older and holds less of a charge the other will drain trying to equalize.