2 Batteries...need help.

[baseball_guy_99]

Ok first off I will be running a 36lb thrust 12v trolling motor, fog lights, nav lights, and 2-12v plug ins.

I have 2 batteries...one is a deep cycle marine battery and the other is a starting battery. My motor is not electric start so I don't have to worry about the battery going dead and not able to start the motor.

Best case scenario I would like to run them in parallel.

Now I know starting batteries are not good for using with a trolling motor because they are not deep cycle...but if I run it in parallel with the deep cycle battery would that make it ok?

Thanks in advance.

 

[devilmutt]

I think you need to have two batteries that are the same...but I may be wrong.

Don't use two different chemistries when connecting a pack. Usually the voltages will be different, but more importantly the charge rates will be different and the capacities may be different, thus resulting in a shortened life span. - Try to match capacities as much as possible. When connecting batteries in a pack you should try to match the capacities as much as possible to avoid discharging one battery quicker than another. A pack operates at a combined voltage so your one cell that discharges quicker will likely discharge deeper than it may be able to recover from.

 

[ScottMD]

You should be using 2 deep cycle batteries. Your starting battery will rob power form your deep cycle as it loses charge.

 

[Ranchero50]

Depends on how long you plan on fishing at one go. I used to run two batteries but realized I wasn't putting a drain on them with 3-4hr trips so i'm running everything off of one. 55lb troller, lights, engine etc. My group 24 battery isn't even getting a good exercise right now so I go 2-3 trips before recharging.

Jamie

 

[Hanr3]

you could use the starting battery, however it wont last long, as in you will shorten its life. Instead of 5 years you will get 1-2 years out of it.

 

[baseball_guy_99]

Well see thats the thing, these 2 batteries came out of my dads Ranger. He used them for probably 3-4 years.

All I need them to do is last til maybe next summer when I plan on getting 2 new ones.

And I have been calling it the wrong thing...I'm hooking them up in a series not parallel.

 

[Ranchero50]

You wire them in series and you'll have 24v...

Series is Boat negative to battery 1's negative, battery 1's positive to battery 2's negative boat's positive to battery 2's positive.

Parallel is Boat negative to both batteries negative, boat positive to both batteries positive.

I'm doing a split parallel with the troller on one battery and the boat on another, both grounds going to the hull and a switched wire connecting the positives so I can tie the troller battery into the starting battery if needed.

Jamie

 

[baseball_guy_99]

Ok, then parallel it is...this electrical stuff is way to complicated.

Like I said...I think I'm going to go ahead and do it because I only need the batt's to last 1 year or so then I will replace them.

 

[jillyronald]

I thing there are no problem with using two batteries. A very good solutions are covered here with informative information. This post is really nice, it help people to how to use two batteries in one time, I hope that people will really like it.

 

[baseball_guy_99]

The only thing I have notice with having both batteries hooked together...they never get fully charged.

Anyone know why this may be?

 

[russ010]

You can hook them up and run them together - BUT - I wouldn't advise it on the batteries you currently have.

You will most likely kill off both batteries faster since they are not the same age, amp reserve hour, nor are they the same type of battery if one is a deep and one is for starting.

Run your electronics off your starting battery, and keep only your trolling motor on the deep cell. It will last you til next year in that scenario, and actually, you can probably keep the starting motor with the accessories going a bit longer.

The deep cell is going to retain more charge than the starting battery will, and the starting battery will draw power from the deep cell the whole time it's hooked up. So basically, you'll have both charged to 100% when you're ready to start fishing... but if one holds more charge than the other (i.e. starting battery fully charged at 12.9 and deep cycle at 13.3) the starting batt is going to use the deep cycle as a charger to try and get to an equalized state of charge

 

[baseball_guy_99]

Great explanation Russ! I will give that a go and see how it works. Thanks a million!

 

[baseball_guy_99]

I ended up just taking out the starting battery...it weighs about 75lbs so I figured that would help free up some weight. And I don't really plan on fishing any tourney's out of this boat so no need for the battery to last 8+hours. I'm thinking about just buying a new battery already anyways.