Boat Batteries

Hey all,
I have 2 1/2 year old “Northern” Batteries that gave out. The starting battery failed to start the motor while on the water after a short run. The starting battery has a 90HP merc 4 stroke, Hds 7 and 8, a re-circ and fill pump for the livewell and now a 12ft Talon to power. It is a 27 Series battery so I will be increasing the size. I am wondering what to look for in a motor starting battery with electronics attached? I have googled it and searched this site recently on the topic, but it seems the information I am finding talks about AGM batteries being newer technology, is this still true? Any recommendations welcome! I am considering simply going with the same Northern battery in a larger size for around $100?, assuming I can get 2 years out of it. Do the higher end blue tops etc. actually last much longer to make them worth the big price tags?

What ever brand you buy… make sure it is a dual purpose battery !

I have an Optima that is going on 10 years and still going strong. They hold their charge for a long time too.

Get a group 29 Interstate for starting/electronics.

big_g wrote:

Get a group 29 Interstate for starting/electronics.

I second that. I average 7-10 years with these if you keep them maintained.

As far as dual purpose, the guy at the interstate batteries store talked me out of it. He said they’re more intended for starting/trolling motor. He felt the starting battery would be more than sufficient for electronics/livewell/starting. So far he was right.

Costco has Interstate for about 2/3 the cost of other retailers.
Im not sure if they have group 29 but you can get 2 #27 and run them together for a longer reserve than a 29 and dual 27s from costco would still be cheaper than a single 29 other places.

Do you have an onboard charger that maintains your starting battery? If not your outboard will never keep the battery charged and could be the reason your battery is not holding up.

I have helped rig a couple of boats for a past PWT champion. He used group 31 deep cycle batteries in all his boats. My prov came from the factory with battery trays that accommodate group 31 batteries. With all the power needed in a fishing boat now days, bigger is better. The only thing to look for is if your motor needs a minimum MCA, just make sure it has enough. It does not hurt a deep cycle battery to start the motor. When I needed a new starting battery 3 years ago, eddy lybeck from lybeck marine sold me a group 31 AGM. It has been flawless so far. That is the same battery that he puts in all the new boats that he sells.

Not to highjack the thread, but I sold a little boat I had and included a battery that I typically used for my bigger boat. I’m looking to get a battery that runs my electronics, radio, and a 55lb thrust trolling motor. Any suggestions? It is located under the steering counsel of my boat, while the starting battery is in the back of the boat…

puddlepounder wrote:

I have helped rig a couple of boats for a past PWT champion. He used group 31 deep cycle batteries in all his boats. My prov came from the factory with battery trays that accommodate group 31 batteries. With all the power needed in a fishing boat now days, bigger is better. The only thing to look for is if your motor needs a minimum MCA, just make sure it has enough. It does not hurt a deep cycle battery to start the motor. When I needed a new starting battery 3 years ago, eddy lybeck from lybeck marine sold me a group 31 AGM. It has been flawless so far. That is the same battery that he puts in all the new boats that he sells.

3.5 years on exide 31 deep cycles. Cranks over a Yamaha 150 plenty with lots of juice to run everything else in the boat.. I do have it connected to the battery charger though. Never an issue. $120 at Home Depot.

biggill wrote:

if you keep them maintained.

Tom P. wrote:

Do you have an onboard charger that maintains your starting battery? If not your outboard will never keep the battery charged and could be the reason your battery is not holding up.

I’ve been on a few of these battery threads the past couple of years. Since I now keep my batteries maintained year round, I quit buying new ones all the time. Some brands are definitely better than others but taking care of them can have a significant impact too.

drewbop wrote:

Not to highjack the thread, but I sold a little boat I had and included a battery that I typically used for my bigger boat. I’m looking to get a battery that runs my electronics, radio, and a 55lb thrust trolling motor. Any suggestions? It is located under the steering counsel of my boat, while the starting battery is in the back of the boat…

it is not a good idea to run your electronics off of your trolling motor batteries as it may cause interference on the electronics and you are burning up juice meant for the trolling motor.
get the biggest battery that fits in the compartment for the trolling motor. Have all other electronics wired to the starting battery. I would also direct wire your gps/sonar units to the starting battery with inline fuses. Your electronics will not shut off when starting the big motor when the battery starts to get weak. If your electronics are wired into a fuse panel, they will draw down on power when you turn the key and shut off the unit/units.

I have been running Interstate series 31 AGM’s now for a while and they perform flawlessly. 3 depth finders, pumps, lights, audio system, plus enough power to start my big engine (250 HO, G2) with power to spare. I also have an on board charger to assure it’s at capacity when I head out. I agree that the motor itself will have a hard time keeping the battery at it’s fullest capacity. Just got back from Lac Seul and the baitwell pump ran constantly yet never had an issue. Plugged it in each night.

An AGM deep cycle is a dual purpose battery. Mine have 1100 cca.

Thanks All! I went with an Optima Blue Top AGM for the cranking and dual interstate 27s for the trolling motor. At a $530 price tag total I hope the Optima Blue top continues to work as it does, considering 100% charging when not in use by a top end trickle charger. So far so good!

You shouldn’t charge a discharged AGM with a trickle charger. It will never get to its full potential even if it says its fully charged. A discharged AGM can take more input amps than you can find in a typical charger. You need a 3 stage charger that puts out a least 10 – 15 amps on the bulk stage.