Buying new batteries…. I need your expertise!

My boat has been sitting for 3 years. I’m setting it up for this year, and need to purchase all new batteries. I’ve read all of the posts on batteries, but still need your help for my specific situation. I have a 115 hp engine that says it needs 350 CCA to start. I have to power a radio, bilge pump, live-well pump, lights (the small % of time they will be needed), and a Humminbird Helix 10. I plan to do hook all of these up to one battery. I can’t decide if it should be a dual-purpose, or if I can just use a deep cycle, maybe around a 29 (my preference). I also have a 24v trolling motor that I plan to hook up to 2 of that same type of battery. My research has me confused because some people swear you need a cranking or dual purpose battery to start the engine, but some people say the deep cycle is fine, plus lasts longer for the other stuff I listed.

Also, I plan to get an on-board charger for the TM batteries, but a guy told me today that I can’t do that because the batteries are hooked together. He said I have to unhook those 2 batteries and charge them individually.

Can you guys tell me what you do and what I need to do. It appears that I can get the deep cycle size 29 battery for around $100, so I’d really like to get out of this for only $300 if it’s not going to leave me disappointed on the water.

I see no way of doing this for $300 for 3 batteries and an onboard charger.

If u just want to get back on the water, go find two of the largest deep cycles for $100/ea and the largest dual purpose for $100 and enjoy the water you’ve been missing for 3 years. It’ll work. You’ll get on the water. And you’ll have fun! But you may need to hit up sales to find these batteries.

If “I” was going to do it, id be watching cabelas, fleet farm, batteries+bulbs+flashlights+Meters+everything…and looking for a sale on AGM batteries. They last a long time on the water, mine have lasted up to 10 years in the boat, and less maintenance required over those 10 years.

Running anything but the biggest agm batteries you can get will be a recipe for a bad day on the water.

I tried to go cheap on batteries for basically the same setup you had and was always dealing with drained batteries. That trolling motor will use a lot of juice.

If you spend a bit more now it will save you money in the long run.

As bob mentioned, you can find deals if you look around. I’d look for deals but don’t compromise on the batteries to save a few bucks now.

When you get to Rainy you will use that trolling motor 10 times more than the outboard.

You can leave the batteries hooked up when charging with a onboard charger (kind of the point). Good idea to unplug trolling motor though. If you can swing it I’d splurge on a 3 bank. That way you can charge your starting battery too. You will always know all 3 batteries are topped off anytime you hit the water.

I’d get the same 3 batteries all around. Deep cycle is actually recommended as a starting battery so long as it has the proper cca.

Chris Aker wrote:

Also, I plan to get an on-board charger for the TM batteries, but a guy told me today that I can’t do that because the batteries are hooked together. He said I have to unhook those 2 batteries and charge them individually.

This is flat out wrong. You leave them hooked up.

Do not go cheap on your batteries unless you want to replace them in 2-3 years.

Interstate batteries are popular and for good reason. They have a very good reputation for quality especially with the flooded lead acid batteries. I personally buy them myself. I would go to an Interstate Batteries store and talk to one of their experts.

Thanks to all of you who responded. The $300 was just for the batteries, and I knew that was pretty much a dream. I shopped a bit more last night, and have adjusted my number up a bit. Luckily, I have a few months until I will be able to get out, so I can shop for deals until then. Any suggestions on places to keep an eye on that don’t necessarily show up on basic google searches would be appreciated.

I’ve had great service from the lead acid deep cycle batteries that are sold under the Duracell name at Sams Club. They have a 105 Ahr that you can get for $100 or a 120 that was about $139. If you want to go AGM, they have those as well and the prices are very good. They are USA made. Keep these charged and on a maintainer and they last 4-5 years if you take care of them.

Grouse

Also, the Interstate group 29 is the same as a group 31. In most cases the Ah, CCA and other specs are better than others group 31.

TheFamousGrouse wrote:

I’ve had great service from the lead acid deep cycle batteries that are sold under the Duracell name at Sams Club. They have a 105 Ahr that you can get for $100 or a 120 that was about $139. If you want to go AGM, they have those as well and the prices are very good. They are USA made. Keep these charged and on a maintainer and they last 4-5 years if you take care of them.

Ditto Grouse. Your $300 budget just isnt gonna do it though if you include tbe onboard charger. Id find the extra monies and get an onboard though. Its a game changer, when u get home all you do is park, plug in, and clean fish. Not sure all onboard chargers work on agm batteries, id check that out if going with those. Imo lead acids are the way to go unless you have oodles of money. But that option is a whole different topic.
Grouse

Here is what I replaced my batteries with, 3 for trolling motor 2 seasons ago and 1 for the main last season. Yep that makes 4 of them!
Interstate AGM

Red Eye wrote:

You can leave the batteries hooked up when charging with a onboard charger (kind of the point). Good idea to unplug trolling motor though. If you can swing it I’d splurge on a 3 bank. That way you can charge your starting battery too. You will always know all 3 batteries are topped off anytime you hit the water.

X2

Red Eye wrote:

You can leave the batteries hooked up when charging with a onboard charger (kind of the point). Good idea to unplug trolling motor though. If you can swing it I’d splurge on a 3 bank. That way you can charge your starting battery too. You will always know all 3 batteries are topped off anytime you hit the water.

X3

That salesman is an idiot.

But I’ve never unplugged my TM before while charging, not sure what you would gain by doing so??

If a battery “cooks” does the voltage skyrocket and wreck a TM???

What about charging a starting battery without a master switch?? Will it fry your outboard and all of the electronics in the boat?? Never heard of that happening….??

Side note: if you haven’t used your boat for three years…..I wouldn’t buy top-of-the-line batteries in case it sits for three years again…..

I’ve pretty much decided on buying 3 Interstate SRM-29’s. It looks like they retail for $141, but I’m going to hang on for a sale if I can find one. I’m also going to get an on-board charging system, probably a 3 bank. Will there be an issue with having 2 batteries on one side of the boat for the TM, and the other on the other side? I mean, should I get one 2 bank charger for the TM’s and a single bank for the other, since they will be on opposite sides of the boat?

From what everyone says, I need to get an on-board battery charger. I’ve done a small amount of research, and it looks like the NOCO Genius Gen3 3-bank 30 amp charger is the best for me, best price I could find so far is $200. There are others, but they are 8 amp, 10 and 20. I assume 30 is better than 20, etc, but I don’t know. What do you think? Also, does the on-board charger actually charge the batteries while out on the lake, or is it just something that I plug into at home to make charging easier and more effective?

Most are just an AC charger for use at home or at a dock.

From my understanding, this Walmart battery had been made by interstate and is considered a 1:1 matchup – EverStart Maxx Marine Battery, Group Size 29DC.

Chris Aker wrote:

I assume 30 is better than 20, etc, but I don’t know. What do you think?

30 will charge faster than 20. Not necessarily better. People that need a fast 6-8 hour recharge would pay extra for it. I would get the cheaper option of you aren’t using it 5 days a week.

Chris Aker wrote:

Also, does the on-board charger actually charge the batteries while out on the lake, or is it just something that I plug into at home to make charging easier and more effective?

It only charges when you plug it in at home. The advantage of an onboard charger is that you don’t have to hook up terminals like alligator clips directly to the batteries every time you want to charge it. Also, onboard chargers have technology built in to prevent over charging and for charging them the best way possible to ensure a long life. They are worth every cent.

I recently bought a NOCO charger myself and can say I would definitely buy another.

Getting an on board charger is an excellent choice. Get a 3 bank and all your batteries will be charged when you hit the water. Mine is plugged in anytime the boat isn’t moving. If you are at a resort that has power at the dock, plug it in.

Batteries can be located anywhere in the boat. You will just have to do more work running the wires if they are spread out. My on board charger is in the back by the starter battery and the trolling batteries are in the floor by the windshield. Pay attention to the recommended wire gauge for the length of wire to get to the batteries.

In my opinion, you can get buy with cheaper batteries by using an on board charger.

To save some $$$ , Interstate stores usually have “Blems” that can save you some dollars. I’ve been using them for a couple of years with no problems.

I am switching to AGM batteries, Group 31. Is there a better deal than Duracell AGM Deep Cycle Marine (Group Size 31), $180 at Sam’s Club? The specs look the same as other batteries selling for $300. Has anyone used these batteries?

Specifications
1 amp hour rate:68.2
100 amp hour rate:110
20 amp hour rate:105
BCI Group Size:31
CCA at 0 degrees F:800

Thanks.

Dennis Williams wrote:

I am switching to AGM batteries, Group 31. Is there a better deal than Duracell AGM Deep Cycle Marine (Group Size 31), $180 at Sam’s Club? The specs look the same as other batteries selling for $300. Has anyone used these batteries?

Specifications
1 amp hour rate:68.2
100 amp hour rate:110
20 amp hour rate:105
BCI Group Size:31
CCA at 0 degrees F:800

Thanks.

Dennis, the farm/fleet AGM is the same battery with a different sticker on the case (east penn ‘deka’ battery), I got those for my TM and very impressed over the lead acid batteries I had prevoiusly. I caught a spring sale and got them for 160ish I think.

poomunk- Thanks for the info. I got to FF at least once a week. Will check them out.