Choosing start and graph batteries

So last year my starting battery drained while running my aerator and graph, and left me floating on the lake. That battery was likely old and weak to begin with, but since I’ve recently upgraded to an HDS Live, and will be running an Elite 12 at the bow, I’m wanting to make sure I have enough juice for a day out on the water… I think all the accessories will be drawing between 6-8amps per hour at full capacity.

My Alumacraft has a group 24 starting motor. I *think* I can fit a group 27 if I replace the battery tray.

My boat has an Etec 90, and is outfitted with onboard 2-bank charger for the trolling motor batteries, and a Minn Kota Alternator connecting the start battery to charge the trolling motor batteries when the Outboard engine is running.

Questions I have:

I’m considering buying a dedicated battery for the graphs only. How could this be set up to charge when the Outboard is running? Parallel with the start battery? Or do guys just charge that battery at the end of the day?

Is there a recommended solution for a combination start/graph battery?

I would consider Lithium, so that’s an option too.

Thanks!

The general thought is that you should use as big of a battery as will fit. If you can upgrade to size 27’s, do it. I use size 27 batteries for both my deep cycles (24 volt bow mount) and my cranking battery. I would not be able to go to a size 31 because they wouldn’t fit.

If you have room for a dedicated cranking battery for the outboard and another one dedicated for electronics, pumps, lights, etc, then you can do that too.

Lithium will give you longer run time on your bow mount and reduce weight. Just keep in mind that lithium batteries cost a lot more up front and require a dedicated charger. Not every charger that works for lead acid or AGM will work with lithium. You also cannot charge them in colder temperatures without a battery heater or warming them up.

Something else you can add is a booster pack like a noco in the event you have a dead battery. Jumper cables also work. I have both.

I am running a dedicated 12v 50AH lithium to power my 3 graphs and live scope. In the next year or so I will be upgrading my current 36v set up to all lithium’s. Just debating if I want to go with 3 12v batteries or jump up to 1 36v battery. If you can shop around you can get a good lithium for not much more than what regular deep cycles are costing. I bought a 50AH epoch lithium for $200 and it has Bluetooth and is also heated so I can charge it when it gets below freezing. It would probably be worth spending the extra money and going with Lithium’s in the long run.
The only downside is not being able to run lithium’s as a starting battery. I know newer motors you can and some guys have been doing it anyways, but to me its not worth the risk of wrecking an engine.

I use a 125 a.h. ionic lithium to run a 9″ and 10″ Garmin w livescope. Also starts a 90hp Suzuki. I charge it in the spring and maintain it over the winter. Never had a problem or ran out of power.

I run 2 12,s and a 9 off same 31 as my starting battery. Haven’t needed a jump. If I do I have a switch that I can turn and jump off TM batteries. Have ran all day with this set up and need to start a 250 merc. Been doing it for years. Same setup in previous boat.

I ran my Garmin 73sv off my cranking battery last year and had no problems but I only have a 25 Suzuki so probably less power used to start. I am adding one more 73sv this year and some interior lights. Planning to connect it all to a rocker panel and power that all off the cranking battery. Assuming this should work? I have separate deep cycles for both trolling motors and assume accessories should not be run off of those. The big motor is running a good amount of the time on my boat so my cranking battery should be staying topped off even when powering other stuff I would think?

Whatever you decide you should have a battery jumper with you, just in case-when I ran out of juice my biggest concern was I could not tilt my motor up, leaving it dangerously close to pavement. Good Luck

tim hurley wrote:

Whatever you decide you should have a battery jumper with you, just in case-when I ran out of juice my biggest concern was I could not tilt my motor up, leaving it dangerously close to pavement. Good Luck

I have a 2021 Mercury 60HP. It has a way to lift motor without power. Maybe your motor has one.

MANUAL TILTING
If the outboard cannot be tilted using the power trim/tilt switch, the
outboard can be manually tilted.
1. Turn out the manual tilt release valve 3 turns
counterclockwise. This allows manual tilting of the outboard.
Tilt the outboard to the desired position and tighten the manual
tilt release valve

This is what my set up looks like on my Alumacraft Voyageur. I built a cabinet under my rear flip down platform and mounted a series 24 deep cycle in the center (there is enough room for a series 27 when I need to replace it). I bought a Blue Seas charging system that charges the house battery with my outboard alternator. I run 2 Helix 9’s, an old 899 for mapping, a mega 360, and a deckhand 40 off the house battery and always have had enough power. I run from spot to spot quite a bit so that probably helps to keep the house battery well charged. All of the other accessories run off the cranking battery, (lights, bilge, live well, radio, and networking switch). I do keep a set of jumper cables in the boat in case the cranking battery would ever go dead.

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tbruno, how does the 115 Yamaha push your Voyageur?

Hodag Hunter wrote:

<div class=”d4p-bbt-quote-title”>tim hurley wrote:</div>
Whatever you decide you should have a battery jumper with you, just in case-when I ran out of juice my biggest concern was I could not tilt my motor up, leaving it dangerously close to pavement. Good Luck

I have a 2021 Mercury 60HP. It has a way to lift motor without power. Maybe your motor has one.

MANUAL TILTING
If the outboard cannot be tilted using the power trim/tilt switch, the
outboard can be manually tilted.
1. Turn out the manual tilt release valve 3 turns
counterclockwise. This allows manual tilting of the outboard.
Tilt the outboard to the desired position and tighten the manual
tilt release valve

problem is the weight of the motor. i had to manually tilt an old 75hp 2 stroke once and about blew my back out! i would probably be in the hospital if i tried it with my 150hp Yamaha?

Those lithium jump packs are a must in every boat if you fish big water.

nord wrote:

tbruno, how does the 115 Yamaha push your Voyageur?

My 115 works great on that boat. By myself fully loaded with all my gear, and I carry alot of stuff onboard, she will do 40 to 41 mph (GPS Speed) on relatively flat water, and about 38 mph with two of us in the boat with the stock prop.

By your original post you have no onboard charger for your starting battery?

tbruno wrote:

she will do 40 to 41 mph (GPS Speed) on relatively flat water, and about 38 mph with two of us in the boat with the stock prop

I feel like you should be getting better speed with a 115. I have a 75 and can go that fast using an aluminum prop.

gim wrote:

<div class=”d4p-bbt-quote-title”>tbruno wrote:</div>
she will do 40 to 41 mph (GPS Speed) on relatively flat water, and about 38 mph with two of us in the boat with the stock prop

I feel like you should be getting better speed with a 115. I have a 75 and can go that fast using an aluminum prop.
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Speed depends on a lot of factors. My “Slight” addiction to tackle and gear may have something to do with the top end speed and I’m not a little guy either.

To the original post; I have 3 graphs and run them off of my group 31 AGM starting battery and it has been perfect for the past 4 years or so. I am likely to add another MSI unit and will likely be adding a house batter at some point with that installation. I like Tbruno’s installation if you have the room.

Tbruno, that looks like a very nice and clean installation that provides a lot of options, nice work and thanks for sharing the idea.

Gimruis, if I remember right you have a modv hull and that runs a lot different than an Alumacraft Voyager V hull, so the speeds are not really very comparable.

I run a 27 for my starting battery, a pair of 27’s for my house battery’s for lights screens and pumps then a pair of 31’s for my trolling motor. Seemed like overkill but I always have enough juice.