Looking for some battery advice for trolling motor

Greetings everyone,

I recently purchased a used 9.4′ Sun Dolphin Water Tender to run in our backyard community waterways in South Florida. I got a Minn Kota Endura 2 (40lb thrust) trolling motor with it along with an Everstart Plus Group Size 65 (750CCA / 935 CA at 32 degrees F) and charger.

What I’ve been trying to figure out is the following and would appreciate any insight or suggestions to ensure I’m doing things right.

1) How long should this battery last on a full charge since there is only a gauge on the charger?
2) Should I purchase a second battery to ensure I don’t run out of juice 2-3 miles from my backyard?
3) If by chance we were to get caught on the rain, would the exposed batter be affected by getting wet?
4) Is there a suggested accessory so I could see the battery level while out on the water?

Thanks ahead for any answers or guidance.

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For starters, no pun intended, you have the wrong type of battery. You have a starter battery for a car when you need a deep cycle marine battery. Group 29 would easily get you full day fishing on a pond or lake in calm conditions.

Really? Oh wow. I’ve taken my little kids for 45 min rides the last 3 days.

Thanks.

Well, it’ll work, but you’ll get longer run times and more longevity if you use a deep cycle battery. They’re more suited to deeper discharges–starting batteries are not made to deeply discharge.

Swift Shark wrote:

2) Should I purchase a second battery to ensure I don’t run out of juice 2-3 miles from my backyard?

Assume one day that everything will go wrong because it will. At minimum you should at last have a paddle or two to cover some distance. Whether that’s enough to get somewhere to call for a ride, walk home, or maybe even paddle if the wind is favorable will tell you how badly you want the insurance of a second battery.

x2 on getting a deep cycle battery. Right tool for the job.

patk wrote:

At minimum you should at last have a paddle or two to cover some distance.

I have canoe paddles in my 21′ boat. I hope I never have to use them, but they’re there, just in case.

Swift Shark wrote:

1) How long should this battery last on a full charge since there is only a gauge on the charger?
2) Should I purchase a second battery to ensure I don’t run out of juice 2-3 miles from my backyard?
3) If by chance we were to get caught on the rain, would the exposed batter be affected by getting wet?
4) Is there a suggested accessory so I could see the battery level while out on the water?

1) That’ll depend on a lot of things (load in the boat, wind, current (probably no current), battery age), but with a boat that small, I’d think you could get quite a bit of run time out of it. Keep in mind, if you’re running it at near 100%, that will drain the battery way quicker than if your moving along at 25% power.
2) In a boat that small, I would hesitate to add another heavy battery, but I’d also want a backup plan, like Pat K mentioned. A paddle or two would at least get you to shore in an emergency.
3) I wouldn’t be concerned about rain.
4) You can get cheap a 12V battery gauge. At best, I’m sure they’re a bit better than an estimate. I can’t point you toward any one in particular.

Do you plan on running any sort of sonar? If so, you can usually monitor the output voltage through that.

I used to have a boat a little larger than that one and could usually fish at least 3 days on a lake that was about a mile long using a 45 pound thrust motor. My fishing style was to motor to the windward end of the lake and fish down wind using the motor and wind/current for power.

Thanks everyone for your replies and suggestions. I will get the right battery asap and will install some oar locks and get two paddles. I do have one small collapsible paddle currently but with the width of this boat it would be a pain to try and get anywhere with one paddle.

Really appreciate the replies!

If you have a lead acid flooded or AGM battery,make sure it is fully charged after use.
LifePO4 batteries are a different animal,they are happy sitting at 50% charge.And much lighter and prices are getting more affordable.

Ralph Wiggum wrote:

Well, it’ll work, but you’ll get longer run times and more longevity if you use a deep cycle battery. They’re more suited to deeper discharges–starting batteries are not made to deeply discharge.

SuperDave1959 wrote:

For starters, no pun intended, you have the wrong type of battery. You have a starter battery for a car when you need a deep cycle marine battery. Group 29 would easily get you full day fishing on a pond or lake in calm conditions.

Deep Cycle battery for sure. And recharge to a full charge as soon as possible after using. I would also never go out on the water without some sort of secondary propulsion, a paddle is the most common for an electric driven craft. You can probably buy a battery gauge to rig inline with your battery to keep an eye on how much “juice” you still have. Too many variables to guess on length of time you will have good power. I will not, cannot guess. Looks like a fun little boat!!!!

Marine volt meters aren’t cheap. I’d get a digital multimeter to keep in a waterproof container in the boat. Plano has a good line of waterproof utility boxes. Search for digital multimeter on Amazon.

milemark_714 wrote:

If you have a lead acid flooded or AGM battery,make sure it is fully charged after use.
LifePO4 batteries are a different animal,they are happy sitting at 50% charge.And much lighter and prices are getting more affordable.

Great. I looked these up last night. Which would you suggest? 20ah or 24ah?

robby wrote:

Looks like a fun little boat!!!!

Yes its a fun little boat to putter around the lakes with the kids.

Ron wrote:

Marine volt meters aren’t cheap. I’d get a digital multimeter to keep in a waterproof container in the boat. Plano has a good line of waterproof utility boxes. Search for digital multimeter on Amazon.

Excellent suggestion.

I will post back with what I ultimately did for future thread searchers. Thanks all.

Shark, ignore the lithium battery suggestion. You are looking for battery with 200AH + rating. I even think going AGM is too high dollar for your little putt around rig unless you are comfortable spending more on a battery than your boat is worth.

SuperDave1959 wrote:

Shark, ignore the lithium battery suggestion. You are looking for battery with 200AH + rating.

Agreed. Just go buy a traditional lead/acid battery. Something like this is what you want. Group 27, 29, or 31. The bigger the number, the bigger/heavier the battery, but the longer run times you’ll get.

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SuperDave1959 wrote:

Shark, ignore the lithium battery suggestion. You are looking for battery with 200AH + rating. I even think going AGM is too high dollar for your little putt around rig unless you are comfortable spending more on a battery than your boat is worth.

A 12v 200AH battery is huge,like 125 lbs or so.The highest AH 12v 31 series I
could find was 103AH,and that was a Northstar AGM,and weighed 77lbs.Others are less AH.
Google”Peukert’s law”for info on batteries.

The only true way to find out how long your battery will last on a charge is to use a watt meter to monitor amp draw.

A lot of kayak guys are using 54AH LifePO4 batteries and have no issues.And that is a battery that weighs about as much as a bowling ball.

milemark_714 wrote:

<div class=”d4p-bbt-quote-title”>SuperDave1959 wrote:</div>
Shark, ignore the lithium battery suggestion. You are looking for battery with 200AH + rating. I even think going AGM is too high dollar for your little putt around rig unless you are comfortable spending more on a battery than your boat is worth.

A 12v 200AH battery is huge,like 125 lbs or so.The highest AH 12v 31 series I
could find was 103AH,and that was a Northstar AGM,and weighed 77lbs.Others are less AH.
Google”Peukert’s law”for info on batteries.

You are correct, I was thinking about my doubled up 12v batteries.

Although it’s not a deep cycle battery, you might just run with the one you have until it dies, unless you have another use for it. Monitor the voltage and never run it below 50% charge, and recharge it fully after every use. The chart attached shows charge % at different voltage readings.

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Greetings everyone. Just wanted to come back to post what I ended up getting for any future people searching for info and stumbling on this thread.

I ended up buying an Everstart DC27 Deep Cycle Marine battery with 750 cranking amps and 109 ah. I should note that I settled on this primarily due to weight considerations since the boat caps out at 395lbs. While there were mixed reviews (as with apparently all batteries I researched online) I decided on this one because A) It was walmart and I know I can easily swap it out within a year, B) I have an Everstart Battery Charger for the original battery I posted so figured I’d keep it all as compatible as possible, and C) I got it for $75 all in after finding a coupon.

I also ordered a set of angled oar lock sockets, a set or oar locks, and purchased a used set of lightweight aluminum oars from a desperate seller on offerup.

All in I spent around $115 and feel very confident with the end result. This morning my 12 year old and I ran the 40lb thrust motor at max speed for 3 hours while eploring the waterways and the second battery had more than enough juice left once we got home. (The original battery lasted just over an hour and I swapped before it ran all the way down)

Thanks again everyone, your input has been most appreciated!

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