Battery Selection for 80lb thrust Ulterra

[Bobby Winds]

Originally Posted by DW

I have a Sportfish 1750 with a single Group 31 from Sams powering a 12v 55 pound ipilot (with combiner). The battery is in the center bow compartment. My sense is that the boat rides too bow heavy evidenced by a spray pattern that is too forward.

In your case the weight of the kicker may offset the battery weight so far forward to an extent, but not necessarily. I recommend that you use temporary ballast to replicate batteries in various placements. Consider placing them in the consoles under the windshield including splitting them one on each side.

Now that everyone has probably convinced you to go big with big batteries, note that they go silent when you have to deal with the problems the weight creates.

It sounds like you might have other issues then one Group 31 battery being too heavy for your boat. That battery weighs 59 lbs, a Group 27 is 53# and the small Group 24 is 45#.

I have 2 Group 31 AGM Duracell batteries in the bow of my boat and they weigh 67.35 lbs each so 134.70 lbs. That's 75.7 lbs more then you have in your bow and I'm not experiencing that my bow rides too heavy whatsoever.

Hope you figure it out,
Bob

[Ltrain]

Originally Posted by DW

I have a Sportfish 1750 with a single Group 31 from Sams powering a 12v 55 pound ipilot (with combiner). The battery is in the center bow compartment. My sense is that the boat rides too bow heavy evidenced by a spray pattern that is too forward.

In your case the weight of the kicker may offset the battery weight so far forward to an extent, but not necessarily. I recommend that you use temporary ballast to replicate batteries in various placements. Consider placing them in the consoles under the windshield including splitting them one on each side.

Now that everyone has probably convinced you to go big with big batteries, note that they go silent when you have to deal with the problems the weight creates.

Bobby beat me to it but I can't imagine an extra 15 pounds here or there can mess a boat ride up. What happens when an extra rider gets in the boat? Heck one of my tackle boxes weighs 75 lbs, lol. I'm not sweating the weight of a larger battery, the increased runtime far outweighs any negative of a few pounds.

Also I will add that I have 4 group 31 Duracells and a Dual pro 4 bank charger in the bow of my boat, roughly 300 lbs. That kinda weight does change ride dynamics. I use a mercury High 5 prop to get that bow up. So if weight ever does become an issue, a 4 or 5 blade prop can help you out.

[Ozark Bob]

OP, Keep in mind: the farther forward the more effect the weight will have on bow lift. Plus the more effect the weight to the side will affect list. So, between 1/4 and 1/3 of the way toward the stern is probably a better balance point. Only you know where your compartments are that are the best to fill with batteries. Do as much research as you can before you start cutting cables installing ends and drilling holes. Good luck Bob

[DW]

Originally Posted by Ozark Bob

OP, Keep in mind: the farther forward the more effect the weight will have on bow lift. Plus the more effect the weight to the side will affect list. So, between 1/4 and 1/3 of the way toward the stern is probably a better balance point. Only you know where your compartments are that are the best to fill with batteries. Do as much research as you can before you start cutting cables installing ends and drilling holes. Good luck Bob

That is what I am getting at: place the batteries further aft for better fore/aft balance. The older Sportfish are already renown as bow heavy to start with. Putting a 67.5 # battery plus charger in the fore compartment cantilevered over the water when planing is a BIG shift in trim, let alone two 67.5# batteries. That is why
I recommend the OP experiment with ballast before finalizing the battery installation.

Since that boat is difficult to induce a porpoise, I would consider and trial placing the two trolling batteries in the 2nd aft compartment by the transom. My guess is that he will find placement under the consoles is best considering he is running a kicker.

Don’t assume what works for one boat necessarily works well in a different boat.

[masterchither]

Originally Posted by DW

That is what I am getting at: place the batteries further aft for better fore/aft balance.

Since that boat is difficult to induce a porpoise, I would consider and trial placing the two trolling batteries in the 2nd aft compartment by the transom. My guess is that he will find placement under the consoles is best considering he is running a kicker.

Don’t assume what works for one boat necessarily works well in a different boat.

Interesting, I am glad I decided to follow this thread. I just happen to be researching this topic on batteries. I have identified in another thread I am going with two new 12v batteries in parallel However, you and the other's above pointed out something else for me to consider. Weight, and battery placement.

With the wet batteries you'd have to keep them upright, but with the AGM since it's not wet you can put them on it's side. And easier to mount in an odd area. Now I am looking at my boat diagram and considering the weight. I really don't thing it will be that much of an issues as far as bow heavy adding one more battery. Right now I have a Northern 27EV. Since I am getting two and running them parallel, I could get by with two 27 or 31 AGM. I am already increasing my AMP hours, so 27 would work.

My 1650 crestliner the battery compartment is just after the windshield. The picture I am attaching just shows the complete rod locker/storage/battery compartment.

[DW]

^^^^

Your boat has a rated weight carrying capacity of about 1,500#. When you add the weight of all the items including motors, fuel, livewell, crank battery, and all the gear you put in your boat, your remaining unused weight capacity is probably less than 1/3 of the boat total capacity before anyone even steps onto your boat.

How do you want to use that precious useable remaining weight capacity? People, or additional batteries? There isn’t a one size fits all, but as the captain you need to figure it out and make the tradeoffs. That is why I cringe with the typical response: you can’t have too big a trolling motor and too many batteries.

Your 12v motor is adequate for your boat. My boat is a little bigger and I also have a 12v. Rather than carrying an additional battery I have one 31 AGM for the trolling motor. I can get away with this because I use a combiner. I suggest you initially install one 31 with a combiner and don’t add another in parallel unless you determine you must have more capacity. It is amazing what a combiner can do particularly with an AGM battery which recharges 2 to 3 times faster than a wet cell on shore power and when charging with the main engine.

[Ches]

Go with the biggest/most powerful batteries you can fit in. I have 5 group 31 AGM's. A wise man once told me he never heard anyone complain of having too much trolling motor power or too much battery power. Words to think about.
Ches.

[masterchither]

Originally Posted by Ches

Go with the biggest/most powerful batteries you can fit in. I have 5 group 31 AGM's. A wise man once told me he never heard anyone complain of having too much trolling motor power or too much battery power. Words to think about.
Ches.

Yes indeed, I went with to 31 group wet-cell batteries! Now I just have to get the wire to make em parallel!

[Ltrain]

Originally Posted by masterchither

Yes indeed, I went with to 31 group wet-cell batteries! Now I just have to get the wire to make em parallel!

Looks like a perfect fit. I don't remember if you covered it yet but i recommend a good charger. Ideally 15 amp but at least 10 amp. I've had luck with Dual pro and Minn kota( have them both on the boat now). I also have had bad experiences with Promariner.

[masterchither]

Originally Posted by ltrain

Looks like a perfect fit. I don't remember if you covered it yet but i recommend a good charger. Ideally 15 amp but at least 10 amp. I've had luck with Dual pro and Minn kota( have them both on the boat now). I also have had bad experiences with Promariner.

Thank you ltrain! I like the Minn Kota Precision too! That is the way I am leaning!