Battery - Which one is best for my setup?

[rayborbon]

Hi,

I have a 55lb thrust trolling motor which I just picked up. I also was able to get a fish finder with it... I am looking to get the correct battery for my setup. Otherwise the most ideal, if not the "correct" battery. I will be using this motor to push a canoe around and would like to get as much battery life as possible. After reading about batteries I became a little confused about the best purchase for me would be. I was even more specifically confused about what group size means and how it would apply for my setup. If anyone is out there and could lend me some advice and information I would appreciate the help and information.

Thank you and good luck fishing.

-Ray

[The Quadfather]

I run a 55lb thrust MInn Kota, as well as fishfinder, and a couple other electronics. The Group Size thing refers to the "Typical size" of the battery tray holder for various automobiles. I would not sweat that at all in your canoe. You are not limited to a battery tray holder from a particular automobile.
Sorry, there are people here who may speak up with more direct information about the draw that you 55lb thrust motor puts on your battery... and how many amp hours or whatever you should start with.
Just forget about the Group Size thing in your canoe. Of course you want Deep Cycle... don't cheap out with a "Car, starting battery" you could look at the electric motor and see what the draw on it is... take that back to the battery store and have them pair it to a Deep Cycle battery that will give you the most hours.
The most important thing in my experience is.... do not run your electric motor on full tilt. This will drain any battery. With a canoe, you shouldn't have to go more than 50% on the throttle at most times. It's not that complicated really.

(my first battery was a Trojan. Lasted about 4 years, with constant use and constant re-charges.) On my 2nd battery, sorry can't remember the name. but most important, look at what the electric motor draws, and give that info. to the battery store, and of course go Deep Cycle.)

[rayborbon]

Thank you. I was getting the impression group size had to do with the physical size of the battery like you mentioned and was not certain about it and if it also implied a performance measurement. I'll take the motor or owners manual over and get a deep cycle battery when I get some spare cash. Do you have any specific recommendations for a charger and would it be wise to get two batteries if I can afford it? I have not looked at the cost of the chargers yet.

[Amx]

Group 24 is the physical size of the battery.

With a canoe I'd go with a 24 as the biggest, you're more concerned about the weight in a canoe.

Most cars came with a 24 so look to see what your car has. If it's bigger like a 27 then figure a 24 will be about an inch or 2 smaller in each direction.

If you can find a smaller battery use it. Deep cycle of course.

Interstate and Trojan are about the best there is. Limit Out Marine sells both as well as another brand that I don't remember the name of. Call them.

[Amx]

If you use a water cell battery most any name brand charger will suffice. My Sears charger has worked great for many years. If you get a gel cell/AGM battery a good AGM designed charger is best.

[G-Man]

It really depends upon what you expect from your setup and how much you are willing to pay. A high end, light weight lithium ion battery with enough capacity to push your canoe around would run in the $500+ range. Next in line is the AGM lead acid batteries that hold a charge for a much longer time and charge much quicker than standard lead acid batteries and are typically 50 to 100% more in cost than a standard lead acid battery. Then you have your standard lead acid batteries in two formats, regular and deep cycle. For your application, you should look at the deep cycle standard battery at a minimum. As for size, the bigger and heavier the battery, the longer it will power your equipment. With the lithium ion batteries, you have a weight savings of around 50 to 70% over an equivalent capacity lead acid battery. Group size is a rating of the outside dimensions of the battery, what you are really after is capacity rating. Capacity rating will be in Amp Hours and gives you an approximate number of hours a battery can sustain a constant current of X. ie a 80 amp hour battery can sustain 5 amps at 16 hours or 20 amps for 4 hours. Knowing how much current your system draws would give you an approximate run time. Please note that battery manufactures are known to fudge their ratings and describing how to calculate the true rating woudl take a bit of time. Just know that if you are comparing batteries with similar ratings, the one that weighs more will most likely deliver more capacity. One last note, your electric motor may impart signal noise onto your fish finder. If you find that this is the case, your best option is to pick up a second sealed lead acid battery just for your fish finder. This second battery can be one of those small types that are rated for 7 to 12 amp hours which you can can pick up at places like Fry's, Grainger and even Ebay. They are typically used to power emergency lights and elecrical panels in the event of a power outage and run in the $20 range.

[Bodofish]

Specifically for your second battery it will be a 7.2AH gel cell. You will need a little 12v wall wart to charge it. You can get a cheap battery for about $10 at Vetco in Bellevue on Northup. Probably a charger too. They have a supplier that keeps all the portable devices in the hospitals batteried up. The batteries have a life of about 5 years and the hospitals are required to replace them every 6 months. They're a good buy and right down the street.

A general rule of thumb for lead acid batteries is the heavier one is always better, it has more lead. Battery group is nothing more than physical size or dimensions for the battery, a good group 24 will provide more power than a cheap group 27. As has been stated, Interstate or Trojan are probably the best straight Lead Acid Batteries one can easily buy at retail around here. I would think a group 24 or 27 would serve you well and 2 would even be better. If you’re inclined to go the AGM route make sure you do your homework and really study the specs before you buy, there doesn’t seem to be any manufacturing standard so you could line 4 group 24 AGMs and all will have widely differing specs. Be on your guard.

Remember the hard fast rule about electric boats, never run the motor farther than you’re willing to row.

Lead acid battery 101:
1. Try to never run a battery below 50% of it's capacity.
2. Always charge low and slow, Group 24 and up is best charged at 2 amps for a long time. Unless you have a high frequency charger, then, not so much.
3. Always make sure the cells are full, distilled water to the mark in the cell. Make sure the top is clean, you don’t want to contaminate the acid.
4. Never boil the acid in the cells during the charge.
5. Do not leave the batteries in a discharged state. Always charge as soon as possible. Lead acid batteries love to be kept charged, all the time!
6. A float charger is a good investment if you leave the batteries un-used for long periods.

[hewesfisher]

Very good info so far. The most important "spec" for your consideration will be reserve capacity. Reserve capacity is the number of minutes a battery will sustain a 25amp load before the voltage drops below 10.5vdc.

In your application, CCA, CA, MCA and case size (aka Group size) don't have any value in your search from a performance perspective. Your best bang for buck will be the battery that sustains itself the longest with your electrical loads and has a good lifespan, that's where reserve capacity and charge cycles come in.

An AGM would be a great choice, but they are pricey. Most AGMs can be charged with a standard charger too, it's primarily the gel batteries that require a unique charge profile a standard charger can't produce. Any smart charger will work well for a battery that meets your needs.

A good brand wet cell will be just fine when cared for properly. Folks here have posted positively about Costco brand deep cycle batteries in the past. Shop around and see what you can find, just be sure to compare reserve capacity numbers on any batteries you're considering.

I've run FFs off my trolling motor battery in the past with no issues, so I'd try it that way first before buying a second battery. If you don't have interference, you don't need another battery.

We've had a couple good battery threads in the past, here's one you may find useful.

[rayborbon]

Thanks guys. Very helpful information. I like this place.

[renpeg]

call up the interstate battery in Everett. Ask them if they have any deep cycle blems around $45 bucks Come with 1 year warranty. or so.. (They normally cell out fast.) If your not in too much of a hurry just call every week or so.
https://www.google.com/maps?q=&layer=c& ... =0CKABEKcf