New Boater battery Question

[kball]

Hello all, I've been using this site since I bought my first boat back in January and have been thrilled with the info you all post. I'm currently looking at batteries for my trolling motor. I was just wondering what the "Group" number was on batteries. Is it just the physical size of the housing or is there more to it? <br />More relavently...I'm getting the Minn-Kota 68PD Pontoon model motor and don't know which battery size, amperage etc I will need. (Obviously I will need 2)<br /><br />Thanks in advance<br /><br />Hawk

 

[Boatist]

Re: New Boater battery Question

Welcome to the board.<br />In the old days there were not that many types and sizes of batteries. Today there hundreds. Just some old basics. A group 26 is about right to start 4 cylinder motors. Group 24 bigger and good for V8 starting. Group 27 bigger still and a good trolling motor battery. Group 31 is bigger still. <br />For a trolling motor you will want to get a deep cycle battery not a starting battery. You do not always need two unless your trolling motor is 24 volts. The size of the boat and conditions make a big difference. I fish on a 19 foot bass boat and when we fun fish we use one battery. Fishing a Tournament then always take 2. Most days the one battery works fine but if it windy then one group 27 will be pretty week by the end of the day. <br /><br />Another way to look at it would be a group 26=AAA, group 24=AA, Group 27=C Group 31=D<br /><br />There lot of sizes and lot of ways to wire. If you are going to troll all day then you will need two big batteries. If your going to use motor to bass fish and work a spot or shore line then one battery may be enough.

 

[Sea Six]

Re: New Boater battery Question

The group 24 is the standard size for car batteries, and is about 11 inches long by 7 wide by 10 high. The group 27 is about 2 inches longer, and a little heavier. Grp 27 also provides more power for a longer time. Buy the best ones you can afford, and get deep cycle for a trolling motor. You can't buy too much battery - the motor will only take what it needs. A larger battery will last longer between charges. remember to hook them in series to get 24 Volts, not parallel.

 

[18rabbit]

Re: New Boater battery Question

Welcome. All good stuff above. Yes, the group number is an attempt to standardize the physical size of batteries for the purpose of exchanging/replacing them. The group number is only a reference to the bat’s size and not necessarily the bat’s potential. There can be a huge difference in battery performance between battery types of the same group number. The most common battery groups (sizes) for recreational boating are:<br /><br />16 – 6v deep-cycle that also works great as a starting bat.<br />24 – 12v available as starting, deep-cycle, or dual-purpose.<br />27 – 12v available as starting, deep-cycle, or dual-purpose.<br />31 – 12v available as starting, deep-cycle, or dual-purpose.<br />4D – big 12v available as starting or deep-cycle.<br />8D – really big 12v available as starting or deep-cycle.

 

[Silvertip]

Re: New Boater battery Question

Don't be confused by all of the battery sizes (physical dimensions or group numbers). Just by the largest capacity batteries that will fit in the available space. The cost difference is insignificant unless you get into the high-tech types. The only mistake you can make is buying batteries with too little capacity. For your trolling motor you will want a deep cycle or dual purpose. You should also consider a two output on-board charger to charge those batteries after a day on the lake. Your engine will need to run wide open for days to keep them charged.

 

[jtexas]

Re: New Boater battery Question

hey boatist, when you take 2 batts for your 12v trolling motor, do you wire 'em parallel or switch mid-day? Windy day, mine gets weak by end of day, thinking maybe 2 might be the answer. just curious - thanks,<br />jtw

 

[Richard Petersen]

Re: New Boater battery Question

Pontoon boats have big electric start O B's plus your trolling motor. Waves are getting higher so is the wind. Are you now happy - you have 2 seperate size 27 - both deep cycle batteries? 1 is almost dead from trolling. The other is fully charged and and the big motor barks to life instantly. No crap about if we are going home now. NEVER-NEVER use your starting battery for anything but starting the BIG motor. If you can not afford 2 batteries - do not use the trolling motor till you can. Your life will one day depend on it. All major chains sell the Nautilus series of deep cycle batteries- size 27 for $60 get 2.

 

[Boatist]

Re: New Boater battery Question

JTexas<br />When we take 2 batteries we wire Minus or ground sides together. Hook up one positive and at the first sign of weakness switch to other battery.<br /><br />This is just me but I am not a big fan of parallel batteries and I will tell you why. When wired parallel both batteries only as good as the weakest battery. Both batteries have to be same type and age. If a cell goes bad in either battery it will discharge both. If I wired in parallel I would put a big 50 amp diode off each battery to isolate batteries. Then the storngest battery would supply most of the current and a bad battery would not discharge the good battery. Only down side to this is will loose .4 to .7 volts acrossed the Junction of the diode and the diode should have a heat sink. Also if isolated with a diode both batteries no longer have to be the same size, type and age.<br /><br />Another thing I would do that most will not is to charge the battery with the main motor unless your motor is a older motor with only 8 amps or less. On newer motor with 30 amp belt driven alternators I would always charge my starting battery and trolling battery thru a battery isolator or battery combiner. I think good for trolling motor battery and will get some more life out of it if you move from spot to spot. With older small alternator I would not hook up to charge as it may put a large strain on your small alterntor charging at it max it could over heat and go bad.<br /><br />On My largest boat I do not have a electric trolling motor but do have a group 24 starting battery and a group 27 deep cycle. Starting battery has every thing needed to safely run the boat. Deep cycle Has every thing else. I charge both with the motor's 45 amp alternator thru a battery isolator. Wired that way since 1980 and have not had a battery that did not last 6 years.

 

[Richard Petersen]

Re: New Boater battery Question

Boatist is doing a almost perfect job of covering his bets. Except that the 50 amp isolating diodes do not tell you when 1 of the 2 batteries has dropped dead, forever. You will then run down the only good battery trolling all day and not be able to start the big main motor. KEEP them seperate or put in 2 volt meters so you know when 1 has died, and make a beeline for a new battery.

 

[Silvertip]

Re: New Boater battery Question

I think everyone is missing something here. The original post indicates this is a 68# PowerDrive. Anything over 55# in the current Minnkota line is 24V which is probably why he indicated he was buying two batteries. If it is a 24V motor, he would hook those batteries in series for 24 volts -- not parallel as is being suggested for 12V systems using two batteries.

 

[Boatist]

Re: New Boater battery Question

Mac & Bride<br />If Smoke is right and I think he is then get two group 27 deep cycle batteries and wire in series. Keep your starting battery seperate. Also buy a good automatic 24 volt battery charger and always charge your battery back up ASAP.

 

[Boatist]

Re: New Boater battery Question

Richard<br />I would never run a trolling motor off my stating battery. Also I would never run any battery below 50 percent of charge unless it was a life threating emergency. If you run a starting battery below 80 percent or a deep cycle below 50 percent of charge then your batteries will not last 2 years. I have never had a battery that did not last 6 years.

 

[jtexas]

Re: New Boater battery Question

yeah, boatist you hit my nail on the head - older 6 amp alternator is why my trolling motor batt is separate & not charged by the outboard. I appreciate the good advice Richard; I would be actually adding a third battery if I went that route.<br /><br />MacHawk & bride, welcome to the forum, sorry if we took your thread a little off-topic, hope you got the answer you needed.

 

[Richard Petersen]

Re: New Boater battery Question

Boatist , should we tell everybody to remove the cell caps every year to replace the lost "distilled" only water. Even if the battery is called maintenance free. More batteries die a needless death from that, than anything else that is done to them.

 

[Boatist]

Re: New Boater battery Question

Richard<br />Good advice for any battery that has caps you can remove. Only thing I would add is after adding Distilled water I like to charge the battery. Once or twice a year works good for me. Boaters with manual chargers or alternators that charge at a high rate may need to check more often.

 

[Richard Petersen]

Re: New Boater battery Question

For you guys like me, Big motor in little engine box. Hot summer I top off the cells every 2 months. Black canvas, over powered, dries out the battery fast.I have 3 years on it.-------------------------My canvas covers the engine box completly, NO air movement at all when covered.

 

[kball]

Re: New Boater battery Question

Don't worry, the guy I bought the boat from is setting me up with a starting battery. I ws just wondering for the trolling battery(completely separate from the starting system) The whole 2 battery, 24V system is new to me and I want to make sure to do it right. <br /><br />Thanks for all the info. <br /><br />Mac

 

[kball]

Re: New Boater battery Question

OK, Since we're on the topic....and you guys are great help. I see a lot of charging systems available. Here's my situation, our neighborhood association has a dock on the lake where boat is moored all summer. There is no power at the dock. I was planning on pulling the batteries out bringing them back to our house (about 100 yards from the lake) and charging them in my garage. I see these "on board chargers" and other systems. How do you get power to these chargers (I've only seen them in catalogues and am assuming that they won't work for me) Bass Pro also has a 12V solar charger for dirt cheap, but I'm a little leery about using a charger that is only $30. Just doesn't seem right. Anyway, back to the point of the post, what advice would any of you have for convienient charging? I can get an indoor deep cycle charger for fairly cheap, and just transport the batteries, unless anyone has a better idea without breaking the bank.<br /><br />Mac

 

[Silvertip]

Re: New Boater battery Question

Forget the solar charger. A 30 buck unit would take forever to charge a battery. Approach the association and see what they say. In my view, you have two options. 1) Run power to the dock. If you have power to the dock, add an on-board automatic charger to your boat(www.Cabelas.com). Simply plug into a receptacle on the boat and forget about it. The charger will not overcharge the battery. These chargers are available in single, dual, or triple circuit versions for one, two or three battery setups. 2) Your other option is run a 100 yard extension cord to the dock. That would require at least 12 AWG wire to avoid severe voltage drop in that run. Oh ya -- there is the third option -- continue lugging the batteries to where you have power.

 

[kball]

Re: New Boater battery Question

That's what I figured. It really isn't that big of a deal to lug the batteries back and forth. I just figures if I need to buy a charger anyway, maybe there was a better way to doit<br /><br />Thanks<br /><br />Mac