# Deep Cycle Batteries



## ENCORE (Sep 19, 2005)

The on board charger shuts down the constant 2amp charge, once the batteries are at full charge.

I called the dealer this morning and discussed it again with him. He remembers me complaining about how short a run that I got with the trolling motor. We discussed it and the only thing that he can believe it is, is that one of the cells in one of the batteries must have been bad from the start. He told me to just call him the day before I stopped in, and he'd replace both batteries for FREE.

He assured me, that the wiring was absolutely, 100% correct in the boat. Which I pretty much thought that it would be. They sell enough Lunds to know how to do it properly. He said that he's calling a person that repairs MinnKota trolling motors, and will ask him if there's a possibility of the motor drawing too much juice or, a potential problem with the motor. He said that he's never had it happed, but stranger thngs have happened.

I guess if he replaces the 2 year old batteries for free, I can't complain one single bit. They've been such a good dealer, that I think that I'll plan on spending some time there and actually have them check the batteries that I have. If there's nothing wrong with them, I'd rather they locate the real problem.

Hopefully, I'll (we'll) get to the bottom of this.......


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## WALLEYE MIKE (Jan 7, 2001)

ENCORE said:


> The on board charger shuts down the constant 2amp charge, once the batteries are at full charge.
> 
> I called the dealer this morning and discussed it again with him. He remembers me complaining about how short a run that I got with the trolling motor. We discussed it and the only thing that he can believe it is, is that one of the cells in one of the batteries must have been bad from the start. He told me to just call him the day before I stopped in, and he'd replace both batteries for FREE.
> 
> ...


That would be my first thought is a battery, step #1. Even tho both are new, one still can be faulty from the start. Once you eliminate that from the equation you will just look into other solutions one by one. But I got a feeling it the battery.

I went thru 3 fuel pumps this August before I got one that worked. All new and not rebuilt (and OEM).

Also check your prop for fishing line. Plugged up with line might also cause a drag.

One of the best tools is a battery/charger tester. Cost about $20. Its handy when you need to use one.


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## greg123 (Oct 6, 2004)

How heavy gauge is the wiring between the batteries and the plug for the motor? If the wire isn't large enough, it could be heating up and cause issues.


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## Damark Marine (Mar 26, 2008)

Batteries are a neat subject aren't they. The only thing I would add is to buy the biggest you can afford, keep them full of water as we lose this with the constant charging. Another thing to remember about deep cycle batteries is they are meant to discharge slowly, and need to be charged slowly--min 24 hrs--due to the thickness of the plates inside the batteries.


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## REG (Oct 25, 2002)

One other thing, with lead acid batteries, I believe if they get fully discharged, they will not take back a full charge. The more this happens, the less charge the batteries will take back.


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## Girtski (Apr 29, 2009)

Damark Marine said:


> Batteries are a neat subject aren't they. The only thing I would add is to buy the biggest you can afford, keep them full of water as we lose this with the constant charging. Another thing to remember about deep cycle batteries is they are meant to discharge slowly, and need to be charged slowly--min 24 hrs--due to the thickness of the plates inside the batteries.


Slight hijack; 
I am currently shopping for an on-board charger for my trolling motor batteries. Mine are mounted under the step between the walk thru windshield. I always thought slow and low was the way to charge batteries. I was at Cabelas a couple weeks ago and was told something different. The gentlemen helping me in Marine Electronics area was explaining that the batteries needed a minimum of 10 amps per battery recharge rate. If any lower, the batteries "memory" would be negatively affected. Consequently, he recommended nothing less than a 20 amp 2 bank charger to charge my two batteries. ( I don't believe I need to charge the start/crank battery since the engine does). What's the straight scoop?


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## Landsend (Dec 22, 2006)

Although not a marine mechanic, I am an ASE Certified (including electrical systems) heavy truck mechanic and have devoted much time to training and understanding electrical systems. They all work the same, cars, trucks, boats, etc. Here are my recommendations:

1.) Have the batteries tested! Yank them puppies out and either test them yourself (with handheld tester) or take them in. If one battery has a bad cell, there will be a short (plates touching) which now makes your 12v battery a 10v battery (Most batteries have 2v per plate, 6 plates). Now, if one battery is shot with a bad plate, it is going to draw away from the other one, shortening your charge capacity and run rate. Think of it this way, if one battery is rock solid, the other has bad plate and is running at 10v, then the good battery has to run your troller AND makeup for the loss of the battery. In your case, this could be a possibility of what is happening.

2.) If you have a handheld Multimeter, you can do a few checks to test your motor. With the use of an amp clamp, you can run your troller, clamp the lead wire and determine how many amps your motor is running at each speed setting. Now I'm not exactly certain of this amp chart, and what they should be, but the information should be available online. Test the amp draw of your motor, this will determine whether it is a battery or motor problem (especially after #1 above).

3.) The notion that your deep cell or cranking battery has a "memory" is bogus. The only battery that has a memory is a Ni-Cad battery, which is found in remote cars, laptops, cordless phones, etc. Let me repeat, your car/truck/boat/deep cell battery DOES NOT have a memory. It does, however, have a declining maximum charge as time goes on. It is all chemistry - your battery is full of lead plates and acid that results in a chemical reaction to provide a "charge/voltage". I'll try to paint a picture, your battery contains millions and millions of atoms that are interacting with each other due to the lead plates. Over time, some of these atoms get spent. So after say a year of service, your battery -which once had (let's just say) 2 million atoms inside, has spent 100,000 atoms and you are now left with 1.9m atoms. The output of the battery is not the same due to this loss of atoms. I hope this makes sense.

4.) I believe it was Walleye Mike that correctly stated how to determine your battery life. You will see a number on your battery of 'X' amount of Amp/hrs. If your amp hours is 350, and your troller runs 25 amps (rated per hour), then simple arithmetic tells you 350/25 = 14 hours (a little high but this is an example). This tells you running your troller at 25 amp/hr from a 350am/hr battery will give you 14 hours of usage. Again, if you can find a chart, you can determine your run time. With two 12v batteries run in series (to provide 24v) you DO NOT increase your amp/hr rating, if you have to batteries at 350amp/hr each, then you have a total of 350amp/hrs. Some people mistaken this for parallel systems, where you have two batteries tied together (hot to hot, ground to ground) which now maintains 12v, but doubles your amp ratings. In a 24v system, you have whatever it says. It is important to have 2 batteries with the exact same amp/hr rating in a 24v system because if they are mixed, one will run out before the other and you have a risk of damaging the stronger battery. Again, I hope this makes sense.

5.) The battery wire and connections do play a part in voltage loss, but very little. For every connection from the battery, you lose 0.1v (this is the tolerance anyways). So if your batteries show 12.6v, and you have two connections from battery to troller, the allowable voltage at your troller should be no less than 12.4v, this will help determine if you have a wiring problem. If the reading is within acceptable range at your troller connector, this eliminates the wiring, but not the motor itself (that is where an amprage draw test comes in).


I tried to explain this as clear as possible, so I hope I provided an understanding. it is really hard for me to troubleshoot your problem sitting here behind my laptop, but if I had to guess I would say the problem lies with one weak battery, or your troller is drawing too many amps (possible motor winding short), reducing your time. I don't know where you are located, but send me a PM and I can guide you through it through PMs, texts, or phone calls. If you live close enough, I can swing by and troubleshoot it for you. I don't know how old your batteries are, and age is not the key indicator (how many charges/discharges is a better measurement), but you may be needing some new juice. If you buy new ones, make sure they are deep cell (constructed to withstand frequent charge/discharge cycles), and make sure they are the exact same size and brand for that matter.

One more thing, to answer your question about charge rate...It is better to charge a Deep cycle battery at a lower amp rate. Why? Because it falls back to chemistry: the higher the charge rate, the crazier those little atoms go bonkers and burn out. Higher rates burnout atoms at a quicker rate than low amp rates. Basically, lower amp charges will extend the life of your battery. Here is an exception - if you have the charger, it will be wise to charge it on its highest setting for the first half hour, then drop down to a low amp. The high amp charge helps prevent corrosion from building up on the plates. This only needs to be done about two charges per season, especially the first charge of the season if you let it get down that low.

Seems like I wrote a book here, but I'm just trying to explain it so everyone understands it. Again, PM for more info if you need to. Good luck!


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## Landsend (Dec 22, 2006)

Girtski said:


> Slight hijack;
> I am currently shopping for an on-board charger for my trolling motor batteries. Mine are mounted under the step between the walk thru windshield. I always thought slow and low was the way to charge batteries. I was at Cabelas a couple weeks ago and was told something different. The gentlemen helping me in Marine Electronics area was explaining that the batteries needed a minimum of 10 amps per battery recharge rate. If any lower, the batteries "memory" would be negatively affected. Consequently, he recommended nothing less than a 20 amp 2 bank charger to charge my two batteries. ( I don't believe I need to charge the start/crank battery since the engine does). What's the straight scoop?


A 20amp w-bank charger only gives 10amps to each bank. It is 20amps divided by two banks, not 20amps each bank. 10amp charge rate seems reasonable, but wouldn't go much higher. I use a 5amp charger for my batteries; yes it takes longer, but will extend battery life.


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## Girtski (Apr 29, 2009)

I fully understand your response to my hijack (sorry about that ENCORE) and will now utilize the lower amp 2 bank charger that I initially wanted. I don't fish with the 24 volt system often and when I do, there is plenty of time between uses to allow a lower amp (read less cost) charger to completely charge the batteries prior to next use. 

I probably should have started a new thread, but since we're here, are there any features of specific models that I should consider before my purchase...Any recommendations?


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## Landsend (Dec 22, 2006)

Girtski said:


> I fully understand your response to my hijack (sorry about that ENCORE) and will now utilize the lower amp 2 bank charger that I initially wanted. I don't fish with the 24 volt system often and when I do, there is plenty of time between uses to allow a lower amp (read less cost) charger to completely charge the batteries prior to next use.
> 
> I probably should have started a new thread, but since we're here, are there any features of specific models that I should consider before my purchase...Any recommendations?


I would stick with a Minn Kota because admittedly, I am loyal to them. Just make sure whatever you buy is fused, in case of malfunction. Here is the one I own: Link

Again, any one you buy will probably work, I tend to stick with what works for me (past experiences). 2 banks, 5 amps each, 10-12 hour recovery time, I have never had a problem with recovery time. Another little trick I use is the cheap solar charger from harbor freight, it only produces like an amp, but I setup the solar panel on my rear deck while I'm out and it helps out a bit. Thinking about buying another one for cranking battery to help with all the electronics I run. Again, the solar panel does not really do much, more of a maintainer but I run them anyways, like a trickle charge.


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## ENCORE (Sep 19, 2005)

Landsend said:


> Although not a marine mechanic, I am an ASE Certified (including electrical systems) heavy truck mechanic and have devoted much time to training and understanding electrical systems. They all work the same, cars, trucks, boats, etc. Here are my recommendations:
> 
> 1.) Have the batteries tested! Yank them puppies out and either test them yourself (with handheld tester) or take them in. If one battery has a bad cell, there will be a short (plates touching) which now makes your 12v battery a 10v battery (Most batteries have 2v per plate, 6 plates). Now, if one battery is shot with a bad plate, it is going to draw away from the other one, shortening your charge capacity and run rate. Think of it this way, if one battery is rock solid, the other has bad plate and is running at 10v, then the good battery has to run your troller AND makeup for the loss of the battery. In your case, this could be a possibility of what is happening.
> 
> ...


That's a lot of information.......... *THANK YOU!*

I'm going to print it out and take it with me when I go to the dealer. He seems to think also, that one of the batteries is bad and always has been. He's offered, free of charge, to replace both for me. One thing that I noticed, is that these batteries that I use with the MinnKota are called: "DUAL PURPOSE" batteries. Could this be part of the problem?
If I should have "deep cell" only batteries for the trolling motor?

I can help with a muzzleloader, I can fix any ergonomic problems that anyone has. But..... I'm not familiar with 12v wireing....:lol:


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## Landsend (Dec 22, 2006)

Deep cell for trolling....absolutely. Again, they are made to be charged/discharged (designed with thicker plates to prevent warping). Dual purpose is sort of a multipurpose battery, it's kinda in-between cranking and deep cell, as it is designed to crank but not designed to withstand charge/discharges like a deep cell. Two good (high rated) deep cells is what I recommend, even those Wally World Johnson controls, just go as high on the cold cranking amps (CCA) and reserve amps (RA) as your budget will allow. 

One big key, not too sure how many people practice this, is to remove your batteries from your boat each winter. I put mine in my garage on a battery maintainer through the winter, it keeps them fully charged and prevents freeze-ups, which will destroy a battery. I'm just a tightwad so I prefer to spend $20 on a maintainer than $100 on a new battery each year :lol:

If you have any questions, just PM me. I don't mean to sound like a guru, I just know a lot about batteries and electrical systems. Again, no not a marine mechanic, but highly skilled in 12v systems, and they are all pretty much the same.


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## ENCORE (Sep 19, 2005)

As I have had a problem from the start with these batteries not lasting over 2 or 2.5 hrs, the dealer had just told me that he'd replace them for FREE and with deep cells only. He also asked me to bring along the bow mount for them to check for AMP draw. Well I drove over today with the original batteries and the trolling motor.

Before he even took the took a battery out of the back of the truck, he tested it. He instantly said it was "junk". It showed that it had a full charge, but when he load tested it, it failed miserably. He then tested the second battery and found that it was just about as bad. I guess its just my run of luck.... right off the bat, with a new boat and new batteries, one was bad right from the manufacturer.

From a previous discussion that I had with the dealer, I asked about going to the 31's instead of replacing them with the 27's and I'd be glad to pay the difference. He had two new 31's setting on the bench waiting. BEFORE we put them in the back of the truck, he did the test on them so that I could verify that they were ok. Everything checked out and they loaded them up. They only charged me $30 to upgrade to the 31's.

Now I've owned a boat of some kind or another since I was eight (8) years old. So in over 50 years, I've had my share of dealings with marinas and dealers.... That said:

This I have to say and will be DAMN PROUD to say it, *Maple Bay Marine in Brutus has been nothing but TOP NOTCH *and the best dealer that I've delt with. PERIOD! Not just because of this battery issue, but because of ALL the service that they've provided me since I purchased my Lund from them. When I've called with a question, I received an answer. When I had a problem, they took care of it IMMEDIATELY. They've been helpful in every way. I highly recommend Maple Bay Marine. I thank them for all the outstanding service that they've provided me.


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## high brass (Dec 28, 2010)

Sounds like you solved your problem. I have a 24v. auto pilot ,and troll with it all summer.We have never run out of juice,even after [email protected] 1.7,I do usually go with the wind,however. I was curious if the charge indicator on the base of the motor was showing a full charge when you were having you're problem?I have found that to be a more dependable indicator than what is showing on the charger.Good luck this season ,hope everything works perfectly.


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## ENCORE (Sep 19, 2005)

Had my first chance to use the new 30 series batteries and after 4 hours of non-stop trolling, the battery indicator on the motor showed a 3/4 charge left. From start to stop, I never had to increase power to maintain my speed.

Pretty happy about it now........... thanks.


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