Trolling motor batteries issue

I have a terrova 24V motor, I leave the boat on a lift at my cottage between fishing trips. I have a pro mariner 3 bank onboard charger that I leave plugged in while on the lift. The other day I unplugged the charger and away I went fishing. it was fairly windy so I went to my spot and hit the anchor(spot lock) the motor held me there for a few minutes and then suddenly the motor is going steady and it just keeps going off my mark in a straight line. I grab the remote and go to head back to my spot and I can tell the steer motor is very slow and sounds weak. I click up the speed on the motor and its really weak. WTH? I open up the back compartment and both batteries and the charger are fairly hot! the engine start battery and ALL cables(even the ones to trolling motor) are cold. (By the way, the engine battery works fine and reads good on voltage) So my question is what would cause the batteries AND the charger to be hot?

Since then I have been trying to figure out what went wrong, did the batteries just go bad? did the motor fail? is there a short? is the charger bad?

When I came back in i was afraid the charger was bad so i plugged it in and checked it periodically to make sure it wasnt hot…it never got warm at all, after about an hour the green light came on that said “ready” (charged). the next day I went out and the exact same thing happened, weak operation, motor even shut down a couple times when i clicked up the speed too high(I’m assuming a safety feature built into the motor)

The next time I went up I brought a volt meter, while the charger was on it showed just under 15 volts on all batteries. I pushed the battery level button on the trolling motor and 4 lights lite up, makes sense with 15 volts, then I unplugged the charger, one battery is at 12.8 and one is at 10.9, the test light on the motor is only at 3 lites. I go out fishing and its the same deal, not as windy so I limped along but weak. I also tested the batteries while under load, and they drop down to 6 and 8 volts. Obviously the batteries are shot, but why? they are only 3 years old and have always been plugged in even throughout the winter to maintain. They are X2 power agm deep cycle batteries SLI31AGMDPM

last nite I took up 2 separate battery chargers and disconnected cables, charged them individually and today, same results. so the charger seems to be fine and the batteries seem to be bad.

Anyone have any info? I hate to get 2 new batteries and then find out the charger ruined them. What would have caused the batteries to get hot. If something fails in the battery would it cause the charger to get hot?

thanks

I am not familiar with your charger. Does it go into a maintainer mode once the battery is charged? Maybe the charger is over charging the batteries and shortening the life.

I know the minnkota chargers have that technology.

I think your batteries have some bad cells, and if they’re only 3 years old, get them into the dealer and let them load test them, and get your warranty working for you b4 you don’t have any warranty left!
I just had to replace two 31 series deep cycle interstate batteries this last summer. 1 year old!!! Took them to dealer and they couldn’t believe it. But, come to find out there was a bad batch and I got two of them. It happens….

Have you ever checked the water level of the batteries? The plates inside need to be covered. I find that I have to add at least a quart of water to all of my batteries spring and fall.

Sorry, just noticed they were AGM. Disregard for this particular issue.

Sounds like you have one battery not taking a charge , based on your voltmeter readings after charging . When I bought my optima agms , I read that if they were too deeply discharged they were hard to charge , so you need to hook your charger to the good battery , then run jumpers from this battery to the discharged battery . Hope this helps

update to battery/charger issue

I took the batteries back to batteries plus, they tested them and confirmed they were both shot. There is a 4 year full replacement warranty, so they replaced them at no charge. I didn’t want to use the old charger if it was the cause of the battery failure. I called pro mariner and asked if there was a way I could test the charger, they said put all 3 leads on to a good fully charged battery, plug in charger and test voltage, they said it should be 14.7 while charging, and then when “ready” it should “maintain” charge at 13.3 volts. so I hooked up to one of the new batteries today. When I first plugged in charger it went all the way up to 16.9 volts for maybe 20 sec. and then it dropped to 13.4. I thought maybe 16.9 was high? I called back and they said yes it seemed too high of voltage. I said “so maybe that is what wrecked my batteries? He said possible OR your batteries failed and that caused the charger to fail? They offered me a new a new charger shipped to my door for about 80.00 less than a new one, seemed like an ok deal plus I didn’t want to risk wrecking the new batteries.

Anyone have any insight on what failed first? the charger or the batteries? what do you think about the 16.9 volts on charge?

I don’t see how a bad battery would mess up the charger? Maybe the heat or an internal short, but that seems unlikely to happen to both batteries, I think it was the charger first. I definitely wouldn’t be using a pro mariner again. are they suitable for agm batteries? I know some agm batteries will work better and last longer with a charger that is designed to work with agm batteries. Good luck! Hopefully you can fish in the wind from now on!

yeah, just been looking at some reviews, sounds like a minnkota or dual pro would be a better choice. Maybe I can send it back? I think you are correct the charger failed and then toasted the batteries. the new gen 3 sounds like it has better safety features but now I’m not sure.

a couple of thoughts,a charger should never be left on for long periods,why??
they are not designed to be maintainers for one as when the battery is topped off,they still trickle charge at a very low rate and you can over charge a battery(s).
when they do this,the battery can get hot enough to actually read low and the charger will go into charge mode and it make things even worse.
then you run the risk of overheating,fire,etc.

if you are bound and determined to use it as a charger and maintainer,at least put a twenty four timer on it for a few hours a week,the batteries will hold a charge when full for quite some time and it gives the charger and batteries a break.

sixteen volts on an agm battery is not overly high as long as it doesnt charge that high for extended periods,they do charge differently than a lead acid battery and different voltages to ” boost” the initial charge,and they require their own type of charger to be efficient.

sadly you can get a bad battery or two that are bad from the get go,I know,I have been selling a top of the line battery for over twenty five years or more now,and it does happen.

if you have a good electrical repair shop near by,have the chargers diodes,rectifier,and transformer checked,for what ever reason the last couple of years,we have seen our fair share of defective chargers of what ever brand,its not just one brand.
the diodes and rectifiers fail and will induce an A/C voltage charge into the battery ruining it immediately.
a good shop can repair the charger to better than new at low cost,and or at least prove if its working correctly or not giving you peace of mind.

if you ever want to know more about batteries than you ever knew possible,stop into an interstate battery outlet and just ask,they are more than happy to teach you.

iowaboy, thanks for the info. Most of the new chargers claim to have systems that monitor and only charge when needed. Is this false? It makes sense that the charger isn’t needed all the time throughout the winter, but what about in the cold is it best to keep plugged in or best to remove the batteries and keep warm?

I would bet the better charges do as they claim,but then everyone else jumps on that band wagon and makes the same claim in falsehood,and you get to pay the bill.

my experience and thoughts are this,a battery that does not see frequent use can not be kept warm by a charger,why??even when cold they will still read ample voltage and not trigger the charger to charge it up,it,and,(the charger) can not tell if the battery is cold or not unless it has a thermal sensor as part of it and most dont as the cost is too high and something else to maintain,( the temp probe).

the best advice I can give anyone who has battery that does not see frequent use in the winter time is to remove it,put in the basement or other warm room in a shop for example to keep it from freezing temps.
dont worry about setting it on concrete with todays batteries,they WILL NOT drain from setting on the concrete,I would put in a plastic box or tote to protect the floor though.
for those who still believe,rest your minds and set it on piece of wood if it makes you feel better

it once was true that they would,how?? a hundred years ago batteries were made with wooden cases,the electrolyte would seep through the wood case and gather under it on the ‘crete creating a puddle,this would in fact set up a small drain on the battery as it completed a circuit under the battery.

I apologize for a longer answer than you asked for,just my way of thinking out loud.

Batteries work by a chemical reaction. Chemical reactions are less efficient at cold temperatures and more efficient at warm temperatures. For winter storage, top off the water, charge the batteries and then disconnect all leads from the batteries and they will be fine.

makes sense, I have left the batteries in the cold throughout winter with the charger plugged in for 3 years. I wonder if that ever hurt them if they were frozen and the charger kicked on? a couple years ago it was way below zero for a spell.

I’m going to take them out this winter….pain in the arse cause they are 75 pounds each and I have to turn them a couple times to get them out of the compartment.

maybe I should just insulate my garage and keep it heated LOL

unless I am misunderstanding,you only got three years out of agms??
it is not unusual for those things to go six to eight years or more.
you got your goody out of your charger if you left it on for three years,not being a smart arse here,but that is a lot of time!!

like they say about the meaning of the word boat: Bust Out Another Thousand!!

yep 3 years and toast. thats what I figured…batteries were probably good…charger failed.

What would you suggest as far as charging. Should the batteries be charged everytime I use the boat or should I skip charging it sometimes and not leave it plugged in all the time? can you elaborate on the timer suggestion?

I would almost have that charger mounted and hung on the wall in the ‘ole cave if it held out for three years being plugged in that long!!
most things made for the general public these days have a design life of only a couple of hundred hours if that.

yes,charge the batteries when done for the day so its ready for the next use.

as far as the timer,go get a on/off programmable timer,good ones are not cheap,about fifty bucks.
if you have never used one,you can set it up so it charges for several hours or up to twenty four hours on one day,then only an hour or two on any given chosen day there after for a week at a time then it starts over.

google leviton or honeywell timers,hope that helps!!

in the summer I fish enough times that I could probably have the charger shut off after 24 hours and I’d be fine till the next trip, and then in the winter I could just have it turn on once a week to maintain. Do you think that would be OK?

that will work,just keep track of when it was charged last

I have a Minn Kota 3 bank in my boat and it stays plugged in 24/7/365. 1st charger had a bank fail after about 7 years so I replaced it with a new one. Works great for me!!!

Don’t take the batteries out and not charge them over the winter. That will definitely shorten their lifespan. Keeping a maintenance charge on them all winter will lengthen their life span considerably.

another update…I called pro mariner and left a message on saturday that I wanted to cancel the order(hopefully it hadn’t shipped) I then drove to the nearest minn kota dealer that had one in stock and picked up an MK 330 PC.

so far so good, easy to hook up and set for battery type.

DT, I will maintain the batteries no matter what but don’t you think it would be better to take inside vs leaving in cold?

I was thinking if I took them inside and charged once a month it would be better than keeping them outside and keeping the charger on full time? seems it would be easier on both batteries and the charger. what do you think?

If you keep them outside on the charger they will stay somewhat warmer. Inside would be better if you could them charged.

I love my MK charger. Never have to even think about it.

I have a Dual Pro Sportsman that has been plugged in over 6 years 24/7 here’s the manual that explains these chargers I have had great luck with mine I’ve used them since 2001 in this boat!

http://www.dualpro.com/wp-content/uploads/2014/10/New-Professional-and-Sportsman-Series-Manufacture-Date-After-3-9-09.pdf

Stan

good info stan, I would have bought a dual pro but couldn’t find one close by and I wanted to get the charger on the batts right away cause I had used the boat and was going to use it yesterday eve too. One thing I saw on the MK too somethig about “equalizing”, but I think it was only on lead acid cells, have to look into it on agm’s do you do that on yours throughout the winter?

I leave it plugged in in the cold garage all winter I check water level now and occasionally unplug and replug the charger which puts it into equalize mode I use Maxx lead acid batteries
Stan

The MinnKota chargers are the only ones I’ve good luck with.

Also, I spoke with an Interstate rep last summer who told me that the 5-6 years of life I have been getting is about as good as one can expect from a marine battery that’s well maintained, like what’s being described in this thread. A poorly-maintained battery will die after a year or two. For what it’s worth.