Trolling Motor Battery Issues

[Meadows]

I've got a 24v Minn Kota Fortrex 80# thrust and have been running Interstate 27 Batteries.

In the past 3 years I believe I've gone through 3 different batteries, the most recent was purchased in May of this year and it just went bad this past weekend.

The charger is a Minn Kota 315, 5amp per bank. I put a meter on my charger and it's giving 5 amps to each battery, so no problem there. And the batteries are full on water.

The past couple times I've taken the batteries back under warranty and they have replaced them due to bad cells.

I went fishing this past Saturday, TM was practically dead at 10:30, charged the batteries once I got back home and it took almost 2 days to charge one of the trolling motor batteries and even though it said it was fully charged, my meter only read 11.xx volts. (That's the one that's currently dead)

I highly doubt that I'm just getting a bad battery every year, so my question is... I have my TM batteries connected in Series. Would this be causing the issue? Should I have them connected in Parallel instead?

[billnorman1]

No, series is the only way to get 24 volts. Your problem could be that you are only buying one battery at a time instead of two evenly matched batteries at the same time. Your charger is also rather low on charging power at 5 amps rating, when new. A 10 amp or better charger boils off sulfation much better.
When you have mismatched batteries, the weakest battery will fail more quickly and the newer battery will force reverse current through its cells which is very damaging to them.
I think you will be better served with TWO new 29 or 31 series batteries that match, and a better charger. Walmart sells a 29 series marine battery for $99.97.
Sams Club has new Dekas badged as Duracells at a good price too.

[moetorola]

As Bill Said...Batteries in series for 24 volts.


What concerns me and stands out, is when you said "even though it said it was fully charged, my meter only read 11.xx volts."

That is not good!

First off as Bill mentioned, I would upgrade to a batteries with Reserve Capacity (RC) rating of 180 or 210 the higher the better.

It is very hard on a battery to drain them beyond 50% continuously, depends on your use if that is happening.

Do you charge your batteries immediately at the end of the day?

I do believe you may have a bad charger though.

I would not worry much with the current (Amp's)... The main concern is the charger completely and fully charging the batteries. During the bulk and absorbtion modes charge just before it enters float mode you should see a voltage of up to 14~14.5volts (varies with manufacturer). After a battery is fully charged the charger should maintain the battery at a float voltage of between 13.4~13.8 volts (again varies with manufacturer) some just go to sleep and then turn back on when voltage drops to a certain voltage typically 12.6volts or higher.

IMO it is your charger. It should NOT have showed a fully charged battery showing 11volts.

[moetorola]

I found the manual for your charger I believe.

Download and Read the PDF file.

https://www.minnkotamotors.com/Products/MK-315D/

[Meadows]

I originally thought it was my charger as well. But after sticking a meter on it and seeing that it's providing 5 true amps at each bank, I figured I might have my batteries connected wrong.

Norman I thought about what you said as well. And it does seem that it's always the newer battery that goes dead first, which would prove your point. I don't mind buying a new charger, or new batteries. I just don't want to buy one just to see that it was the other thing that was the problem.

[moetorola]

A side note:

And I know you did not ask for my opinion,,,,but I will share it anyway..LOL

I absolutely HATE the minnkota chargers!

I have owned two different models one was a Linear version the other a digital version.

Both had issues, one would under charge one of my battery (seems as though possible what your is doing) the other over charged one of my batteries to the point of boiling the battery dry at nearly 17volts. Luckily I caught it in time, the smell was horrible.

I was strapped for cash at the time so I picked up a promariner gen3 sport 20amp 3bank, best choice I ever made... been very happy the 2 or so years with it. It was about $160 to 180 I believe and has a nice feature called distributed on demand feature which charges my Trolling batteries faster. I leave all my chargers plugged in 24/7.

I almost went with NOCO, but after my buddy had to replace his twice under warranty loosing banks, I went a different direction.

I am not sponsored by them,,just giving my honest opinion,,,but you know what they say,,,everyone's got one!

[moetorola]

I originally thought it was my charger as well. But after sticking a meter on it and seeing that it's providing 5 true amps at each bank.

Forget amps... measure the voltage before, during and after charging. On all batteries and write it down on paper for each battery.

If you suspect a bank is giving you issues, try swapping the banks and see if the issue moves.

[billnorman1]

I originally thought it was my charger as well. But after sticking a meter on it and seeing that it's providing 5 true amps at each bank, I figured I might have my batteries connected wrong.,,,,,,,,,,,,,,,,,,,,.

Don't take this too personal, but if you don't understand the difference between series and parallel are you sure you know how to measure amperes? Some people on this site say the newer battery works harder and will fail sooner than an old one but in theory and with past experience I disagree. The older battery will drop below a safe level and fail first unless it has a larger capacity than the newer one. You need matched batteries. You also have two circuits and both must deliver adequate current.
2 matched batteries, reliable charging.

[Nova Kaw 650]

Don't take this too personal, but if you don't understand the difference between series and parallel are you sure you know how to measure amperes?

I was wondering the same thing.
Plus the fact that the charger is showing "fully charged" on a battery that meter's out 11v afterward makes me suspect the charger as well.

[Meadows]

Because I ask if my batteries should be connected in series or parallel somehow makes you question my ability to read a multimeter??

I do understand that batteries connected in series gives you more voltage and less amperage, and the opposite is true with parallel. I just thought I would get some opinions since I've been having some issues lately, and was questioning myself. Obviously, I don't claim to know it all. I guess some people do.

Thanks for the responses. I'm probably going to get a new Dual Pro charger as I've had those on previous boats and never had a problem. If that does not fix the issue then I will go ahead with 2 new TM batteries, probably the X2 AGM 27 from Batteries Plus.

[Jonestrollingmotor]

don't take this as a "slap", but may I ask what you were measuring the amps with. I ask because most VOMs will not read DC amps past a certain point due to overloading the meter. There are hand held DC amp meters to be purchased that use a clamp to go around the positive lead, but most of your everyday workbench doesn't have them for various reasons. Also, when a battery charger says 5A output, that is while it is in the bulk stage mode (initial charge mode), then once it heats the batteries (reason for a temp sensor) it backs off the charger, gradually getting down to a shut off and monitoring or a slow trickle. Interstate batteries are known to be a "thirsty" battery, meaning it seems they go through water quicker than other lead/acids. Are you monitoring the electrolyte level in the battery at regulator intervals, adding water when necessary.
I don't think you have a charger problem, although it is a possibility. I think you're problem is in the batteries, possibility battery maintenance, possibility to small a battery for what you're asking it to do and continuously over discharging to shorten the battery life.
John

[Ann-Marie]

A big battery killer is discharging batteries too deeply, especially if the batteries are not matched so one dies first and the other forces current through it.
Consider using a Trollbridge24.
Batteries are kept in parallel until you use the trolling motor so even if not matched they get equalized frequently.
They are both charged by the alternator on your main motor so they don't get discharged so deeply and/or you get longer running time.
A single output shore power charger can charge all 3 batteries.
Many find it makes them independent of shore power depending on alternator output capacity and length of run to the dock/trailer.

[Meadows]

don't take this as a "slap", but may I ask what you were measuring the amps with. I ask because most VOMs will not read DC amps past a certain point due to overloading the meter. There are hand held DC amp meters to be purchased that use a clamp to go around the positive lead, but most of your everyday workbench doesn't have them for various reasons. Also, when a battery charger says 5A output, that is while it is in the bulk stage mode (initial charge mode), then once it heats the batteries (reason for a temp sensor) it backs off the charger, gradually getting down to a shut off and monitoring or a slow trickle. Interstate batteries are known to be a "thirsty" battery, meaning it seems they go through water quicker than other lead/acids. Are you monitoring the electrolyte level in the battery at regulator intervals, adding water when necessary.
I don't think you have a charger problem, although it is a possibility. I think you're problem is in the batteries, possibility battery maintenance, possibility to small a battery for what you're asking it to do and continuously over discharging to shorten the battery life.
John

Thanks John. Here's the meter I used... https://www.boschdiagnostics.com/diy...nal-multimeter

I checked the water level in the battery that was reading 11 volts and it seemed to be fine. However I did not check the levels of the other battery, I'll do that when I get home. I truly believe it's a charger problem, as I've also had issues with my cranking battery. I may go that route first, and get new batteries together afterwards, if needed.

[Jonestrollingmotor]

I looked at the meter and it will do up to 10A, so you should be OK with it. However, the instructions on measuring the amps was unclear as I was comparing to measuring in a series circuit. Normally, you would disconnect the positive wire from the battery, connect one charger lead to the VOM lead, the other VOM lead to positive post on battery to check it in the series. The charger has to "see" the battery before it will turn itself on.
A better test would be to check the voltage of all the batteries before plugging the charger in. Plug the charger in and give it about half an hour, then check voltage readings again. You should see apx 2V increase up to the charger set point (around 14.5V) on all the batteries. If you don't, then switch charger leads on batteries and repeat the test. If the same battery flunks, then battery is not able to take charge. The the leads flunk (a different battery not charging) the charger is not delivering the charge.
John

[Meadows]

I looked at the meter and it will do up to 10A, so you should be OK with it. However, the instructions on measuring the amps was unclear as I was comparing to measuring in a series circuit. Normally, you would disconnect the positive wire from the battery, connect one charger lead to the VOM lead, the other VOM lead to positive post on battery to check it in the series. The charger has to "see" the battery before it will turn itself on.
A better test would be to check the voltage of all the batteries before plugging the charger in. Plug the charger in and give it about half an hour, then check voltage readings again. You should see apx 2V increase up to the charger set point (around 14.5V) on all the batteries. If you don't, then switch charger leads on batteries and repeat the test. If the same battery flunks, then battery is not able to take charge. The the leads flunk (a different battery not charging) the charger is not delivering the charge.
John

I like this plan. I'll try it out this evening.

[billnorman1]

Because I ask if my batteries should be connected in series or parallel somehow makes you question my ability to read a multimeter??

I do understand that batteries connected in series gives you more voltage and less amperage, and the opposite is true with parallel. I just thought I would get some opinions since I've been having some issues lately, and was questioning myself. Obviously, I don't claim to know it all. I guess some people do.
..................

Sorry, I didn't know that you had a 12/24 volt motor.