TM battery charging question

I’ve got a brand new 12V group 31 marine deep cycle battery, rated for 1050 amp hours. This will be powering an older but pristine condition Minn Kota Powerdrive 50 bow-mount.

The user manual of my Minn Kota Powerdrive 50 says that not recharging my battery within 12-24 hours of use can cause premature battery failure. Can anyone speak to this from personal experience?

I’m going to be camping on an island for 3 days. I don’t have an on-board charging system or an inverter to use with my outboard, and I’m not lugging a generator along. It won’t bother me if the TM battery only lasts 1 day of fishing, I’m perfectly happy fishing at anchor or drifting. But my concern is damaging the battery. If we drain it on day 1 and it sits for 72 hours before I can plug it in, am I asking for trouble? I would potentially just leave the TM at home.

I would use then recharge as soon as you get back do not wait 3 weeks to recharge do it the day you get back. It is best to recharge battery after each use even it is for a short time. I get 5 to 6 years from lead acid batteries check water level frequently and keep on a charger / tender when not in use.

Mwal

mwal wrote:

I would use then recharge as soon as you get back do not wait 3 weeks to recharge do it the day you get back. It is best to recharge battery after each use even it is for a short time. I get 5 to 6 years from lead acid batteries check water level frequently and keep on a charger / tender when not in use.

Mwal

Thank you. I understand all these concepts and will always charge as soon as I get home. But in this situation, you’re saying waiting 3 days isn’t likely to harm my new battery?

I cannot answer that it is just what I would of done. I would not run it all the way down to fully discharged. I would hope to use wind to help drift along etc. you mentioned inverter. DOes the main motor have electric start? Perhaps could hook up to the alternator

Mwal

Go and enjoy your trip. Plug it in when you get home. Everything we do to our batteries shortens their life a small part. Deeper discharge, leaving them at partial state of charge, storing them in hot spaces, etc. It’s all going to take a percentage point or two off the life of the battery.

If I end up replacing my battery at 5yrs instead of 5.5yrs because I took some fun trips that shortened the life of my battery, I consider that the cost of owning a boat.

fishingchallenged wrote:

Go and enjoy your trip. Plug it in when you get home.

If I end up replacing my battery at 5yrs instead of 5.5yrs because I took some fun trips that shortened the life of my battery, I consider that the cost of owning a boat.

X2, that’s 100% on the money. Remote trips are hard on batteries but they’re good for the soul.

Any chance that battery is dual purpose? Where I’m headed is that if you had some long runs then you could use it as the starting battery. That way at least a little juice will come off the alternator on the main motor.

One tip, if you can use the available wind to your advantage. will greatly extend how long that TM battery will have juice.

Thanks folks. It’s unfortunately not a dual purpose, just a deep cycle.

I just learned that a friend’s parents have a cabin where I’ll be (Kabetogama). If things work out I may be able to charge up the battery there. Otherwise, I’ll just plug it in as soon as I’m home.

before installing a minnkota mk2-dc charger in my boat to recharge the tm batteries.
we used to run jumper cables to recharge our tm batteries.
we would hook up the neg wires. and one positive connection.
start the motor and connect the second pos connector.
ride around for a while to charge the tm battery.
disconnect the pos wire.
and run another 5 minutes or so to ensure the starting battery was still charged up.

eyekatcher wrote:

before installing a minnkota mk2-dc charger in my boat to recharge the tm batteries.
we used to run jumper cables to recharge our tm batteries.
we would hook up the neg wires. and one positive connection.
start the motor and connect the second pos connector.
ride around for a while to charge the tm battery.
disconnect the pos wire.
and run another 5 minutes or so to ensure the starting battery was still charged up.

Interesting idea but in this scenario, back country with my kid, I’m not going to do anything to put any more stress on my main outboard.
I don’t think my old 50hp merc would really put much out anyway?

A follow up here.

My battery is a group 31 Duracell ultra marine & rv deep cycle. It’s not a maintenrnace free AGM battery, it has several screw caps on top to check fluid. The model # is SLI31MDC.

My charger is a diehard dh-10ma. It can do 10a and 2a. I need to select between two automatic modes — one is for “maintenance free and deep cycle” and the other is “conventional and low maintenance.”

I’m stuck because my battery is deep cycle, but not maintenenance free. My instinct says the deep cycle mode is only for maintenance free AGM type batteries and that I should use the conventional/low maintenance mode. Thoughts?

Deep cycle is a deep cycle. It recharges better with a slightly different charging profile than a starting battery one.

gizmoguy wrote:

Deep cycle is a deep cycle. It recharges better with a slightly different charging profile than a starting battery one.

So it doesn’t matter that it’s a flooded cell deep cycle? I’m inclined to trust you after reading another post detailing the SERIOUS electronics setup in your boat.

It shouldn’t. Deep cycle batteries are designed differently than a starting type battery weather flooded lead acid or AGM type.

gizmoguy wrote:

It shouldn’t. Deep cycle batteries are designed differently than a starting type battery weather flooded lead acid or AGM type.

Thank you sir! Just trying not to EFF up a brand new battery before I even use it.

Looking forward to a trip report. Go getem.

pool2fool wrote:

Interesting idea but in this scenario, back country with my kid, I’m not going to do anything to put any more stress on my main outboard.
I don’t think my old 50hp merc would really put much out anyway?

It wouldn’t stress your outboard, but it wouldn’t make that much of a difference anyway. Older outboards aren’t like cars, they put out only a trickle of current to top off the starter battery. You’d have to run many hours to really recharge a deep cycle to any significant degree.

You won’t hurt hour new battery that much. Lack of use is what’s hard on batteries, not letting them go for a few days without charging.

Grouse

Thanks guys. Charging up now. Want to get out on the river this week to test the TM before I leave for Kab.

can’t imagine three days would have a major effect, but like mentioned by another poster I wouldn’t drain them all the way down.

check the alternator output for your motor.
some older motors actually output more amps than newer models.
this is where some of the cost cutting has occurred in newer motors.
E.G. my 2011 90 hp mercury outputs 55 amps
whereas the newer motors only have a 35 amp output.

I made a lot of long weekend type trips where I didn’t have a chance to recharge the batteries. Two or three days of fishing, and then back on the charger when I got home. In general I think lead-acid batteries don’t like sitting around discharged, but any real damage is going to happen over weeks, not a couple of days. I usually get 5-7 years out of a trolling motor battery.

Have fun and report back!

SR