Trolling motor battery died - replacement recommendations?

[Woody B]

Go lithium.  The price sting will be gone after a while.  I was getting 4 hours out of my 88 amp hour Interstate.  (that came in my boat new).  I can fish all day with my 125 amp hour lithium and still be at 70%.   Lead acid batteries (conventional or AGM) lose voltage as they discharge.  The lower voltage slows the trolling motor, and causes amp draw to go up....discharging them even faster.  There's very little voltage drop with lithium.   You only "really" get 50% with lead acid batteries.   You get it all with lithium.   

[padlin]

Not exactly. My understanding is an SLA (lead acid) deep cycle battery can be recharged about 500 times if discharged down to 20%, meaning you used 80% of the total capacity. You get about 1000 recharges if you only take them down to 50%, so twice the life. This is why it is recommended to not go below 50%. This is the damage you hear folks mention when you go beyond 50%.

 

It makes no difference to lithium battery life if you draw it down to 50% and 20%. Life time of a Dakota Lithium is said to be 2000 recharges, Battleborn says 3000-5000 for theirs.

 

Voltage level of an SLA slowly drops till it gets where the TM will not function. A lithium stays at top voltage till it hits about 20%, then it drops like a rock. So you have full power till that point.

[gim]

2 hours ago, Woody B said:

Go lithium.  The price sting will be gone after a while.

The weight is the biggest advantage I see thus far. The price for the life of one isn’t there for me yet in terms of value. I can get a standard lead acid battery for about 100 bucks or less and make it last 5 years, or more. I literally just replaced my original cranking battery from 2015 that came with my boat a month ago.

 

If I’m going to pay 400 bucks for a lithium battery, I would expect to get four times the lifespan. Not the case, yet.

[BayouSlide]

According to Minn Kota (https://www.minnkotamotors.com/support/trolling-motor-installation-guides/trolling-motor-wiring-and-battery-guide):

 

What type of battery do I need to run my Minn Kota Trolling Motor?

A Minn Kota trolling motor will operate with any lead acid, deep cycle marine 12-volt battery/batteries. For best results, use a deep cycle, marine battery with at least a 110-ampere hour rating.  

 

RUN-TIME   VOLTAGE   GROUP SIZE   AMP-HOUR

Good                12                  24                  70-85

Better              12                   27                  85-110

Best                 12                   31                  95-125   

 

For a 24-volt motor, you will always get maximum performance from two identical batteries of the same age.

[IneedAnewScreenName-98161861]

Well we ended up picking up 2 31 group deep cycle AGM batteries and man what a difference. 

 

Unfortunately we don't have anything that can tell me exactly how much battery we used per trip but I've ran it 3 times now. When we got back it seems like we've only used 20-30% of life, and it also charges so quick. Super happy with them, but I will say they are pretty large and quite heavy. We just couldn't take the plunge to lithium yet. Maybe on our next boat!

 

Anyways thanks for everyone's help, I'm so happy with the AGM's I have 100% confidence I could be out all day and not take it down below 50%

 

Oh hey does anyone know some type of product I could buy that tells me exactly how much battery I've used?

[Tennessee Boy]

7 hours ago, IneedAnewScreenName-98161861 said:

Oh hey does anyone know some type of product I could buy that tells me exactly how much battery I've used?

When I added a lithium battery earlier this year I bought a charger that has a Bluetooth interface that tells me how many amp hour of charge it took to charge the battery.  It also tells me the battery voltage at the beginning and end of the charge.  You could also buy a shunt that will tell you how many amp hours you have used.  Here’s one from a good company.  There are also cheaper ones on the market.

 

https://www.amazon.com/Victron-SmartShunt-500AMP-Bluetooth-Battery/dp/B0856PHNLX/

[GaryH]

The beauty of Ionic lithium batteries