Trolling motor batteries

[gb1234]

Maybe my old 80# Terrova needs service but I definitely gave it a work-out yesterday. I only have a 16' aluminum boat, but it was 2.5mph into the white caps, pulling 6 lines. I did have the Yamaha providing a little forward motion, but the Minn Kota had to go to full power most of that 6 hours just to maintain the direction.
On calmer days, it will only require about half power and will last 16 hours plus. And since mine is a 24v system, my two 100 ah batteries in series only give me 100 ah, compared to your 140. Are you trolling with your Minn Kota? How big is your boat?

[airshot]

Maybe my old 80# Terrova needs service but I definitely gave it a work-out yesterday. I only have a 16' aluminum boat, but it was 2.5mph into the white caps, pulling 6 lines. I did have the Yamaha providing a little forward motion, but the Minn Kota had to go to full power most of that 6 hours just to maintain the direction.
On calmer days, it will only require about half power and will last 16 hours plus. And since mine is a 24v system, my two 100 ah batteries in series only give me 100 ah, compared to your 140. Are you trolling with your Minn Kota? How big is your boat?

I also have a 16' aluminum but probably not as big as yours. I mostly use the spot lock, but early in the season use it to troll for walleye. I also have a little kicker, a 2.2 hp Merc just for forward thrust when it gets windy. This year, the little kicker was not needed, the MK averaged around 4-6 on the speed control ( 1-10) and was part of the 20 hrs time on my battery. Your 24v uses half the amps my 12v volt motor uses. These Lipo batteries are quite impressive at least in my eyes.

[gb1234]

Update: My replacement Li Time LiFePO4 got its second test last Saturday. I was only perching, so just needed the Terrova for spot lock. However, it was very windy so that required the Minn Kota speed/power to run between 6 and 10. This time, I got about 5 minutes out of spot lock and the Minn Kota shut off. I restarted it and it ran another 5 minutes and died. It did this a few times and then wouldn't turn back on at all. The batteries were fully charged of course.
My theory is that the Minn Kota pulls too high a current when it kicks up to 10 and the Li Time BMS shuts it down. That could be a Minn Kota maintenance problem or it could be that the BMS just won't work with this kind of load.
So I bought two Millertech 100 Ah LiFePO4s. (Thanks for the recommendations). Today was their maiden voyage. It wasn't quite as windy today as Saturday, but pretty close. I did see the Minn Kota spike to 9 a couple times. It never cut out for the 6 hours we were on the water.
Both Millertech and my model of Li Time say they allow a 100 amp discharge, but the Millertech says it will allow 300 amp for 5 seconds. Li Time recently introduced a model with a similar feature. Maybe that's the key for trolling motors - they need that short-term burst.
I must say I love having the blue tooth app which shows me exactly the percent of charge remaining. As a bonus, it also shows me the battery's temperature, which is nice to know because it was a nippy 42 degrees this morning when we started.
We'll see if it keeps working, but my initial impression is good.

[airshot]

Remember that the Lipo4 batteries give 13.3 volts rather than 12.6 from a lead acid battery. Many trolling motors can't handle the 13.3 volts at wot and will shut off. MK actually recommends not running the trolling motors at wot as they will overheat and can shut off or be damaged. MK recommends a max of 8 out of 10 on speed when using these LifPo4 batteries.

[Ltrain]

Remember that the Lipo4 batteries give 13.3 volts rather than 12.6 from a lead acid battery. Many trolling motors can't handle the 13.3 volts at wot and will shut off. MK actually recommends not running the trolling motors at wot as they will overheat and can shut off or be damaged. MK recommends a max of 8 out of 10 on speed when using these LifPo4 batteries.

That's exactly what's happening. MK specifically says not to run their older trolling motors with brushed motors at max speed with lithium batteries. The new Quest brushless motors are 100% lithium compatible.

[gb1234]

That stinks because sometimes 8 isn't enough.
How does the MK know when to try again? Last time out with the Li Times, I reconnected after a couple hours but the MK still wouldn't turn on. But it came on right away with the MillerTechs. That made me think it was the Li Time BMS preventing operation and not the Minn Kota.

[airshot]

In my experiments, I found that using the 8 setting with a Lipo battery is the same speed as a 10 setting with Lead Acid batteries ! That extra 13.3 bolts from the LifePo4 is actually making the trolling motor overpowered and overheating from to much volts. I have jumped my 12v MK up to the 10 max speed on a few occasions but didn't leave it there very long. So far no issues, but the 8 setting gave me the same speed as a 10 setting with LA batteries so your not losing any speed !

[gb1234]

The thing I'm struggling with is that I have just a little 16' aluminum boat. It's not even a deep V. It's about as light as you can get, and not tall enough to catch much wind. I have an 80# thrust Minn Kota. Shouldn't that be more than enough power for my little boat?
It's not like I'm going out in gale force winds.
And yet spot-lock - even on the lee side of an island - is still taking it to 10 with LiFePO4s. And auto-pilot also takes it to 10 when trolling. Maybe my Minn Kota is bad?

[pfk]

The thing I'm struggling with is that I have just a little 16' aluminum boat. It's not even a deep V. It's about as light as you can get, and not tall enough to catch much wind. I have an 80# thrust Minn Kota. Shouldn't that be more than enough power for my little boat?
It's not like I'm going out in gale force winds.
And yet spot-lock - even on the lee side of an island - is still taking it to 10 with LiFePO4s. And auto-pilot also takes it to 10 when trolling. Maybe my Minn Kota is bad?

if your auto pilot takes you to speed 10 without you setting it on 10, there's a problem with your motor. get it to a certified service center and get it fixed right.