Brushless TM & Lithium ion batteries

[clc48301]

Hello everyone, there is alot of backgroung, and the question all the way at the bottom if you want to skip the wall of text.

       I've been wanting a new boat for awhile now, but I'm a little bit hesitant about taking on the boat payment for 12 years at some inflated interest rate they give for boat loans.  So I'm comparing the pros and cons if just updating my boat to make it a little more capable.

   Currently i have a 1984 slyvan supper snapper, 16.5' deep V side console with a 25hp mariner.  I have a gen1 terrova MK 12V 55lb thust without the i pilot link, which is now discontinued for legacy models.  The trolling motor struggles in high wind.  I have 2 group 31 deep cycles in parallel that powers the whole boat, so house batteries, starting and trolling motor off the 200 Ah.

    I would like to make the jump to a stronger trolling motor which requires completely redoing the battery setup.  But I also have weight constraints, so adding additional batteries to achieve 36v is difficult because the boat is already near full weight capacity with the casting decks I added and all the gear and passengers.

I've seen warnings from MK that the Li batteries have a higher voltage that doesn't work well with their brushed motors.  So i will likely have to go brushless.  The brushless motors are more efficient and have lower current draw, and the lithium batteries maintain a higher voltage longer these benefits should work together, I think i can use less battery capacity.  In my head i should be able to double the power of my TM from 55lbs to 120lbs by using the lowrance ghost.  And i should be a little lighter with lithium using to batteries 36v 100ah for trolling and a 12v 100Ah lithium ion for house and cranking.

          Does anyone run their ghost off a 36v lithium battery?  How does it hold up to a long day if fishing?

 

[Tennessee Boy]

Don't confuse Lithium Ion (Li) batteries with LiFePO4 Lithium batteries that are normally used on boats these days.  Minn Kota warns against using Li batteries not LiFePO4.

 

https://www.minnkotamotors.com/support/faqs/can-i-use-lithium-ion-batteries-my-minn-kota-trolling-motor

[clc48301]

Thanks fore the clarification.  Yes im looking at the LiFePO batteries, 36v 100ah to power the ghost TM.

[MN Fisher]

1 minute ago, clc48301 said:

Thanks fore the clarification.  Yes im looking at the LiFePO batteries, 36v 100ah to power the ghost TM.

A single 36v/100ah battery is no different than 3-12v/100ah batteries hooked in series far as power is concerned.

 

What you do save is the weight.

[Deephaven]

51 minutes ago, MN Fisher said:

A single 36v/100ah battery is no different than 3-12v/100ah batteries hooked in series far as power is concerned.

 

What you do save is the weight.

Except you shouldn't drain a non-Lipo as far down requiring nearly 2x the capacity if you want to get any life out of them.  I would prefer to see the ratings based on charge cycles and usage.  That would make it easier to compare.

[MN Fisher]

19 minutes ago, Deephaven said:

Except you shouldn't drain a non-Lipo as far down requiring nearly 2x the capacity if you want to get any life out of them.  I would prefer to see the ratings based on charge cycles and usage.  That would make it easier to compare.

I was assuming that the 12v were also LiFePo's.

[Tennessee Boy]

The bottom line.  Going from 55 lbs thrust with two 12v batteries to a 120 lbs thrust trolling motor with a 100 ah 36V battery on a 16.5 foot boat will give you a huge boost in performance.  I don't know how heavy your boat is but if you're using a 25hp outboard it can't be very heavy.  I would expect a 36V 100ah LiFePO battery to give you more power than you will ever need for fishing.

[Deephaven]

1 hour ago, MN Fisher said:

I was assuming that the 12v were also LiFePo's.

That would make sense   I assumed the opposite by comparing to his current setup but that is 24v so not comparable anyways.

 

36v 100ah will be enough for using it all day.  Unless you are using it for lots of full speed long runs....but even then it may be fine.  

[clc48301]

Does anyone know when Minn kota is coming out with a brushless TM?  Seems like they are falling behind the competition with new technologies.

[evo2s197]

1 hour ago, clc48301 said:

Does anyone know when Minn kota is coming out with a brushless TM?  Seems like they are falling behind the competition with new technologies.

Minnkota will have a brushless trolling motor out soon enough and the recent offerings will be the ones catching up, then you have the upcoming power pole trolling motor but I'll probably be long dead before thats released and I'm only 38 ?

[Junger]

6 hours ago, evo2s197 said:

Minnkota will have a brushless trolling motor out soon enough and the recent offerings will be the ones catching up, then you have the upcoming power pole trolling motor but I'll probably be long dead before thats released and I'm only 38 ?

 

I'm waiting for the TM with electric rods to shock up fish on those really slow days.

[WRB]

No reason having a 36V /120 lb thrust trolling motor on a 16’-17’ aluminum boat with 25 HP outboad.

Simply use 2  gr 31 12V AGM’s In series  with standard charger to power the spot lock TM.

Use a smaller gr 24 12V to crank your outboard and run your electronics. TM battery shouldn’t be used to power your sonar units.

You're putting more money you don’t have into a boat not worth the effort imo.

Tom

[Alex from GA]

First an 80 lb 24v trolling motor is plenty for any 16' boat.  Second 2 50ah lithium batteries will power your trolling motor easily all day.  Third a group 24 lead acid or 30 ah lithium battery will power your engine and electronics.  Forth a 36v or 24v charger, that you'll have to have is expensive.  Get 12v batteries.  Your boat must have high sides to require a bigger trolling motor than a 55 lb.  My 16' has a 46 lb and I can't imagine needing anything higher.