Lithium Iron Phosphate (LiFePo)- Boat Batteries

[CNC Molds N Stuff]

Lithium Iron Phosphate (LiFePo)- Boat Batteries
By
Bob La Londe
July 20, 2024

Originally posted on YumaBassMan.com
https://www.yumabassman.com/2024/07/20/lithium-iron-phosphate-lifepo-boat-batteries/

I've been following along on the lithium news for a while.  As you may be aware Lithium Ion batteries can have some serious issues including a likelihood of catching fire (and being very hard to put out) if abused.  Lithium Iron Phosphate (LiFePo) batteries are supposed to be better in many regards, and more safe to use.  The thing is they are expensive.  For me the cost benefit never added up.

I looked for a while at Dakota Lithium because they seemed to be heavily marketing towards the marine industry.  They are still expensive, and I think they are trading on the name they have built by spending a lot of money on advertising.  I have no idea of their failure rate, but there are a high number of people who report on-line that they have issues getting warranty coverage when they do have a failure.  I don't have much time to fish, and I sure don't have time to jerk around with a company if I have a failure and then have issues with warranty coverage.  I want to put my boat in the water and go when I have time to go.

Until now I've stuck with lead acid deep cycle marine batteries.  I don't even buy AGM batteries.  Sure I get about twice the life out of AGM batteries, but at twice the price.  The only cost benefit savings might be not having to go to the store or order batteries quite as often.

Trust me this is related.  As you might be aware if you follow me I recently purchased yet another boat.  I bought Triton176's Triton 176.  It's a 17ft 6in Triton aluminum bass boat.  I've had the honor of being invited to fish out of it in the past, and when he stopped fishing so much, I even thought about calling him to ask if he wanted to sell it.  When he decided he wanted to sell it he called me.  I've helped him out with it a few times in the past, repairing seats, installing a trolling motor, etc.  I know what is and isn't good about it.  It's a good boat, although it could use new seats and definitely needs new carpet or other floor covering.  The old carpet is almost totally gone.

When I bought the big 20'10" Procraft 210 from yumabasser I just threw new lead acid batteries in for the trolling motor.  The cranking battery is still taking a charge, but I probably should replace it soon.

Since buying the Triton it sat in front of my shop.  I've been busy taking care of customers in my mold making business, taking care of my mom, and managing my dad's estate.  I've just been too busy to do much with it except rip out another piece of rotten carpet as I walk by.  I'm starting to get back on schedule in the shop.  I only have one job left that's behind schedule and I plan to complete it today.  Anyway, I've been taking a little time to catch up other stuff besides customer jobs finally.  Cleaning and organizing in the shop.  Looking at my boats.  I even spent 5 minutes on the canal bank the other day not catching fish and didn't feel guilty about it.  I also tested all the batteries in the Triton.  The cranking battery took a charge.  It's almost four years old, but my charger didn't have any issues bringing it up to a full charge.  The trolling motor batteries are almost totally flat.  One reads 2 volts, and one reads 4.  I do have a charger that "might" restore those.  It has a reconditioning cycle, but that's pretty darn flat.  They might restore and work, but they wouldn't last long on the water.  They are also over seven (7) years old according to the date stickers.  I decided they need to be replaced.  Probably the cranking battery does too.

There is a little bit of a twist.  As some of you know most fairly basic trolling motors can run just fine on lower voltage.  They just have less power.  I have a 36volt Tour 109 on The Tin Can, but I've only been running it on 24V for years.  Works just fine and has about the power of a Tour 82.  Triton176 had a similar setup on the Triton 176.  It's a good motor that was fairly new when I sold it to him, and it has very low hours.  I decided I wanted to see about switching it to 36 volts.  I had two options.  Run three lead acid batteries using the cranking battery as the base ground battery of the 36 volt circuit or buy a 36 volt LiFePo.  No.  There is no room to install a fourth battery, and yes, I have used the 36 volt 3 batteries only configuration before.  My old BassCat Cougar FTD was setup that way the whole time I owned it and it worked just fine.  Yumabasser ran that way with the Champion he owned before he bought the Procraft.  Lots of people have used that configuration when they wanted a 36volt trolling motor but didn't have room for four batteries.

I actually like the group 29s Deep Cycle Maxx marine batteries from Walmart, but there was no room for a cranking battery that big in the Triton.  There is plenty of room to change out the battery trays on the other side for the trolling motor, but I would need all three batteries to be the same (at least I have always done it that way.)  I really didn't want to downsize to 27s, although two 27s are what Rick ran for the trolling motor before.  Three 27s might have been fine for me since I don't tend to fish all day or fish 8+ hour tournaments much anymore.

I called yumabasser and in his ever-optimistic way of cheerfully telling other people to spend more money he said get a lithium (for me that means only LiFePo).  I wasn't crazy about that, so I thought about if for a while.

I have been following lithium battery technology for a while.  One channel I follow on YouTube specializes in home backup power.  The host buys batteries from various manufacturers, tests their specs against the advertised specs, and then rips the battery apart to inspect the assembly quality.  They are all "pretty much" made the same.  A bunch of little, tiny lithium battery cells strung together in series and parallel groups to get the desired net voltage and current capability.  There are strips welded to cells, battery management system (not a charger but among other things it manages charging to the cells), wiring, various packing to keep everything in order, and the output terminals.  He looks to see how well they did the job and inspects their choice of components.  One he reviewed that he seemed genuinely surprised had a good controller, decent components, and good assembly quality was from a company called Li Time.  Its significantly cheaper than Dakota Lithium and advertises a five (5) year warranty.  I agonized over it a little bit, and then finally I bought one.  If (IF) I get a solid five years out of it there is a small cost benefit to it over lead acid.  If I get the ten-year advertised life the cost benefit is huge.  It also advertises 4000 cycles at almost full power and full discharge.  For a pro fishing 4-6 days a week that's not long.  For me that's many years, and its not dead at 4000 cycles.  It just starts to have lower capacity.

I have no certainty if it was a good purchase or not.  Maybe I just threw my money out in the street, but I will let you know.  I bought a 36V 55AH battery.
Yes, I know a lot of guys with their 20 plus foot fiberglass boats say they get a 100AH battery.  The thing is I don't tend to fish all day or even 8 plus hour tournaments anymore.  5 hours is a long day for me anymore.  I'm also running it in a much lighter boat.  I won't need to run at full power much at all.  I just want to be able to pull a current rip around a hard point in the river, and then as soon as I get out of the pressure wave drop back to fishing speed.  If it works out, and I still have the big Procraft when it needs new batteries (I just bought new lead acid ones for it a couple months ago) I might buy the 100ah LiFePo for it.  In the meantime, I will be gaining experience with one on the smaller boat.  I also bought a 36volt 25 amp charger.  If I have done the math right that means it should fully charge the battery I bought from full discharge in a little over 4 hours.  In reality that probably means more like 6 hours.   It actually puts out a higher voltage than that, so it might be shorter depending on how the battery's BMS manages it. 
FYI:  Full discharge does not mean flat.  The BMS does not allow the cells to discharge to a point where they will be damaged.

From what I understand the first thing you are supposed to do is give it a full charge.  My new battery and charger should be here later today.  I'll try to keep you guys up to date and let you know how it goes.  If it turns out to be a bad call I'll tell you.

The battery and charge just arrived while I was writing this.  I carried them back to the shop, and its a lot lighter than I thought.  I know they have a higher power to weight ratio than lead acid, but I was still surprised at how much lighter it felt like to pick it up and carry it back to the shop.  I think its lighter than just one of the two group 27s I took out.