Choosing lithium Marine batteries

I’m a 71 yr old guy, generally fit. That said I find the weight of my batteries a problem. This is most evident in managing these in my battery compartment. Give the dimensions of same I have to maneuver these a bit each time I charge them. Given that these are close to aging out, I am looking into lithium batteries.
I have a Minn Kota ipilot 80 lb thrust, 24 V. Currently I have 2 100 Amp size 31 batteries.
We max out at 6-7 hours per day on the water.
Questions
I am aware that Minn Kota suggests 100 Amp batteries. Yet I see a number of references to lithium batteries at 54/60 Amp hours being essentially equal to 100 Amp hour traditional batteries. Does any know more about this issue.
Also, I have seen 24v 100 Amp hour batteries for essentially the same cost of 2 12v batteries. While the is convenient, I have had to jump start boats with my deep cycle battery and I don’t know if a 24v battery would damage my starting motor on a boat.
Any observations, references or suggestions would be great.
Regards
DuckMtnDick

Dick Forbes wrote:

I am aware that Minn Kota suggests 100 Amp batteries. Yet I see a number of references to lithium batteries at 54/60 Amp hours being essentially equal to 100 Amp hour traditional batteries. Does any know more about this issue.

You can almost fully discharge lithium batteries so a smaller one is equivalent to what you can actually use out of a 100ah lead acid battery.

I saw not long ago minnkota was recommending not to run their motors above 8 for a extended period of time if you have lithium batteries. Because of the higher voltage.

Interesting I have done a lot of online searching, but had not read that.
Thanks

Thank you for your reply. From my online exploration the ALMOST, is key for the batteries health. Sorry to use almost, I understand when using quotation marks some posts get rejected.
DuckMtnDick

I have two 100A-h Battleborn batteries to power my 80# Ulterra.

Q1 – I don’t believe a 60A-h lithium battery can have “essentially” the same capacity as a 100A-h SLA. I have seen that rumored occasionally. I don’t know why people are saying that. 100a-h = 100a-h.

When you use an SLA battery at high loads for an extended period it will generate more heat than lithium and that will result in some lost capacity. This would help explain some capacity loss but not 50%.

So my recommendation is that if you need 100A-h then get 100A-h. Any benefits you get from reduced heat loss, better discharge profile, etc. will just mean extra time on the water.

Q2 – When choosing 24V versus 12V I went with the 12V for the reasons you mentioned. You can use the battery as a backup for all the other 12V applications in your boat, PLUS it is much easier to source 12V marine chargers.

Some other things to consider…
-You cannot charge lithiums when the temp is below freezing.
-Lithiums have a PCB which monitors battery performance, temp, etc. and these are evolving. I had to send one of mine back to BB due to a faulty board. The warranty was 10 years. They sent a new one out the next day.
-I have NEVER used the full capacity of my batteries but I only have a 16′ boat and typically use the Ulterra on a thrust of 5 or less even in heavy current.

Hope this is helpful. If you have any other questions PM me.

J

JasonP wrote:

100a-h = 100a-h

Kind of pedantic but only if you are comparing the exact same discharge times because capacity diminishes as amperage increases (Peukert’s Law) and the effect is greater with lead-acid than with lithium. The voltage of a lithium is also going to be higher than a lead-acid through the whole discharge which means lower amperage draw which magnifies the first point. Lead-acid is usually advertised at a 20hr discharge which doesn’t accurately reflect trolling motor usage if you run it out faster than that. Do those things make up 40AH, I don’t know, I was just explaining why smaller lithiums are advertised as equivalents.

“…You cannot charge lithiums when the temp is below freezing.”

This is the part that concerns me about Lithium batteries in our climate. I don’t want to find out… but I don’t know if lithium batteries just won’t charge when its that cold – or you will damage them if you try ~

JasonP wrote:

I have two 100A-h Battleborn batteries to power my 80# Ulterra.

Q1 – I don’t believe a 60A-h lithium battery can have “essentially” the same capacity as a 100A-h SLA. I have seen that rumored occasionally. I don’t know why people are saying that. 100a-h = 100a-h.

When you use an SLA battery at high loads for an extended period it will generate more heat than lithium and that will result in some lost capacity. This would help explain some capacity loss but not 50%.

So my recommendation is that if you need 100A-h then get 100A-h. Any benefits you get from reduced heat loss, better discharge profile, etc. will just mean extra time on the water.

Q2 – When choosing 24V versus 12V I went with the 12V for the reasons you mentioned. You can use the battery as a backup for all the other 12V applications in your boat, PLUS it is much easier to source 12V marine chargers.

Some other things to consider…
-You cannot charge lithiums when the temp is below freezing.
-Lithiums have a PCB which monitors battery performance, temp, etc. and these are evolving. I had to send one of mine back to BB due to a faulty board. The warranty was 10 years. They sent a new one out the next day.
-I have NEVER used the full capacity of my batteries but I only have a 16′ boat and typically use the Ulterra on a thrust of 5 or less even in heavy current.

Hope this is helpful. If you have any other questions PM me.

J

Every time you run a lead acid battery below 50% it’s going to degrade the battery. If you continually use 70% or more of the 100 amps you will lose capacity. Especially if you can’t charge them right away. Lithium you can use almost the whole 100 ah

This info is from Amp Outdoors manual:

Look at the charging and discharge temps.

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Another thing to watch if you go with a smaller ah battery is the max continues amp draw. I know a guy that has some smaller 40ah lithiums in his jet and he will trip his bms when running his motor to hard and has to use a jump pack to get them to reset.

I have been looking at them a few years but have not pulled the trigger yet. My hold up is the lack of cold weather charging unless you nearly double the price for a self heating battery. The cheaper option is to find one with low temp charging protection. Which excludes most of the ones targeted at marine use.

James Almquist wrote:

This info is from Amp Outdoors manual:

Look at the charging and discharge temps.

Yeah – the inability to charge below freezing is the biggest con in my opinion. I fish the river till it freezes and have a detached garage where my boat is stored so it becomes a pain to keep my batteries charged up.

j

Prior to lithium coming around, I had never heard the arugement that lead core batteries start to deteriorate when more than 50% of the charge is expended. This supposedly from the first usage, and also why some guys use a trickle charge when using their batteries. I’m not managing the latter on my 16 footer.
Thanks again for the feedback.

I have read that because of heat generated by the battery itself, that you cand start the charge if you do it shortly after getting your boat out.
Also with the weight issues, I could now remove mine from the boat much more easily. and charge it my van. I only once did that with my lead core batteries and was really too uncomfortable with this.

I like the point around the charger availabilty.

Question: can I use a 24v lithium battery to jump a 12v regular battery?

Sylvanboat wrote:

Question: can I use a 24v lithium battery to jump a 12v regular battery?

You could always try that if you were in an emergency situation, but I wouldn’t recommend doing that otherwise. You would likely exceed the voltage specifications for the starter and any other accessories on that circuit (sonar, etc.).

If you are running a 24V TM battery and want a safe backup for your 12V starting battery I would recommend checking out the Noco Boost which can get you out of a bind and should hold a charge for an entire season.

J

FryDog62 wrote:

“…You cannot charge lithiums when the temp is below freezing.”

This is the part that concerns me about Lithium batteries in our climate. I don’t want to find out… but I don’t know if lithium batteries just won’t charge when its that cold – or you will damage them if you try ~

The battery should have a PCB which monitors the temp and switches off the charging circuit until the battery is within temp spec. This is even true of the batteries for my ION auger.

I am hoping that the weight decrease will aid in removing and charging indoors. In my case this isn’t an issue, as in the colder weather we don’t go out twice in a day. I am from Winnipeg Canada and I know fall fisher-folk but no one who is rabid for those freeze up days.

Sylvanboat
That overloading a motor, if it came to jump starting it, is a question I have as well.
Although when considering your answer it occurs to me if I was jump starting another boat, I’d just use my own starting battery.

I must say I have had nothing but thoughtful and informative responses to my first post on the site.

Wouldn’t an onboard charger be an easier fix to the problem.

JasonP wrote:

Yeah – the inability to charge below freezing is the biggest con in my opinion. I fish the river till it freezes and have a detached garage where my boat is stored so it becomes a pain to keep my batteries charged up.

It is a $50 add-on to have a battery that warms itself with the inbound current from the charger before the battery accepts the charge.

https://norsklithium.com/product/100ah-heated-lithium-deep-cycle-battery/

Norsk’s solution to this concern is very slick and essentially renders cold temp charging a non-issue. Note that all Norsk internally heated batteries are sold out. The permanent ice house guys and anglers that fish early and late season have caught on to this feature and cleared Norsk out for the season already with the next round of inventory due to arrive in November. If you fish in cold temps or store the boat where it isn’t possible to warm the batteries before a charge cycle the Norsk heated Lithium Batteries are the way to go.

JasonP wrote:

The battery should have a PCB which monitors the temp and switches off the charging circuit until the battery is within temp spec. This is even true of the batteries for my ION auger.

Correct. A quality lithium battery will have a Battery Management System (BMS) integrated into the internal circuitry that is tasked with protecting the cells from events such as short circuit, reverse polarity… and charging when cell temps are too cold for charging. You can plug in a battery with a good BMS but it won’t take a charge until the cells are warmed.

My biggest question is can I use my current on board charger or will I need a special charger for lithium?

I don’t know what charger you have so I can’t respond specifically to your scenario but I have been using a minn kota precision charger for the last two years to charge my lithium batteries using the AGM charging mode and it has been flawless. I would bet the Minn kota precision charger is the most popular brand and model charger ever sold so many anglers already own a lithium compatible charger and likely don’t know it. Of course if you buy a new charger, like the Minn kota precision pcl model that came out this spring, it will have a specific lithium charging mode built into it.