Curious about Lithum batteries

[exMaggieDrum]

Polux,
You don't measure capacity of Lithium batteries the same way you would lead acid batteries, whether flooded or AGM. You can approximate the "capacity" of a lead acid battery by measuring its voltage as it steadily drops in voltage from a full charge at 12.7 -12.8v to about 12.1v they are around 50% down. You can take them farther into the 11v range but they don't like that (i.e. will not last as long). So most boats will start recharging at least at 12.0v to get the longest life out of them. So you see a steady drop in voltage as you use them.

Lithium batteries do not work the same way - at all. They run in the 13+ volt range from full to almost completely "empty" and then they basically stop providing enough energy for the devices which need it on your boat. E.g. if you have every used a Li battery drill/driver hand tool you know that they work at basically full rate until they just stop. They don't gradually slow down, they stop. But you can pull 80-90% of the capacity out of the cells before that happens. And they recharge very fast.

You can't and don't compare the different batteries in the same way. That is comparing apples to oranges as we say. And you have to charge them carefully as you can easily overcharge them to the point of ruining them. You can also over-discharge them which dramatically cuts down their usable capacity as well. Lead acid batteries don't behave the same way at all. There is lots of info on this on numerous posts.

My apologies if I misunderstood what you were saying.

[reed1v]

And of course you got the idiot that replaces a lead acid battery with a lithium in a two battery system so you got one L and one LA linked together getting charged by the same charger. Not good, dangerous even.

[mcarling]

Originally Posted by reed1v

And of course you got the idiot that replaces a lead acid battery with a lithium in a two battery system so you got one L and one LA linked together getting charged by the same charger. Not good, dangerous even.

Correct.

Lead-acid and LiFePO4 batteries should never be connected in parallel. The resting voltage of the LiFePO4 battery is a float charging voltage for the lead-acid battery, so the lead-acid battery will drain the LiFePO4 battery down to about 1% SoC. If left connected for a long time, as the lead-acid battery continues to self-discharge, it will suck the remaining 1% out of the LiFePO4 battery pulling the voltage down to harmful levels.

There is no charging regime which will work for both lead-acid and LiFePO4 batteries. Any charging regime that will work for one will damage or destroy the other. LiFePO4 batteries are not a drop in replacement for lead-acid batteries. The charging parameters must be changed.

[senormechanico]

Originally Posted by Polux

I don't understand what you are trying to say. A Lithium Iron phosphate is a Lithium Ion battery. The word Ion refers to the " lithium ions (that) move from the negative electrode to the positive electrode during discharge and back when charging."

I posted to your answer in regards to the post #6 above yours.

Lithium Iron Phosphate cells are indeed lithium but definitely different from lithium ion.

[mcarling]

Originally Posted by senormechanico

Lithium Iron Phosphate cells are indeed lithium but definitely different from lithium ion.

Lithium Iron Phosphate cells are indeed among the different chemistries of the Lithium Ion family. Lithium ions move back and forth between the Lithium Iron Phosphate cathode and the carbon anode. The very term Lithium Ion nearly makes me cringe because it is so unspecific.

[44'cruisingcat]

Originally Posted by roland stockham

Like most people my experience with lithium batteries is in phones, cameras and computers where they work very well. The drawback is a relatively short life (2-4yrs). Do the big ones use a different technology? Is it just a scale factor? Or do they also have a relatively short life?
Not thinking of this as an option at present so not read up on it but does anyone have a short simple answer! And please I am not looking to start another long debate on the 'best' battery type!!!!

Short, simple answer. The Lithium batteries people use in boats are not the same chemistry as the ones used in phones etc.

The LiFePO4 batteries used in boats should handle many more cycles than camera or phone batteries. Arguably, even the lead acid batteries will.

[roland stockham]

Just for fun I looked at the price of the Mastervolt battery that would be a replacement for my current bank in the West Marine catalog. To be cost effective it would have to last at least 130years.... But it would take up a bit less space and the low volts alarm on the inverter would probably go off less often when I put the kettle on. As they say 'watch this space'

[Pete O Static]

I will be looking at a battery replacement for my boat in about 24 months and seriously considering Lithium.

Currently, I have FLA and don't see the advantage for the added cost of AGM. Lithium however, in my opinion is the future.

The initial cost of lithium is falling. I used Lithium Polymer batteries for flying RC aircraft several years ago. A battery pack that would generate 200 amps of power was around $400.( 2006 ) Today, that pack can be purchased for around $25. Initially, people were burning their houses down when charging but they were charging at 2C to 5C. and that was Lithium Polymer, not Lithium Iron Phosphate. A lot has been learned since then as well. I hope to see the cost come down in the marine industry but I think you will see that happen first in the RV and solar home world before here. Hint, start hanging out at home shows, not boat shows.

[Polux]

Originally Posted by senormechanico

I posted to your answer in regards to the post #6 above yours.

Lithium Iron Phosphate cells are indeed lithium but definitely different from lithium ion.

No, Lithium Iron phosphate is a Lithium Ion battery. I had already explained that Ion refers to lithium ions and pointed you for the explanation on the wikipedia and to Mastervolt that says they lithium iron phosphates batteries are Lithium Ion batteries. If you continue to think otherwise, well, it is up to you.

Mastervolt says about their lithium Ion batteries: "Safest Lithium Ion technology available. The term Lithium Ion encompasses multiple chemistries, having slightly different compositions of materials. These differences result in variations of energy and power density, lifespan, cost and safety. As safety is our primary concern, Mastervolt chooses to use only the safest available Lithium Ion chemistry, Lithium-iron phosphate (LiFePO4)."
Mastervolt - Innovative power systems<br>for autonomous use

[Polux]

Originally Posted by exMaggieDrum

Polux,
You don't measure capacity of Lithium batteries the same way you would lead acid batteries, whether flooded or AGM. You can approximate the "capacity" of a lead acid battery by measuring its voltage as it steadily drops in voltage from a full charge at 12.7 -12.8v to about 12.1v they are around 50% down. You can take them farther into the 11v range but they don't like that (i.e. will not last as long). So most boats will start recharging at least at 12.0v to get the longest life out of them. So you see a steady drop in voltage as you use them.

Lithium batteries do not work the same way - at all. They run in the 13+ volt range from full to almost completely "empty" and then they basically stop providing enough energy for the devices which need it on your boat. E.g. if you have every used a Li battery drill/driver hand tool you know that they work at basically full rate until they just stop. They don't gradually slow down, they stop. But you can pull 80-90% of the capacity out of the cells before that happens. And they recharge very fast.

You can't and don't compare the different batteries in the same way. That is comparing apples to oranges as we say. And you have to charge them carefully as you can easily overcharge them to the point of ruining them. You can also over-discharge them which dramatically cuts down their usable capacity as well. Lead acid batteries don't behave the same way at all. There is lots of info on this on numerous posts.

My apologies if I misunderstood what you were saying.

I was replying to somebody that said this:

Originally Posted by moseriw

Sorry to say but the industry should know it better.
Charging is about 14,3V
almost all electric units need at least 11V to work as they should.
So it is bloody useless to be able to discharge down to 2V
The range ist from 13,8V (full) to about 11,3V empty
To supply 120Ah you need 3x 225Ah max capacity AND it simple does not matter who provides it.
...

Thanks for the explanation that pretty much coincides with what the Mastervolt technician said to me.

Versus a normal battery a Lithium Ion battery with the same capacity can indeed provide more charge simply because when a normal battery has to be re-charged at 50% capacity a Lithium Ion battery can go to 30% or even less without problem, not to mention that it recharges much faster.

[BigNut]

Does anyone here know of a good book to read on the topic of LiFePo4 batteries?

Steve


Steve Cronjé

[Pete O Static]

Yes Polux, that is how I understand it too. The term Lithium Ion refers to multiple battery chemistry's, each containing lithium and sharing the same electrochemical process. These are all Lithium Ion battery chemistries.

Lithium Cobalt,
Lithium Polymer,
Lithium Manganese,
Lithium Iron Phosphate,
Lithium Titanate,

etc....

[44'cruisingcat]

Originally Posted by BigNut

Does anyone here know of a good book to read on the topic of LiFePo4 batteries?

Steve


Steve Cronjé

There's a thread on this forum that is probably longer than most books.

[senormechanico]

This debate about which chemistry is lithium ion reminds me of a customer I had years ago when I repaired consumer electronics for a living.

"Ours is not Beta, it's VCR."

[Polux]

Originally Posted by Pete O Static

I will be looking at a battery replacement for my boat in about 24 months and seriously considering Lithium.

Currently, I have FLA and don't see the advantage for the added cost of AGM. Lithium however, in my opinion is the future.
...

Maybe I can answer you about that since I changed from FLA to AGM and I am very satisfied with the change.

Changing only the batteries I will agree with you, it does not make much sense even if it is as little better since as they can be depleted a bit more than FLA batteries without negative effects in battery longevity, so they will provide you with a bit more useful charge before have to be charged.

But if you change your set up putting two alternators or a much bigger alternator that's a completely different story because AGM batteries can absorb charge a lot more faster than the FLA if you provide the juice. I mean if you change the alternator for a bigger one with FLA batteries the difference will not be big, with AGM it will be huge.

With AGM you have to buy also a good regulator since the batteries are more sensible to overcharge voltage.

If you modify all set up the difference is huge in the time you need to have the engine running for charging the batteries. On my case almost half the time. That for a price that is not a frightening one, like Lithium Ion, can make a lot of sense.

There is also another very useful feature regarding FLA: when you have the boat on the hard for winter they only need to have a full charge each 6 months or so. That may be not important to you but for the ones that have the boat faraway from home can be very important.