Cost of LiFePo4 vs Lead in Your Market

[ranger58sb]

Originally Posted by 2geer

Being an owner of a set of aging Lifeline GPL-4CT batteries and facing the decision of what to replace them with

Can you hum a few bars about your 4CTs? How many, how charged, how often charged, how OLD, etc.?

Ours are too young to predict lifespan...

-Chris

[a64pilot]

Our GPL-4CT’s are just shy of four years old, have lost near as I can tell no capacity, however I have from the beginning been determined as much as possible to fully recharge then as often as possible. This really became best accomplished when we got our Magnum inverter / charger and it’s associated battery monitor, because it enabled the charger to be held in absorption voltage until trailing end amps were reached during the charge cycle, so they are completely, fully charged.

I did mess up badly when they were new, I put the charger Into equalization mode and left, it’s timer was supposed to drop it to float in five hours, I came back at the end of the week and the bank was still at equalization voltage (15.5 V).
I don’t know how much harm this did to them, but surely it was bad.

We have 6 of them, split into two different banks, 4 and 2 but battery switch is always left in “All”. We have no other batteries.

[Kelkara]

Originally Posted by Dockhead

No, it's all amp hours AT 24V.

You can divide the per amp hour costs of ALL of the batteries by 2, if you want 12 volts.

This is the analysis I did for my own boat, which is 24v.

I still think you ought to double-check your arithmetic for the Lifelines.

[AliaVita]

If some real life stats helps anyone, we have Mastervolt Li-ion batteries installed in 2009. In the subsequent 9 years, I would estimate the boat has actually had someone onboard for 7 of them. Mastervolt claim the batteries are good for a minimum of 2000 full cycles, and our system has so far recorded just 356 full cycles. Charge efficiency is currently at 95%, we are told that when that gets down to about 70% it’s time to start thinking about replacement. We aren’t losing any sleep just yet!

[Paradox111]

Anyone try these LiFePo4 from alibaba, the price is right.
https://www.alibaba.com/product-deta...5.1.URnbV6&s=p

[newhaul]

Originally Posted by Paradox111

Anyone try these LiFePo4 from alibaba, the price is right.
https://www.alibaba.com/product-deta...5.1.URnbV6&s=p

not really as good of a price as you think once you include the shipping costs.
I ordered bare cells from camel via Alibaba and the shipping cost doubled the price by the time my company received them. Check the total prices carefully .

[john61ct]

Originally Posted by AliaVita

Charge efficiency is currently at 95%, we are told that when that gets down to about 70% it’s time to start thinking about replacement.

Could you give details as to how your setup measures CEF?

The 70% EoL measure is usually based on residual AH capacity.

[john61ct]

Originally Posted by Paradox111

Anyone try these LiFePo4 from alibaba, the price is right.
https://www.alibaba.com/product-deta...5.1.URnbV6&s=p

Those are "drop-in style", meh.

If you aren't buying a System from OceanPlanet (Lithionics), Victron, MasterVolt, Redarc (Oz specific?)

Then at least look for known-good prismatic cells: ​Winston/Voltronix, CALB, GBS, A123 & Sinopoly

[Dockhead]

Originally Posted by john61ct

Those are "drop-in style", meh.

If you aren't buying a System from OceanPlanet (Lithionics), Victron, MasterVolt, Redarc (Oz specific?)

Then at least look for known-good prismatic cells: ​Winston/Voltronix, CALB, GBS, A123 & Sinopoly

Amen!


Lithium made to imitate form factor and functionality of lead -- meh indeed. It's wishful thinking, to suppose you can just drop in something like this instead of a lead battery and turn the key. Stick with lead if you don't want to invest in working out a real lithium power system, would be my advice.

[rgleason]

PowerTech Systems Cost Comparison might be useful
but it is using DoD100% for Lifepo, which is different than most here. Nevertheless it might provide some relative values.

[john61ct]

Just depend what voltage you choose to **define** 0% and 100% DoD.

[rgleason]

So DoD100% is whatever one chooses? Not an absolute point related to battery chemistry?
For Example: For FLA what is DoD100%?
Using V

12.85v full

12.1v (according to Trojan) start charging, that's SoC50%, also DoD50%
so what's DoD100% which we never hit using FLA? 11.4v?


Now very very confused.


This Winston website shows various DoD80%, DoD100% etc on the chart, as though it is an absolute value.
http://evcomponents.com/lifepo4-cell...00ah-cell.html
Cycle Life

DoD80% >= 5000

DoD70% >=7000

[Dockhead]

Originally Posted by rgleason

So DoD100% is whatever one chooses? Not an absolute point related to battery chemistry?
For Example: For FLA what is DoD100%?
Using V

12.85v full

12.1v (according to Trojan) start charging, that's SoC50%, also DoD50%
so what's DoD100% which we never hit using FLA? 11.4v?


Now very very confused.


This Winston website shows various DoD80%, DoD100% etc on the chart, as though it is an absolute value.
Winston LiFeYPO4(LiFePO4) 3.2V 100Ah Cell - LiFePO4 battery cells - EV Components
Cycle Life

DoD80% >= 5000

DoD70% >=7000

When I was doing my calculations, I took the nominal capacity of both types of batteries, and figured that 80% of that was usable in case of lithium, and 50% for lead. Simples.


I believe that all the charts relate to nominal capacity, although, as you point out, what is 100% full and what is 0%, are somewhat arbitrary numbers.

[john61ct]

Originally Posted by rgleason

So DoD100% is whatever one chooses? Not an absolute point related to battery chemistry?

Yes that is the case, as I keep repeating. My use of the word "arbitrary" does not mean "at random", the choice should be sensible, logical, but in the end it is an individual choice.

From a **strictly** chemical / physics POV, 0% SoC is dead dead flat, shorting across the terminals overnight.

Which will permanently destroy an LFP bank.

So the maker chooses a resting-voltage point that they then call 0%. Actually going there may not "damage" the batt short-term but will reduce lifespan, and by a **lot** if done regularly.

For lead that zero point is standardized at 10.5V for 6s strings. As Maine Sail mentioned, there is no agreed industry standard for LFP.

Using 11.999V is sensible for 4s strings, since there is very very little useful AH capacity between any lower resting voltage and that point,

while you in actual usage you are avoiding the bottom shoulder where longevity starts to get more dramatically reduced.


> For FLA what is DoD100%?

Defined by the maker, generally using endAmps at Absorb.

Voltage is not an accurate measure.

[tanglewood]

Originally Posted by Dockhead

This is how it boils down here:


Attachment 176615

Maybe I'm being really dense here, but I don't get the lifeline calculation. Pardon the $ due to my US keyboard - the numbers are in BP.



$690ea. A 24V bank will be 2 batteries @210AH each nominal, 105 usable. That's 690*2/105 = $13.12 per usable Ah.


So I think you are off by a factor of 2.


But back to the point, and switching to USD, I recently bought CALB 180 cells for about $250ea, so $2000 for 180ah@24V (nominal). That's $13.88 per usable ah assuming 80% usable. That's a lot more $$ than you Winstons, and about 25% more than AGMs here. And that cost does not include any BMS.


But given the more favorable charging characteristics of LFP, and greater expected cycle life, I find them pretty compelling at this point. But if I had to buy a packaged system at more like 3-4x the cost of AGMs, I don't think I could justify it personally.