How do you ever get those Lifepo batteries charged?

[Dockhead]

Originally Posted by Swift Drift

. . .
Basically your question is irrelevant because:
a) a lithium bank (even a very large one) will charge faster than an your current FLA given the same charger capacity.
b) there is no need to charge lithiums to full.

Yeah, this.

One of the several great things about lithium are you only think about putting in whatever power you need; you can forget about the hours-long finishing charge lead batts need.

It's worth having a large-frame, heavy duty alternator, however, and with proper regulation, so uou don't burn it up

[Dockhead]

Originally Posted by rabbi

Things become complicated when trying to make the batteries go the theoretical 6000 cycles. Then it's better to stay 30-80% SoC, limit charge / discharge currents according to SoC and temp, do cell balancing at 100% every few weeks, pressurize the cells, etc.

I simply configure the charger & BMS once, accept that the cell will only do 3000 cycles, and call it a day.

"Theoretical 6000 cycles" because both me & the cells age anyway and neither of us will survive the 30+ years it takes to reach 6000 full cycles.
Replacement cost in 10 years will be much lower than today so I don't really care.

It just needs to be safe, not perfect.

3000 cycles will last most of us longer than we will own our boats.

[sailorboy1]

what is a "cycle" to a LFP house bank?

[CaptainRivet]

Originally Posted by sailorboy1

what is a "cycle" to a LFP house bank?

Like a cycle in general…a lab measurement to quantify the lifespan of a battery.
One cycle is defined for LFP as one discharge from full 3,65V to empty 2,5V and charged back to 3,65V.

[rabbi]

Originally Posted by sailorboy1

what is a "cycle" to a LFP house bank?

Depends on the manufacturer's spec for each cell.

Short description for EVE LF280K (because that is what I have):
300kgf +-20kgf pre-pressure applied to the cells, 0.5C charge/discharge rate, 2.5-3.65V cell voltage, temperature 25° C
Test is passed when capacity ≥80% after 6000 cycles


The full test conditions are in the cell's spec sheet attached, section 3.

I have however no idea how many partial cycles count towards a full cycle. But honestly I don't care.

[CaptainRivet]

Originally Posted by rabbi

Depends on the manufacturer's spec for each cell.

Short description for EVE LF280K (because that is what I have):
300kgf +-20kgf pre-pressure applied to the cells, 0.5C charge/discharge rate, 2.5-3.65V cell voltage, temperature 25° C
Test is passed when capacity ≥80% after 6000 cycles


The full test conditions are in the cell's spec sheet attached, section 3.

That’s the lab conditions that cycle is measured for your cells.
So one cycle for the EVE is full charge battery according to conditions above 3,65V, discharge it to empty 2,5V and charge full again to 3,65V with 0.5C=140A

For house on boats it’s recommended and mostly the case you are staying under 0.3C dis-/charge means your house will last more cycles. This because above 0.3C the cells start to differ much more and a passive balancer found in most BMS has a hard time to keep house balanced.

The EVE conditions are common for good quality cells. Cheap dropin mod this to 2,3V till 4,2V with 20A=c20 to market big figures for cycles and for AH capacity too.

[smj]

Ive had my lithium installed for almost 3 months and on my Victron app it says I’ve had 4 total charge cycles. If the batteries will last 3000 cycles does that mean I have 187 years of life left in them?

[rabbi]

Originally Posted by smj

Ive had my lithium installed for almost 3 months and on my Victron app it says I’ve had 4 total charge cycles. If the batteries will last 3000 cycles does that mean I have 187 years of life left in them?

Yes! And no.

Cells age based on calendar and use.
Just like your car's tires. If new tires are good for 30000km and you drive 1000 km per year they should last 30 years. Yet they start to disintegrate after a few years in the sun:


Also I have no clue how the Victron counts "cycles".

[CaptainRivet]

Originally Posted by smj

Ive had my lithium installed for almost 3 months and on my Victron app it says I’ve had 4 total charge cycles. If the batteries will last 3000 cycles does that mean I have 187 years of life left in them?

Nope, Victron measures what you specify…not what the cell manufacturer states.

It’s lab data anyhow…so real world you have sometimes over 100 microcyles a day plus your bank doesn‘t get fully dis-/charged too.
In marine house use Calendar aging will degrade the cells more then their cycle life

Cycle life is important for commercial use eg public busses or staplers, they will have couple of full cycles full to empty a day.

[sailorboy1]

Originally Posted by sailorboy1

what is a "cycle" to a LFP house bank?

since there were answers posted I will tell you want I believe it is

It is whatever it took for the manufacturer to make the claim based on what part of the lab testing data they had in order to just barely not be out and out lying!

I am pretty sure none have done enough controlled discharges/charges to get 10,000 or whatever cycles.

Assuming a C20 discharge and 4 hours to recharge it would take 10,000 days/27 years

[CaptainRivet]

Originally Posted by sailorboy1

since there were answers posted I will tell you want I believe it is

It is whatever it took for the manufacturer to make the claim based on what part of the lab testing data they had in order to just barely not be out and out lying!

I am pretty sure none have done enough controlled discharges/charges to get 10,000 or whatever cycles.

Assuming a C20 discharge and 4 hours to recharge it would take 10,000 days/27 years

Most likely true and they wil just test 200 cycles, get degregation and then theoretically extrapolate it.
Or with cheap ones they just take the lab testing from the supplier of the cells and recalculate everything with c20 instead 0.5C or whatever they spec to make it look better.
Unde same condition a lead does approx 300 cycles till dead, so 3000 cycles tells you your LFP will last 10x longer in theory…