wpns
Solar Joules are catch and release
So you should only ever use 80% of your LFP battery?
LFP Batteries below 20 percent?
- Thread starter wpns
- Start date
Suijkerbuijk
I cannot be held responsible for this information.
Yes looks like it on that battery company.
Victron the same .
And my own battery tell the same . (Brand Ultimatron Frans )
80%
zanydroid
Solar Wizard
Pretty sure car manufacturers are cool with recommending 100% on LFP. And they have to contend with the 10 year/70% degradation battery warranty law.
olivinelife
New Member
10-90% to account of "user error". This is a cell manufacturer after all. They don't know how good you are at matching cells, busbar, BMS quality etc when you build your pack. Let alone 10% SOC means different things to different BMS/manufacturers.
Suijkerbuijk
I cannot be held responsible for this information.
Its not the same .
Those battery are active cool or heat .
Those battery are grade a+
Custom beult bms .
And its are round cells
Its not a home made battery in the Barn .
And than we can not even have graden a+ cells
We use standard bms from a store.
For the rest my own battery have 5 years warranty on it.
And are registered in the systeem by Victron Blue Power shop in my country on my name.
So it can always see if i have warranty with out to look for my receipts.
ShirBlackspots
New Member
To be pedantic, its LiFePO4
ShirBlackspots
New Member
Yes, but if you want to maximize the cycle count to the maximum of 8000 cycles, you do 30-80%. Otherwise 0-100% is probably half that.
ksmithaz1
Solar / EV Junkie
When my batteries are below 10% I start to notice if the load is high and the HVAC cuts on. I used to let them drop to 5% when I only had 30KWH. I upped it to 10% when I bumped capacity to 60KWH. I would like to have a little reserve in case I'm out of juice and the power goes out, I don't have a generator and my backup power is the grid. In closed loop setting things to 0 seemed to cause some problems, but I have two loop s of different branded batteries one on each inverter. The system seems to do percentages based only on the batteries connected to the primary inverter, which at the bottom of the charge reads about 2% higher than the slave's batteries, So I really see 10%/8% at cutoff.
For generator start this gives a margin of error.
What if the generator does not start? And if you are away or asleep? The 20% gives time to discover the issue and attempt a fix. Nobody is shutting down the system at 20%. Yes I would keep the furnace and freezer on until 0%.
Suijkerbuijk
I cannot be held responsible for this information.
In my country we use the words lipo4 to make it shorter .
Alibaba use the same words for it to.
See attach files
Attachments
teal95
Solar Addict
Automakers aren't using 100% of the battery, despite what they are displaying. They are using even less because they increase the capacity used as the battery ages. This is due to government requirements on the battery maintaining range past the point where the battery starts losing capacity. (ie when new they are using 15-90%, but at 100k miles they are using 10-95%.)
ksmithaz1
Solar / EV Junkie
Which if you do the math is beyond silly. 80-30 = 50, thus you get 8000 half cycles or 4000 full cycles. So if you buy twice as many batteries, and only charge them 30-80 you will get twice the lifetime, spending twice the money up front. So if the batteries last 10 years, and your rack costs $10K, you can spend $10K now and something similar in 10 years, or $20K now to the same end result. Further assuming that in 10 years there will not be a better tech that is more efficient and less expensive. It's just stupid.
This is a pet peeve.
olivinelife
New Member
Remember, OP is talking about the PowerPro pack which not made in a barn, and has a warranty of >8000 cycles @ 80% DOD 0.5C
Suijkerbuijk
I cannot be held responsible for this information.
I dit not talk about that battery pack from ts (topic starter)
But over a car pack vs other systeem.
See on who i quote on.
Company that cell power packs in a complete unit are design for it and use compleet other cells we have.
Really the reaction that i do on the quote is offtopic.
Boron
New Member
Who wastes time on LABS AGMs or Lions any more. Praise be to LFBs
And what is the absurd fetish for pushing LFBs right to their operating limits? Stay within their comfort zone and enjoy a decade of faultless service - whats not to like? Worry about your inverter - there's a can of worms.
And what is the absurd fetish for pushing LFBs right to their operating limits? Stay within their comfort zone and enjoy a decade of faultless service - whats not to like? Worry about your inverter - there's a can of worms.
sunshine_eggo
Happy Breffast!
Please show me a datasheet that supports either claim.
ShirBlackspots
New Member
There are a legion of examples just by Googling for it. Do you know to use a search webpage?
This is one example: https://www.bravabatteries.com/lifepo4-battery-discharge-and-charge-curve/
sunshine_eggo
Happy Breffast!
Very adept at Google, and I've read dozens of cell data sheets which do not support your claims (not a single one). You can visit the resources section of this website to download a multitude of manufacturer's cell data sheets.
Furthermore, the one example you provided does not support your claim.
ShirBlackspots
New Member
Ok, whatever. You have your bias, and obviously can't be convinced of the legion of data out there supports what I have said..
olivinelife
New Member
Cycle degradation as a function of DOD is a highly nuanced subject for LFP (unlike nickel-based lithium batteries). It is also highly confounded in the lab by temperature/C-rate, BMS drift, and balance point. Unless you want to dig deep in the rabbit hole, start your cycles at 100% and prefer as big cycles as possible (big DOD), like how it's meant to be used.
I imagine based on power in vs power out as opposed to voltage? Otherwise I have no idea how to determine it based on voltage alone with such flat discharge curve as LFP has.
Guys, It is perfectly possible for some manufacturers to recommend one and others the other. I happen to use EVE and Higee cells which both say in their datasheets their cycle life numbers are given 0% to 100% aka standard charge, but they also say at 80% or 70% SOH in the same sentence. It means after 6000 cycles of 0% to 100% charge discharge cycles the battery should still have its 80% capacity left (10K cycles in case of EVE MB31). So there is potential for confusion there. But I don't deny the existence of datasheets that give cycle numbers based on less than full discharge-charge cycling.
There are also other limitations to cycle numbers. For example my Higee cells are rated at 1C charge and discharge with max pulse discharge of 3C, but the 6k cycle life is based on 0.5C charge/discharge. So there you have it. More than one way to skin a... whatever you skin, definitely not a cat(as a cat owner).
Those are prismatic cells by the way.
And again, unless everyone is cycling their cells at optimal 25C, you'll have degradation well beyond the different between 0%-100% and 20%-80%. With LFP, what you really need to do to get optimal life cycle is temperature control. Cycle at 40C and watch it drop in half. Why is this important in this thread? Because it gets hot where OP is located.
ShirBlackspots
New Member
When I am finally able to buy a DIY 16S 280Ah battery box, my intention is to keep my batteries between 20-90%
ShirBlackspots
New Member
From what I've read, and how I've interpreted it, they state 6000 cycles for 0-100% and 8000 cycles for that 20-80%
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