3.2v 280Ah LiFePo4 Batteries - Cycle Life Numbers?

[CitizenCane]

I'm about to pull the trigger on 8 of these bad boys from Dongguan Billion Electronic Technology for $830 shipped to Australia.

Lf280 3.2v Lifepo4 High Capacity 280ah Rechargeable Batteries Lipo4 Battery Bank Prismatic Cell For Energy Storage Solar Ev Car - Buy Lf280 3.2v 280ah Rechargeable Lithium Battery,3.2v 280ah Lifepo4 Battery Cell,Lifepo4 3.2v Prismatic Cell Product on

Lf280 3.2v Lifepo4 High Capacity 280ah Rechargeable Batteries Lipo4 Battery Bank Prismatic Cell For Energy Storage Solar Ev Car - Buy Lf280 3.2v 280ah Rechargeable Lithium Battery,3.2v 280ah Lifepo4 Battery Cell,Lifepo4 3.2v Prismatic Cell Product on Alibaba.com

www.alibaba.com

They are $60 cheaper than Dongguan Lightning and $90 cheaper than Shenzhen Xuba, for what seems like identical cells.
Haven't found any bad buyer experiences from a search of these forums.

- Is there any reason I should be aware of to NOT buy from Dongguan Billion?

Also. one thing I've noticed trawling through listings on Alibaba is, there seems to be quite the discrepancy in the quoted Cycle Life of identical spec'd batteries.
They vary from "Cycle life: 2000 Times" to "Cycle life: >4000 times".
EG: These batteries list a Cycle Life of only 2500 times (1000 less than the ones I am about to buy from Dongguan Billion)

Xld Prismatic Size 3500 Cycle Rechargeable Lithium 3.2v 280ah Lifepo4 Bateria 280ah - Buy Battery 280ah,Battery Lithium 280ah,3.2v 280ah Lifepo4 Bateria Product on Alibaba.com

Xld Prismatic Size 3500 Cycle Rechargeable Lithium 3.2v 280ah Lifepo4 Bateria 280ah - Buy Battery 280ah,Battery Lithium 280ah,3.2v 280ah Lifepo4 Bateria Product on Alibaba.com

www.alibaba.com

- Are these just numbers the sellers are pulling from thin air or is there a reason why some are double the cycle life of others?

 

[idontknowwhatimdoing]

I tried to buy through them and waited agess to hear back, so I searched elsewhere. Then found xuba.
Tell Amy your from these forums at xuba. She is amazing. Great service so far. Worth the extra $ so far. Threw in busbars. I ordered my cells this week. Just received a video of them running the multimeter over them showing v+ and resistance. Nice and consistent. Mine are coming to Australia too

 

[Steve_S]

The "Life Cycles" or Charge Cycles will vary depending on how the cells are used and how they are packaged up. For example and EV would draw more & more deeply than say a residential storage system and subsequently would see deeper discharges. An EV will also charge faster generally at a much higher C-Rate and that affects the cells as well.

LFP is best if bundled snuggly with a slight bit of compression. The A-Typical 280AH cell you are looking at are not good for an EV (1C discharge rate would not cut it) but they can also take a 1C Charge rate without being "abused".

Charge Cycles are a point that has been beaten to death and then some and often ending up in big idiotic arguments. LFP is NOT Li-Ion or Nicad or any other chemistry and many argue on points related to other chemistries, not realizing their on about Oranges when we are talking Potatoes. One FULL Cycle is from 0% SOC to 100% SOC (State of Charge), a partial Cycle is from 50% SOC to 100% SOC. How many actual cycles a pack will see is relative to how it was used and how deeply it gets discharged. MOST LFP Spec Sheets & Docs provide info related to cells being Compressed or not and the different effects, including how it affects Charge Cycles, some are as clear as the muddy pond after you've 4x4'd through it while others simply "elude or hint" at it and a few are fairly clear on it.

BTW: The majority of folks will not run their batteries from 2.50V per cell (0% SOC) to 3.65V per cell (100% SOC) because such deep discharge & charge does indeed shorten their lifecycles. Typically, Battery Packs are set to be used between 80-90% of total capacity, usually keeping the battery at no less than 10% and no higher than 90% to ensure the most bang per buck from the investment.

The numbers most vendors post are the optimal potential cycles if properly built & assembled BUT they are not clear as to what the manufacturer considers such a build. It's almost like arguing is a 2x6 wall built at 24" on Centre is weaker than a 2x6 walls built at 16" on centre, it's one half dozen or the other.

 

[CitizenCane]

Cheers for the detailed reply.
In a nutshell, the rated life cycles that the sellers list don't really mean much?
So I should just consider the other specs, and if they are used or Grade A or B?


While I have your ear, I was going to buy this 120 Amp BMS ( 4SLFP120A UARTRS485 ) which I have seen recommended on these forums:

51.8US $ |4s Or 3s Li Ion Battery Smart Bms Or 4s Lifepo4 Bms With 60a To 120a Constant Current And Uart Or Rs485 Communication - Integrated Circuits - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

The system I am hoping to build will have 8 x 3.2v 280Ah at 24v.
The ratings of the batteries are: Max Charge current = 1C
So the constant discharge current will be 280A ?

Does this mean I need a 300A BMS?
That's the closest (and largest) size I can find.
Or should I buy multiple BMS's with a smaller Amp rating?

The fact that it will be a 24v (not 12v) system doesn't matter, what matters is the voltage of the individual cells, 3.2v ?

Sorry for the newb questions but I'm having a hard time researching this.

 

[SV Third Day]

I ordered my 20 cells from Amy at Xuba. Paid on May 13th received cells at my shipping address in San Diego on July 1st.
So about 45 Days, which is about normal for shipping from China.
Happy as a Clam at this point. Getting ready for Capacity tests and then installation in my boat, to replace my no 6yr old 400AH Bank with this Larger bank!

 

[Steve_S]

Cheers for the detailed reply.
In a nutshell, the rated life cycles that the sellers list don't really mean much?
So I should just consider the other specs, and if they are used or Grade A or B?


While I have your ear, I was going to buy this 120 Amp BMS ( 4SLFP120A UARTRS485 ) which I have seen recommended on these forums:

51.8US $ |4s Or 3s Li Ion Battery Smart Bms Or 4s Lifepo4 Bms With 60a To 120a Constant Current And Uart Or Rs485 Communication - Integrated Circuits - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

The system I am hoping to build will have 8 x 3.2v 280Ah at 24v.
The ratings of the batteries are: Max Charge current = 1C
So the constant discharge current will be 280A ?

Does this mean I need a 300A BMS?
That's the closest (and largest) size I can find.
Or should I buy multiple BMS's with a smaller Amp rating?

The fact that it will be a 24v (not 12v) system doesn't matter, what matters is the voltage of the individual cells, 3.2v ?

Sorry for the newb questions but I'm having a hard time researching this.

Most importantly, the Cell Grade being A or B is important, while making sure to steer clear of used UNLESS you "know" the provenance. Do not accept what a vendor will tell you in regards to their used cells.

The EVE 280AH cells are shown below.
Note that in this instance 1C = 280 Amps. Charging @ 1C will generate Heat !, so will discharging at that rate.



BMS:
The BMS is sized relative to the Inverter you are using and the loads being pulled from the battery assembly. A 24V/4000W Low-Frequency Inverter can pull 166A but it has (Low Freq) 3X surge capacity of 12,000W or 500A @ 24VDC. High-Frequency Inverters can only do 2X Surge.

You have 8 cells which is what it takes to build a 24V/8S pack, therefore you require an 8S BMS, which provides one balance lead per cell. If you are looking at a "Smart BMS" with balancing & monitoring features & functions, you most certainly want to watch "every" cell and balance the pack accordingly. A "General Rule" on BMS', is to get one that has 25% more capacity than what you will draw, most especially on MosFET based BMS' where you do want some elbow room. FET Based BMS' usual CAP at 200A because after that you get into serious heating issues and require cooling and/or active heat dissipation. If you go with a Relay/Contactor controlled BMS TinyBMS, Chargery and such, then it is the Relay/Contactor that is carrying the amperage and they can go up to 1,000A.

It is nearly impossible to recommend a BMS without knowing what exactly you are going to be doing, how many amps continuous & how much surge potential you are going to have. As well, what features & functions do you "need", then "want" and of course would "like to have", will have a definite narrowing down and affect the cost as well. More Features & Functions = More Bucks.

TinyBMS: https://www.energusps.com/shop/product/tiny-bms-s516-150a-750a-36?category=4
Chargery BMS8T: http://chargery.com/BMS8T.asp
ElectroDacus SBMS: http://www.electrodacus.com/

FET BASED: used by members here and with several threads on them. There are several but these are the two most common types.
Daly High Current SmartBMS: https://www.aliexpress.com/item/4001052946588.html?spm=2114.12010612.8148356.4.39f32332fBIqC3
Xiaoxiang BMS:

US $38.0 |smart bms bluetooth 8S 30A/40A/50A 24V Lifepo4 smart bms pcm with android Bluetooth app UART bms wi software (APP) monitor|bms pcm|pcm bmslifepo4 bms - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

EDIT - OOPS: I forgot to mention, a BIG Issue too, is if you are building a Common-Port or Separate-Port system. Common-Port uses the same wires for Discharging from the battery to Charge the Battery. Separate-Port has one set of lines for Discharge and one set for Charging. The Majority of BMS' do not charge at the same rate they can discharge, this varies by Type of BMS ad how they are handling the power.

 

[CitizenCane]

Thanks again, it seems like every question I find an answer to raises two more questions, haha, but I love learning about this stuff so I'm not complaining.

I'm actually planning on running almost everything off 24v DC.
I've already bought all 24v LED's, will be buying DC to DC converters to run my Router, Monitors, Amplifier, USB devices etc and will get DC-DC PSU(s) to run my PC.
I've been planning on doing this for a long time so almost everything I've bought over the last few years is either powered by USB or an external AC to DC brick.

I want two DC-AC Inverters:

-One small one to run my fridge that will be switched on and off via temperature sensors, that will only need about 300W peak (I think).
Fridges have a decent surge when they switch on apparently so I'll go for a small watt Low-Frequency Inverter there.
Credit to this guy from r/vandwellers who gave me that idea:

https://www.reddit.com/r/vandwellers/comments/4efrgd

-One bigger 2000 - 3000W one that I will only switch on for induction cooking or using my coffee machine (and maybe microwave or water heater).
I think I can get away with using a High-Frequency Inverter there because I don't think there's much of a surge from those appliances.
I can run only one of these appliances at the one time if necessary, so I don't think I need to go too overboard on the inverter capacity.

So it's pretty hard for me to estimate what my power usage will be, considering I'm going to try to keep most of my power usage as DC only, but I guess there will be an hour or so each day when I might both inverters and all the DC gear at once.
I'll go for an oversized BMS so I have a bit of headroom, and it's somewhat future proofed.

 

[G00R00]

I got 16 cells from billionelectronic . . . took about 45 days and they arrived and are perfect. I suggest asking for extra good packing as one of the boxes was damaged and one cell had a small blemish. Nothing to worry about though! I was quite happy with them, and the cells are beautiful.

 

[gnubie]

-One bigger 2000 - 3000W one that I will only switch on for induction cooking or using my coffee machine (and maybe microwave or water heater).
I think I can get away with using a High-Frequency Inverter there because I don't think there's much of a surge from those appliances.

Beware with induction hot plates. A lot of them use phase angle switching to control the coils and that gives them a quite poor power factor and an even worse current waveform. Your inverter may not appreciate that sort of load, some people on the forum certainly have had problems with HF inverters and induction heating.

 

[Dzl]

While I have your ear, I was going to buy this 120 Amp BMS ( 4SLFP120A UARTRS485 ) which I have seen recommended on these forums:

51.8US $ |4s Or 3s Li Ion Battery Smart Bms Or 4s Lifepo4 Bms With 60a To 120a Constant Current And Uart Or Rs485 Communication - Integrated Circuits - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

The system I am hoping to build will have 8 x 3.2v 280Ah at 24v.

That BMS will not work with a 24V pack. You need an 8S BMS.

The ratings of the batteries are: Max Charge current = 1C
So the constant discharge current will be [could be] 280A ?

I think you are better off sizing your BMS on an estimate your system will draw, not the max C rate of your batteries unless you actually realistically expect to draw anywhere close to that (7kW) in which case a FET based BMS is probably not the best option. Most people don't come close to continuous currents of 1C for solar applications.

I'm actually planning on running almost everything off 24v DC... I've been planning on doing this for a long time so almost everything I've bought over the last few years is either powered by USB or an external AC to DC brick.

I want two DC-AC Inverters:

-One small one to run my fridge that will be switched on and off via temperature sensors, that will only need about 300W peak (I think).
Fridges have a decent surge when they switch on apparently so I'll go for a small watt Low-Frequency Inverter there.
Credit to this guy from r/vandwellers who gave me that idea:

https://www.reddit.com/r/vandwellers/comments/4efrgd

-One bigger 2000 - 3000W one that I will only switch on for induction cooking or using my coffee machine (and maybe microwave or water heater).
I think I can get away with using a High-Frequency Inverter there because I don't think there's much of a surge from those appliances.
I can run only one of these appliances at the one time if necessary, so I don't think I need to go too overboard on the inverter capacity.

So it's pretty hard for me to estimate what my power usage will be, considering I'm going to try to keep most of my power usage as DC only, but I guess there will be an hour or so each day when I might both inverters and all the DC gear at once.
I'll go for an oversized BMS so I have a bit of headroom, and it's somewhat future proofed.

Steve's recommendation of sizing BMS to the inverter is common (and sound) advice, but reflects a typical off-grid, traditional home wiring, design/mindset, where the home wiring is all AC and all or most loads are AC loads. Its a little more complicated for mobile and marine builds where many or most of the loads are DC. In this case, you need to account for DC and AC loads.

Alternatively you can estimate a ballpark 'allowance' for DC loads, add this to your max inverter current. One easy way that I sometimes use to get a rough (and conservative) estimate, is if you are using a DC fuse block find the rated current of the fuse block, add this to the current of the inverter.

For instance a Blue Sea fuse block is rated for 100A, a 2000W inverter will draw 2000W / 0.85 efficiency / 24V = 98A, so the max total concurrent continuous AC + DC current is 198A @ 24V. Of course this is a very conservative estimate, it would be quite unlikely to ever draw anywhere near 100A on the DC side unless you have a DC aircon, or other high draw DC loads.

Of course you could sidestep this (at least in regards to a BMS, would still need to consider for wiring, circuit protection, etc) by going with a BMS like the SBMS0, or a relay based BMS like the Chargery, neither BMS is constrained by current.

 

[CitizenCane]

I got 16 cells from billionelectronic . . . took about 45 days and they arrived and are perfect. I suggest asking for extra good packing as one of the boxes was damaged and one cell had a small blemish. Nothing to worry about though! I was quite happy with them, and the cells are beautiful.

Thanks for your (and everyone else's) recommendation.
I decided to go with Billion Electronic.
Xuba sounds good, but saving $90 USD was too hard to pass up.

Alternatively you can estimate a ballpark 'allowance' for DC loads, add this to your max inverter current. One easy way that I sometimes use to get a rough (and conservative) estimate, is if you are using a DC fuse block find the rated current of the fuse block, add this to the current of the inverter.

Cheers, Now the batteries are on the way I have to wrap my head around all the electronics, and do some serious online shopping.
Want to sort out what I need as early as possible to give things time to be shipped from Aliexpress.

Next on the list is:

200 to 300w 24v Low-Frequency Pure Sine Wave Inverter (for running the fridge only)
3000w 24v High-Frequency Pure Sine Wave Inverter
* Smart Battery Sense / Low Temperature Disconnect Sensor
8S BMS (up to 300A)
* MPPT Solar Charge Controller
* Alternator Charge Controller
* 240v AC Mains Charge Controller
Heaps of DC to DC Buck Converters

And extra tools and accessories:

Crimping tool
Cable Stripper
Battery terminal connectors
Lots of suitable gauge / resistance cables
Large Hose Clamps for Batteries

Two additional questions:
* Do I really need Low Temperature Disconnect Sensor, given that I live in Australia and the temperature almost never gets below 5 deg C, and even if it gets that cold outside it will never be that cold inside?
* Do I need three separate Charge Controllers for Solar, Alternator and 240v Mains charging? I'm sure there must be Charge Controllers around that can handle all three inputs.

If there's anything I'm missing, or if anyone has recommendations for where to buy and/or research this stuff please let me know

 

[Dzl]

200 to 300w 24v Low-Frequency Pure Sine Wave Inverter (for running the fridge only)
3000w 24v High-Frequency Pure Sine Wave Inverter

You may want to consider flipping this around. As I understand it, LF inverters [tend to*] have higher no-load power draw, so using one for your 'always-on' fridge inverter will cost more in efficiency, also I'm not sure if there are any LF inverters available at that low wattage (but this last point is just speculation and might be wrong).

Was there a particular inverter you had in mind?

* Smart Battery Sense / Low Temperature Disconnect Sensor

This will only be necessary if your BMS doesn't have low temp protection.

* MPPT Solar Charge Controller
* Alternator Charge Controller
* 240v AC Mains Charge Controller

For alternator charging Victron, Sterling Power, Renogy, Cotek and Redarc are the companies I'm aware of. Of those Renogy and Cotek both offer combined alternator and MPPT chargers for small systems.

Two additional questions:
1. Do I really need Low Temperature Disconnect Sensor, given that I live in Australia and the temperature almost never gets below 5 deg C, and even if it gets that cold outside it will never be that cold inside?
2. Do I need three separate Charge Controllers for Solar, Alternator and 240v Mains charging? I'm sure there must be Charge Controllers around that can handle all three inputs.

1. Probably not considering your situation, but it would be cheap insurance and bring some extra peace of mind. If the lowest temps you will see are 5*C exterior ambient its a pretty low priority feature, considering that those lows would be seen at hours of the night when the sun ain't shining.

2. I don't think there are any chargers that combine the functionality of all three charge sources into one. You can get a charger that handles solar + shorepower, or alternator + solar, but I'm not aware of any that do all three. There may be products on the market that do this that I'm not familiar with, or products specific to the Australian market that I'm not aware of.


*edit: added "[Tend to]" in case there are exceptions to the above observation.

 

[G00R00]

*it is coldest at sunrise . . .

 

[Dzl]

*it is coldest at sunrise . . .

This is actually a good point that I hadn't really considered. That said, PV charge current will be pretty low for the first few hours after sunrise, right? But then, batteries have a lot of thermal mass so will be slower to warm than the ambient temperature, but on the flip side will also be slower to cool over night.

Personally, I'd choose to just sidestep all this thinking and use low temperature disconnect if freezing temps were a possibility. But based on OP's scenario (occasional 5*C lows outside, warmer in battery space) low temp protection is probably closer to a 'nice to have' than a necessity.

 

[HRTKD]

CitizenCane, where are you planning to install your batteries? Inside or outside? What is this system going into.

The RV I'm going to upgrade normally has the batteries installed outside on the tongue. For my LiFePO4 batteries, they'll be installed inside the trailer. I don't expect the batteries to come anywhere close to 32° F when the trailer is in use, even though the outside temps are expected to get as low as 8° F. When the trailer isn't in use the temps will go below 0° F so a low temp disconnect is necessary.

 

[CitizenCane]

where are you planning to install your batteries?

In a stealth van conversion I'm building over the next few months. They'll definitely be in a cupboard in the van somewhere.

When the trailer isn't in use the temps will go below 0° F so a low temp disconnect is necessary.

Good point, I was only considering the times when I'm actually in the van.
I've already got a deisel heater so it should be toasty warm when I'm staying in the van, but one day I plan on integrating it with an off grid solar setup w/ additional batteries in my main house, so the low temp disconnect will come in handy for when it's parked in the carport.

Was there a particular inverter you had in mind?

Not yet, l still have to research what are the most efficent / best value ones I can buy. Still got a lot of reading to do. Open to any suggestions.

Renogy and Cotek both offer combined alternator and MPPT chargers for small systems.

Cheers I'll definitely check them out. Sounds like what I need.


I'm planning on ripping out my PC's PSU and using DC-DC Power Supplies to eliminate the wasted overhead.
During my research I noticed you were going to do the same thing using a picoPSU. Did you end up building your DC only PC?
Do you have any suggestions on where / what I should get?
This page I found seems pretty helpful for starting a shopping list.

 

[JoeHam]

@Dzl the LF Inverter will likely be much better suited to the fridge compressor startup current.

Likely higher idle consumption as you state but no free lunch and all that.

 

[BiduleOhm]

You may want to consider flipping this around. As I understand it, LF inverters have higher no-load power draw, so using one for your 'always-on' fridge inverter will cost more in efficiency, also I'm not sure if there are any LF inverters available at that low wattage (but this last point is just speculation and might be wrong).

HF inverter is a bad idea for the motor bearings (in short: HF inverter = high power harmonics = eddy currents = bearings wearing fast). What you can do is pilot the inverter with the fridge thermostat but you need to know exactly what you're doing and it needs to be a good old mechanical thermostat as electronic ones need power to work... You can also add another thermostat set to a little lower temperature so it turns on the inverter just before the fridge turns on the compressor.

 

[Dzl]

@Dzl the LF Inverter will likely be much better suited to the fridge compressor startup current.

Likely higher idle consumption as you state but no free lunch and all that.

While I agree with you, My thinking is that because the dedicated inverter will only be running the fridge, that's pretty low wattage maybe 50-150W continuous. We are on the same page regarding the startup surge being very high and LF inverters being better for that, but for such a low wattage device, you can get a cheapish 800-1000W HF inverter and have a ton of overhead (like 500% continuous) without having to even think about surge rating. This should be cheaper and more efficient (for the purpose) than a dedicated LF inverter. I believe this is done relatively often with small victron inverters (which I believe--but am not positive--are HF or hybrid HF?).

So basically, I agree with you, but considering the ecomomic angle i cant see how a dedicated fridge inverter can make financial sense unless its (1) cheapish, and (2) efficient/low idle consumption, which pretty much rules out LF right.

That said, I can't argue with anything Bidule said and , I trust his opinion on most things.

HF inverter is a bad idea for the motor bearings (in short: HF inverter = high power harmonics = eddy currents = bearings wearing fast). What you can do is pilot the inverter with the fridge thermostat but you need to know exactly what you're doing and it needs to be a good old mechanical thermostat as electronic ones need power to work... You can also add another thermostat set to a little lower temperature so it turns on the inverter just before the fridge turns on the compressor.

So I'll modify my opinion. If you go with an LF inverter, it probably doesn't make economic or energy efficiency sense to go with a dedicated LF inverter for the fridge and an HF inverter for everything else. Go with just a single larger LF unit. Maybe I'm missing something or not understanding the design goals.

As always, this is just my half formed opinion so if you think i'm misunderstanding anything school me on it.

 

[CitizenCane]

Go with just a single larger LF unit

I'm designing the setup so that everything besides the fridge and cooking appliances are run off 24V.
I'll only be cooking here and there so I'll just switch on the bigger inverter for that.

My understanding is that running a 3000w inverter for ONLY a 120w fridge is less efficient than running a 200-300w inverter?
If it's just as efficent at low power draw then I'll save the cash and just buy a big 3000w inverter to use 24/7.