They're definitely used in buses and trucks in China.
Ask Me Anything About LFP Batteries and More! – Industry insider at top EV firm
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They're definitely used in buses and trucks in China.
Has been discussed this already on the forum many times, including my posting (link below) - incl. EVE's map and algorithms
Science based discussion on charging LiFePO4 below 32°F
I am not sure if any BMS has more than 2 states, on and off. Besides… Isn’t this what charge controllers are designed to do (scale current): I am not sure I would want a more complex BMS as it would likely reduce reliability. And for the last line of defence, BMSs need more reliability if...
diysolarforum.com
The temp/SOC/charge map from EVE for the LF280K shows zero charge strategy below 0 degrees C.
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Sverige
A Brit in Sweden
It’s possible the thick electrode (optimised for high Ah capacity) ESS cells we use are different in this respect (ie. low temp charging) than the thinner electrode (optimised for high peak current) cells @batteryprofessional is accustomed to in the EV world.
Since thicker electrodes amplify damaging effects due to problems with ion transfer across them, you would expect them to be more sensitive to low temp effects and require greater caution.
Since thicker electrodes amplify damaging effects due to problems with ion transfer across them, you would expect them to be more sensitive to low temp effects and require greater caution.
Looks like @battery_professional will have 50 questions to answer when he's back... Let me tack on another one.
You mentioned BYD and CALB as reputable LFP making companies. I don't think you ever mentioned EVE in this context. Is there a reason, or could they be mentioned in the same group as BYD and CALB? The question is, do you think EVE cells are less of a good product than BYD/CALB?
As for programming the BMS with temperature dependent charging curve. I'm not aware of a common JK/Heltec BMSes supporting such a thing. They just have max charging amps and don't allow charging at all below a certain temp. No curve possible... (someone please correct me if I'm wrong... I'd really love this to be a feature of these BMSes as I have few already)
You mentioned BYD and CALB as reputable LFP making companies. I don't think you ever mentioned EVE in this context. Is there a reason, or could they be mentioned in the same group as BYD and CALB? The question is, do you think EVE cells are less of a good product than BYD/CALB?
As for programming the BMS with temperature dependent charging curve. I'm not aware of a common JK/Heltec BMSes supporting such a thing. They just have max charging amps and don't allow charging at all below a certain temp. No curve possible... (someone please correct me if I'm wrong... I'd really love this to be a feature of these BMSes as I have few already)
See my link above - I do that with my custom integration.
Other BMS's also do that. Pylontech, Puredrive and FoxESS both reduce charge rate below certain temperatures as well as SOC. IIRC Pylontech reduces rate below 5 degrees C and FoxESS have a strategy that reduces at 15 degrees C, then reduce further below 10 degrees C.
As discussed in this posting/thread, amongst others...
Solis RAI not charging Fox-ESS LV5200 correctly
Hi all, hoping someone can shed some light on this. My Solis RAI charger is programmed to charge the battery from the grid for 4 hours every night on cheap-rate electricity, but it is not getting much of a charge. Software I have on the computer shows 640W going out to the workshop, where the...
diysolarforum.com
zcskywire2
Solar Enthusiast
If you review the more EV focused cell datasheets in the resources it is easy to see this. A few selections from various brands. Still wouldn't charge storage cells below 0c having reviewed them they do have charts preventing charge below 0c. It seems as the cells get to higher power rates they do much better in cold.
CALB L300F177A, 9A = .05C, 18A = .1C
EVE LF22K, 4A = .18C
CATL 20Ah 34189 Cyclindrical cell
SVolt 147Ah Blade
zcskywire2
Solar Enthusiast
I have two questions to ask you right now
The first is: What happened to Sodium Ion batteries that prevented them from charging in the cold (-20C). I've talked with many a manufacturer of sodium ion cells and they all say the same do not charge them in the cold. I've even been told to ignore cell datasheets on this point. Obviously the Lithium Carbonate price crash put a damper on R&D but its been over a year now and they can not meet one of their big selling points to me
The other is a weirder question. I wanted to know if you had any insight on using Lithium Niobium or other Niobium materials as a replacement anode instead of graphene or Lithium Titanite Oxide in high discharge rate batteries
Q-Dog
¯\_(ツ)_/¯
You should probably start your own thread, but to answer your question. Ask the inspector for the specifications. Fire doors have ratings (listed in hours in the US). If they are requiring a fire door they must state the rating of said door. I would assume the closet must also be constructed to the same fire rating.
battery_professional
New Member
Lots of factors. Safety, cost, capabilities of existing production lines. Most of the case, its the total energy required and operational voltage determines the capacity. For example, if the powertrain guy deciedes they want to use a 800 volts powertrain with 80 kWh battery pack.
You can directly calculate the capacity of individual cells will be around 80k /800 = 100 Ah cells if you only use 1p. For 2p, that goes to 50Ah etc.
And the capacity of individual cells determines the volume needed to put enough active materials for that capacity.
battery_professional
New Member
Once the thermal runaway processes starts, its self-sustaining. Which means the heat generated will be enough to initilize the thermal runaway for all the electrodes in a cell and surrounding cells. It will normally generate more heat than its charged energy because the electrolyte and active materials will burn. So the key is to take away as much heat as possible from the pack.
I don't know this product. It reads like it will inject aerosols to the room once the thermal diodes detect high temperatures? Aerosols are good to stop propogation of heat during thermal runaway. But I doubt it can insulate so well that stops the thermal runaway.
battery_professional
New Member
Sorry I missed your questions.Just quoting my question above in case you missed it @battery_professional as you’ve answered questions posted after it.
Also, to tack on another Q, can you expand on how oxidation of the electrolyte due to overcharge limits cycle life in LFP? I would have guessed it would reduced capacity rather than cycle life, but will be interesting to learn more about that. On a similar subject can you explain how overdischarge damages LFP and where the danger zone begins?
And I’d better stop there as I’m asking altogether too many questions!
1. There is a magic additives in LFP batteries which is call VC(vinylene carbonate). This additive will protect other electrolyte molecules from be reduced by lithium in the anode. VC will form a dense poly-VC SEI layer in the anode. But during cycling, graphite will expande and shrink which cracks the layer. And VC molecules and EC molecules will react with lithium to repair the layer. LFP does not like NCM which can still deintercalate lithium ions. When we talk about LFP in 3.65/3.8 Volts especially at constant voltages, there are almost no lithium in the LFP lattice. In this case, all you current will be used oxidize and reduce the electrolyte spontaneously at the electrodes. This processes will consume lithium and your additives at the same time, so you will get lower cycle life and lower capacity.
2. Overdischarge, SEI layer is reduction product. If we recall our chemistry class in high-school, reduction product is normally easy to be oxidized. In discharge, the voltage in the anode will raise and make the environment for oxidative and it will utimately starts to oxidize your SEI layers. Which means the layer that a lots of VC additives sacrificed themselfs are now gone. I think for low charging/discharging rate, you better not discharge your cells below 2.8 Volts. Also, better not store your batteries at around 0 SOC% at high-temperature cuz its the same story.
battery_professional
New Member
Thanks for your information. Good to know.Has been discussed this already on the forum many times, including my posting (link below) - incl. EVE's map and algorithms
Science based discussion on charging LiFePO4 below 32°F
I am not sure if any BMS has more than 2 states, on and off. Besides… Isn’t this what charge controllers are designed to do (scale current): I am not sure I would want a more complex BMS as it would likely reduce reliability. And for the last line of defence, BMSs need more reliability if...
The temp/SOC/charge map from EVE for the LF280K shows zero charge strategy below 0 degrees C.
This charging map seems rather conservative to me. It will be the case if they used a really thick electrode design and very high packing density.
battery_professional
New Member
CATL and BYD are both top-tier LFP makers. Other companies lag behind by a large margin in both market share and talent recruit.
CALB and EVE are in the second-tier. The point is technologies do not come from nowhere. Its the talent they recruit and R&D investment they put into developing and refining their product.
It's very easy for CATL/BYD to recruit graduates from top 50 or even top 10 universities in both mainland China and around the World. They got most of the talented people that was around. There investment in R&D also lead the industry by a far margin in mainland China if you read their annual report. They also got way more production capacity, which means more stable production line and more mature quality management.
Their cells might be very good product in a specific field where the big fishes didn't focused. But generally speaking, CATL/BYD > others.
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battery_professional
New Member
1. Sodium ion batteries is like lithium ion batteries in 2010 or 2005. The technology itself is not mature. That means no individual reason that limits its performance. It's all of them. It's cathode material is not stable enough during long cycling except prussian blue cathode. It's electrolyte is not optimized. The Mr.Right electrolyte additives has not been developed etc. Or it can be the manufacturer is more conservative.
Generally speaking, sodium ion batteries should have better low temperature performance mainly because it use hard carbon not graphite as its anode. Hard carbon intrinsically has larger pore size and lower packing density which make both the ions transport and intercalation easier. It also has lower solvation energy compare with lithium. There is still a long way to go for sodium ions especially given the current lithium carbonate price. If lithium carbonate price stays where it is today, I don't think sodium ions batteries have a chance in both ESS and EVs.
2. I attended the AABC battery conference in Strasburg, France in May and talked with a few guy promoting niobium. To my knowledge niobium is very expansive material, and I haven't heard mainstream applications but lets see where it goes. It might have a chance in some nichey high-power market.
ScrotpusGobbleBottom
Corn Pop was a bad dude.
Thank you for all of this!
SoggyShoes
Solar Enthusiast
@battery_professional thank you so much for spending the time to answer our questions!
So for storing LFP batteries above -20°C, it sounds like it is better to just turn off charging and discharging at the BMS (charging to avoid the risk of lithium plating and discharging to make sure the cells don't get too drained), than to try to heat the cells and create a large thermal gradient.
It would be difficult to heat a battery evenly because attempting to do so, would make it very difficult for the BMS thermo sensors to be accurate.
So much simpler!
Thanks again.
Thank you for answering too
Very interesting about sodium. Considering sodium cells cost slightly above LFP with the few sellers that do sell them I see no point for them on the market right now. I actually think having them "fail a market test" may be bad for the development of the tech until as you said lithium prices go up(which none of us wants, but at the same time we want more cheaper options for ESS).
Regarding my "cell position" question from page 2 post #39 of this thread. If you had some input it would be great as I'm about to rip my already commisioned pack apart in next few days... We had a moderately long heated debate about cell position here few weeks ago at the end of which I concluded I see no scientific evidence for harm caused by them being stacked atop another as in my photo (or on the short edge as another poster said), but based on another person's experience of failures happening seemingly because of it I decided better safe than sorry. There is an idea that when lying on its side (long or short) parts of the jelly roll are above the electrolyte and get starved. I posit capilary action should take care of that, but what is the truth I don't know.
Very interesting about sodium. Considering sodium cells cost slightly above LFP with the few sellers that do sell them I see no point for them on the market right now. I actually think having them "fail a market test" may be bad for the development of the tech until as you said lithium prices go up(which none of us wants, but at the same time we want more cheaper options for ESS).
Regarding my "cell position" question from page 2 post #39 of this thread. If you had some input it would be great
as I'm about to rip my already commisioned pack apart in next few days... We had a moderately long heated debate about cell position here few weeks ago at the end of which I concluded I see no scientific evidence for harm caused by them being stacked atop another as in my photo (or on the short edge as another poster said), but based on another person's experience of failures happening seemingly because of it I decided better safe than sorry. There is an idea that when lying on its side (long or short) parts of the jelly roll are above the electrolyte and get starved. I posit capilary action should take care of that, but what is the truth I don't know.Cabin Rising
New Member
Still not what I was asking. Why is the individual cell so small? If you need 50 of them for a certain function, then why not a bigger single cell and use less of them? What keeps that single cell to remain that size?
Hedges
I See Electromagnetic Fields!
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- Mar 28, 2020
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Because there was already mass production of flashlight cell sized lithium batteries?
That's what Tesla put in their first, and subsequent cars.
Some newer products, those with LiFePO4 cells, don't parallel any. Just one series string. As you suggest.
Now, it is simply enough to achieve desired voltage, about 400V so 100 or so cells.
That's what Tesla put in their first, and subsequent cars.
Some newer products, those with LiFePO4 cells, don't parallel any. Just one series string. As you suggest.
Now, it is simply enough to achieve desired voltage, about 400V so 100 or so cells.
Also I imagine for redundancy, many of these small cells can fail and the pack in theory should be fine, but one big cell fails and your entire pack is dead. This is why having a single string may not be ideal.
Not just charging/discharging, also the BMS self consumption. Several BMS (like the JK) have an option to turn themselves off completely at a certain cell voltage to prevent draining due to the BMS power requirement. Storing at cold temperatures also slows calendar ageing, so if you have a summer cottage in e.g. Finland or some other cold place, and the cottage is not in use in winter, you can use this feature to prevent the battery from draining while at the same time have a lower calendar ageing because of the cold.
Australia is 3 million square miles in area, the EV market here has stalled and thousands of EV's are sitting in storage areas at the docks.
No one is buying them and those that did follow their dreams of reducing their carbon footprint often left footprints walking home!
This is mainly due to a lack of charging infrastructure.
But Australia is currently very busy covering large parts of the 3 million miles with solar and wind turbines to try and be the first in the world to power it's grid through sun wind and storage.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Love the FUD: Vehicles unloaded must be processed & forwarded to delivery points for prep & released to customers. OZ is well covered on the EV front so leave the Murdochisms were they belong (that stanky outhouse in the outback).
Top selling BEVs in Australia in May 2024 were:
- Tesla Model 3 — 1,958 sold in May (year to date 8,823)
- Tesla Model Y — 1,609 sold in May (year to date 9,610)
- BYD Seal — 1,002 sold in May (year to date 3,306)
- BYD Atto 3 — 737 sold in May (year to date 3,366)
- MG4 — 565 sold in May (year to date 2,476)
- Volvo EX30 — 466 sold in May
- BMW i4 — 198 sold in May (year to date +768)
- Kia EV6 — 181 sold in May (year to date 902)
- BYD Dolphin — 175 sold in May (year to date 1,044)
- Mercedes Benz EQA — 172 sold in May
SOURCE: https://theconversation.com/chinese...-car-market-are-we-getting-a-good-deal-232829
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Sverige
A Brit in Sweden
Thanks for your answer to the two new questions I added above @battery_professional , but you still missed my original question which is here. I would appreciate if you could take a look at that
Brucey
Solar Wizard
It's a very interesting market there because Tesla and the Chinese manufacturers are free to race to the bottom price wise with no government intervention to protect non existent domestic producers. Three price cuts to the model Y, AUD$10,000 hit for the early adopters.
Actually latest figures show a 33% drop in Tesla deliveries:
"Deliveries fell by 10 per cent last month – in a new-car market down 3.9 per cent overall (including Polestar data) – and market leader Tesla recorded a 33.3 per cent decrease.
It is the second year-on-year decline in EV sales since 2020 – the other instance being a 3.6 per cent slide in April 2024 (again including Polestar numbers) – and the single largest electric-car sales reduction since August 2020.
However, industry analysts say the electric vehicle market has not collapsed, rather its growth has just slowed.
Research locally has shown there are still uncertainties among potential buyers over electric-car charging infrastructure, while there remains a gulf in EV purchase prices compared to equivalent petrol-powered vehicles."
Electric car sales fall in Australia after record highs, but the EV market hasn't 'tanked'
The honeymoon for the electric vehicle sales boom in Australia may be over – but don't panic yet.
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