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Thank you guys. I was just having fun with my weekend and I have already sent my transcript in myequals (online credential platform in AU/NZ https://www.myequals.edu.au/) to the administrator. It's so fun for me to see folks think I'm an AI and cannot stop laughing. It's so interesting for me...

Very good question. Beginning at 30% SOC and top at 80% SOC% will make your cycle life significantly longer by a factor of almost 1.5 to 2. That means its not 0.5 cycles and its more like 0.25 or 0.3 cycles. Jeff Dahn even published a paper on NCM been cycled at a middle SOC range and it can...

Generally speaking, for prismatic cells, you don't need to stack atop another. Just do your layout like what CATL does. If we ignore the pressure difference cause by different stacking. The most important factor becomes free electrolyte inside battery can. Normally when a cell is been developed...

Hi Sverige, Sorry I missed you question. I would not recommend to charge at 3.65V with a 0.05C tail current. LFP is very different from NCM where they normally have the constant voltage stage in charging profile. LFP have a very shape open circuit potential curve above 3.42V which means it...

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...

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...

Thanks for your information. Good to know. 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.

Sorry I missed your 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...

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...

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...

I think you can set your system to around 40-60% SOC depends on the self-discharge rate and turn if off. Storage at 100+F with a relative low SOC won't hurt the battery by much. Just be sure its SOC won't drop to below 10% SOC when you got back. Storage at very low SOC will hurt the...

In theory they don't have a upper limits as long as your powertrain can take that voltage. And the insulation at every spot of your pack can tolerate that voltage. 800V 280Ah has no problems for buses where the got a lots of room for power distribution systems, heat management and wires. It can...

I don't think EVs will use cells with 280-304Ah. You can tell this battery very likely is used for either energy storage or electric buses or trucks if you are working in this field. Modern EV's normally got less than 200 Ah capacity for safety purposes. When you make an EV, you want the...

Most EV burn you saw on social media is either because metal debris defects in batteries or the pack was hit by rocks/metals on the road which make the battery interal short. 120F is bad for cycle lifes but LFP are expect to not have thermal runaways before almost 200 degree Celcius. It's much...

Part a: LFP can be charged below freezing. EVs do have thermal management to heat its pack but for slow AC charging they will do around 0.1C-0.2C charge daily at -10 degree Celsius for LFP batteries. I would say most first-tier EV batteries manufacturers' LFP can do 0.2-0.3C charge at -10 to 0...

There are lots of ESS types like hydro, batteries, flow batteries, supercapacitors, fly-wheels etc. I'm refering to him indicating ESS = ultracapacitors.

I actually did a project using the powertrain and motor inductor to generate AC currents when the car is parked for winter self-heating. LFP's have no problem with high frequency ripples above 10 Hz. You can do sustained 2C AC currents at 10 Hz without problem even at winter times.

There are lots of testing in companies like CATL and BYD before a cell can be delievered into customer or making packs. Most of the failures happends during the coating processes where they use lots of X-rays to detect mass loading uniformity and CCD's to detect metal debris. Once the cell...

What are you even talking about? ESS stands for energy storage system and have nothing to do with been supercapacitors which is a type of ESS. It's a fact 'batteries' used in ESS got more electrolyte to ensure more life cycles. You understand batteries designed for ESS and EV's are different...

Most EV firms design their BMS boards in-house and outsource the PCB and SMT to 3rd parties. And then write their control algorithm into the boards. For different EV packs, the number of cells will be different and so does the BMS boards design. So there are no particular All-in-one brands that...

Sorry I'm not an expert on retail BMS boards. I don't even know what's the major brands for BMS boards on the retail market.

Sodium-ion batteries has a long way to go to replace LFP. Prussian blue sodium ion battery has reasonable cycle life but significantly worse energy density. High energy density sodium-ion batteries's cycle life are way worse than LFP yet more expansive than LFP. Also, hard carbon is more...

LMAO. I'm not an AI. I actually tested GPT4 with our entry job exams and its no where near the capabilities of waht an expert level human can do.

For LFP, I think LMFP (lithium manganese iron phosphate) will gradually replace it because of similar price but higher energy density. Its happening now but at a slow pace. The main problem is LMFP's cycle life is significantly worse compared to LFPs at around 35-45 degree Celcius. I don't...

No. We don't use the terms bulk and absorb in EV LFP. We use MSCC/CC/CV(multiple-stage constant current, constant current, constant voltage). In experiments, its been charged at around 1/3C all the way to 3.8 Volts and stop for standard testing and charging. In cars, the normal upper safety...

Thank you! It certainly hurts the batteries at a very high voltage ( > 4 Volts). As for the danger zone, its around 3.60-3.65 Volts in EV battery system design. In EVs they don't normally do constant voltage stage during charging process which is very different from cell phones and NCMs. The...

For newly developed battery packs, they will normally use a polymer foam with a certain stress-strain curve between the batteries. And the stress-strain curve for the foam can be adjusted given specific requirements. EV firms will test for a few hundread cycles to get the expansion rate - stress...

I mainly use chatgpt for coding and proofreading. I won't use it for knowledges related to my expertise because its answer is too entry level for me. No, Australia have good people, reseachers and universities but its EV industry base is non-existent.

Exsiting LIBs use liquid electrolyte to transport ions. Therefore, the interface between cathode, separator and anode is extremely important. Despite the fact batteries have expansion during cycling, having a compression force is still very important in ensuring the contact between...

MSE: Materials Science and Engineering. No serious business will recycle LFP batteries for commercial purposes as LFP batteries are extremly cheap from a raw materials perspective. Big players doing recycling is mainly for regulatory purposes. For secondary life useage, the grading of batteries...

It really depends on the cell design. Prismatic and pouch cell should have very similar voltage curves given the same design and compression force. Discharge voltage curves depends on the internal resistance, open circuit voltage, and current which only depends on the cell design like mass...

One of the major upcoming innovations that I think will become a game changer is ultra-fast charging (at a reasonable cost). LFP is more suitable for fast-charging applications because it can tolerate a higher maximum operating temperature comparing to NCM/NCA. Starting from the end of this...

Hello DIY Enthusiasts! I'm thrilled to join this vibrant community. I'm not a solar expert but I hold a PhD in MSE and currently working at a top EV firm, where I specialize in Lithium Iron Phosphate (LFP) batteries development and their applications (BMS algorithms). Why I'm Here: 1. I'm...