- MemberApril 21, 2022 at 10:24 am
Here is an amazing bit of news on LFP battery research from Gotion High Tech. They have 210 wh/kg now, 230 wh/kg soon and potential for over 260 wh/kg by the end of the year. 210 is already likely enough to make the weight disadvantage at a pack level negligible (LFP Packs need way less packaging / cooling which is ~15-20% of the total pack). The future is definitely LFP.
- This discussion was modified 3 weeks ago by bbelcamino.
- MemberApril 21, 2022 at 2:51 pm
They certainly seem promising. what type of batteries will the Aptera have?
- MemberApril 21, 2022 at 3:17 pm
Standard 2170’s IIRC
- MemberApril 21, 2022 at 3:26 pm
- MemberApril 21, 2022 at 4:04 pm
Sorry if this dupes – the forum just did something weird and ate my edit.
Aptera will definitely ship with NMC 2170 which are still very solid. They are a good off the shelf option with a very proven history. Speculatively, I think their is a strong chance Aptera will eventually switch to LFP for the shorter range versions (potentially up to the 600 mile); just as Tesla did with their standard range lineup. This allows frequent full use of the battery (0-100%) without degradation, better safety, lower cost, and reduced environmental impact (no cobalt or nickel).
Chris has experience with LFP and said in an interview that even he as the CEO wants the 400 mile version (also the most popular choice). They will source components which are available and LFP wasn’t performance competitive 2 years ago when development started; it would have undercut much of their extreme efficiency. LFP has improved dramatically over that time and is continuing to while being produced in insane quantities for the chinese EV market.
Note: It is also definitely not trivial to redesign the battery pack for LFP; it may take years until a redesigned pack is ready and trying to develop it too early would add risk for the company. Aptera needs to ship units to raise funds via sales / IPO not spend what they have redoing perfectly acceptable engineering. As prices shift the urgency will go up as nickel and cobalt prices rise and it will eventually be necessary.
- MemberApril 22, 2022 at 6:59 am
Respectfully, I’ve seen some variation of the “This allows frequent full use of the battery (0-100%) without degradation,…” statement in numerous venues and I just haven’t seen any “data” to support it. Any chance you can point me to some?
I’m a big fan of LiFePO4 (LFP) and will likely use it for an off-grid system for my home/shop.
- MemberApril 22, 2022 at 10:20 am
To be clear LFP does still degrade with usage just FAR slower.
- MemberApril 22, 2022 at 2:52 pm
- MemberApril 21, 2022 at 9:36 pm
NMC is the current best-in-class for range, but if “good enough” LFP batteries are available, this will have a lot of benefits: no expensive cobalt from war-torn Congo, no nickel from Russia, much reduced chance of fire, longer battery lifetime. LFP is definitely coming. But maybe eventually sodium-ion batteries that do away with the lithium and its skyrocketing price. A lot of hard engineering work still to be done, but these things are on the horizon.
- MemberApril 22, 2022 at 7:21 am
I’d be willing to drop down from the 600 pack to the 400 pack to get LFP instead of NMC…
- MemberApril 22, 2022 at 9:36 am
This looks promising, but still a long way from mass production.
- MemberApril 22, 2022 at 10:04 am
It will be interesting to see where battery tech lands in the next few years. Eventually one type will reach a tipping point and then all further development will be focused on that. It could be that it’s already happening with LFP but it’s to early to call the game.
I started designing computers in the early 70s so I lived through the chip technology battles. When I started there were three distinct types of chip technologies. There were two bipolar types, TTL and ECL and several types of MOS, NMOS, PMOS and CMOS. Supercomputers like the Cray 1 used ECL because it was the fastest, but it also was the lowest density and highest power. Minicomputers used TTL which was slower than ECL but higher density, lower power and cheaper than ECL. Microprocessors used MOS which was very slow but had the advantage of much higher density and much lower power and much lower costs than either of the bipolar technologies. Because of that cost, power and density advantage of MOS it was used in memories as well as microprocessors. Those applications had the volumes which justified higher investment. The higher investments yielded faster scaling which made MOS faster as well, higher density increased and lower costs. That was a virtuous circle that quickly caused the bipolar technologies to disappear. In the late 80s there was an attempt to use Gallium Arsenide instead of silicon as an alternative to CMOS but that went nowhere for logic and memory although it survives in optical applications. Today we just say silicon chip, everything uses a decedent of CMOS although there are lot’s of variations in each process.
I expect something similar to happen with batteries. The winner will emerge in the next few years but it will take another 10 to know which battery tech won the war.
- MemberApril 22, 2022 at 12:12 pm
Curtis, LFP batteries do sound promising, but I am curious as to their cold weather performance. Do you you know if their longevity or utility is significantly degraded (more than other battery chemistries) when operating and charging at extremely cold temperatures ( say around -30F)? Do you know if decent BMS can mitigate any potential issues?
- MemberApril 22, 2022 at 12:19 pm
LFPs are very sensitive to cold. When Tesla introduced LFPs in Europe there were a lot of reports in the Tesla forums of horrendously slow charging, Superchargers were running at L2 speeds. Tesla fixed the BMS software and this last winter Bjorn reported that the LFP Model 3s were charging faster than the NMA Model 3s.
- MemberApril 22, 2022 at 12:28 pm
Tesla had software issues with their LFP initially but it looks like it is solid now.
- MemberApril 23, 2022 at 7:56 am
Always takes a while to work out the kinks in something new. Worthwhile when done though. Admire persistence to get something right.
- MemberApril 22, 2022 at 12:34 pm
One more thing about LFPs. It’s harder for the BMS software to figure out the charge level. The voltage on NMAs and NMCs drops fairly steeply as they discharge, LFPs have a much flatter voltage level.
- MemberApril 23, 2022 at 8:05 am
If I’m not mistaken, for LFP (LiFePO4) it’s best to count Coulombs in and out rather than rely on voltage.
- MemberApril 23, 2022 at 6:16 am
As another “data point”, the regulations for the next Bridgestone World Solar Challenge were just released and the LiFePO4 “allowable cell mass” for the competitors has been reduced from 40 KG to 36 KG while it has remained constant for the other chemistries.
- MemberApril 23, 2022 at 7:54 am
Those of us that have technical skills other than solar appreciate you sharing your expertise in this area especially because we are all interested in having more knowledge of one of the main features of the Aptera. Helps us to gain a greater appreciation of the engineering going into this great vehicle.
- MemberApril 23, 2022 at 8:08 am
I really enjoy sharing it!
- MemberApril 29, 2022 at 7:49 am
Let me start by saying I love lifepo4 batteries. I have a 12KW 24V SOK system in my motor home.
But here’s why it’s not the best solution for a car. You can not charge a Lithium Iron phosphate battery below freezing. If you live in sunny California that’s great. I live in not so sunny Minnesota where the air hurts for 4 months out of the year and 7 months of the year you can dip below the magic 32F.
Putting a charge to a lifepo4 battery below 32F will destroy the battery almost immediately. Buying a lifep04 batter without a BMS that has cold temp cutoff… well that up to you and where you live.
You could put a circuit to self warm the battery but it’s capacity has already been reduced by the cold. The good thing is that you can pull power from them when they are below freezing.
I remove the cables from the battery pack after taking the charge down to 75%. I’m on year 3 of this pack…. Like I say I love the freedom it gives.
Check out sodium ion technology. It’s not mainstream yet but it checks all the boxes for me.
- This reply was modified 7 months ago by Garry Sandeen.
- MemberApril 29, 2022 at 8:05 am
Nice! How big is your 12kw 24v system? Or did you mean 12 kwh?
So what happens to NMC batteries when they’re charged under 32°F? With the cobalt it still charges ok? I’ve noticed my Kia Niro EV with an NCM pack can still pull in 18kw when the pack is under 32°F
- This reply was modified 7 months ago by Peter Jorgensen.
- MemberApril 29, 2022 at 3:51 pm
Hi Peter, I have 4 205 amp hour SOK batteries, so 13.6v x 820 amp hours = 11,152 watts . When fully charged I see 12,040 watts on the display and that’s the metric usually watch as the batteries get depleted. I charge these with 3 24V MPPT 40 amp solar charge controllers. I also have 24v 37 amp and 50 amp AC chargers. This is enough power to run my 32″ TV, media server, 24v compressor refrigerator, and furnace for a week no problem without sun. I still have to add more solar panels as the goal is 24×7 AC with a mini split. These are awesome but lifepo4 batteries have water in them and if you push the angry pixies the wrong way when it’s frozen they are toast. Maybe there new tech that allows these cells to charge when frozen but I’m guessing the BMS has a circuit to put a load on the battery to warm it up.
As far as the cells used in the Aptera pack, if the information that I have is correct the INR21700-50E cell shows a charging range of 0 – 40C. It’s up to the BMS how it charges, when it charges, and when it doesn’t charge. I wish I could see the parameters they are using. It’s not uncommon for it to be -15F in my garage in Jan. Hell it was 25F Monday
- MemberApril 29, 2022 at 2:41 pm
Great comment but, if you don’t mind, I’d like to point out to readers that the key is to not charge LiFePO4 (a.k.a. LFP) when the BATTERIES themselves are below 32 deg F (0 C). Many might interpret that they shouldn’t be charged when AMBIENT is below 32 F and that, of course, is not the case.
I found the following video to be helpful.
- MemberApril 29, 2022 at 2:52 pm
Batteries have active thermal management in modern vehicles (except the leaf). This allows temperature issues for charging to be handled (with some efficiency losses). Tesla LFP has shown this isnt really an issue (once they got the software dialed in) even for northern climates. Wider temperate tolerance for sodium batteries could be massively useful for stationary storage but isn’t really a big deal for EVs since the battery is not very far from the occupants and people generally like similar temperatures.
- MemberAugust 27, 2022 at 11:21 am
Full US made-sourced Kore Power’s iM3NY battery; LFP with 2.8% degradation after 2600 FAST CHARGE cycles! We will see incredible advances soon/now, …available, hopefully helped along by Biden’s IRA incentives.