What makes you say they’re the same chemistry? If these are indeed semi-solid, then I think we can conclusively say the chemistry is not the same as a Li-po. (I have noted that their marketing literature refers to “solid-state”, which AFAIK makes no sense when it comes to batteries. I attribute this to translation issues.)
Semi-solid lithium batteries are already being mass produced so it wouldn’t surprise me to learn that Foxtech managed to get a few cells for the drone market. I do not have one of these batteries, so can’t drive a nail through it to test. Right now, I’m giving them the benefit of the doubt, coming from a combination of sales literature, cell test documentation, and prior experience with Foxtech.
My understanding is that solid state batteries are still several years away from commercialization and general availability. Hence my skepticism. Toyota and others might have a prototypes in EVs this year or next.
If the foxtech cells are indeed solid state then that would explain the cost and their marketing claims. Availability seems to be a question. Crossing fingers the price can be reduced. The future looks good for electric transportation.
My guess is that they are just plain old LiPo graphene batteries. Many companies that make graphene batteries like to call them diamond batteries. I don´t understand why they do this as graphene is quite different from diamond, but they do.
If this is the case Foxtech batteries are not truly solid state, and even if they where I still am not seeing many performance advantages over Bonkas like you would expect for paying twice the money.
I was under the impression that graphene batteries usually were for high power density. These Foxtech Diamond batteries are quite low power density, all things considered.
I’d definitely pay 2x to get batteries which can be accidentally abused without risk of fire-- esp. because that might allow eliminating the BMS, thus further reducing complexity, weight, fire hazard, and price.
But if they’re just graphene batteries with a mixed-message marketing campaign, I’m don’t see the advantage. A 10% energy density bump over the Bonka, but at the cost a several X decrease in power density, seems like it should cost less not more.
Interesting. I don´t know how I missed it for this long, but the foxtech batteries we are talking about are actually li-ion pouch cell batteries which is where the safety and improved cycle life is coming from. They won´t have the safety of an 18650 or 21700 li-ion, but it will be better than a lipo. I still am confused as why they claim their batteries are solid state as they can´t be, but they might actually be onto something.
I don´t get why everyone thinks that li-ion batteries need a BMS. The li-ion battery works just like lipos with the same peak voltage, identical nominal voltage(assuming you discharge to the same level), but they can handle going down to 2.5-2.75v depending on the cell without being damaged and all the way down to 0v without being a fire hazzard. The only reason most li-ion batteries have a BMS is that it is just as easy to wire up one as it is to wire up a balance harness, but the BMS adds an additinal level of safety, helps the battery last longer, and removes the need to use a more expensive and slower balance charger. I also disagree that the BMS increases the risk of a fire. I believe for every fire a BMS caused it has prevented well over a hundred.
If you really want to know more I would recommend talking with Mr. Bratwurst. He has been making custom paramotor li-ion batteries for about as long as I have known paramotors existed and he is very focused on making all of his e-ppgs as safe as possible.
I might have to go back to battery school, but I thought li-po was just li-on chemistry in a plastic bag (as opposed to a steel can) and that plastic bag is called the pouch. Which would imply that the Diamond is both a li-on and a li-po.
I’m no battery expert so if I got that wrong, point me in the right direction and I’ll educate myself.
I think we’ll have to disagree to agree here.
We’re on the same page that BMS have (likely) prevented orders of magnitude more damage than they have caused. My point is that they still can cause damage-- faulty solder connections, faulty components, abrupt shut-off of current at high power causing an ESC explosion, etc…-- and so they are a risk factor. If we had as-of-yet-imaginary batteries which did not need a BMS to stay safe from fire, then the BMS adds fire risk.
Personally, I see BMSes as one of the biggest risks in the powerchain. There is no clear consensus on whether you need one, and even if you agree you need one there are a myriad of application toplogies. And even if you agree on the topology, there are sound arguments that balancing should happen on the discharged side or on the charged side.
The end result is that we’re splicing in high-energy components without really understanding what problems we’re solving. The solution is to throw tons of money at the BMS so that it has extremely high reliability and never, ever, ever incorrectly shuts down while we’re on takeoff. But no one wants to spend $1k on a BMS which has unclear value, so there’s a ton of crap on the market and the only way to disambiguate is word of mouth.
They are not quite the same. Its like saying a square is a rectangle. A lipo battery is a type of li-ion battery, but a li-ion battery doesn´t mean its a lipo battery. A LiPo/ lithium polymer battery is more correctly a li-ion polymer battery. The difference is that they replace the liquid electrolyte in the cell with a polymer. This allows for much lower internal resistance and very high discharge rates, But it limits the cells to being flat, decreases safety, decreases cycle life, and increases the cutoff voltage which then limits capacity.
There are flat li-ion cells. They are very common in dji drones and I believe that most electric car manufactures (Tesla not included) use flat li-ion cells.
This is probably where we see things different. The BMS has a fairly clear job which is to ensure that the battery operates within specific parameters deemed safe. For example, the battery gets too hot and it shuts it off. One of the series in the battery gets overcharged, so it restively drains off some of the power. It also prevents overcharge, over-discharge, overcurrent, and more. The biggest problem with the BMS is that most people don´t put the parameters correctly which can cause a lot of problems. The other problem is that when the BMS detects problems it shuts down the battery. This is being solved by programming parameters into the esc that will limit power such so you have lots of warning to help prevent you from completely loosing power.
Okay, so I think I’m getting it. Lemme know if the following understanding is correct:
LiPo and Li-ion can be the same thing from a cathode/anode chemistry perspective, and thus LiPo/Li-ion batteries which share the same chemistry inherit the same chemistry properties.
So a LiFePO4 in a pouch is similarly resistant to exposure to O2 as LiFePO4 in an 18650 can.
However, the electrolyte is different because a LiPo uses a gel and a Li-ion uses a liquid.
The gel electrolyte is inherently more dangerous than the liquid electrolyte. (Why, though?)
Previously, in order to use a liquid electrolyte, you had to place the battery in a metal can.
As an aside, the metal can further enhanced safety, by increasing puncture resistance.
The FoxTech batteries use a liquid electrolyte, but in a pouch construction.
This is a novel development, as per the prior point.
Therefore, the FoxTech batteries are safer because the electrolyte is safer, not because their cathode/anode chemistry is a more stable chemistry.
While the FoxTech batteries are not in a can, they encase them in aluminum yielding similar puncture resistance.
Is that about right?
I think the challenge is to define “safe”, since protection can mean so many things. A colleague once told me that the difference between a hobbyist and and engineer are the edge cases. And aviation has those in spades!
Case in point, a few years back an eGlider pilot doing a powered landing at a nearby airport wound up crashing into a house when the battery pack cut out. Arguably, the pack protected itself from a deep discharge, at the expense of the airplane and pilot. (Fortunately, while the plane was destroyed no one was hurt).
Not excusing the chucklehead behavior of a glider pilot who made the bad decision setting up the crash, but reportedly if the pack had not cut out and had instead allowed itself to be irreparably damaged by a 100% DoD, the plane would have landed without issue. Or maybe it would have caught on fire? Which was the “right” answer here?
In a more frequent scenario, a BMS which abruptly cuts off the power can cause an inductive spike which blows up the ESC, shooting fire and sparks. So the outcome of preventing a possible fire can be a very real fire.
I have seen great arguments all around for:
whether or not a BMS should balance batteries,
whether or not a BMS should be able to cut off a battery pack
whether or not a BMS should be monitoring per-cell voltage
In the meantime, I haven’t seen a consensus develop for battery technology. And that’s before we get into aviation, where imprudently applied technological safeguards can lead to loss of life. (737Max coughcough.)
I’d love to be wrong on this, so if you think you can point to resources which would allow me to see/understand the consensus, I’d be much appreciative.
the new molicel 45 P will still be available in 2022. We are really looking forward to it. I’ll report back as soon as I’ve done the first series of tests. you can already say that it’s a step forward, no matter whether it’s for thermal eppg or a large e-trike. everything can use the larger capacity. regards
my personal opinion: if the 45 p are in the range of euros / dollars 6 per piece without tax, that’s fine with me. you have to consider that you get more capacity on the one hand and the 2 point is because the cells have much less internal resistance, the number of cycles that is possible increases significantly with higher loads. I suspect you can fully use the pack for around 20 to 25% longer. so around 600 cycles should be possible. it’s just guesswork. but think the experience like back then with the sony (murata) VTC series there it was very similar and you only won in all areas.
Looking at the figures, the P45 is really going to shine if used in a smaller 6P configuration of the feather battery pack. It’s higher discharge rating and increased capacity under hard discharge will really get the most out of the 6P pack running in the 20A continuous range. At 20 A discharge the P45 significantly outperforms the existing P42 delivering 12.2Wh VS 10.7. That would give the feather battery a 15% range improvement or a max flight time of 35-40 min.
Im curious how much benefit would actually be seen with using this cell in a 11P configuration of the larger battery pack. If cruising at 4-6KW like most pilots seem to be, you are only pulling continuous 5-10A from each cell string, and it looks like in that range the P45 delivers 13.1 Wh vs 12.4 from the P42. Not a considerable improvement.
If climbing power was not important, and you were willing to limit your max current to 110A, or about 10KW on a full pack, and 6.5-7KW on an empty battery, would would actually be better off with the Samsung 50S cells in an 11P configuration, yielding a possible 12% improvement over the current 1hr pack.
it’s faster than expected. the cells can be delivered from around the end of july. I look forward to it. perfect for my fully faired carbon trike and the geiger hpd 16 - MGM 50063 with 160 cm 3 blade e-props + dudek boson 34 I would be happy if maybe other pilots who use the new molicel soon share their real experiences here.
Where are you seeing an expected deliver of July? Is there any interest from the community to do a group buy for a couple hundred cells ( or a thousand) ?
If I built a pack and tested it out, would there be any interest from anyone for me to build them additional packs?
in the usa it might be possible, yes. in europe you can only get cheaper prices as a company from wholesalers. but if you then resell parts of an order to private individuals, you have to add the cost recovery margin. That’s around 20 percent or more. when you order for others, you are just an intermediary dealer. therefore, in the end, the same price comes together as if you ordered directly from the large dealer as an individual end-customer. of course, friends can get together privately and order together. But that only makes sense if you live nearby. you have to split the goods up and send each one by packet, it gets complicated again because of dangerous goods and the costs in general.
It lets me simulate running a single pack, or even two packs in parallel for a hybrid battery. Currently, I have data for P42A, P45B, Foxtech Diamond Li-ion, and A123Systems LiFePo4.
It shows that the P45B-- in theory-- gives ~20% longer loiter time after takeoff for my eGlider.
If you’re familiar with Julia, I can walk you through how to set up the simulator for your use case.
I’d be interested, but it probably makes sense to split up by region (I’m in the US)
I would be happy if maybe other pilots who use the new molicel soon share their real experiences here.