ch.ess wrote:
Unlike the Gill / Concord swap, I guess this change is difficult without STC…
I suspect it will always need an STC due to the requirement for monitoring and connection to some sort of indicator in the panel. It’s not just a straight swap like most of the Gill/Concorde batteries are.
The Aviation Consumer mentions the sodium-ion battery as being the likely next step, very similar to lithium batteries in terms of weight and performance but without some of the disadvantages. There is a lot of focus on battery research and development these days, mostly for cars. Time will tell how fast that moves forward. Aviation usually has some sort of knock on benefit, but with a 5-10 year delay.
The main thing with using sodium instead of lithium is that sodium is extremely abundant. However, you won’t ever get as much energy density out of a sodium ion battery compared to a lithium ion battery. But for starter batteries this isn’t quite as important as it’ll still be smaller than a lead acid battery, and will likely have many other attributes that makes it better than lead acid.
chflyer wrote:
I suspect it will always need an STC due to the requirement for monitoring and connection to some sort of indicator in the panel. It’s not just a straight swap like most of the Gill/Concorde batteries are.
Not necessarily. When it comes to fire hazard, lithium-iron phosphate batteries aren’t any worse than lead-acid ones, here is a good video about it:
In addition, they don’t contain corrosive acid like lead-acid ones, and are 5-10 times more durable (in terms of charge-discharge cycles) than lead-acid. They can also be engineered as straight swaps for lead-acid batteries.
Ultranomad wrote:
Not necessarily. When it comes to fire hazard, lithium-iron phosphate batteries aren’t any worse than lead-acid ones, here is a good video about it:
As far as I understand the EarthX documentation, the monitoring element is required as part of the TSO approval. Perhaps I’m wrong. So the danger isn’t the reason an STC is needed, but rather installation needing a monitor capability in the cockpit (either status/condition light(s) or display on an EFIS). But an increasing amount of stuff is installable as a minor change with or without NORSEE (in the US). I have no idea what EASA’s approach would be to it. In any case, experimentals can certainly go ahead which is why Airteam.eu has it on their site. The price is about the same as a similar spec Concorde battery from Airpart Supply UK. With the much reduced weight and increased starting power, I would think it to be an almost no-brainer whenever it can be legally installed. Their web site shows a long list of additional STC AML additions expected in Q4 2023, especially for 24V needs…. but we all know how these plans can slip.
To be honest I would just be happy to put an odyssey battery in my pa28.
If only I new a way to convince the maintenance organisation that I use.
:“In addition, they don’t contain corrosive acid like lead-acid ones,”
How much acid is in a sealed lead-acid battery?
I would like a lighter battery because instead of carrying a 20kg toolbox I could carry a 30kg toolbox 
Only slightly kidding – on a TB20, battery in the back, that would translate directy into something useful. I just don’t think we are there yet in terms of reliability of the technology. Lithium batteries have a different cell voltage to lead acid and cannot be charged using the constant-voltage method used in conventional vehicles for the last 100 years; the best one can do is have electronics in the battery which emulate a “12V” or “24V” lead acid.
And this simply must be very reliable because if it fails, the primitive alternator / regulator system is going to go unstable with likely damage to avionics. There are regulators which don’t need a battery connected but AFAIK the GAMI Supplenator (does it actually exist??) is the only example.
Peter wrote:
Lithium batteries have a different cell voltage to lead acid and cannot be charged using the constant-voltage method used in conventional vehicles for the last 100 years
LiFePO4 batteries are much closer to lead-acid in their behaviour than Li-ion. They will tolerate constant-voltage charging if you don’t pump too much current into a deeply discharged battery. They also have a convenient voltage of 3.2 V per fully charged cell
But AFAIK nobody is making LiFePO4 standard size batteries, or are they?
