The issues surrounding lithium batteries.

[skippydiesel]

14 hours ago, BurnieM said:

Are Lithium batteries actually an advantage in aircraft ?

Their lighter weight is often a negative for COG.

 

Why go with them ?

 

Can only speculate -

 

Weight is the enemy of all aircraft, so any weight reduction is attractive. Reduced weight generally = better performance in almost all parameters.

 

As for "...negative for COG...." If your aircraft has been designed/configured such that the battery (weight) location is critical to Cof G there will need to be adjustments made, if you change that weight/location. In most instance this is not an insurmountably problem. In a few, the solution would seem to be using ballast - not a great idea a this negates, to some extent, the advantage of weight reduction, inherent in the Lithium battery ie may as well just stick with the original lead acid battery.

 

Then there is performance & service life in a small lightweight package - My Earth X  ETX 900  has the following specifications:

 

Voltage: 13.2
Weight: 2.4kg
Cold Cranking Amps (CCA): 390
Peak Cranking Amps (PCA): 800
Amp Hour (1C Rate): 15.6
Dimensions: 166mm L x 76mm W x 168mm H

Holds charge when not in use, much better than AGM

Service Life: 4,000 charge cycles - up to 8 years

 

The Earth X is expensive, 2-3 times the price of a good quality AGM motorcycle battery, that will do the same job, at higher weight and volume.

 

Lead acid batteries are not without their risks - I have had a battery explode and recently my Son had his trucks 24V (2 X 12V) dangerously overheat (suspected plate collapse/internal short, due to a lot of rough road travel) to the point of thermal runaway - could have been very nasty!

 

😈

[Kyle Communications]

The biggest problem with using Lithium batteries in a aircraft especially with a Rotax is the regulator that is supplied is NOT designed for Lithium charging.

If you have a reg designed to do this then this is the first layer of protection you have. The second layer is the BMS inside the battery but there are many many cases that the BMS fails to take the grubby signal from a old style regulator. This is why they then catch fire. Its not a rare occurance either

If you have a regulator that can supply the BMS in the battery with a set of paramters that can do both Lithium and lead acid then thats a good ...or better safeguard.

 

 

[skippydiesel]

1 hour ago, Kyle Communications said:

The biggest problem with using Lithium batteries in a aircraft especially with a Rotax is the regulator that is supplied is NOT designed for Lithium charging.

If you have a reg designed to do this then this is the first layer of protection you have. The second layer is the BMS inside the battery but there are many many cases that the BMS fails to take the grubby signal from a old style regulator. This is why they then catch fire. Its not a rare occurance either

If you have a regulator that can supply the BMS in the battery with a set of paramters that can do both Lithium and lead acid then thats a good ...or better safeguard.

 

 

I have replaced my Ducati/Rotax VR, with a CARMO CARR 5115 MOSFIT -  compatible with my Earth X ??

 

😈

Edited September 13 by skippydiesel

[Kyle Communications]

Roger my guru mate has tested the Carmo a lot compared to the original and said that it is by far better to use than the genuine Rotax ones for charging Lithium batteries. It actually puts a short on the alternator windings when its up to voltage. This doesnt hurt or cause excess current or heat in the windings.

Roger has used my CDI setup to do the testing on them and now has made up a unit to test all types of regs even the 3 phase ones used on the newer rotax engines.

So if you are replacing your reg use the Carmo one its by far better than the original one

 

 

 

 

[RFguy]

On 10/09/2026 at 7:46 PM, Moneybox said:

I bought sodium ion last time. They were lighter than lithium for a higher CCA but low AH rating. For a start battery I need the CCA to spin a cold engine over rapidly but usually for just a few seconds. Sodium ion is perfect for that and the chemical composition says it’s not going to burst into flames ever.

Moneybox, how did you get the Sodium Ion compatible with the charging and discharge system ?

sodium ion are WILDLY different in min and max voltage.... ?

If you have like 4 cells in series , the effective useful capacity would be about 20% of the label .

 

 

[Moneybox]

2 hours ago, RFguy said:

Moneybox, how did you get the Sodium Ion compatible with the charging and discharge system ?

sodium ion are WILDLY different in min and max voltage.... ?

If you have like 4 cells in series , the effective useful capacity would be about 20% of the label .

 

 

I fitted a brand new 80A 24V alternator and connected the two 12V batteries in series as the lead-acid batteries were. The maximum charge shows as 28.2V so the Sodium ion batteries will never reach maximum charge however these batteries are not voltage sensitive when it comes to keeping them healthy. They don't have to ever reach 30V and they can be safely drawn down to Zero voltage without long term negative results.

 

I also swapped the Sherpa Big Air 200LPM air compressor from the lithium house batteries to the sodium start batteries. If the lithium batteries were a little low their BMS would often spit the dummy on startup.

 

I'm no expert, just going on what I've read. So far they are performing well but they don't work hard. The Isuzu 4.8L Turbo diesel starts instantly when the key is turned so no cranking beyond a second or two, hot or cold.

[RFguy]

good explanation

Most battery BMS's are designed by people with little experience. It is seen as a "simple product" when the reality is, there is devil in the practical use detail. 
I avoid them unless they're simple shunt cell devices.

 

How many Sodium Ions did you use in series ?

 

FYI others- sodium ion vary between about 2V and 4V. There's a fairly linear ramp between those two voltages

Where as Lithium Iron Phosphate (LIFEPO4)  the useful range is about 2.8 to 3.35 (peak at charge termination of 3.65) . 

 

[Moneybox]

12 hours ago, RFguy said:

good explanation

Most battery BMS's are designed by people with little experience. It is seen as a "simple product" when the reality is, there is devil in the practical use detail. 
I avoid them unless they're simple shunt cell devices.

 

How many Sodium Ions did you use in series ?

 

FYI others- sodium ion vary between about 2V and 4V. There's a fairly linear ramp between those two voltages

Where as Lithium Iron Phosphate (LIFEPO4)  the useful range is about 2.8 to 3.35 (peak at charge termination of 3.65) . 

 

I only replaced the two original lead acid start batteries. 

 

 

 

The lead acid batteries are very good as a start battery but this one change saved me 25kg. If the Sodium ion batteries last as long as advertised then there's more than just a significant weight saving.

[RFguy]

Yeah, it bring up an interesting argument for them (Sodium Ion batteries) - (moneybox where did you buy those packaged cells - (I use cylindrical individuals) ?) 

(I am using them where safety is important in another application )

that  they have high surge current  (for these purposes 'cold cranking current"

and  the voltages from the cells are mismatched form the system in terms of acheiving optimal use of the capacity.

 

But if you are happy to forgo the capacity, then they do what you need - start the airplane and dont weigh much

The usual caveats apply for weight and balance of course.

In the small jabiru, J160, J170, that weight up the front is important for safe CG operation and to meet the specifications for the design of the airplane  (important - you can't just ignore this sh1t) 

in the J230, which are generally nose heavy the way they are loaded when not much in them, the lower nose weight  might be some advantage in most weight configurations. But you would need to make an ammendment to the AFM/POH data  (and be competent to do so) 

 

 

 

 

[Moneybox]

3 hours ago, RFguy said:

Yeah, it bring up an interesting argument for them (Sodium Ion batteries) - (moneybox where did you buy those packaged cells - (I use cylindrical individuals) ?) 

(I am using them where safety is important in another application )

that  they have high surge current  (for these purposes 'cold cranking current"

and  the voltages from the cells are mismatched form the system in terms of acheiving optimal use of the capacity.

 

But if you are happy to forgo the capacity, then they do what you need - start the airplane and dont weigh much

The usual caveats apply for weight and balance of course.

In the small jabiru, J160, J170, that weight up the front is important for safe CG operation and to meet the specifications for the design of the airplane  (important - you can't just ignore this sh1t) 

in the J230, which are generally nose heavy the way they are loaded when not much in them, the lower nose weight  might be some advantage in most weight configurations. But you would need to make an ammendment to the AFM/POH data  (and be competent to do so) 

 

 

 

 

https://energystore.au/collections/aeson?srsltid=AfmBOooTLc3NDQ_1kHXnMWK_hFpJT8eqmSpDyYjPw4jqIVhIidybl5SF

 

I have no idea what's inside. These batteries are designed as a Stop-Start battery for those modern vehicles that shut down and restart when driving in the city.

 

Key Features of AESON Sodium-Ion Start Batteries

• High Cycle Life: Delivers up to 120,000 to 180,000 start-stop cycles, vastly outperforming standard lead-acid alternatives. [1, 2, 3]

• Extreme Temperature Tolerance: Operates reliably across wide and harsh temperature ranges without losing functional cranking efficiency. [1, 2]

• High CCA (Cold Cranking Amps): Provides instant, high-power starting capabilities for modern and high-performance vehicles (such as the AESON NaForce SS H7/LN4 AGM 12V with 800 CCA). [1, 2]

• Safety: Inherently stable chemistry with no risk of thermal runaway, making them robust and secure under heavy vehicle vibration and use

 

All these features were important to me.

Edited September 15 by Moneybox

[skippydiesel]

All good information.

 

I apologise if already stated;

What are the relative dimensions & cost of the Sodium-Ion compared with an equivalent CCA battery:

• Earth X  ETX 900 ?
• AGM motorcycle battery ?

😈

 

 

[Moneybox]

2 hours ago, skippydiesel said:

All good information.

 

I apologise if already stated;

What are the relative dimensions & cost of the Sodium-Ion compared with an equivalent CCA battery:

• Earth X  ETX 900 ?
• AGM motorcycle battery ?

😈

 

 

https://www.aerolithium.com/batteries 

 

 

SODIUM  AIRCRAFT  BATTERIES ! !
WHY SODIUM ?
1. predictable voltage curve   2. No BMS failure points  3. Simple, not complex like lithium  4. Wider temperature operating range, cold temp resilience. 5 .Ah capacity very similar to lithium. 6. Cranking power similar to lithium.
7. Reliability on par or > lead or lithium   8. No ' fault ' lite needed    9. Less expensive than lithium   10. Won't cut itself off from the electrical system  11. Cannot be overcharged or over discharged vs lithium
12. Slightly heavier than lithium to aid in weight and balance
13. Imitates lithium's charging voltage and lead acid's  natural charging current limit so, easier on your alternator      14. Life span 8+ years   15. About 85% the cost of similar lithium

Edited September 15 by Moneybox

[skippydiesel]

No mention of dimensions - smaller - same - larger than the equivalent CCA battery ??

 

Item 12. - ".....aid in weight and balance"  Odd statement. 

 

The suggestion is, by dint of it's particular characteristic (Sodium), this battery participates in W&B of an Aircraft.

 

(Just having fun no offence intended)

 

😈

 

 

 

[skippydiesel]

Moving Earth X discussion to this Thread:

 

 In most if not all Rotax 9xx engine installations the alternator can not be turned off while the engine is running. Smoke in the cockpit from a bad connectionlike you almost had, tuff.

 

Does your earth x battery have the "fire vent tube" fitted to vent nasties overboard? 

 

"alternator can not be turned off" -  I think you are literally correct, however the Gen switch can be, which will go some way in isolating an electrical fire.

"fire vent tube" - In short no. Speculation - My battery ;

• is non TSO'd so does not feature this enhansement.
• predates the availability of the firetube.

Update on loss of electrical supply in flight -

 

Replaced overheated spade connectors. Same again but with (Narva) spring loaded female side, in the hope of a more secure connection;

 

 1.2 hr test flight saw voltage rise to 14.2  and amps go down to 1. All good! 😈

 

[Thruster88]

These knife connectors provide a more reliable connection for high current use in aircraft. They each have male and female parts. 

[facthunter]

I wouldn't consider spade connections up to it in high current situations.  Better to be sure, than sorry. Nev

[facthunter]

You should avoid having many connections in the wires themselves You can go to a Bus box with Proper terminals with screws. In flight fire is about the worst thing possible . Nev

[Moneybox]

57 minutes ago, Thruster88 said:

These knife connectors provide a more reliable connection for high current use in aircraft. They each have male and female parts. 

I can't say I've ever seen them. How do you insulate them?

[facthunter]

Heat shrink or better. Nev

[skippydiesel]

1 hour ago, Thruster88 said:

These knife connectors provide a more reliable connection for high current use in aircraft. They each have male and female parts. 

Thanks Thruster.

 

Will have to be next time - Job Done! & working as expected.

 

I am also echoing  Moneyboxe's question - Never seen this sort before ( source?)

 

What about Bullet connectors? (which I have never liked).

 

Aircraft Spruce (possibly the only supplier in stock);

Red Knife Disconnect	22-16	32446	$1.13	Quantity
Blue Knife Disconnect	16-14	32448	$4.79	Quantity
Yellow Knife Disconnect	12-10	35762	$3.69

 

 

 

😈

 

 

 

[facthunter]

It's common to use 'Cannon Plug's in Planes and spaceships. They can also give trouble depending on the Quality.  Nev

[Moneybox]

2 hours ago, facthunter said:

Heat shrink or better. Nev

If you are going to heat-shrink them, why not a soldered join?  Or crimp if you prefer.

[facthunter]

I prefer no joins at all outside of the Bus Bar concept. Your problem with insulating the section exposed with the Join had be covered by a pliable piece of rubber tube.. Nev. 

[Kyle Communications]

I use all Deutsch connectors for all connections where possible in my aircraft. Proven for good connections in earthmoving equipment and high end machinery. I first came across them more than 2 decades ago when I started doing all of Hastings Deering (Catepillar) work for radio and electronic equipment. The standard was Deutsch. I have been using them ever since. You cant beat them

 

[Moneybox]

18 minutes ago, Kyle Communications said:

I use all Deutsch connectors for all connections where possible in my aircraft. Proven for good connections in earthmoving equipment and high end machinery. I first came across them more than 2 decades ago when I started doing all of Hastings Deering (Catepillar) work for radio and electronic equipment. The standard was Deutsch. I have been using them ever since. You cant beat them

 

They are good terminals and sealed plugs but you have to buy the correct tools to crimp them properly. I have a couple of their big grey assortment boxes somewhere but I no longer have the tools to work them.