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New EarthX Batteries STC's for 150+ 12V Aircraft!

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Joined
Jan 7, 2026
Posts
7
EarthX Lithium batteries received FAA STC approvals for 150+ 12V Aircraft!

The following 12V models were approved:

Alon A-2, A-2A

Bellanca 14-19, 14-19-2, 14-19-3, 14-19-3A, 17-30, 17-31, 17-31TC, 17-30A, 17-31A, 17-31ATC

Cessna 150D, 150E, 150F, 150G, 150H, 150J, 150K, A150K, 150L, A150L, 150M, A150M, 170, 170A, 170B,190, (LC-126A, B, C) 195, 195A, 195B, 206, U206, P206, U206A, P206A, TU206A, TU206B, TP206A, TP206B, U206B, P206C, P206D, TP206C, TP206D, TP206E, U-206C, U206D, U206E, U206F, TU206C, TU206D, TU206E, TU206F, U206G, TU206G, 210, 210A, 210B, 210C, 210D, 210-5 (205), 210-5A (205A), 210E, 210F, T210F, 210G, T210G, T210H, 210H, 210J, T210J, 210K, T210K

Ercoupe 415-C, 415-CD, 415-D, E, G

Extra Flugzeugproduktions EA 300, EA 300/S, EA 300/L, EA 300/200, EA 300/LC

Extra Aerobatic EXTRA NG

Forney F-1, F-1A

Gamebird GB1

Maule Bee Dee M-4, M-4, M-4C, M-4S, M-4T, M-4-180C, M-4-180S, M-4-180T, M-4-210, M-4-210C, M-4-210S, M-4-210T, M-4-220, M-4-220C, M-4-220S, M-4-220T, M-5-180C, M-5-200, M-5-210C, M-5-210TC, M-5-220C, M-5-235C, M-6-180, M-6-235, M-7-235, MX-7-235, MX-7-180, MXT-7-180, M-8-235, MX-7-160, MXT-7-160, MX-7-180A, MXT-7-180A, MX-7-180B, M-7-235B, M-7-235A, M-7-235C, MX-7-180C, M-7-260, M-7-260C, MX-7-160C, MX-7-180AC, M-4-180V, M-9-235

Mooney M10

Piper J3C-40, J3C-50, J3C-50S, J3C-65, J3C-65S, PA-11, PA-11S, PA-16, PA-16S

Stinson 108, 108-1, 108-2, 108-3, 108-5

Taylorcraft 15A, 19, 20, F19, F21, F21A, F21B, F22, F22A, F22B, F22C
 
That's a list of aircraft but does not seem to indicate which batteries were approved.
 
To find more go to - List of Approved STC's

then click on the aircraft, then follow a link from the right side, which may require scrolling back to the top.

It appears the only CubCrafters aircraft with STC approval is the CC-19.
 
In total, EarthX has over 350 airframes now with STC's for the 12V charging systems and we are awaiting on a large submittal for 24V charging systems and we are hopeful for this approval in the next month or so. We are trying hard not to make this an "advertisement" but instead, just inform all of you that we have this now if it is of interest to you. :)
 
@earthxbatteries welcome to the forum, great to have you join us. Are you going to continue to produce the ETX-104? If so, would you consider a modification to the BMS to limit the charge rate from 15A to under 10A? I'm sure you've seen our discussion on using this battery as a drop in replacement for a 12V AGM ignition backup battery solution as discussed, it's a 10A circuit which has been some cause for concern. Not sure if maybe releasing an ETX-104 v2 would be an option with the above change.
 
Hi Neal and thank you for the question. We are still offering the ETX104, which is a 4Ah backup battery. The max charge rate it is designed to accept is 15A so a 10A charge rate is no problem.

We have recently released a competing product to the TCW IBBS back up battery, it is an 8Ah battery, and the max charge rate for this battery is 4A: EBBS PAGE
 
We are still offering the ETX104, which is a 4Ah backup battery. The max charge rate it is designed to accept is 15A so a 10A charge rate is no problem.
Thank you for the reply. The problem is that we need to make sure the BMS does not allow over 10A. We don't have any control over the current from the alternator, for example. If the ETX-104 can take a 15A charge, that exceeds our circuit fused and breakered at 10A. So what I'm asking for is a version of the ETX-104 that will in no circumstance ask for or allow over 10A.

I'm aware of your other solution (EBBS) but it's not a drop in replacement for a 12V battery like CubCrafters uses for the ignition backup in the FX-3. The EBBS is more along the line of the TCW IBBS which requires a different wiring installation. The ETX-104 is a great drop in replacement for the PowerSonic P1221S 12V AGM CubCrafters is using with the only downside as mentioned being the charge rate of the BMS exceeds the 10A circuit in place. This size battery (4 AH) really shouldn't need more than a 5A charge rate in my opinion.

Hope that makes a little more sense.
 
No. The wire size used is not rated for it.

I’m curious though how the max charge rate is paired to a battery. It seems 15A is a bit high for only a 4 AH capacity.

If you would consider a revised design I’d buy and I’m sure others would too. We need to remain within the 10A limit. Just seems 15A max charge rate is excessive for a small 4AH battery. I think your 8 AH EBBS is 2.5A max charge rate.
 
but
wouldn't it be an easy fix to change your fuse to a 15 amp fuse?
No. The circuit includes a Schottky blocking diode rated at 9 A and wiring rated for no more than 10. Accepting 15 A maximum charge current would require significant alteration to the aircraft system. If this battery is to be used there must be a current limiter.

I agree with Neal that 5 A is more than sufficient and would not require any change to the aircraft. I have never seen the instrumented AGM battery in my aircraft take more that 2 A.
 
Thanks for considering the feedback.

I would seriously consider replacing the existing 2 AH AGM with an ETX104 if I was sure it could not take more than 5 A charge current following an almost complete discharge and with charging voltage of 14.3 V.
 
We have recently released a competing product to the TCW IBBS back up battery, it is an 8Ah battery, and the max charge rate for this battery is 4A: EBBS PAGE
@earthxbatteries - I have been looking into replacing the default, somewhat complex backup architecture for the critical systems with a simpler one based on the EBBS (Neal has been working on a more "drop-in" update of the existing 2 Ah AGM battery with the ETX-104). However, the documented current limits of the EBBS (3 A per output pin, 8 A continuous, 12 A <30 seconds) appear to make this hard.

A Carbon Cub EX-3 with the default "IFR" panel (Garmin G3X Touch-based) and dual electronic ignition has about 12 essential IFR items, with some, such as the VHF transmitters, having peak currents of 7.5 A, as documented. So it appears that I need to attach 3 A fuses to each of the 5 output pins, then connect them all to a common critical systems bus so that all loads can be distributed across all output pins. I am in the process of measuring the actual current draw to confirm the book numbers to see if it is possible with just a single EBBS.

Is there someone at EarthX I can talk to who is familiar with the EBBS?
 
In total, EarthX has over 350 airframes now with STC's for the 12V charging systems and we are awaiting on a large submittal for 24V charging systems and we are hopeful for this approval in the next month or so. We are trying hard not to make this an "advertisement" but instead, just inform all of you that we have this now if it is of interest to you. :)
Regarding 12 V "charging" systems, I have been trying to understand the charging behavior of the ETX-900 battery. As I recall, the "classic" Lithium charge has 2 phases: a first constant-current phase, followed by a constant-voltage phase that requires a specific "charger" to implement. However, when an ETX series battery directly replaces an older design battery, there is no current limiting between the alternator/generator and the battery (only a fuse and/or breaker).

For example, in the Carbon Cub EX-3 that I have, there is a 50 A breaker connecting the 40 A alternator to the main bus and a 40 A fuse connecting the ETX-900 battery to the main bus. Since the ETX-900's specified maximum charging current is 80 A, it would appear that we should be experiencing blown fuses and breakers. Is this just because I have never discharged the ETX-900 significantly? Or is there some charge current limiting implemented in the EarthX ETX BMS?
 
Sorry for the novice question but I am new to all this. Is there a EarthX battery that can be used currently in a FX3?
The Carbon Cub EX-3/FX-3 currently includes an option to use the EarthX ETX-900. If you do not use a belly pod, then the vented version can be used (ETX-900VNT); otherwise, the unvented ETX-900 is used. Some people are using the ETX-680, but the factory is using the ETX-900, which, in my personal experience, works really well once you have the matching external charger / DC power supply.
 
Sorry for the novice question but I am new to all this. Is there a EarthX battery that can be used currently in a FX3?


You can use any battery you like in the FX-3. The aircraft is experimental and no approval from anyone is required.

After bad experience with the CubCrafters supplied SBS J16, and also with a new replacement of the same type, I fitted an ETX680C. It has been in service for a year and I'm happy with it so far.
 
Regarding 12 V "charging" systems, I have been trying to understand the charging behavior of the ETX-900 battery. As I recall, the "classic" Lithium charge has 2 phases: a first constant-current phase, followed by a constant-voltage phase that requires a specific "charger" to implement. However, when an ETX series battery directly replaces an older design battery, there is no current limiting between the alternator/generator and the battery (only a fuse and/or breaker).

For example, in the Carbon Cub EX-3 that I have, there is a 50 A breaker connecting the 40 A alternator to the main bus and a 40 A fuse connecting the ETX-900 battery to the main bus. Since the ETX-900's specified maximum charging current is 80 A, it would appear that we should be experiencing blown fuses and breakers. Is this just because I have never discharged the ETX-900 significantly? Or is there some charge current limiting implemented in the EarthX ETX BMS?
Thanks for the question and you are always welcome to call our tech support line at 970.674.8884 for more detailed answers.

There are many types of lithium batteries, different battery management systems, and different manufacturers/brands so I will only speak to the EarthX brand that is a lithium iron phosphate chemistry. We do not require a specific charger, but we do specify to not use a desulphating charger as this is a charger designed to output high voltage to a lead acid battery that has sulphated. A lithium battery does not sulfate so this type of charger should not be used. More details on battery charging found here: How to Charge an EarthX Lithium Battery

The rating on the ETX900 of 80 amps is provided so that someone who has a 120 amp alternator would not use this battery but instead choose the ETX1200 that is designed for this type of higher current. If you have a 40 amp alternator, this is well below the 80 amps so it is no issue whatsoever for the battery. This rating is for the battery, its design, and the limitation so you get the longest possible life and performance from it.

Your alternator is designed to put out 40 amps. You have a 50 amp fuse to protect the alternator if it is outputting more than it is spec'd to do. The battery is the recipient of the charging system. Our rating of 80 amps is to say the battery is designed to handle this amount of current. Less is fine, more is not. If it is more, you will shorten the life of the battery.

Hope this helps explain things.
 
You can use any battery you like in the FX-3. The aircraft is experimental and no approval from anyone is required.

After bad experience with the CubCrafters supplied SBS J16, and also with a new replacement of the same type, I fitted an ETX680C. It has been in service for a year and I'm happy with it so far.
I guess I am still confused about the discussion above as it related the 10A limit for charging? Can someone explain what that means in relation to using an EarthX in a Carbon Cub. Is it related to a particular carbon cub model or EarthX battery? Any issues with the battery tripping breakers ?
 
I guess I am still confused about the discussion above as it related the 10A limit for charging? Can someone explain what that means in relation to using an EarthX in a Carbon Cub. Is it related to a particular carbon cub model or EarthX battery? Any issues with the battery tripping breakers ?
This is related to my MOD replacing the POS PowerSonic AGM battery used for the backup ignition with an EarthX ETX-104 in this thread as a result of the EX-3 N40DT accident discussion thread that inspired this change.
 
Is it related to a particular carbon cub model or EarthX battery? Any issues with the battery tripping breakers ?

You need to distinguish between the MAIN/STARTER battery and the IGNITION BACKUP battery.

The standard FX-3 uses a 2 AH AGM SLA battery for ignition backup. The standard FX-3 has been fitted with a variety of MAIN/STARTER batteries. At one time the SBS J16 battery was an extra cost option. It later became standard fit and, even later, an EarthX option was offered.

To the best of my knowledge CubCrafers has never offered any alternative to the 2 AH AGM ignition battery. That battery has been discussed many times in different groups with several posters having doubts as to its suitability for intended function.
 

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